Virtual Testing: Fatigue Life (S-N Curves) Simulations for Commercial Vehicle Axle Components

Abstract

Current trends in vehicle development, including both automotive and commercial vehicles, are characterized by short model life cycles, reduced development time, concurrent design and manufacturing development, reduced design changes, and reduced total cost. All of these are driven by customer demand of higher load capacity, reduced weight, extended durability and warranty requirement, better NVH performance and reduced cost. These trends have resulted in increased usage of computational simulation tools in design, manufacturing, and testing, i.e. virtual testing or virtual prototyping. This paper summarizes our work in virtual testing, i.e. fatigue life simulations using computational fracture mechanics for commercial vehicle axle gearing development. First, fatigue life simulation results by using computational fracture mechanics CRACKS software were verified by comparing with gear teeth bending fatigue test data and three point bending fatigue test data. Then the CRACKS program is used to evaluate the effect of various factors on bending fatigue life S-N curves computationally, such as steels with different alloy contents, residual stresses from standard shot peen, high intensity shot peen, ultrasonic impact process, and laser shock peen, initial defect size, steel properties such as fracture toughness and crack growth threshold values. The computational mechanics tool was effective and allowed us to conduct design optimizations as well as to reduce prototype testing and reduce design cycle time.