A practical, universal method for predicting the fatigue life of elastomeric components—Bubble inflation and the concept of dynamic stored energy

Chapter 14 is part of a duology. The chapters describe research conducted over nearly 20 years into a reliable universal rubber fatigue predictor. Three factors promoted the research: i) Previous methods for predicting elastomeric fatigue were based on fracture mechanics and considered crack growth and hence assumed that failure was already underway; ii) To predict fatigue life, it is necessary to know where the peak complex stress appears in a rubber component, hence a method of fatigue testing needs to measure multiaxial stresses. iii) The flaws in rubber that promote failure are larger than those first envisaged. Consequently, this chapter describes a theory for elastomeric fatigue life prediction that is based on the concept of dynamic stored energy. Further, it shows the existence of large flaws in rubber and sets out the development of a bubble inflation cyclic test system that measures multiaxial stress without the presence of stress concentration.