Multimode Fatigue Criteria for Filled Non-crystalizing Rubber ‎under Positive R Ratios

Antivibration isolators are made from both crystalizing rubbers and non-crystalizing rubbers. Their fatigue resistance is different. Although the recently developed effective tensile stress criterionhas been validated in crystalizing rubber under different R ratios (the ratio between the minimum stress value and the maximum stress value), its application to non-crystalizing rubbers has never been verified. In this study, this criterion was tested against a non-crystalizing rubber using two types of samples under R ≥ 0 conditions for 168 fatigue cases with different loading modes. Considering that a shape change may also cause fatigue damage, a new shear stress criterion was derived and subsequently tested. The unified S-N curves (2×10² - 3×10^6 cycles) obtained have achieved narrow bands with a scatter factor of 1.35 with a correlation coefficient R² ≥  0.90 using these two criteria. This potential novel approach could be more effective than the current methods, which use fitting functions with adjustable parameters determined from an additional experiment. This offers greater choices and flexibility to engineers in their selection of the most appropriate suited criteria for their design in anti-vibration applications.