Abstract-converted (1).pdf

ABSTRACT Crankshaft is large volume production component with a complex geometry in the Internal Combustion (I.C) Engine. This converts the linear (or) reciprocating motion of the piston in to a rotary motion of the crank. In this project the product is modeled in a 3d model with all available constraints by using advanced cad software like CATIA-V5. This model will be converted to Initial Graphic Exchange Specification (IGS) file format and imported to ansys workbench to perform static analysis . Finite element analysis (FEA) is performed to obtain the variation of stress at critical locations of the crank shaft using the ANSYS software.Here we compare the results and select the best sutiable material

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CHAPTER -1 INTRODUCTION A crankshaft contains two or more centrally-located coaxial cylindrical ("main") journals and one or more offset cylindrical crankpin ("rod") journals. The twoplane V8 crankshaft has five main journals and four rod journals, each spaced 90° from its neighbors.

Figure 1. 1 Main Parts Of A Crankshaft Example (2-Plane) Crankshaft The crankshaft main journals rotate in a set of supporting bearings ("main bearings"), causing the offset rod journals to rotate in a circular path around the main journal centers, the diameter of which is twice the offset of the rod journals. The diameter of that path is the engine "stroke": the distance the piston moves up and down in its cylinder. The big ends of the connecting rods ("conrods") contain bearings ("rod bearings") which ride on the offset rod journals. (For details on the operation of crankshaft bearings, For important details on the motion which the crankshaft imparts to the piston assembly. Forces Imposed On A Crankshaft The obvious source of forces applied to a crankshaft is the product of combustion chamber pressure acting on the top of the piston. High-performance, normally-aspirated Spark-ignition (SI) engines can have combustion pressures in the 100-bar neighborhood (1450 psi), while contemporary high-performance Compression-Ignition (CI) engines can see combustion pressures in excess of 200 2

bar (2900 psi). A pressure of 100 bar acting on a 4.00 inch diameter piston will produce a force of 81050 N. A pressure of 200 bar acting on a 4.00 inch diameter piston produces a force of 16202 N. That level of force exerted onto a crankshaft rod journal produces substantial bending and torsion moments and the resulting tensile, compressive and shear stresses. However, there is another major source of forces imposed on a crankshaft, namely Piston acceleration. The combined weight of the piston, ring package, wristpin, retainers, the connecting rod small end and a small amount of oil are being continuously accelerated from rest to very high velocity and back to rest twice each crankshaft revolution. Since the force it takes to accelerate an object is proportional to the weight of the object times the acceleration (as long as the mass of the object is constant), many of the significant forces exerted on those reciprocating components, as well as on the connecting rod beam and big-end, crankshaft, crankshaft, bearings, and engine block are directly related to piston acceleration. The methods for dealing with those vibratory loads are covered in a dedicated article. Combustion forces and piston acceleration are also the main source of external vibration produced by an engine. The tensional excitation contained in the engine output waveform is discussed in a separate article. These acceleration forces combine in complex ways to produce primary and secondary shaking forces as well as primary and secondary rocking moments. The combinations of forces and moments vary with the cylinder arrangement (inline, opposed, 60°V, 90°V, 120°V, etc.) and with the crankpin separation (60° / 90° / 120° / 180°, etc.). They must, to the maximum extent possible, be counteracted by the implementation of the crankshaft counterweights. Many of the common engine arrangements allow for complete balancing of primary and secondary forces and moments. Examples are inline six cylinder engines with 120° crankpin spacing and 90° V8 engines with conventional 90° crankpin spacing. Certain other engine arrangements do not allow for the complete counteracting of all the forces and moments, so there are design compromises which must be optimized. For example, an inline-four has a secondary vertical shake as 3

the result of the secondary piston acceleration forces. In road vehicles, the secondary vertical shake is often suppressed by unbalanced counterweight shafts rotating at twice crank speed. The 90° V8 engine with a single-plane crank such as is used in Formula One, IRL and Le Mans-style V8 engines produces a substantial external horizontal shaking force at twice the crankshaft frequency ("second order"). Because the secondary piston acceleration forces are parallel with the cylinder axes, in this engine design the vertical components of those forces on a given crankpin cancel each other, but the horizontal components add together. At 18,000 RPM (Formula One) the horizontal shake frequency is 600 Hz. (2 x 18000 / 60) while at 9000 RPM (IRL) the frequency is 300 Hz. The amplitude is proportional to the magnitude of the secondary piston acceleration. This shake can become a major concern for designers of the chassis (or airframe) and the bits that attach to the engine. In addition to these reciprocating forces and the resulting

moments, there is a rotating mass associated with each crankpin, which must be counteracted. The rotating mass consists of the weight of the conrod big end(s), connecting rod bearing(s), some amount of oil, and the mass of the crankshaft structure comprising the crankpin and cheeks. These rotating forces are counteracted by counterweight masses located in appropriate angular locations opposing the rod journals. The following shows a single-plane V8 crankshaft, in which the counterweights are directly opposite their associated rod journal. A fullycounterweighted inline-4 cylinder engine has a similar layout. However, the counterweights are not always directly opposite the rod journals. For example, the commonly-used production version of a two-plane 90° V8 crankshaft has no counterweights around the center main journal, as show. In that case, the Centroid of each counterweight, instead of being 180° from its respective journal, is offset (to approximately 135°) in order to place the net counterbalancing forces in the optimal location. Note also that the front and rear counterweights are larger (thicker) than the others in order to fully counterbalance the end-to-end moments. 4

Crankshaft Manufacturing Processes Many high performance crankshafts are formed by the forging process, in which a billet of suitable size is heated to the appropriate forging temperature, typically in the range of1950 - 2250°F, and then successively pounded or pressed into the desired shape by squeezing the billet between pairs of dies under very high pressure. These die sets have the concave negative form of the desired external shape. Complex shapes and / or extreme deformations often require more than one set of dies to accomplish the shaping. Originally, two-plane V8 cranks were forged in a single plane, then the number two and four main journals were reheated and twisted 90° to move crankpins number two and three into a perpendicular plane. Later developments in forging technology allowed the forging of a 2-plane "nontwist" crank directly.

Crankshafts at the upper end of the motorsport spectrum are manufactured from billet. Billet crankshafts are fully machined from a round bar ("billet") of the selected material. This method of manufacture provides extreme flexibility of design and allows rapid alterations to a design in search of optimal performance characteristics. In addition to the fully-machined surfaces, the billet process makes it much easier to locate the counterweights and journal webs exactly where the designer wants them to be. There is an old argument that a forged crank is superior to a billet crank because of the allegedly uninterrupted grain flow that can be obtained in the forging process. That might be true of some components, but with respect to crankshafts, the argument fails because of the large dislocations in the material that are necessary to move the crankpin and counterweight material from the center of the forging blank to the outer extremes of the part. The resulting grain structure in the typical V8 crank forging exhibits similar fractured grain properties to that of a machined billet. More than one crankshaft manufacturer has told me that there is no way that a forging from the commonly used steel alloy SAE-4340 (AMS-6414) would survive in one of today's Cup engines. Some years ago, there was an effort at Cosworth to 5

build a Formula One crankshaft by welding together various sections, which comprised the journals, webs and counterweights. The purported intent was to be better able to create exactly the shape and section of the various components, thereby reducing MMOI while achieving the same or better stiffness.

Figure 1. 2 Component Of Crankshaft

While no one was willing to divulge details about the effort, it is rumored to have been run once or twice then abandoned due to the high cost and complexity compared to the measurable benefits. In certain cases, there are benefits to the use of a built-up crankshaft. Because of the ‘master-rod’ mechanism necessary for the implementation of the radial piston engines that powered most aircraft until well

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into the second half of the 20th century, a bolted-together crankshaft configuration was used almost exclusively. Figure 5illustrates a typical two-row composite radial crankshaft and master-rod layout. The loose counterweights will be addressed later in this article.

