Stiffness Loss in Fatigue

We present here an analysis of how the growth of crack precursors in rubber leads, under the action of dynamic loading, to degraded stiffness properties.  The analysis is based upon a fracture mechanical characterization of damage development, coupled to a simple uniaxial empirical representation of the cyclic softening effect.  The analysis accurately captures the difference between stiffness degradation under strain and stress control.  When coupled with critical plane analysis, and implemented for use with the Finite Element Method, stiffness loss can be computed for rubber parts operating under multiaxial, variable amplitude loading.