Abstract

Weld of mining dump truck (MDT) frame is prone to fatigue damage due to the unreasonable local structure of cavity with stiffeners. However, there are considerable limitations in the engineering implementation of both size and topology optimization of the frame. Therefore, a discrete optimization method for the structure composed of cavity with stiffeners like MDT frame joint is proposed. Considering the possible early failure, the joint with failure-prone welds is extracted from the frame as the research object. The structural stress of every node on the weld line defined by the Verity method is analyzed and the structural stress spectrum of each weld node is obtained. Then, the ground structure of the frame joint is established with every possible stiffener so the joint structure can be defined by the birth or death status of every stiffener. The constraint of joint mass is transformed into the constraint of the number of stiffeners to improve the optimization model for feasibility and efficiency. By the utilization of the multi-island genetic algorithm (MIGA) without gradient information, the anti-fatigue optimization of MDT frame joint with discrete design variables is realized. Under the premise of maintaining manufacturability, the minimum fatigue life of the welds on the optimized frame joint increases significantly while the weight of the joint is lessened.

摘要

矿用自卸车（MDT）车架的焊缝由于带加劲肋的空腔局部结构不合理，容易产生疲劳损伤。然而，在框架的尺寸和拓扑优化的工程实施中存在相当大的限制。为此，提出了MDT框架节点等加劲肋型腔结构的离散优化方法。考虑到可能的早期失效，从框架中提取容易失效焊缝的接头作为研究对象。对Verity方法定义的焊缝上各节点的结构应力进行分析，得到各焊缝节点的结构应力谱。然后，用每个可能的加劲肋建立框架节点的地面结构，从而可以通过每个加劲肋的出生或死亡状态来定义节点结构。将节点质量约束转化为加强筋数量约束，提高优化模型的可行性和效率。利用无梯度信息的多岛遗传算法（MIGA），实现了离散设计变量MDT框架节点的抗疲劳优化。在保持可制造性的前提下，优化后的车架接头焊缝的最小疲劳寿命显着增加，同时接头重量减轻。实现了离散设计变量MDT框架节点的抗疲劳优化。在保持可制造性的前提下，优化后的车架接头焊缝的最小疲劳寿命显着增加，同时接头重量减轻。实现了离散设计变量MDT框架节点的抗疲劳优化。在保持可制造性的前提下，优化后的车架接头焊缝的最小疲劳寿命显着增加，同时接头重量减轻。