A Computational Methodology for Multi-Objective Fatigue Life Optimization of Welded Brake Flange on Full Beam Axles

Weld failure of a brake flange can put a driver’s life at risk. Two critical loading situations-torsional loading and vertical beaming loading-can result in brake flange failure. Two corresponding laboratory tests have been performed to ensure that the brake flanges pass the minimum standard requirement. The first is a brake reaction test, which is conducted in a situation that replicates the sudden braking operation of a vehicle. For this test, length, size, and penetration depth of the weld are critical parameters for determining the ability to prevent braking load failure. Among these factors, the length is the most crucial. The second test is a vertical beaming test, which is done in a condition that mimics the situation where a vehicle encounters a pot hole. Contrary to the previous test, an increased weld length can be detrimental in this case when the weld is moved to a higher stress location. Weld location and position can play an important role in maximizing the fatigue life to prevent such brake flange weld failures. In this paper, a computational approach is proposed for obtaining the optimal parameters to satisfy both tests. The weld life prediction is performed using a traction-structural stress method. A two-stage parametric modeling approach is suggested to perform the optimization process. The first stage determines the viability of uninterrupted/continuous weld to meet the two tests by positioning it along the inward and/or outward side of the brake flange. The second stage involves determining the optimal weld length by using a Design of Experiments (DOE) approach. When the length and positioning of the weld are optimized, components’ performance can significantly improve and the need for experimental testing is largely reduced.