Effective strain criterion under multimode and multiaxial loadings – A rubber S–N curve with the scatter-band factor of 1.6 from 90 fatigue cases

Abstract

The effective strain criterion, unifying multimode and multiaxial loadings to a single parameter and being expressed in analytical form with no need to rotate a plane to search the maximum damage parameter, is proposed for the fatigue design of anti-vibration components. The validation procedure was performed on 90 cases in two aspects: fatigue damage and crack orientation. All predicted fatigue cracks were located at the places where the effective strain reached its maximum and was consistent with the experimental observations. The failure planes predicted correlated with the experimental measurement. The S–N curve covered over 102 to 2.4·106 cycles and achieved high accuracy with the scatter-band of 1.8. The proposed approach was applied to two non-proportional loading cases (one in a phase angle 45° and the other in a phase angle 90°). The results seemed to indicate the suitability of the approach for the non-proportional loading calculations. It would be possible to combine the proposed approach with the critical plane method in non-proportional loadings: using the proposed approach to find the critical loading range and then using the critical plane method to determine the maximum values of the required damage variables. Both the proposed concept and the obtained S–N curve would be beneficial in rubber fatigue design. More engineering cases may be needed to verify this approach further.

Keywords

• rubber
• fatigue
• modeling and simulation
• damage mechanism
• effective strain