| Considered as the main transport vehicle in large open mineral sites,the domestic market of the mining dump trucks has long been occupied by imported products.In order to promote the research and development of independent products,the mining dump truck is classified as major technical equipment by State Congress in key areas.Therefore,the researches on the mining dump truck by advanced technology are in line with national policy requirements,which could enhance the major equipment manufacturing level,and ensure the normal national energy and mineral mining,and have important economic and engineering application value.The mining dump truck runs on the mine road surface year after year,so that the structural performances of this truck have higher requirements under poor working conditions.Especially the key component A-type frame,it will affect the quality and safety of the vehicle because of the early fatigue cracks.Therefore,it's necessary to study the A-type frame's fatigue life.Meanwhile,study in recent years shows that stress below fatigue limit could also cause damage,but the traditional way could not take it into account.So the way to study structural fatigue life with the use of fuzzy theory is considered more in line with the objective reality of things.Meanwhile,with the improvement of gradually mature simulation technique,the researches on the vehicle and engineering equipment by finite element analysis and multi-body dynamics analysis become quite common.However,these techniques combined with structural optimization and fuzzy theory are rarely utilized in the off-highway mining dump truck.For the special structure and working conditions of one domestic mining dump truck,this paper combines experimental work and the numerical simulation technology with fuzzy theory to research the A-type frame's fatigue performances.This paper mainly focuses on:1.Three-dimensional model and finite element model of frame,A-type frame and rear axle housing are established.By the road test,the stress distributions of key components are obtained.Then stress analysis of the three key components under test condition is simulated,and the accuracy of frame,A-type frame and rear axle housing is testified by comparison of stress simulation results and test results.2.The rigid-flexible coupling dynamics model of the mining dump truck involving multiple flexible bodies of frame,A-type frame and rear axle housing is built.The model's accuracy is testified by the comparison of the road acceleration test and the multi-body dynamics analysis.Meanwhile,a cyclic working condition which is more appropriate is built according to the characteristic of mine road and operation of the truck.These works provide the basic data for the load spectrum of A-type frame and fatigue life prediction.3.After modified according to the characteristic of A-type frame,the component S-N curve is gained on the basis of material S-N curve obtained by fatigue life test.Afterwards,fatigue life prediction of A-type frame based on nominal stress method is conducted,then the stress time history of fatigue critical position is extracted and classified.Finally,a new membership function is presented,and it is used in the fatigue life prediction of A-type frame based on fuzzy theory.4.The topology optimization model of A-type frame is built,and minimum mass is regarded as the optimization objective in the optimization.Considering the fuzziness of fatigue damage,this paper transforms design fatigue life into constraint stress in the optimization.After topology optimization under multiple loading cases,the new A-type frame is built according to the optimization result.The analysis of new A-type frame indicates that it not only improves the fatigue life but also achieves lightweight. |
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