Infinite Fatigue Life: Challenges and Solutions in Measuring Rubber's Endurance Limit

Rubber components must sometimes be developed to survive undamaged for an indefinite fatigue lifetime.  Since developers always work with finite testing resources, it may seem impossible experimentally to determine the cyclic load limit that can be sustained indefinitely.  We discuss here some approaches to this problem that have been used in the past, and their strengths and weaknesses.  We then describe an approach that we have recently implemented that allows developers to measure this important parameter.