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 Reliability and mechanical design

Lemaire, Maurice (French Inst of Advanced Mechanics and Blaise Pascal Univ) Source: Reliability Engineering & System Safety, v 55, n 2, Feb, 1997, p 163-170 ISSN: 0951-8320 CODEN: RESSEP Publisher: Elsevier Science Ltd Abstract: A lot of results in mechanical design are obtained from a modelisation of physical reality and from a numerical solution which would lead to the evaluation of needs and resources. The goal of the reliability analysis is to evaluate the confidence which it is possible to grant to the chosen design through the calculation of a probability of failure linked to the retained scenario. Two types of analysis are proposed: the sensitivity analysis and the reliability analysis. Approximate methods are applicable to problems related to reliability, availability, maintainability and safety (RAMS). (12 refs.) Ei controlled terms: Reliability theory - Machine design - Probability Sensitivity analysis - Reliability - Availability - Maintainability - Accident prevention Uncontrolled terms: Mechanical design - Reliability analysis Classification Code: 922.2 Mathematical Statistics - 601 Mechanical Design 922.1 Probability Theory - 921.6 Numerical Methods - 913.5 Maintenance Database: Compendex

 Failure analysis of diesel engine intake valve Goksenli, Ali (Faculty of Mechanical Engineering, Istanbul Technical University); Eryurek, Barlas Source: Key Engineering Materials, v 385-387, 2008, p 29-32 ISSN: 1013-9826 CODEN: KEMAEY Publisher: Trans Tech Publications Ltd Abstract: In this study failure analysis of a mini van diesel engine intake valve is analyzed in detail. Failure occurred at the groove of the valve. First mechanical and chemical properties of the valve are determined. After visual investigation of the fracture surface it is concluded that fracture occurred due to fatigue. Damaged valve, valve seat, cylinder block and piston surface is investigated and construed. Failure constituted 300 kilometers after the rectification of the engine. Therefore rectification and assembly steps of valve and engine parts are analyzed in detail. Considering assembly, design and working conditions of the engine, stresses occurring at the failure surface are calculated. Endurance limit and fatigue safety factor is determined. Because

of high fatigue safety factor, reasons for failure are investigated and effects causing stress increase at groove of the valve are established. These effects are faulty assembly of the valve and valve seat causing a high impact effect. In conclusion effect of impact ratio on stress increase is explained. (4 refs.) Ei controlled terms: Failure analysis - Chemical properties - Diesel engines - Diesel locomotives - Embankment dams - Engines - Mechanical properties - Quality assurance - Reliability - Safety factor - Stresses Valves (mechanical) Uncontrolled terms: Faulty assembly - Impact ratio - Valve - Fatigue safety factors - Valve seats - Engine intakes - Engine parts - High impacts - Fracture surfaces - Visual investigations - Endurance limits Failure surfaces - Cylinder blocks - Working conditions Classification Code: 408.1 Structural Design, General - 421 Strength of Building Materials; Mechanical Properties - 423 Non Mechanical Properties and Tests of Building Materials - 441.1 Dams - 601.2 Machine Components - 612 Engines - 612.2 Diesel Engines - 617.3 Steam Engines - 619.1.1 Pipe Accessories - 619.2.1 Tank Accessories - 652.1 Aircraft, General 654.2 Rocket Engines - 662.1 Automobiles - 682.1.2 Locomotives - 801 Chemistry - 913.3 Quality Assurance and Control - 914.1 Accidents and Accident Prevention - 921 Mathematics - 922.2 Mathematical Statistics 931.1 Mechanics - 951 Materials Science