The Design and Processing of Cast Aluminum Wheels for Impact Performance

This paper examines some processing and design factors which affect the impact performance of cast A356 aluminum wheels, as measured by SAE J175 (13° lateral impact test). Wheel impact performance is discussed with respect to two different failure criteria: (a) failure due to cracking in the hub or spokes, and (b) failure due to total loss of tire air pressure. The general influence of heat treatment on impact behavior is described, and then examined in light of a particular wheel example. Peak-aging heat treatments are compared with underaging treatments, in terms of the critical link between processing, material properties of strength and ductility, and their influence on wheel impact behavior. The effects of the rim flange geometry and other design features are then explored, and illustrated with examples. Evaluation of wheel designs using dynamic, nonlinear FEA to calculate plastic strain is addressed throughout; and the use of high-speed video for analyzing failures and identifying crack initiation sequences is described.