Crankshaft Materials The steel alloys typically used in high strength crankshafts have been selected for what each designer perceives as the most desirable combination of properties. Medium-carbon steel alloys are composed of predominantly the element iron, and contain a small percentage of carbon (0.25% to 0.45%, described as ‘25 to 45 points’ of carbon), along with combinations of several alloying elements, the mix of which has been carefully designed in order to produce specific qualities in the target alloy, including hardenability, nitridability, surface and core hardness, ultimate tensile strength, yield strength, endurance limit (fatigue strength), ductility, impact resistance, corrosion resistance, and temper-embrittlement resistance. The alloying elements typically used in these carbon steels are manganese, chromium, molybdenum, nickel, silicon, cobalt, vanadium, and sometimes aluminum and titanium. Each of those elements adds specific properties in a given material. The carbon content is the main determinant of the ultimate strength and hardness to which such an alloy can be heat treated.

Figure 1. 3 Crank Shaft Material Alloying Elements

In addition to alloying elements, high strength steels are carefully refined so as to remove as many of the undesirable impurities as possible (sulfur, phosphorous, 7

calcium, etc.) and to more tightly constrain the tolerances, which define the allowable variations in the percentage of alloying elements. The highest quality steels are usually specified and ordered by reference to their AMS number (Aircraft Material Specification). These specs tightly constrain the chemistry, and the required purity can often only be achieved by melting in a vacuum, then re-melting in a vacuum to further refine the metal. Typical vacuum-processing methods are VIM and VAR. Vacuum Induction Melting (VIM) is a process for producing very high purity steels by melting the materials by induction heating inside a highvacuum chamber. Vacuum Arc Remelting (VAR) is a refining process in which steels are remelted inside a vacuum chamber to reduce the amount of dissolved gasses in the metal. Heating is by means of an electric arc between a consumable electrode and the ingot. There are other ultra-high-strength steels that are not carbon steels. These steels, known as "maraging" steels, are refined so as to remove as much of the carbon as possible, and develop their extreme strength and fatigue properties as a by-product of the crystalline structures resulting from the large amounts of nickel (15% and up) and cobalt (6% and up) they contain. These steels can achieve extreme levels of strength and maintain excellent levels of impact resistance. As far as I could determine, maraging alloys are not currently (2008) used for racing crankshafts but they have been used in certain extreme application conrods. In the high performance crankshaft world, the nickel-chrome-moly alloy SAE-4340 (AMS-6414) has been a favorite in both forged and billet applications. It is used because of its very high strength and fatigue properties, coupled with good ductility and impact resistance at high strengths. SAE-4340 contains a nominal 40 points of carbon and is often described as "the standard to which other ultra-high strength alloys are compared".

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There is evidence that a lower carbon content provides better impact resistance (reduced notch sensitivity) in certain alloys. The air-hardening nickel-chrome-moly alloy EN-30B is used in some high-end billet crankshafts, in both commercial and VAR forms. This alloy contains 30 points of carbon, and has a nickel content exceeding 4% (400 points). It has good impact resistance at high strengths and is often used in rock-drilling equipment and highly-stressed gears and transmission components. The fact that it can be air-quenched to typical crankshaft core hardness is an added advantage because the distortions and residual stresses which result from oil quenching are avoided. Several manufacturers offer billet crankshafts in EN-30B. At least one US manufacturer of extreme duty crankshafts for NASCAR Cup, Top Fuel, Pro-Stock, early IRL, and other venues has selected a high-purity, lower-carbon version of the 43xx series of nickel-chrome-moly steels, a high-grade variant of E-4330-M (AMS 6427). This material has a nominal 30 points of carbon and has become a favorite for oil drilling and jet engine components because of its very high toughness and impact resistance when heattreated to high strengths. This manufacturer uses slight variations in the chemistry for different applications, but was understandably reluctant to discuss the variation specifics and how they affected the desired properties. The company maintains tight control over the entire process by purchasing its specific chemistry materials from a single, extreme-quality steel manufacturer, and by doing its heat-treating The material which is currently viewed as the ultra-extreme crankshaft alloy is a steel available from the French manufacturer Aubert & Duval, known as 32-CrMoV-13 or 32CDV13. It is a deep-nitriding alloy containing 300 points of chrome, developed in the mid-nineties specifically for aerospace bearing applications. It is available in three grades. GKH is the commercial purity and chemistry tolerance. GKH-W is the grade having higher purity (VAR) and tighter chemistry tolerance. GKH-YW is the extremely pure grade (VIM - VAR) and is said to cost twice as much per pound as the -W grade. According to data supplied by Aubert & Duval, fatigue-tests of the -W and -YW grades, using samples of each grade heat treated to similar values of ultimate tensile strength, show consistently that the -YW grade achieves a dramatic improvement (over 22%) in fatigue strength 9

compared to the -W grade, and the endurance limit is claimed to be just a bit short of the yield stress, which is truly amazing. I have been told that, because of the extreme stress levels on Formula One crankshafts, most of them use the -YW grade, while the lower stress levels of a Cup crank allow the successful use of the -W grade. One well-known manufacturer (Chambon) has developed a process which allows the production of a deep case nitride layer in this alloy (almost 1.0 mm deep, as compared to the more typical 0.10 to 0.15 mm deep layer). They say this deeper case provides a far less sharp hardness gradient from the >60 HRc surface to the 40-45 HRc core, which improves the fatigue and impact properties of the steel. It says that its deep-case process requires several days in the nitriding ovens, but the depth allows finish-grinding after nitriding, using a very sophisticated process to remove the distortions which occurred during the nitriding soak. No discussion of high-end crankshaft materials would be complete without mention of the ultra-high-strength alloy known as 300-M (AMS 6419).This alloy is a modification to the basic 4340 chemistry, in which a few more points of carbon are added (higher achievable hardness and strength), along with 170 points of silicon and 7 points of vanadium. The vanadium acts as a grain refiner, and the silicon enables the material to be tempered to very high strength (285 ksi) and fatigue properties, while retaining extremely good impact resistance and toughness. This material (300-M) is expensive and sometimes hard to get, since it is preferred for heavy aircraft landing gear components. It has been used by a few

manufacturers for extreme duty crankshafts and conrods as well as high-shock aircraft components. However, several of the manufacturers I spoke with told me that they consider their favorite materials to be much better than 300M for crankshaft applications.

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Crankshaft Heat Treating Regarding the steel alloys typically used in high-grade crankshafts, the desired ultimate (and hence yield and fatigue) strength of the material is produced by a series of processes, known in aggregate as ‘heat treatment’. The typical heat-treating process for carbon-steel alloys is first to transform the structure of the rough-machined part into the face-centered-cubic austenite crystalline structure (‘austenitize’) by heating the part in an oven until the temperature throughout the part stabilizes in the neighborhood of 1550°F to 1650°F (depending on the specific material). Next, the part is removed from the heating oven and rapidly cooled ("quenched") to extract heat from the part at a rate sufficient to transform a large percentage of the austenitic structure into fine-grained marten site. The desired martens tic post-quench crystalline structure of the steel is the highstrength, high-hardness, form of the iron-carbon solution. The rate of cooling required to achieve maximum transformation varies with the hardenability of the material, determined by the combination of alloying elements. Distortion and induced residual stress are two of the biggest problems involved in heat-treating. Less severe quenching methods tend to reduce residual stresses and distortion. Some alloys (EN-30B and certain tool steels, for example) can reach full hardness by quenching in air. Other alloys having less hardenability can be quenched in a bath of 400°F molten salt. Still others require quenching in a polymer-based oil, and the least hardenable alloys need to be quenched in water. The shock of water-quenching is often severe enough to crack the part or induce severe residual stresses and distortions. As the hardenability of a material decreases, the hardness (thus strength) varies more drastically from the surface to the core of the material. High hardenability materials can reach much more homogeneous post-quench hardness. Cryogenic treatment, if used, directly follows quenching. The body of belief-based and empirical evidence supporting cryo is now supported by scientific data from a recent NASA study confirming that a properly-done cryo process does transform most of the retained austenite to martensite, relaxes the crystalline distortions, and produces helpful η ("eta") particles at the grain boundaries. The resulting material is almost fully martensitic, 11

