Determination of critical energy flux for filled elastomer based on global energy balance and J-Integral

•Experimental determination of the critical energy flux for crack propagation.•Influence of material softening on crack propagation.•Numerical determination of the critical energy flux using the J-Integral. In this work, the crack growth of carbon black-filled ethylene propylene diene monomer rubber was analysed by experimental investigations and numerical simulations. The investigated sample is loaded cyclically under displacement-controlled test condition. The sample had a defined initial crack length. Due to the cyclic loading, the crack grows further due to excess critical energy flux. A uniform pattern was drawn on the surface of the investigated specimen, therefore the crack propagation per cycle can be determined. The cyclic loads were recorded with a camera. The time of initiation of crack propagation was determined by analysing the recorded pictures and the energy flux was determined based on global evaluation of the dissipation potential and the local evaluation of J-Integral. At the virgin cycle, the energy flux has the largest value, which decreases with increasing number of cycles. This behaviour is due to the stress-softening effect of elastomers. The local energy flux was determined near the crack tip by using the J-Integral. The experimentally and numerically determined energy fluxes show similar decreasing tendencies and have different values. These differences are due to the fact that in the evaluation of the energy flux based on the global energy balance during crack growth, the separation potential and the dissipated potential in the whole sample cannot be separated from each other.