随机载荷作用下扭力轴耐久性优化设计

Durability-based Design Optimization of Torsion Shaft under Random Loading

利用多工况下扭力轴随机载荷时间历程,编制了8级扭矩谱;考虑材料性能、疲劳影响系数等因素的分散性,应用疲劳可靠性理论与方法,建立了耐久性分析模型,计算了疲劳寿命与耐久度。在此基础上,以车辆行驶6 000 km时扭力轴的耐久度作为目标,以刚度可靠性、结构尺寸等为约束,构建基于耐久度的结构优化模型;提出了以双循环策略处理耐久性目标、单循环策略处理可靠性约束的优化求解方法,既保证了目标的计算精度,又提高了优化计算的效率。优化结果表明:扭力轴在满足刚度可靠性等约束的条件下,耐久度得到明显的提高。

The eight-level spectrum of torque is established by using the stochastic loading history of torsion shaft of military vehicles on various types of standard road surface.In consideration of the randomness of factors such as material performance,and fatigue influence coefficient,etc.,the durability model is built by applying fatigue reliability theories.An optimization model,which takes the maximum durability of torsion shaft as the objective function when a vehicle travels for 6 000 km,is built based on the constraints such as rigidity reliability,structure dimension and so on.The approach that introduces the double-loop strategy for durability object conversion and the single-loop strategy for reliability bounds conversion is presented for this optimization model.The high computing accuracy of object value and the high efficiency of optimal computation are obtained.The results show that the durability of torsion shaft is improved obviously.