has reduced residual stress, more homogeneous structure and therefore greater fatigue strength. After quenching (and cryo if used), the alloy steel material has reached a very high strength and hardness, but at that hardness level, it lacks sufficient ductility and impact resistance for most applications. In order to produce the combination of material properties deemed suitable for a given application, the part is placed in a ‘tempering’ oven and soaked for a specific amount of time at a specific temperature (for that alloy) in order to reduce the hardness to the desired level, hence producing the desired strength, ductility, impact resistance and other

process can further improve fatigue strength and notch toughness. The tempering temperature and time must be carefully determined for each specific steel alloy, because in mid-range temperature bands, martensitic steels exhibit a property known as temper embrittlement, in which the steel, while having high strength, loses a great deal of its toughness and impact resistance. Typically, the post-temper hardness which results in the best ductility and impact properties is not sufficient for the wear surfaces of the crank journals. In addition, the fatigue strength of the material at that hardness is insufficient for suitable life. The currently-favored process which provides both the hard journal surfaces and dramatic improvements in fatigue life is nitriding (not nitrating - nitrates are oxygen-bearing compounds of nitrogen).Nitriding is the process of diffusing elemental nitrogen into the surface of a steel, producing iron nitrides (FeNx). The result is a hard, high strength case along with residual surface compressive stresses. The part gains a high-strength, high hardness surface with high wear resistance, and greatly improved fatigue performance due to both the high strength of the case and the residual compressive stress. These effects occur without the need for quenching from the nitriding temperature. The case thickness is usually quite thin (0.10 to 0.20 mm), although at least one crankshaft manufacturer has developed a way to achieve nitride layer thickness approaching 1.0 mm.

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desired mechanical properties. In the case of certain alloys, a double-tempering There are three common nitriding processes: gas nitriding (typically ammonia), molten salt-bath nitriding (cyanide salts) and the more precise plasma-ion nitriding. All three occur at approximately the same temperatures (925 - 1050°F) which, of course, becomes the ultimate tempering temperature of the part. The effectiveness of nitriding varies with the chemistry of the steel alloy. The best results occur when the alloy contains one of more of the nitride-forming elements, including chromium, molybdenum and vanadium. Older crankshaft technology involved heat-treating to a higher core hardness and shotpeening the fillet radii for fatigue improvement. Figure 1.7 shows the relative fatigue strength of 4340 material from heat treating alone, heat-treating plus shotpeening, and heat treating plus nitriding.

Figure 1. 4 Crank Shaft Fatigue Test

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Crankshaft Design Issues In the world of component design, there are competing criteria, which require the engineers to achieve a perceived optimal compromise to satisfy the requirements of their particular efforts. Discussions with various recognized experts in the crankshaft field make it abundantly clear that there is no ‘right’ answer, and opinions about the priorities of design criteria vary considerably. In contemporary racing crankshaft design, the requirements for bending and torsional stiffness (see the Stiffness vs. Strength sidebar) compete with the need for low mass moment of inertia (MMOI). Several crankshaft experts emphasized the fact that exotic metallurgy is no substitute for proper design, and there's little point in switching to exotics if there is no fatigue problem to be solved. High stiffness is a benefit because it increases the tensional resonant frequency of the crankshaft, and because it reduces bending deflection of the bearing journals. Journal deflection can cause increased friction by disturbing the hydrodynamic film at critical points, and can cause loss of lubrication because of increased leakage through the greater radial clearances that occur when a journal's axis is not parallel to the bearing axis. At this point, it is important to digress and emphasize the often-misunderstood difference between STIFFNESS and STRENGTH. Metal parts are not rigid. When a load is applied to a metal part, the part deflects in response to the load. The deflection can be very small (crankshaft, conrod, etc.) or it can be quite large (valve springs, etc). But to one degree or another, all parts behave like springs in response to a load. The ultimate strength of a material is a measure of the stress level which can be applied to a lab sample of the material before it fractures. The degree to which a given part resists deflection in response to a given loading is called stiffness. It is important to understand that the ultimate strength of a material has nothing whatever to do with stiffness.

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Stiffness is the result of two properties of a part: (1) the Young's Modulus of the material (sometimes called Modulus of Elasticity, but more appropriately named Modulus of Rigidity) and the cross-sectional properties of the part to which the load is applied. For example, suppose you have two components which are identical in all respects (same material, same dimensions) except the tensile strength to which those components have been heat-treated. If you apply an increasing load to each component, both will deflect the same amount for each load value, until the component with the lower strength permanently deforms (and breaks if it is loaded and constrained in a certain way) at a relatively low stress level. The component with the higher strength will continue to deform with increasing load until its yield stress is reached, at which point it too will permanently deform. Three major parameters which affect crank stiffness are length, journal diameter and crank pin overlap. The torsional rate of a cylindrical section varies directly with length and with the fourth power of diameter. Crankpin overlap is a measurement of how much crankpin material is horizontally aligned with the material of the adjacent main journals, as illustrated in Figure 8, showing a CPO of 0.225 with a 4.250" stroke crank having 2.100 rod journals and 2.600 main journals. CPO = (main diameter + crankpin diameter - stroke) / 2

Figure 1. 5 Cpo Of 0.225 With A 4.250" Stroke Crank Having 2.100 Rod Journals There is a continuing emphasis on research and design among F1 and Cup teams to increase stiffness with minimal impact on MMOI. However, all the experts I spoke with were understandably reluctant to discuss the specifics of where and how they are adding material and how effective their changes are. From examining 15

some available pictures and gathering data on other engine parameters, I would hazard a guess that the conrod bearing widths are being reduced to make room for thicker webs. It is also possible that main bearing journals are being undercut to produce the required fillet radii at the intersection with the web, again making more room for thicker webs. Undercutting the journals increases the stress levels and locally reduces the section properties. However, the immense fatigue strengths of the contemporary materials and the relative lack of crank failure at the highest levels of racing suggest that the endurance limits can be pushed a bit further. It is apparent that a great deal of FEA work is essential at the top. One stiffness area where most two-plane V8 engine people agree is the use of center counterweights. It has been known for some time that there are significant power gains available in two-plane crank V8s from the use of counterweights around the center main bearing (Figure 1.9).

Traditionally, many two-plane V8 crankshafts had been produced without center counterweights because of economies and difficulties forging the blanks, because the six-counterweight crank typically has a slightly lower MMOI, and because the benefits of an eight-counterweight crank in a short-stroke application were not fully appreciated. However, the bending deflection across the center main at high loadings and high speeds causes measurable losses, so many areas of racing which use two-plane V8 cranks are moving (or have already moved) to eightcounterweight cranks. From an overall engine design perspective, the relocation of the thrust bearing from the rear main to the center main also helps reduce center- main bending deflection. There are varying opinions about whether high stiffness or low MMOI is more important. Low MMOI is most important at high engine acceleration rates. Road-course racing typically involves greater vehicle speed variation per lap, which implies greater requirements for quick acceleration through several gear ratios. In certain classes, the low weight of the vehicle and the high power of the engine can yield very high engine acceleration rates. At the higher-speed Cup racing circuits, 16

the engine acceleration rates at speed are often less than 100 RPM per second, while at some of the shorter tracks, they can exceed 500 RPM per second. Of course, there are restarts and pit stops to be dealt with at all tracks, so it is easy to see how there can be varying approaches to this issue. Reducing MMOI involves removing material, especially from places which are a long distance from the main bearing axis. However, these are also some of the most highly loaded areas as well, so reducing cross sectional properties necessarily increases the cyclic stress levels. Pushing the cyclic stress levels up impinges on the

fatigue life of the component, which is especially important in classes where an engine must, by regulation, survive more than one meeting. Determining acceptable levels of cyclic stresses vs. expected life is not an exact science. Endurance limit testing of materials produces a highly statistical array of results data (as illustrated in Figure 1.7).There has been quite a bit of discussion about the use of bolt-on counterweights in an attempt to reduce MMOI values. An example of this technology is shown in Figure 10. These detachable counterweights are made from variants of the ‘heavy metal’ used to balance crankshafts. This heavy metal is a tungsten-based alloy with several different chemistries (W-Ni-Cu; W-Ni-Fe; W-NiC) depending on the required properties. These alloys have nearly 2.5 times the density of steel, and are extremely expensive.

