NUMERICAL PREDICTION METHOD FOR ELASTO-VISCOPLASTIC BEHAVIOR OF GLASS FIBER REINFORCED POLYURETHANE FOAM UNDER VARIOUS COMPRESSIVE LOADS AND CRYOGENIC TEMPERATURES

摘要

In the present study, the material characteristics of a glass fiber-reinforced polyurethane foam (RPUF) which is widely adopted to a liquefied natural gas (LNG) insulation system was investigated by a series of compressive tests under room and cryogenic temperatures. In addition, a temperature- and strain rate-dependent constitutive model was proposed to describe the material nonlinear behavior such as increase of yield stress and plateau according to temperature and strain rate variations. The elasto-viscoplastic model was transformed to an implicit form, and was implemented into the ABAQUS user-defined subroutine, namely, UMAT. Through a number of simulation using the developed subroutine, the various stress-strain relationships of RPUF were numerically predicted, and the material parameters associated with the constitutive model were identified. In order to validate the proposed method, the computational results were compared to a series of test of RPUF.