考虑疲劳损伤约束的车辆焊接结构轻量化设计

针对车辆焊接结构轻量化与疲劳寿命问题,提出考虑焊缝疲劳损伤约束的轻量化设计方法.采用国际焊接学会(IIW)的焊接接头与部件的疲劳设计评估标准,基于迈纳尔损伤累积理论,预测焊缝的疲劳累积损伤;以结构质量最小为目标,在应力、位移等常规约束基础上,加入焊缝疲劳累积损伤约束,建立了车辆焊接结构的轻量化模型.研究基于有限元分析的结构轻量化优化设计策略,采用试验设计方法对设计空间合理抽样,以样本数据建立近似响应模型,采用数值优化算法寻优,提高复杂工程问题优化计算的效率.利用该方法对某焊接构架进行了考虑焊缝疲劳损伤约束的轻量化设计,采用均匀设计法对14个设计变量进行50次试验,以样本数据及响应值建立径向基神经网络近似模型,采用序列二次规划算法进行优化设计,质量减轻12.5%.对实例的计算证明该方法的可行性与实用性.

Light Weight Design of Welded Vehicle Structure with Fatigue Damage Constraints

Considering the light-weight and fatigue life problems of the welded vehicle structure,a light-weight design method with weld fatigue damage constraints is presented.Using the International Institute of Welding(IIW) standards for assessing the fatigue of welded joints,based on the Miner cumulative damage theory,the accumulated fatigue damages of welded joints are predicted.Adding weld fatigue damages constraints to conventional constraints such as stresses and displacement and aiming at the minimum mass of the vehicle structure,the light-weight model of the welded vehicle structure is designed.The optimization strategy based on Finite Element Analysis(FEA) is studied.Design of Experiment(DOE) is used to provide sample points,and the approximation model for FEA is constructed.The numerical optimization algorithm is followed to seek the optimum solutions.This strategy enhances the optimization computation efficiency.Using this method the light-weight design of the welded bogie frame is carried out.The uniform design method is used on 14 design variables for 50 tests.The Radial Basis Function(RBF) Neural Net Model is constructed on the basis of the sample data.The sequential quadratic programming algorithm is applied,reducing the mass by 12.5% with fatigue damage constraints.The practical example proves the feasibility and practicality of the proposed method.