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Figure 1. 6 Bolt-On Counterweights

Another benefit of bolt-on counterweights is that several of the machining operations are much simpler to accomplish without having to deal with the integral counterweights getting in the way. If journal coatings are used, the more complete access to the journals provided by the absence of integral counterweights could also be a benefit. There were some initial problems with bolt-on counterweights, which resulted (as one Formula One designer told me) in "several deep holes being dug in the surface of a few racetracks". There are tensile and fatigue stress issues, as well as the inevitable fretting between contact surfaces and the requirement for highly developed fastener technology. Usage in Formula One suggests that those issues have been resolved. There is a variance of opinion as to whether bolt on counterweights are being investigated in Cup. One person told me they are explicitly illegal, while two others told me they know of a certain amount of investigation and development going on in that regard. In the world of two-plane V8 cranks, the traditional calculation for the balance-bob weight value is 100% of the rotating weight (big end, inserts and oil)

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plus 50% of the reciprocating weight (small end, wristpin, retainers, piston, rings and oil). However, there are differing approaches to the question of overbalance or under balance. . Some experts stick with the 100% + 50% distribution, while others opt for a 46-47% underbalanced (100% + 47%). Others prefer a 52-53% overbalance, while others add an arbitrary 100 grams to the 50% reciprocating calculation. There was a general reluctance to discuss the expected or observed effects of these strategies. There has been an interesting development regarding two-plane V8 crankshaft lubrication drillings. Traditionally, each rod bearing was fed oil by a single angled hole from the loaded-during-compression side of the rod journal to the less-loaded side of the adjacent main journal, sometimes called ‘straight-shot oiling’, shown in Figure 11. That strategy reduced the effect of centrifugal-force starvation at high RPM and assured the availability of sufficient oil to provide the dynamic film strength for the combustion loading.

The problem with this scheme is that the intersection of the angled hole with the rod journal produces a large elliptical interruption in the journal surface. Add the chamfering usually done around that hole, and what results is a significant interruption of the hydrodynamic surface area. Coupled with the reduced bearing widths, that divot creates a substantial leakage path for the oil to escape. The new approach rearranges the drillings so the holes in the rod journal can be perpendicular to the surface. One method is to drill a perpendicular oil hole into the rod journal, and drill an intersecting parallel hole partially through the rod journal and plug the open end. Next, an angled drilling from an adjacent main journal is made to intersect the parallel drilling. Another method involves horizontal 19

drillings through the main journal, through the CPO into the rod journal, with perpendicular feeds into both journals. This rearrangement enables the lubrication of both rods on the same crankpin from a single main journal. That can be an advantage in view of data showing that two-plane V8 main journals numbers two and four are the most highly loaded, so the rods can be oiled from one, three and five while the oil delivered to mains two and four can do a better job because of reduced leakage and no surface interruptions.

The above figures show examples of this approach. An interesting byproduct of this new drilling strategy is the creation of internal sharp corners and edges where the drillings intersect. These sharp corners introduce the flow- restricting effect of sharp-edged orifices into the lube system at a critical point. Further, sharp corners and machining marks introduce stress concentrations due to of the surface discontinuities. One major crank manufacturer (Bryant Racing) has developed a proprietary extrude-honing system in which an abrasive slurry is pumped through these drillings at high pressure. This abrasive treatment removes the sharp edges and surface flaws which cause flow restrictions and stress concentrations, leaving the inside surfaces of the holes with a mirror finish and nicely rounded intersections, which adds substantially to the fatigue life of the part. Up to now we made a discussion about introduction, its time to enter into literature survey.

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CHAPTER-2 LITERATURE SURVEY According to Farzin H. Montazersadgh and Ali Fatemi’s journal dynamic simulation was acted on a crankshaft from a multi cylinder four stroke engine. Finite element analysis was performed to obtain the variation of stress magnitude at critical locations. The pressure-volume diagram was used to calculate the load boundary condition in dynamic simulation model, and other simulation inputs were taken from the engine specification chart. The dynamic analysis was done analytically and was verified by simulation in ADAMS which resulted in the load spectrum applied to crank pin bearing. This load was applied to the FE model in ANSYS, and boundary conditions were applied according to the engine mounting conditions. The analysis was done for different engine speeds and as a result critical engine speed and critical region on the crankshaft were obtained. Stress variation over the engine cycle and the effect of torsional load in the analysis were investigated. Results from FE analysis were verified by strain gages attached to several locations on the crankshaft. Results achieved from aforementioned analysis can be used in fatigue life calculation and optimization of this component.

Guagliano et al. conducted a study on a marine diesel engine crankshaft, in which two different FE models were investigated. Due to memory limitations in meshing a three dimensional model was difficult and costly. Therefore, they used a bi-dimensional model to obtain the stress concentration factor which resulted in an accuracy of less than 6.9 percent error for a centered load and 8.6 percent error for an eccentric load. This numerical model was satisfactory since it was very fast and had good agreement with experimental results. Payer et al. developed a two-step technique to perform nonlinear transient analysis of crankshafts combining a beam-mass model and a solid element model. Using FEA, two major steps were used to calculate the transient stress behavior of the crankshaft; the first step calculated time dependent deformations by a step-bystep integration using the new mark-beta- method. Using a rotating beam-massmodel of the crankshaft, a time dependent nonlinear oil film model and a model 21

of the main bearing wall structure, the mass, damping and stiffness matrices were built at each time step and the equation system was solved by an iterative method. In the second step those transient deformations were enforced to a solid- elementmodel of the crankshaft to determine its time dependent stress behavior. The major advantage of using the two steps was reduction of CPU time for calculations. This is because the number of degrees of freedom for performing step one was low and therefore enabled an efficient solution. Furthermore, the stiffness matrix of the solid element model for step two needed only to be built up once Literature survey is concluded, and we can move into next chapter to discuss about designing procedure.

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CHAPTER -3 CALCULATION PART When the crank is at dead centre:

At this position of the crank, the maximum gas pressure on the piston will transmit maximum force on the crankpin in the plane of the crank causing only bending of the shaft. The crankpin as well as ends of the crankshaft will be only subjected to bending moment. Thus, whenthe crank is atthedead centre,the bending moment onthe shaft is max. And the twisting moment is zero. The various forces that are acting on the crankshaft are indicated as below. This engine crankshaft is a single throw and three bearingshaft locatedatposition1,2 &3.Lets us assume followingdata forengine We cancalculate the various forces acting on crank shaft connecting rod (Fp), Horizontal and vertical reactions on shaft, and the resultant force at bearing 2 & 3 by below formulae. Now the piston force

Pmax = P * no of cylinders/1248 *106*4000 = 55*4/1248*106*4000 = 44.07 Piston force Fp=π/4 * D2* Pmax =π/4*(69.6)2*44.07 = 167.67 KN Assuming the distance between the bearings 1 &2 as b = 2D = 2*69.6 = 13902 mm b1 = b2 = b/2 = 69.6 We know that due to piston gas load, there will be two equal horizontal reactions H1 & H2 at bearings 1 & 2 respectively. .i.e., H1 = Fp/2 = 167.66/2 = 83.83 KN = H2 Assuming that the length of bearing to be equal i.e. c1=c2=c/2 23

We know that due to weight of flywheel acting downwards, there will be two vertical reactions V2 & V3 at bearings 2 & 3 V2= V1 = W/2 = 9.8/2 = 4.9 N Since, the belt is absent in engine, neglecting the belt tension exerted by belt .i.e. T1 + T2 = 0 Now, let’s design various parts of crankshaft a) Design of left hand crank web

b)

The crank web is designed for eccentric loading. There will be two stresses acting on the crank web, one is direct compressive stress and the other is bending stress due to piston gas load (Fp). The crank web is subjected to the following stresses

i.

