Research On Fatigue And Wear Reliability Of 18Cr2Ni4WA Steel

For 18Cr2Ni4 WA steel,there are the advantages of high strength,high toughness and good hardenability.It is widely used in key components of the large-scale machinery and equipment,such as gears.In this situation,it has great significance in reliability analysis of 18Cr2Ni4 WA steel.Fatigue and wear failure modes are common in mechanical parts reliability.This thesis researchs on the reliability of 18Cr2Ni4 WA steel by the combination of numerical simulation and test.Firstly,the application of 18Cr2Ni4 WA steel and the development of product reliability engineering were described.The significance of researching on the reliability was summarized.The current research situation of reliability at home and abroad was reviewed.The research ideas of fatigue and wear reliability were put forward,and the research contents were presented.Secondly,for fatigue and wear failure modes,combined with the reliability analysis theory,the uncertainty of fatigue and wear was clarified and the calculation process of reliability index was presented.In order to solve the problem of small samples data with strong correlation,a reliability analysis method based on F inspection partial least squares regression in response surface was proposed.The effectiveness of the improved response surface methodology proposed in this thesis was verified by an example.Thirdly,combined with the finite element technique,the response surface methodology and the Monte Carlo method,the reliability for fatigue and wear was analyzed.The material properties and the load are random.According to the improved response surface methodology,the function between fatigue life and random variables was built by the model of fatigue life prediction and the function between the wear amount and random variables was built by the Archard model.The Monte Carlo method was used to simulate the reliability value of fatigue and wear.The influence of each random variable to the response was compared by the reliability sensitivity analysis.Then,the assessment methods of the fatigue and wear reliability were developed.Based on the data characteristics of fatigue life and wear amount,different distribution models were described.The test data of fatigue life is devided two kinds of life-time data and zero-failure data.Respectively,the Pigeon-inspired algorithm based on similarity improvement and the Bayes methods of the fatigue reliability were presented.On the assumption that the wear amount was considered the normal distribution,the random reliability calculation and the fuzzy reliability calculation process were given.Finally,the reliability test and the evaluation system were designed.The reliability test plan of the contact fatigue,bending fatigue and wear was designed separately,and the reliability test was completed.The reliability was assessed according to the mentioned assessment menthods and the test data.The results show that it is feasible to research on the fatigue and wear reliability of 18Cr2Ni4 WA steel by the improved response surface methodology.The MATLAB GUI is adopted to design the reliability evaluation system of 18Cr2Ni4 WA steel to build a communication platform between users and computers.The evaluation system can also be applied to the reliability assessment of other materials or products.