| Under the global background of less energy sources and rigorous law of environment conservancy, the technology and the intensification coefficient of heavy duty truck improve quickly, which improve the strengthen index, lead to the component of frame such as mechanical load increasing. The frame is the skeletons and basis of whole truck, the deformation and stress of which in work situation directly determine the overall performance of the van.In this study, use UG software to establish the finite element model of340T truck frame and put the finite element model into ABAQUS software for analysis.while, the truck often experience with four conditions, bending,twisting, emergency brake and emergency turn. In the four typical working conditions, the bending and twisting is more harmful to frame, therefore, the finite element analysis in these working condition were carried out to get the frame of deformation and stress distribution. In addition, by means of NI equipments, the stress testing experiment has been done to verify the correctness of the finite element analysis. Then,compare the results of finite element analysis with the test results to verify the reliability of the analysis. After the static analysis, the free modal analysis of the frame was also done to study the vibration on the frame structure. And then combine the stress results obtained by ABAQUS software and the time load spectrum, use the fatigue analysis software N-SOFT to study life of the frame.The analysis results show that:in twisting situation of the frame the stress and displacement is bigger and the greatest stress reaches223MPa, located in middle frame the beam. In the front spring of the steel bearing place, stress is bigger, the stress reaches100MPa. Overall, the stress of the frame is not great. The frame of the material yield limit for350Mpa, but the maximum stress of frame is less than yield limit. So the frame structure is more reasonable and ideal, but in the use process, the frame reverse the occurrence of working conditions should be avoided. From the results of the stress test, certain deviation can be found. But it largely reflects the frame strain characteristic and the stress distribution, so that finite element model is reliable. The free modal analysis of the frame indicates natural frequency of frame having not avoided the outstanding excitation frequency. Through optimization of the original frame, the results show that natural frequency of the new frame and engine commonly used operating frequency haven't resonance point exists.so the optimization is more reasonable.Through the analysis of the fatigue analysis result, frame beam and longitudinal middle point of contact and suspension frame and the connection point is fatigue damage points. The minimum life appeared among the longitudinal beam and the contact point, after1010cycle was damaged. But the result is far greater than the service life of the vehicle, therefore, the frame has been optimized, and the optimal results meet with GB/T16877-1997article5.3of the small tractor use fixed number of year which shall not exceed10years (or total work12000hours), and thus the plan in a certain extent meet the required strength, and the scheme than the original plan reduce frame the weight of90.5Kg. |
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