| The semi-trailer is a main vehicle type in logistics transportation. Because it has huge volume, large load capacity, and it is often in high speed running state, truck manufacturers and customers regard it as star vehicle. The frame is the main load-carrying member of components of semi-trailer, and fatigue failure and damage are likely to happen in frame due to alternate loading effect on the semi-trailer. With development and fulfillment of CAE in technology, based on finite element theory, fatigue theory of reliability and optimization design theory, fatigue life and optimal design of frame were analyzed by finite element analysis software and fatigue analysis software, allowing it to meet strength, stiffness and reliability needs, meanwhile attaining lightweight design goal.Taking6×2semi-trailer as research object, its fatigue life and optimal design of frame were analyzed, then fatigue failure position was located, fatigue life was forecasted in order to test if the frame agrees with safe life demanding, finally, size optimization and lightweight design of the frame were carried out.To begin with, according to the semi-trailer and its frame design parameters, structural design and modeling of frame were made, and components and whole three-dimensional models of frame were built by using Pro/E. The whole three-dimensional model should be imported to Hypermesh software, static analysis was executed by finite element model of the frame under the condition of bend and torsion full load, then constraint and free mode analysis were made for the frame. Secondly, Finite element analysis results should be imported to FE-SAFE software, by combining loading of semi-trailer, fatigue type and material parameters of frame, we chose nominal stress method and Miner linear cumulative damage rule to analyse fatigue of frame. The fatigue life was estimated and fatigue damage positions were illustrated by fatigue life nephogram and safety factor nephogram. Finally, size optimization was carried out for frame, so that the frame should meet lightweight design requirement. Static and dynamic analysis and fatigue life analysis were once again made for optimized frame, to validate static property, dynamic property and fatigue reliability.The results of analysis showed that the optimized frame mass was7.74%less than before optimization, fatigue life completely accords with fatigue safe-life demand, fatigue damage locations were bolster and longitudinal beams joints, knowledge and method which are involved in this paper can be used as some references for designing frame of truck. |
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