Mode-I fatigue crack growth analysis of V-ribbed belts

One factor which is critical to the life of automotive serpentine belts is their failure due to propagation of initially small flaws in the elastomer located in the belt rib. This paper aims to develop a predictive fatigue crack growth model for serpentine belts with initially small rib tip flaws. The study combines the fatigue crack growth tests for belt rib material and computational fracture mechanics analysis for V-ribbed belts to predict fatigue life. The belt rib rubber material is tested for its fatigue behavior and the relationship between the fatigue crack growth rate and the tearing energy is constructed. A power law is employed to curve fit the fatigue crack growth rate curve. A global–local finite element analysis procedure is used to compute the J-integral for a through-the-thickness crack in the belt rib tip. The three-dimensional global model is created with relatively coarse mesh using first order continuum elements in ABAQUS. The three-dimensional local model for the rib crack is constructed with significantly finer mesh and employs the second order continuum elements. The boundary conditions for the local model are driven by the displacement solution of the global model. The maximum and minimum J-integrals are calculated for two extreme configurations in one belt running cycle. The range of the J-integral is input into the curve fitted power law to derive the fatigue crack growth rate and hence the fatigue life for the belt.