Development of Accelerated Durability Tests for Commercial Vehicle Suspension Components 2005-01-3565

In this paper, we describe the development of multi-axis, accelerated durability tests for commercial vehicle suspension systems. The objective of the exercise is to design accelerated durability tests that have well-defined correlation with customer usage. The procedure starts with a definition of the vehicle's duty cycle based on the expected operational parameters, namely: road profile, vehicle speed, and warranty life. The second step is determining the durability proving ground test schedule such that the accumulated pseudo-damage (based on spindle loads) is representative of the vehicle's duty cycle. The third step in the process is developing a multi-axis laboratory rig test for the suspension system, such that the accumulated damage in the proving ground is replicated in a compressed time frame. The final step in the process is to design a single-axis, accelerated durability test for the suspension subsystem, such that the damage content in selected areas of interest is equivalent to that of the multi-axis rig test. The last step can be accomplished only if the loading is nearly proportional, such that the stress state at each of the critical locations can be represented by a uni-axial state of stress. We demonstrate the procedure through an example involving a trailing arm used in the front suspension of a class-8 tractor-semi-trailer combination, the duty cycle of which corresponds to a regional-haul application in the Midwestern states.