Fatigue damage criteria for antivibration systems with filled natural rubber under negative and positive R ratios

Abstract

A shape change can initiate fatigue damage in rubber components, which has led to the development of the effective shear strain γt criterion in this investigation. Referring to the previous damage criterion, i.e., effective tensile strain εt, the relation between the two was revealed. To benchmark the effectiveness of different damage criteria, six damage criteria, including the commonly used maximum principal strain, stress, and strain energy density, were compared using cylindrical dumbbell samples in 30 fatigue cases under ± R ratios. A large scatter was generated using either the maximum principal strain or the stress criterion. The strain energy density was in excellent agreement in uniaxial tension loadings but failed in torsional loadings with R = −1. To save significant cost in producing a completed new S–N curve for each rubber material, the derived S–N base functions using both εt and γt have been successfully validated on three independent experiments, i.e., the cylindrical dumbbell specimens, the ring specimens, and the industrial mount MDS. To fully verify the applicability of both εt and γt, the prediction of the crack orientation was performed for the first time using the proposed criteria, to the knowledge of the author, and the results were consistent with the experimental observations. The proposed criteria are useful for antivibration product design.