| With the rapid development of logistics industry, as an important tool of freight, semi-trailer towing vehicle plays an important role. Frame as a very important bearing part, which bears a lot of complex loads from random load, load, related accessories load and so on. So the semi-trailer tractor frame will directly affect the normal work, safety of semi-trailer tractor, reliable and durable. The semi-trailer towing vehicle’s performance not only reflects in strength and stiffness, but also satisfies the fatigue reliability of the frame design. This paper takes the semi-trailer tractor frame as the research object, bases on the platform of computer aided design, fatigue reliability theory, the theory of finite element analysis and optimization technology, to evaluate the fatigue reliability of the frame, and on the basis of meeting the stiffness and strength of the frame appropriate to improve the fatigue life of the frame. This article main contents are as follows:Building semi-trailer tractor frame finite element analysis model and its boundary conditions. To check the stiffness and strength of the frame under the working condition of bending, reversing, emergency braking, urgent turning conditions and so on. And then analysis the frame of modal characteri stics. Finally, to find out the weak part of the semi-trailer tractor frame, and the semi-trailer tractor frame of the top ten order modal frequencies and corresponding modal vibration mode.First, The dynamics model of the frame is built to run on C-class road in Adams. It is used to Calculate the dynamic external load which is excited by vertical displacement in the joint of Suspension and frame and this load spectrum can be used in analyzing the fatigue life of the frame. In fatigue reliability analysis soft of Fatigue, according to the used material performance in the frame, it can simulate the s-n curve of the frame material, and then, through the quasi-static Fatigue life analysis method to calculate the Fatigue life of frame under the worst conditions. Then the multi-objective optimization based on particle swarm algorithm is proposed, and the frame of the vertical and horizontal beams are used as design variables, and the lower stress and lighter quality are the optimization goals, which are used to select reasonable frame beam of reasonable size. The optimized sizes of the frame should be checked the intensity and stiffness under the condition of the corresponding modal characteristics. And the fatigue life analysis of the frame should be analyzed again and the result uses to compare with the fatigue life of the original design size frame. Lastly, it can be find that the optimized frame has a greater strength, lighter quality and the frame fatigue life is increased by 4.4% or so.This topic is relatively comprehensive and system in analyze the semi-trailer tractor frame about the problem in the fatigue life. This analysis method can be used to solve the problem of anti-fatigue design and it also can be used to provide a design reference for others practical engineering problems. |
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