| At present,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 localization of the dump truck and large tonnage, 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 not only in line with national policy requirements, which could enhance the major equipment manufacturing level, but also have important engineering application value and economic benefits.Working environment of the mining dump truck is complex,which runs on the poor mine road surface year after year.The random vibration generated by the mining dump truck under random excitation of road surface will cause the fatigue failure of dump truck components,especially the key component A-type frame. A-type frame is welded by steel plates, in order to ensure the safe use of the vehicle, it is very important to accurately predict the fatigue life of the welded joint of A-type frame.Because the operation process is difficult to be accurately controlled, there are some uncertainties about the quality of the welding seam. Production of mining dump trucks is small, in the actual welding, because of cost control and worker level and other factors, there are also uncertainties in the selection of plate thicknesses and the layout of weld positions. These uncertain factors have influence on the fatigue life of the welded joint of A-type frame, combining the test and structure optimization design and uncertainty related theory, the mining dump truck was studied.For the special structure and working conditions of one domestic mining dump truck, this paper combines experimental work and the uncertainty theory to research the A-type frame’s fatigue performances. At the same time, the anti-fatigue design of A-type frame and the risk position of welding seam are studied. This paper mainly focuses on:1. Three-dimensional model and finite element model of A-type frame are established. By the road test, the stress distributions of key components are obtained.Then stress analysis of the key component under test condition is simulated,and the accuracy of A-type frame is testified by comparison of stress simulation results and test results.The rigid-flexible coupling dynamics model’s accuracy is testified by thecomparison of the road acceleration test and the multi-body dynamics analysis.Meanwhile, The load spectrum of the A-type frame is obtained by kinetic analysis.2. Based on strain controlled fatigue life of weld test, the material ε-N curve of A-type frame is obtained. In the course of welding, there are various kinds of defects or uncertainties. According to the material cyclic stress-strain curve and ε-N curves of the fatigue life test, considering the influence of the uncertainty characteristic of weld fatigue parameters, the material parameters are processed by the interval uncertainty.Based on the uncertainty characteristic of weld fatigue parameters, the fatigue life of A-type frame is analyzed.3. In this paper, the fatigue parameters are considered as interval variables. At the same time, the thickness of the A-type frame is chosen as the design variable, The quality and life of the structure are as the optimization objectives. The anti-fatigue design model of A-type frame is established.4. Based on the results of anti-fatigue design of A-type frame, it is found that the fatigue life of the local weld is low. In this paper, considering the optimal design of the weld position, the fatigue parameters are used as the uncertain variables to seek suitable weld positions. |
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