Impact of temperature on the fatigue and crack growth behavior of rubbers

Abstract

Elasticity and chemical resistance are only two of outstanding properties of elastomers and make them applicable in a broad field of cyclic loaded components. During the cyclic loading, the failure is mainly related to crack growth mechanism. For the description and prediction of the material failure, fracture mechanics concepts represent a valid tool. In the field of elastomer failure under cyclic loading, two main approaches have been developed: (1) the crack nucleation dealing with the lifetime of rubber, due to a specific number of cycles until appearance of a specific crack size and (2) the crack growth approach, devoting the attention to the growth of pre-existing defects. Although both approaches represent effective instruments for fatigue analysis, only little attention has been drawn on the impact of temperature on the failure behavior. Moreover, scientific publications report that temperature influences the fatigue life of rubbers by decreasing the magnitude by four orders. Therefore, a focus on the impact of temperature on the crack growth behavior seems indispensable to rise knowledge in this field. For the evaluation of influence of temperature on the fatigue performance, crack growth tests were implemented. For the characterization of crack growth behavior, pure shear specimens equipped with a camera system to measure the crack growth behavior and the temperature were monitored with contactless thermo-couples to measure the surface temperature during the cyclic loading. Furthermore, the thermal conductivity was measured at different temperatures to allow an accurate evaluation of temperature influence. With the obtained data, a further description of the failure could be provided to extend the fracture mechanics approach through the implementation of the temperature effect within different fatigue models for elastomers.