Crank Rocker

Crank-Rocker Estimated time required: ~100 min Experience level: Lower

Weidong Guo, Mileta M Tomovic School of Technology Mechanical Engineering Technology

Topics Covered

•

Creating a new database file

•

Creating Rank-Rocker model Creating parts Creating joints (constrains) Adding motion

•

Simulating model

•

Measuring model

•

Editing measure plot

•

Exporting measure results Exporting data file Exporting video file

Problem Description

In the rank-rocker linkage shown, driving link AB has a counterclockwise angular velocity ω1 = 1 rad/s. the lengths of four links are l1=120mm, l2=250mm, l3=260mm, l4=300mm.

This problem asks for the motion analysis of rocker CD, to determine its angular translation, angular velocity.

Starting MSC.ADAMS from Windows

The Welcome dialog box appears (See next slider).

Creating a New Model

a.

b.

Replace the contents of the Model name text box with crank_rocker_mechanism. Select OK. ADAMS/View interface appears. ( See next slider)

a

b Note: MSC.ADAMS default start working direction to C:\Documents and Settings\Owner\desktop. You can select or create a new direction by click folder icon .

ADAMS Working Interface

Toolbox

Working Area

Setting Up Work Environment Setting Up Units a. b.

c.

Select Settings/Units from the drop down menu. Select Units for Length, Mass, Force, Time, Angle and Frequency in Units Settings dialog box. Select OK.

a

b

c

Note: Here we use defaults units.

Setting Up Work Environment Setting Up Working Grid a.

Select Settings/Working Grid from the drop down menu. b. Set the grid size along X to 350 and Y to 250. Note! You do not need to enter units because ADAMS/View uses the default units if you do not specify them. c. Set the grid spacing for X and Y to 10. d. Select OK.

a

b c

d Note: OK button and Apply button have the same functions. The difference is that by selecting OK button, the dialog box will be closed and Apply button not.

Setting Up Work Environment Setting Icons a. b. c.

Select Settings/Icons from the drop down menu. In New Size text field enter 20. Select OK.

a b

c

Creating Model Creating Crank a. b. c. d. e. f. g.

Click the working area. Press F4 key. The Coordinates window appears. Select link tool in Main Toolbox. Check Length. In Length text field, enter 120. Move the cursor to (0,0,0) position and click. Move the cursor horizontally. When you see a link appears, click. The crank is created and named as PART_2 automatically.

b

c

a

d e

b

Creating Model Renaming Crank a. b. c. d.

Right-click crank (PART_2). Select Part:PART_2/Rename. In New Name text field enter Crank. Select OK.

a c d

b

Creating Model Modifying Geometry of the Crank a. Right-click the crank again. b. Select -Link:LINK_1/Modify. c. In Width text field enter 12, and Depth text field enter 6. Note! You do not need to enter units because ADAMS/View uses the default units if you do not specify them. d. Select OK.

a b

c d

Creating Model

a

Creating Rocker a. b.

Select Link tool in Main Toolbox. Check Length, in Length text field enter 260. Check Width, in Width text field enter 12. Check Depth, in Depth text field enter 6. c. Move the cursor to (300,0,0) position and click. Note! 300 is the length of fix base (i.e. l4=300mm). d. Move the cursor horizontally and then click. e. The rocker is created and named as PART_3 automatically. f. Rename PART_3 as Rocker.

c

b

d

Creating Model Rotating Rocker When the rank is in horizontal position (i.e. AB position shown in figure), the rocker should be in the DC position shown in the figure and not in horizontal position. So the rocker should be rotated about D (300,0,0) point from horizontal position to DC position (counterclockwise rotated 114º).

Creating Model Rotating Rocker a. b. c. d. e.

Select tool in Main Toolbox. Click View Center button. Click the right end of the rocker. In Angle text field enter 114. Select the rocker by clicking the rocker.

e c

Note! The part must be selected before it is rotated and translated. f. Click counterclockwise rotation button. The rocker should be in the position shown in the figure.

f b

a

d

g

Creating Model

a

Creating Link a. b.

c. d. e.

Select link tool in Main Toolbox. Uncheck Length. Check Width, in Width text field enter 12; Check Depth, in Depth text field enter 6. Click the right end of the crank. Click the top end of the rocker. The link is created. Rename it (PART_4) to Link.

d

b

c

Creating Model Creating JOINT_A a a.

Click Revolute Joint tool in Main Toolbox .

b.

In Construction field, select 1 Location and Normal To Grid. Click the left end of the crank. The JOINT_1 between crank and fixed base (ground) is created. Rename JOINT_1 to JOINT_A.

c.

d.

b

d

c

Creating Model Creating JOINT_D a a.

Select Revolute Joint tool in Main Toolbox.

b.

In Construction field, select 1 Location and Normal To Grid. Click bottom end of the rocker. The JOINT_2 between rocker and fixed base (ground) is created. Rename JOINT_2 to JOINT_D.

c.

d.

b

c

Creating Model Creating JOINT_B a a.

Select Revolute Joint tool.

b.

In Construction field, select 2 Bod-1 Loc and Normal To Grid. Click the crank. Click the link. Click the connection point between crank and link. The JOINT_3 between crank and link is created. Rename JOINT_3 to JOINT_B.

c. d. e. f.

d

b c e

Creating Model Creating JOINT_C a a.

Select Revolute Joint tool.

b.

