Simulation of steel/epoxy laminates for electric engines or generators: part 2—experimentally and numerically established temperature-dependent cohesive zone model

Two waterborne varnishes with an epoxy equivalent weight (EEW) of ~ 500 and ~ 900 g/mol were used for preparation of full-surface-bonded electrical steel laminates. By digital image correlation (DIC)-assisted testing, a nonlinear temperature dependency of the thermal expansion coefficient was ascertained for the laminates. Using double cantilever beam (DCB) specimens and DIC-assisted crack opening measurement, temperature-dependent critical energy release rate (G _Ic) and J-integral (J _Ic) values were determined. The laminates with the higher EEW epoxy revealed higher G _Ic values. Up to 60 °C, high monotonic crack growth resistance was confirmed for both laminates. The G _Ic and J _Ic values were a factor of 10 lower above T _g of the epoxy. The data were used to implement and validate a temperature-dependent cohesive zone model (CZM) based on a bilinear traction–separation law. Such models are essential for the simulation of full-surface-bonded electric engine laminates.