Unified constitutive model with consideration for effects of porosity and its application to polyurethane foam

Polyurethane foam (PUF) is a popular insulation material and has crucial mechanical characteristics under compression in the principal loading direction, including nonlinear behavior dependent on strain rate and temperature, degradation of elastic modulus, and decrease of void fraction. Additionally, its insulation performance relies on the blowing agents in voids. These material characteristics enable the evaluation of the structural integrity and performance of PUF insulation systems, if the prediction of these characteristics and the relationship between change in void fraction and insulation performance are possible. In this paper, a unified constitutive model was proposed for this purpose. This model was verified with corresponding experimental results, and the validation showed that the material characteristics can be depicted successfully. Moreover, for the sake of applicability, the model was used in the evaluation of the insulation system in an LNG Carrier.