Effects of loading rates on durability life of a part for random loads

Abstract

In the current scenario of fierce competition, manufacturers are under tremendous pressure to launch defect free products at the earliest. Cutting down time at every stage of product development is the need of the hour and testing is no exception. Testing and validation in the automotive domain is of immense importance as any small failure can also lead to catastrophic consequences. Continuous emphasis is in place to accelerate the tests across the industry. Multiple methods have been developed over years to reduce the test time. Traditionally, random load simulation, block load cycles and constant amplitude load cycles have been used. Random loads do simulate the loads under actual conditions, maintain the phase differences and considers the mean load and sequence effects but is highly time consuming. Block cycles do reduce the test time but doesn’t consider the sequence effects though the mean load effects are considered marginally. Constant amplitude cycles give the most test acceleration but don’t consider the effects of mean loads and sequence. In this study, an attempt is made to apply the random loads with increased loading rates to study the effects. A part has been strain gauged and strain vs load for different loading rate has been plotted. Strain life prediction has also been carried out for different loading rates. This has been done to accelerate the test still maintaining the mean load and sequence effects.