| Compared to user’s road test and proving ground test, the laboratory roadsimulation test is more efficient and quick. This topic comes from “the simulation anddevelopment for a car sub-frame fatigue test-bed” project of a famous domesticautomobile joint venture. There is a great difference between sub-frame Roadsimulation test-bed’s the test data and real vehicle road test’s data.Based on this background, this paper aims to study the sub-frame’s roadsimulation test-bed system, which uses finite element method and Structuralimprovement methods as Theoretical basis. The goal is to improve the current roadsimulation test rig by finite element simulation analysis and establish an indoor roadsimulation test-bed that its result is near to the proving ground test when simulating asub-frame. In order to achieve this goal, this paper makes a lot of work. the specificcontent is as follows:Firstly, we learn the related knowledge of finite element, including its basic idea,Analytic process and methods. Then I thoroughly studied the process of establishingfinite element model and the difficulties. On this basis, according to the geometricmodel of the sub-frame road simulation test-bed system that the company provides,finally I established the finite element model of sub-frame road simulation test-bedsystem with Hypermesh software. Then, according to the actual load and constraintcondition of the sub-frame road simulation test-bed system, I carry out its staticstrength analysis. I obtain the stress distribution map by calculation and analysis;preliminary verify the accuracy of the established finite element model, laying afoundation for further research.Secondly, learned the related knowledge of dynamic simulation and studied theserious of problems about simulation analysis. After this, based on the original testrig’s configuration and loaded situation, we translated the collecting test signal intofield, and lead into MSC.PATRAN to make transient response to sub-frame road simulation test-bed, get the stress time curves for signal output. Compare thesimulation results with sub-frame test-bed’s result, by continuous adjustment, wefinally make sure that finite element model established is capable of correctlysimulating the current test-bed’s working condition, ensure the accuracy of the model.Thirdly, understand the relevant structural improvement methods. Then, referringthe similar problems of other literature research method, and based on the actualcondition, choose the proper ways to improve the model. Through the analysis andcalculation, finally get the model of the sub-frame road simulation test-bed which cancorrect simulate the proving ground test.Finally, based on the improved test rig, according to the force of real vehicle test,make Life Fatigue Analysis to the sub-frame with MSC. Fatigue software, and get itsFatigue life distribution map. Through analysis of the fatigue strength of whole, foundthat the possible dangerous point, provide certain reference basis for the company’ssteel welding sub-frame further improvement.In this paper, under the condition that great difference exists between sub-frameroad simulation test-bed’s results and the real vehicle road test results, Throughsimulation and calculation, improve the sub-frame road simulation test-bed, determinethe shape and size of materials. When carry out the dynamic loading fatigue test in thesub-frame road simulation test-bed, the fatigue damage of points on the sub-frame isthe same with the road test of EVP, reproduces the vehicles’ real riding condition ofthe sub-frame, reached the purpose of simulating road test by the sub-frame roadsimulation test-bed. This research shortens development the test cycle of sub-frame,reduces the test cost, improve the efficiency and save cost of achieving thelocalization of the steel welding sub-frame. |
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