In Construction field, select 2 Bod-1 Loc and Normal To Grid. Click the link. Click the rocker. Click the connection point between link and rocker. The JOINT_4 between link and rocker is created. Rename JOINT_4 to JOINT_C.

c. d. e. f.

e

b c

d

Creating Model Rendering Model

a

a. Click Select tool. Note! The Select tool is also helpful in many other situations. For example, by selecting the Select tool, you can cancel an operation, such as creating an object. You can also clear the selection of any objects. b. Click Render button to render model. c. Click Set the view orientation to Front button. The model can be seen as Fig. a. d. Click Set the View to isometric button. The model can be seen as Fig. b.

c

Fig. a

e d

b Fig. b

Creating Model Adding Motion a. b. c.

Select Rotational Joint Motion tool. In Speed text field enter 180/PI (1 rad/s). Click “JOINT_A” to apply motion to JOINT_A.

a

b

c

Saving Model

a. b.

c. d.

Select File/Select Directory from the drop down menu. Select an existing folder or Make New Folder to save the model. (Here a new folder ‘ADAMS Model’ is made) Select OK. Select File/Save Database from the drop down menu. The file rank_rocker_mechanism.bin is saved in folder ADAMS Model.

b a c

d

Simulating Model

a. b. c. d.

a

Click Interactive Simulation Controls button. In End Time text field enter 6.283. (6.283*180/pi = 360°). In Steps text field enter 100. Click Start or continue simulation button to start simulation.

d

b c

Animating Model

a. b. c.

Click Animation button. Click Animation: Forward button to start animation. Click Step Forward button to animate model for one step.

a

b c

Measuring Model Measuring Angle „ „

Select Marker tool. Click (350, 0, 0) point. MARKER_18 is created.

a

b

Measuring Model

b

Measuring Angle of Rocker a. b.

c.

d.

e.

f. g.

Select Build/Measure/Angle/New from the drop down menu. In Measure Name text field in Angle Measure dialog box, enter MEA_ANGLE_3. Right-click First Marker text field. Select Marker/Pick from the drop down menu. Click the top end of rocker. First Marker text field is filled with MARKER_4. Fill Middle Marker text field with MARKER_3 (the bottom end of the rocker). Put MARKER_18 into Last Marker text field. Select OK.

d e f

c

g a

d

e

f

Measuring Model

b

Measuring Angle of Crank a. b.

c. d. e. f.

c d e

Select Build/Measure/Angle/New from the drop down menu. In Measure Name text field in Angle Measure dialog box, enter MEA_ANGLE_1. In First Marker text field enter MARKER_2. In Middle Marker text field enter MARKER_1. In Last Marker text field enter MARKER_18. Select OK.

d

c

f a

e

Measuring Model

c

Measuring Angular Velocity of Rocker a a. b. c.

d. e. f.

Right-click the rocker. Select Part: Rocker/Measure from the drop down menu. In Measure Name text field in Part Measure dialog box, enter MEA_ANGULAR_VELOCITY_3. In Characteristic text field, select CM angular velocity. From Component list, select Z. Select OK.

d e

b

f

Post Processing Measure Results Creating Plot a.

b. c.

Click Plotting button in Main Toolbox dialog box. ADAMS/PostProcessor window appears. Select Source to Measures. From the right of the dashboard, set Independent Axis to Data. The Independent Axis Browser appears (See next slide).

a

b

c

Post Processing Measure Results

d

Creating Plot d. e.

f. g.

From the Measure list, select MEA_ANGLE_1. Select OK. The Independent Axis Browser disappears. From the Measure list, select MEA_ANGLE_3. Select Add Curves. The measure result of MEA_ANGLE_3 vs. MEA_ANGLE_1 appears.

e

f

g

Post Processing Measure Results Editing Plot a. b. c. d.

e. f.

From the treeview, double-click page_1. a Double-click plot_1. Click haxis. In the property editor, select the tab Format. Uncheck Auto Scale. Change 400 to 360 in Limits text field.

b

c

d e f

a

b

c

Post Processing Measure Results Editing Plot g. h. i. j. k.

In the property editor, select the Labels. In Label text field, enter Angle 1 (deg). From the treeview, click vaxis. In the property editor, select the Labels. In Label text field, enter Angle 3 (deg).

i

g j h k

b

c

Post Processing Measure Results d

Exporting Results a. b. c. d. e. f.

Select File/Export/Numeric Data. The Export dialog box appears. In File Name text field, enter angle3_angle1. In Results Data text field, enter *. Which *? window appears. Select first three lines. Select OK. Select OK.

e

b c a

f

Post Processing Measure Results Reviewing Results Open file angle3_angle1 file. The numeric data of measure results is shown as figure.

Post Processing Measure Results Creating AVI File a a. b. c. d.

Right-click Page Layout button. Select 2 Views, side by side page layout. Click right view. Select View/Load Animation. The model appears in right view (See next slide).

d

c

b

Post Processing Measure Results Creating AVI File e d. e. f.

g.

h.

Selcect ISO view. Select Dynamic zoom to zoom the model. Select Record card. In File Name text field, enter crank_rocker_mechanism. Click Record ready button. The Record ready button is pushed down. Click Play Animation button. The animation is recorded into the file: crank_rocker_mechanism.

d

h g f

Post Processing Measure Results Viewing AVI File d

e Open the file crank_rocker_mechanism.avi and play it.

h g f

The End

Download: http://www.purdue.edu/discoverypark/PLM/SME/crank_rocker_mechanism.bin