:i. Bending stresses in two planes normal to each other,

ii.

ii. Direct compressive stress and

iii.

iii. Torsion stress

We know that the thickness of crank web is t = 0.65 *dc + 6.35= 0.65* 90 + 6.35 = 64.85 = say65 mm Also width of crank web is, W = 1.125 * dc +12.7 = 1.125 * 90 +12.7 = 113.95 = say115 mm The maximum bending moment on crank web is Mmax= H1 (b2 –lc/2-t/2) = 83.83 (69.6- 186.28/2-65/2)

24

= - 4697.83 kN mm The bending moment is negative; hence the design is not safe. Thus the dimensions are on higher side. Now let’s assume, dc = 45 mm Hence, lc = 372.57 mm This is very high, which will require huge length of crank shaft. To have optimum dimension of crank shaft let’s assume length of crank web as. lc = 24 mm and check whether these dimensions are suitable for the load exerted by the piston, & other forces Now, t = 35.6 & w = 63.32 = say 68 mm This thickness is also on higher side, let’s assume thickness of crank web as t = 13.2 mm As compared to width of crank web thickness is more Bending moment, M = 4275.33 kN-mm Section modulus, Z = 1/6 x w x t2 = 1/6 x 68 x 13.22 = 1974.72 mm3 Bending stress, σb= M/Z σb= 2.165 kN/mm2 The compressive stress acting on crank web are σc= H1 / (w*t) 25

= 83.83 / (68 * 13.2) = 0.09339 kN/ mm2 a) The total stress acting on crank web is σT = σb + σc = 2.2583 kN/ mm2 Thus total stress on crank web is less than allowable bending stress of 83 N/mm2 Hence, the design is safe b) Design of right hand crank web From balancing point of view, the dimensions of right hand crank web i.e. thickness and width are made equal to the dimensions of left hand crank web. c) Design of shaft under flywheel

There are two types of bending moments acting on shaft. Bending moment due to weight &, bending moment due to belt tension. Neglecting the belt tension lets design shaft diameter. Let, ds = diameter of crank shaft Since the length of bearings are equal l1= l2 = l3

= 2(b/2-lc/2-t)

= 2(139.2/2- 24/2-13.2) = 88.8 mm Assuming the width of flywheel = 200 mm C = 88.88 + 200 = 288.88 mm Considering the space for gearing and clearance, Let C = 300 mm Bending moment due to weight of fly wheel, 26

Mb = V3 x C = 4.9 x 103 x300 = 1470 x 103kN mm Also the bending moment of shaft is Ms =π/32 * ds3 x σ allow 1470 x 103 = π/32 * ds3 * 83 d s = 56.50 mm

27

CHAPTER 3 INTRODUCTION CATIAV5R20 CATIA is the leading solution for product success. It addresses all manufacturing organizations. CATIA can be applied to a wide variety of industriesfrom aerospace- automotive- and industrial machinery- to electronicsshipbuilding- plant design- and consumer goods. Today- CATIA is used to design anything from an airplane to jewelry and clothing. With the power and functional range to address the complete product development process- CATIA supports product engineering- from initial specification to product-in-service- in a fullyintegrated manner. It facilitates reuse of product design knowledge and shortens development cycles- helping enterprises to accelerate their response to market needs. CatiaV5R20 is an interactive Computer- Aided Design and Computer Aided Manufacturing system. The CAD functions automate the normal engineeringdesign and drafting capabilities found in today’s manufacturing companies. The CAM functions provide NC programming for modern machine tools using the CatiaV5 R16 design model to describe the finished part. CatiaV5R20 functions are divided into “applications” of common capabilities. These applications are supported by a prerequisite application called “CatiaV5R20 Gateway”. CatiaV5R20 is fully three dimensional- double precision system that allows to accurately describing almost any geometric shape. By combining these shapesone

can

design-

analyze-

and

28

create

drawings

of

product

BASIC PROCEDURE FOR CREATING A 3-D MODEL IN CATIAV5R20: Creation of a 3-D model in CatiaV5R20 can be performed using three workbenches i.e.- sketcher- modeling and assembly. SKETCHER: Sketcher is used two-dimensional representations of profiles associated within the part. We can create a rough outline of curves- and then specify conditions called constraints to define the shapes more precisely and capture our design intent. Each curve is referred to as a sketch object. CREATING A NEW SKETCH: a new sketch- chose StartMechanical DesignSketcher then select the reference plane or sketch plane in which the sketch is to be created. SKETCH PLANE The sketch plane is the plane that the sketch is located on. The sketch plane menu has the following options: Face/Plane: With this option- we can use the attachment face/plane icon to select a

planar face or existing datum plane. If we select a datum plane-

we can use the reverse direction button to reverse the direction of the normal to the plane. XC-YC- YC-ZC- and ZC-XC: With these options- we can create a sketch on one of the WCS planes. If we use this method- a datum plane and two datum axes are created as below.

Displays the structure of the part, assembly, or drawing. Select an item from the feature manager design tree to edit the underlying sketch, edit the feature, and suppress and un suppress the feature or component, for example.

29

An meeting is a aggregate of or extra components, additionally known as components, inside one solid works record. You role and orient components the use of mates that form family members among additives. ➢ This lesson discusses the following: ➢ Adding components to an meeting ➢ Transferring and rotating additives in an assembly ➢ Growing display states in an assembly

modeling of crankshaft “Feature” is an all-encompassing term that refers to all solids, bodies and primitives used in Solid works Form Features are used to supply detail to the model in the form of standard feature types. These include hole, Extrude Boss/Cut, Swept Boss/Cut, Fillet. We can also create our own custom features using the User Defined option. All of these features are associative. Reference Feature sallow creating reference planes, reference lines and reference points. These references can assist in creating features on cylinders, cones, spheres and revolved solid bodies. Reference planes can also aid in creating features at angles other than normal to the faces of a target solid. Dress up Feature options lets modify existing solid bodies and features. These include a wide assortment of options such as edge fillet, variable fillet, chamfers, draft, offset face, shell and tapers. Surface design lets us create surface and solid bodies. A surface body with zero thickness, and consists of a collection of faces and edges that do not close up to enclose a volume. Most Free 30

figure 4. 1 Sketch Profile for Crank Shaft

After creating the crank shaft end, a sleeve has to be designed between cylinder 1 and 2 connecting rod location. Initial sketch profile looks as follows.

figure 4. 2 Sleeve Profile 31

After a couple of operations like Fillets, Revolve Cut, Mirror the final product looks as follows. This part is assembled with the rest of the components to produce the final connecting rod assembly.

figure 4. 3 Symmetry operation

4.7.1. Designing Crank Shaft Ends To design connecting the initial sketch profile looks a follows. This sketch profile is symmetric along the x-axis as shown bellow.

figure 4. 4 Crank Shaft journals 32

figure 4. 5 Symmetry operation to create the second set of Journals

After creating the above sketch profile extrude cut feature is used to remove the material from the solid connecting rod. Two holes are created at the two end of the top portion in to fit the connecting rod end as shown in the figure below.

figure 4. 6 Crank Shaft End or Fly Wheel Flange

figure 4. 7 Crank Nose Basic Sketch Profile

33

Final Design

34

CHAPTER-5 INTRODUCTION OF ANSYS ANSYS a product of ANSYS inc. Is a world's leading, widely distributed and popular commercial CAE package. It is widely used by designers/analysis in industries such as aerospace, automotive, manufacturing, nuclear, electronics, biomedical, and much more. ANSYS provides simulation solution that enables designers to simulate design performance directly on the desktop. In this way, it provides fast efficient and cost efficient product development from design concept stage to performance validation stage of product development cycle. It helps to acceleration and streamlines the product development process by helping designers to resolve issues relation to structural thermal fluid flow electromagnetic effect a combination of these phenomena acting together and soon. In ANSYS, the basics of FEA concepts, modelling and the analysing of engineering problem using ANSYS workbench. In addition, describe of importance tools and concepts given whenever required .this following simulation streams of ANSYS. 1. Structural Analysis Static Structural Analysis Modal Analysis Transient Structural Analysis 2. Thermal Analysis Steady State Thermal Analysis Transient Thermal Analysis

