Fatigue Crack Growth in Rubber: Comparability of Test Results, Material Effects and Transfer to Component Life—A Critical Review

Fatigue crack growth (FCG) relations rank rubber compounds and predict component life, yet a reported rate–tearing-energy curve depends on how it was measured as well as on the compound. This critical review treats the test variables as criteria for deciding whether two results may be compared. Specimen geometry, energy accounting, load minimum, frequency, waveform, specimen temperature, crack preparation, imaging, rate extraction and data independence shape the measured response. A two-stage, seven-item checklist and an eight-domain minimum reporting set are proposed, and the evidence on backbone, filler, cure system, temperature, ageing and chemical environment, graded by strength, is read against them. Formulation rankings hold only within matched test conditions: when compounds differ in exponent, the power-law curves cross, and rankings can reverse within or beyond the tested energy range. Where exponents were reported for both, natural rubber mostly showed a lower exponent than styrene–butadiene rubber, but the backbone was not isolated and exponent values differ between programmes. Component transfer requires geometry-specific crack-driving histories, defect criteria, thermal and load histories, and independent validation. Quantitative comparison needs a shared endpoint and energy convention, with other items matched or bounded by measurement; a single-compound inter-laboratory round-robin would test the checklist.