Optimizing Design of the Bolted T-Joint Part of the Steel-Aluminum Body Frame of an Electric Bus

This work focuses on the optimizing design of the bolt joint of the steel-aluminum body frame of an electric bus. First, a finite element (FE) model is established for the T-joint part of the bus body frame and nonlinear quasi-static analysis is carried out by HyperWorks to understand the effect of the structural parameters of the bolt joint on the concerned performance such as strength and stiffness. Five design variables those are bolt diameter, center distance between the bolts, the thickness of the connecting part, the area of the ribbed plate of the connecting part and the thickness of the connected aluminum part are introduced for optimizing. The maximum deformation and the maximum stress of the joint are chosen as the indicators. Then the function relations between the performance indicators and the design variables are formulated by the polynomial regression analysis method with the data obtained from 25 groups of orthogonal experiment. Finally, a multi-objective optimizing design model is established aiming to make the maximum deformation and the maximum stress of the T-joint to be minimal as possible. The optimizing model is solved by the adaptive simulated annealing (ASA) algorithm which can well deal with the mixed design variables. The results demonstrate that the maximum stress has been reduced by 71.81% in the case that the maximum deformation varies very less with the optimized bolt joint design scheme. Therefore, the proposed optimizing design scheme for the T-joint of the steel-aluminum body frame of the electric bus is believed to be feasible.