35

CHAPTER-6 INTRODUCTION TO ANSYS WORKBENCH

Project Objective In this chapter, we will be able to define: ➢ Understand the types of system ➢ Understand different types of cells ➢ Understand the graphic user interface of the workbench window ➢ Start a new project in ansys workbench windows ➢ Add the first and subsequent analysis system to a project ➢ Set units for the project

Introduction To Ansys Workbench ANSYS WORKBENCH, developed by ANSYS INC., USA, is a computer aided finite element modelling and finite element analysis tool (CAFEM AND CAFEA). In the graphical user interface GUI of ansys workbench the user can generate 3-dimensional and FEA models, perform analysis and generate results of analysis. We can perform a variety of tasks ranging from design assessment to finite element analysis to complete product optimisation analysis by using ANSYS WORKBENCH. ANSYS also enable the combination of standalone analysis system into a project and to manage the project workflow. In ansys workbench this are the list of analysis can be determined: ➢ Modal analysis ➢ Static structural analysis ➢ Transient structural analysis ➢ Steady state thermal analysis ➢ Transient thermal analysis

36

➢ Fluid flow (CFD)

6.2.1 Starting Ansys Workbench 16.0 To start ansys workbench 16.0, choose start- programs/ all programs- ansys 14.0 - workbench 14.0 from the taskbar. Alternatively, we can start ansys workbench by double click on the workbench 14.0.

Figure 6. 1 Starting Of Ansys Workbench Using Taskbar

37

The workbench windows help streamline an entire project to be carried out in ansys workbench 14.0. In this window, one can create, manage, and view the workflow of the entire project create by using standard analysis system. The workbench windows mainly consist of the menu bar, standard toolbar, the toolbar windows, project schematic windows, and the status bar.

Figure 6. 2 The Component Of The Workbench Windows

6.2.2. Toolbox Windows The toolbox windows are located on the left in the workbench windows. The toolbox windows list the standard and customised templates or the individual analysis components that are used to create a project. To create a project, drag a particular analysis or component system from the toolbox window and drop into the project schematic windows or double click on GUI table it will add it into project schematic windows and to create the project

38

Figure 6. 3 The Analysis System Toolbox Displaying Various Analysis System In It. Name

of

Application

of

analysis

loads

Explicit

Loads

dynamics

respect to time

Solution determines

with

Total deformation or

impact

deformation Fluid

flow

(CFX)

Compressible or

Heat transfer

incompressible

or flow of air

of air or gases Fluid (CFD)

flow

Compressible or

Heat transfer

incompressible

fluid

of fluid Harmonic

Periodic

or

response

sinusoidal loads

Resonance, fatigue, effect

and of

forced vibration. Rigid

Constraints and

Forces

dynamics

motion loads

direction

39

or

analysis Static

Static

structural

conditions

load

Deformation, Stresses

and

Strains, Fatigue

tool,

Life, Damages, Safety factor Steady

Temperature or

Heat flux or

thermal loads

temperatures

Transient

Varying of load

Deformation,

structural

conditions with

Stresses

changing of

Strains,

times

Fatigue

state thermal

and

tool,

Life, Damages, Safety factor Transient

Varying

of

thermal

Temperature or thermal loads with changing of times

Table 6. 1 Analysis And Definitions

40

Heat flux or temperatures

Project Schematic Windows The project schematics windows help manage an entire project. It displays the workflow of entire analysis project. To add an analysis system to the project schematic windows, drag the analysis system from toolbox windows and drop into the green coloured box displayed in the project schematic windows.

Figure 6. 4 Static Analysis Imported Into Project Schematic

6.3.1 Custom System Analysis. By default, the custom system toolbox is also displayed in collapsed state in the toolbox. To expand this node, click on + on a custom system. The system in the customs system toolbox is used to carry out the standard coupled analysis like static and thermal analysis(the combination of more than single or multiple of GUI tab). In every GUI tabs, we can drag more GUI tabs makes the links analysis.

41

Figure 6. 5 Sharing Of Engineering Data, Geometry And Model

Units In Any Workbench: In any workbench, you can use any of the following predefined unit systems. Units

Mass

Length

Time

Voltage

Temperature Current Forces

Metric

Kg

M

S

V

OC

A

N

Metric

Tonne

Mm

S

Mv

OC

Ma

N

US Cust.

Lb

In

S

V

OC

A

N

SI

Kg

M

S

V

K

A

N

US Engg

Lb

In

S

V

Rankine (R)

A

Lbs

Table 6. 2 Units

Component Of The System: An item that is added from the toolbox window to the project schematic windows is known as a system and the constituent elements of the system are known as cells. Each cell of a system plays an important role in carrying out a project and are discussed next Engineering Data Cell The engineering data cell is used to define the material to used in the analysis. To define the materials, double click on the engineering data cell, the workbench corresponding to this the engineering data cell will e displayed. 42

Engineering cell-double click-clickon the shell system (engineering data book)-select general materials in the outline of the engineering data sources- select materials in the outline of general materials

Figure 6. 6 The Engineering Data Workspace

Geometry Cell The geometry cell is used to create, edit or import the geometry that is used for analysis. To create a geometry for analysis, double click on geometry cell, the design

modeller

windows

will be displayed.

Figure 6. 7 The Shortcut Menu Displayed On Right Clicking On The Geometry Cell The new geometry option in the menu is used to get into design modeller windows, where you can create geometry or import the geometry from the existing geometry file create in another CAD software packages. 43

Model Cell The model cell will be displayed for mechanical analysis system and is used to discredited geometry into small elements, apply boundary and load conditions, solve the analysis, and so on.

Mesh Cell The mesh cell will be displayed for fluid flow analysis and is used to mesh the geometry, on double clicking on this cell, the meshing windows will be displayed . In other words, this cell is associated with the meshing windows. Setup Cell The setup cell is used to define the boundary conditions of an analysis system, such as loads and constraints. This cell is also associated with the mechanical workspace.

Solution Cell The solution cell is used to solve the analysis problem based on the conditions defined in the cells above the solution cell. The cell is also associated with the mechanical workspace. Results Cell The results cell is used to display the results of the analysis in the user specified formats, this cell is also associated with the mechanical workspace.

44

CHAPTER 7 STATIC STRUCTURAL ANALYSIS

Project Objective In this project, we will be able to define total deformation and stress, etc ➢ Create the static structural analysis system ➢ Apply different types of materials ➢ Applying of boundary conditions ➢ Apply a different type of constraints ➢ Apply different loads ➢ Generate the results as per required ➢ Generate project reports In this project, we imported the geometry of the component show the dimensions for the component with respect to the load applications. The material to be applied on the model is Stainless Steel. Next, you will run the analysis under two conditions and evaluate the Total Deformation, Directional Deformation, Equivalent Stress, Maximum Principal Stress, and Minimum Principal Stress. Introduction To Static Structural Analysis The Static Structural analysis is one of the important analyses in ANSYS Workbench. It is available as Static Structural analysis system under the Analysis System toolbox in the Toolbox window, This system analyses the structural components for displacements (deformation), stresses, strains, and forces under different loading conditions. The loads in this analysis system are assumed not to have damping characteristics (time dependent). Steady loading and damping conditions are assumed in this type of analysis system. To start a new Static Structural analysis system, double-click on Static Structural in the Analysis Systems toolbox in the Toolbox window; the Static Structural analysis system will be added to the Project Schematic window. To start an analysis, first you need to specify the geometry on which the analysis is to be 45

done. To do so, you can import the geometry from an external CAD package, or you can create the geometry in the ANSYS's Design Modeler software. After the model is specified for an analysis, you need to double-click on the Model cell of the Static Structural analysis system to open the Mechanical window. In this window, you can specify the parameters and run the analysis.

