Fatigue fracture characteristics of natural rubber components

This paper investigates the application finite element method (FEM) and fracture mechanics to the use of FCGC for fatigue life prediction of natural rubber components and to form the fatigue crack growth characteristic (FCGC) from Natural Rubber Engineering Data Sheets (NREDS) data. The key technique used is to calculate the strain energy release rate by using FEM to model the clacked component. Experimental tests with fatigue loading using the pure shear test piece were carried out to obtain the FCGC to validate the FCGC based on FEM modelling. It was found that FEM models could produce accurate strain energy release late and FCGC can be determined fi om FEM results if crack growth rates are available. The FEM technique was then applied to the case of a rubber cushion connector, the fatigue testing of which was also carried out. The results showed excellent agreement between FCGC obtained from this test and the FCGC from the pure shear test piece. Finally, the NREDS tension fatigue test using ring type test piece was simulated by FEM to deduce the FCGC. The results indicated that the deduced FCGC showed similar trend, but with conservative crack growth late.