Figure 7. 1 The Static Structural Analysis System Added To The Project Schematic Window

Figure 7. 2 The Mechanical Window

As discussed in previous chapters, analysis can be carried out in three major steps: pre-processing, solution, and post-processing. The tools required to carry out 46

these steps are discussed next. Pre-Processing

The pre-processing of an analysis system involves

specifying the material, generating a mesh, and defining boundary conditions. In ANSYS Workbench, the various tools related to boundary conditions are available in the Environment contextual toolbar, which is displayed when you selectthe Static Structural node in the Tree Outline

Figure 7. 3 The Environment Contextual Toolbar In order to provide a support to the model, you need to choose the required tool from the Supports drop-down. Similarly, to add a load, choose the desired tool from the Loads drop-down in the Environment contextual toolbar. Also, when you choose any tool from the Environment contextual toolbar; the corresponding entity is placed under the Static Structural node in the Tree Outline. The main purpose of an analysis is to evaluate the results. After the boundary condition is set and loads are applied, you need to specify the desired outcomes of the analysis. In ANSYS Workbench, you can analyze various parameters such as deformation, stresses, strains, and so on. To do so, you need to specify the results required and then evaluate them. You can use the tools available in the Solution contextual toolbar to specify results, refer to Figure 9-4. Alternatively, right-click on the Solution node in the Tree Outline and then use the desired option from the shortcut menu displayed.

Figure 7. 4 The Solution Contextual Toolbar

47

In order to evaluate deformations, stresses, strains, and so on, choose the desired options from the drop-downs available in the Solution contextual toolbar. Solution

In an analysis, after pre-processing (meshing, specifying material,

and specifying boundary condition) is done, the next step is to solve the analysis. In ANSYS Workbench, you will use the Solve tool from the Standard toolbar to run the solver. The solver runs in the background of a software and acquires results of an analysis, based on the specified boundary conditions. Post-Processing After the analysis is complete, you need to generate the report in the Mechanical window. To do so, choose the Report Preview tab from the bottom of the Graphics screen; the ANSYS Report generation in progress message is displayed on the screen. After sometime, this message vanishes and the report is generated.

Figure 7. 5 The Report Generation In Progress...

48

7.3. Project Overview In this project, you will create the model of a crankshaft, as shown below . The dimensions to create the model and its boundary and loading conditions are also given in the same figure. Run a Static Structural analysis on the model and evaluate the Total Deformation and the Directional Deformation. Determine Directional Deformation along the X, Y, and Z axes. After evaluating the results, interpret them. (Expected time: 3 hr) 1. Start a new project and create the model. 2. Generate the mesh. 3. Set the boundary and loading _conditions. 4. Solve the model. 5. Duplicate the existing analysis system. 6. Interpret results. 7. Save the project. 7.3.1 Starting A New Project And Creating The Model The first step is to start a new project in the Workbench window. 8. Start ANSYS Workbench. 9. Choose the Save button from the Standard toolbar; the Save As dialog box is displayed. 10. Double-click on Static Structural in the Toolbox window; the Static Structural analysis system is added in the Project Schematic window. 11. Rename the Static Structural analysis system (if). 12. In the Cantilever analysis system, double-click on the Geometry cell; the Design Modeler window along with the ANSYS Workbench dialog box is displayed. 13. In the ANSYS Workbench dialog box, set the unit to millimeter. Now, create the model on the XY plane 14. Exit the Design Modeler window to display the Workbench window.

49

7.3.2. Adding The Material To The Engineering Data Figure Workspace After creating the holes in the model, you now need to apply the material to it. The Material to be applied is Stainless Steel. 1. Double-click on the Engineering Data cell of the crankshaft analysis system; the Engineering Data workspace is displayed in the Workbench window. 2. Choose the Engineering Data Sources toggle button from the Standard toolbar; the Engineering Data Sources window is added to the Engineering Data workspace. 3. In the Engineering Data Sources window, select the General Materials library to display the Outline of General Materials window. 4.

In the Outline of General Materials window, choose the plus symbol corresponding to Aluminum Alloy; the material is added to the Engineering Data in the Outline window of the Engineering Data workspace.

5. Again, choose the Engineering Data Sources toggle button from the Standard toolbar to switch to the default view of Engineering Data workspace. Choose the Return to Project button from the Standard toolbar to display the Project Schematic window.

50

7.3.4. Table Of The Composite Material 92% Aluminum+6.74% Steel+0.2% Carbon+0.32% Silicon+0.7% Maginesum+0.02% Phosphorus+0.02% Sulphur

Material

Percentage Densit % Density y

Poison Ratio

Aluminum Alloy 92

3720

3422.4

Steel

6.74

7480

504.152

0.29

Carbon

0.2

7870

15.74

0.29

Silicon

0.32

3180

10.176

0.23

Magnesium

0.7

1.827

0.012789

0.35

Phosphorus

0.02

1823

0.3646

0.15

Sulphur

0.02

2070

0.414

0.15

Composite

3953.259389

Table 7. 1 Composite Material I (Medium Steel Alloy) 7.3.5 Table Of The Composite Material (Nickel + Chromium +Steel+ Cast Iron+ Aluminum) Nickel + Chromium+ Steel+ Cast Iron+ Aluminum+ Molybdenum

Material

Z

Density % Density

Poison Ratio

Aluminum Alloy

92

3720

3422.4

0.29

Steel

2

7480

149.6

0.29

Nickel

1

8900

89

0.23

Chromium

2

7180

143.6

0.35

Cast Iron

1

7200

72

0.15

Molybdenum

2

10220

204.4

0.35

Composite

4081

Table 7. 2 Composite Material I (Ni Cr Mo Steel Alloy) 51

Figure 7. 6 Specifying A Material

52

Generating The Mesh After the model is created in the Design Modeler window, you need to generate the mesh for the model in the Mechanical window. 1. In the Project Schematic window, double-click on the Model cell in the static structural analysis system; the Mechanical window is displayed. 2. Select Mesh in the Tree Outline to display the Details of "Mesh" window. 3. In the Details of "Mesh" window, expand the Sizing node, if it is not already expanded. Also, notice that Default is displayed in the Element Size edit box. The Element Size edit box is used to specify the size of an element. The element size specified in this edit box is according to the size of the geometry. However, this edit box will not be visible when the ➢ On: Proximity and ➢ On: Proximity and Curvature options are selected from the Use Advanced Size Function drop-down list. When Default is displayed in the Element Size edit box, it indicates that a default value, based on the size of the geometry, is already specified by the software. 4. Choose the Generate Mesh tool from the Mesh drop-down in the Mesh contextual toolbar; the mesh is generated.

Figure 7. 7 Mesh Generated With Default Mesh Controls

53

5.

Expand the Statistics node in the Details of "Mesh" window to display the

total number of elements created. On doing so, you will find that the total number of elements.

Specifying The Boundary Conditions After you mesh the model, it is required to specify the boundary and loading conditions. 1. In the Mechanical window, select the Static Structural node from the Tree Outline; the Details of “Static Structural” window is displayed along with the Environment contextual toolbar. 2. Choose the Fixed Support tool from the Supports drop-down in the Environment contextual toolbar; Fixed Support is added under the Static Structural node. Also, the Details of“ Static Structural” window is displayed 3. Click on the Geometry selection box to display the Apply and Cancel buttons

Figure 7. 8 Choosing The Fixed Support Tool From The Supports Drop-Down 4. Choose the Face tool from the Select toolbar to enable selection of faces. 5. Select faces on the model. Next, choose the Apply button in the Geometry selection box; the selected faces turn purple indicating that Fixed support is applied 6. Choose the Force tool from the Loads drop-down in the Environment contextual toolbar; Force is added under the Static Structural node in the Tree Outline. Also, the Details of “Force” window is displayed 7. Click on the Geometry selection box to display the Apply and Cancel buttons, if they are not already displayed. 8.

Next, select the circular face on the right of the model, as shown in Figure. 54

9. Choose the Apply button from the Geometry selection box; the cylindrical face turns red indicating that the Force load is applied. 10. In the Details of “momentum” window, expand the Definition node, if it is not already expanded.

Figure 7. 9 The Loads Drop-Down

11. Select Vector from the Define By drop-down list, if it is not already selected. 12. In the Details of “momentum” window, click on the right arrow next to the Magnitude edit Box; a fly-out is displayed. 13. Choose Constant from the fly out, if it is not already chosen, as shown in Figure. The Constant option is chosen when the force applied remains constant with respect to Time, 14. In the Magnitude edit box, enter number. 15. Click on the Direction selection box to display the Apply and Cancel buttons. As the application of force under consideration is vertically downward, you need to Define the direction by selecting edges for the force vector. 16. Select any vertical edge on the model, as shown in Figure 949, to specify the direction of Force application 17. Next, choose the Apply button from the Direction selection box; a downward force is specified for the analysis. After you have selected the edge for specifying the direction, you can flip the direction 18. Specified by choosing the Flip button available in the Graphics screen. 55

Solving The Fe Model And Analyzing The Results After the boundary and load conditions are specified for the model, you need to solve the analysis. After solving, you will get the Total and Directional Deformations due to the given condition. Also, you will get Equivalent Stress, life , and damage. 1. Select the Solution node in the Tree Outline; the Solution contextual toolbar is displayed. Also, the Details of “Solution” window is displayed.

Figure 7. 10 The Details Of Solution Window

2. Choose the Total tool from the Deformation drop-down of the Solution contextual toolbar; Total Deformation is added under the Solution node.

Figure 7. 11 Choosing The Total Tool From The Deformation Drop Down

3. Choose the Equivalent (von-misses) tool from the Stress drop-down in the Solution contextual toolbar; The Equivalent or von-misses stress is the criteria by which the effect of all the directional Stresses acting at a point is considered 1" his helps in finding out whether the model will fail Or bear the stress at that particular point. 4. Choose the life option from the fatigue tool drop-down in the Solution contextual 56

toolbar; life is added under the Solution node. 5. Choose the damage option from the fatigue tool drop-down in the Solution contextual toolbar; damage is added under the Solution node. 6. Choose the Solve tool from the Standard toolbar; the parameters are evaluated 7. In the tree Outline, select Total Deformation to visualize the results; the deformed model is shown in the Graphics screen 8. In the Details of “Total Deformation” window, expand the Results node, if it is not already expanded. Note that the maximum and minimum deformations displayed are respectively.

57

RESULTS

Total Deformations In the Details of “Total Deformation” window, expand the Results node, if it is not already expanded. Note that the maximum and minimum deformations displayed are respectively. 8.1.1 For Medium Steel Alloy

Figure 8. 1 The Values Of Total Deformation Obtained From The Legend Display In Color Bands.

58

8.1.2. For Ni Cr Mo Steel Alloy

Figure 8. 2 The Values Of Total Deformation Obtained From The Legend Display In Color Bands.

Equivalent Stress In the Details of “equivalent stress” window, expand the Results node, if it is not already expanded. Note that the maximum and minimum deformations displayed are respectively. For Medium Steel Alloy

Figure 8. 3 The Values Of Equivalent Stress Obtained From The Legend Display In Color Bands 59

For Ni Cr Mo Steel Alloy Figure 8. 4 The Values Of Equivalent Stress Obtained From The Legend Display In Color Bands.

Fatigue Tool

Graph 8. 1 Strain Life Graphs

60

Life In the Details of “life” window, expand the Results node, if it is not already expanded. Note that the maximum and minimum deformations displayed are respectively.

Damage In the Details of “damage” window, expand the Results node, if it is not already expanded. Note that the maximum and minimum deformations displayed are respectively.

For Ni Cr Mo Steel Alloy Close the existing Mechanical window; the Workbench window is displayed. A body is called to be deformed if its shape is changed temporarily or permanently. The temporary change of shape is known as elastic deformation and a permanent change of shape is known as plastic deformation. In ANSYS Workbench, You can determine deformation in terms of Total and Directional Deformations. Total Deformation is the total change of shape in a given working condition. You can view the Total Deformation induced in any component by using the Total tool from the Deformation drop-down in the Solution contextual toolbar. Directional deformation is the total change of shape in a particular axis, due to given working conditions. You can view Directional deformation by using the Directional tool from the Deformation drop-down in the Solution contextual toolbar. Total Deformation is the summation of all directional deformations produced in a certain region of the model. The following equation describes the Total Deformation: If

Deformation in the X-axis

Ux

Deformation in the Y-axis

Uy

Deformation in the Z-axis

Uz

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Then Total Deformation. U will be given as follows: U = (U 2+ U 2 + U 2) 1/2 x

y

z

The Legend has colors arranged in a band from top to bottom. Depending upon the type of analysis and the parameters evaluated, each color will indicate a different value. A typical Legend displayed when Total Deformation is selected from the Tree Outline. The blue color in the Legend indicates the minimum value of Total Deformation. In this case, it displays 0 which means there is no deformation at that region.

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13. Exit the static structural analysis - Mechanical window

Results From Workbench 16.0 8.6.1 For Medium Steel Alloy

Figure 8. 5 Summary Results

Figure 8. 6 Weight

For Ni Cr Mo Steel Alloy

Figure 8. 7 Summary Results

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Figure 8. 8 Weight

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Results and graphs

Total Type

Weights Deformation

Stress

Material I

10.93

4.82E-06

1.55E-02

Material II

9.7775

4.96E-06

1.55E-02

Table 9. 1 Results

Graph 9. 1 Weight

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Graph 9. 2 Total Deformations

Graph 9. 3 Stress

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CONCLUSION ➢ The Model weight was reduced after change of materials from 10.93 kg to 9.773 kg at a density Kg/m3 from the table 7.1 and 7.2 . ➢ From the above results it is suggest that the design modification was acceptable. ➢ In the working of the engine, the engine generate 10 to 12 torque at beginning it may varies by increase of acceleration. Because of continuously cycle or stokes the crankshaft gets deforms. At a peek of cycles the crankshaft is unable to generate smooth transmission of the power to rear wheel. ➢ In this project we consider the composite material in real time MEDIUM STEEL ALLOY and replace the material with other material name NI CR MO STEEL ALLOY so that the weight and deformations are decreased and life increase. ➢ by analysis the life of the crankshaft is increased ➢ weight was reduced

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REFERENCES 1. Altan, T., Oh, S., and Gegel, H. L., 1983, “Metal Forming Fundamentals and 2. Applications,” American Society for Metals, Metal Park, OH, USA. 3. Ando, S., Yamane, S., Doi, Y., Sakurai, H., and Meguro, H., 1992, “Method for Forming 4. a Crankshaft,” US Patent No. 5115663, United States Patent. 5. Baxter, W. J., 1993, “Detection of Fatigue Damage in Crankshafts with the Gel 6. Electrode,” SAE Technical Paper No. 930409, Society of Automotive Engineers, 7. Warrendale, PA, USA. 8. Borges, A. C., Oliveira, L. C., and Neto, P. S., 2002, “Stress Distribution in a Crankshaft 9. Crank Using a Geometrically Restricted Finite Element Model,” SAE Technical Paper 10. No. 2002-01-2183, Society of Automotive Engineers, Warrendale, PA, USA. 11. Burrell, N. K., 1985, “Controlled Shot Peening of Automotive Components,” SAE 12. Technical Paper No. 850365, Society of Automotive Engineers, Warrendale, PA, USA. 13. Chien, W. Y., Pan, J., Close, D., and Ho, S., 2005, “Fatigue Analysis of Crankshaft 14. Sections Under Bending with Consideration of Residual Stresses,” International Journal 15. of Fatigue, Vol. 27, pp. 1-19. 16. Fergusen, C. R., 1986, “Internal Combustion Engines, Applied Thermodynamics,” John 17. Wiley and Sons, Inc., New York, NY, USA. 18. Guagliano, M., Terranova, A., and Vergani, L., 1993, “Theoretical and Experimental

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