PROGRESS IN NUMERICAL MODELING OF THE THERMOFORMING PROCESS

A finite element code to simulate the thermoforming process was developed. A dynamic approach, a membrane hypothesis, and a second order explicit integration method were considered in developing the code. Tensile tests were carried out on a servohydraulic Instron device to validate hyperelastic and memory integral constitutive laws. An original experimental approach was designed and built to measure the displacement of the surface of the sheet at several points during the forming stage. A validation mold was instrumented to measure the in-mold pressure profile during the forming process. Some preliminary attempts were carried out to consider the transient sheet heating stage and to evaluate its influence on the subsequent forming step. (C) 1995 John Wiley & Sons, Inc.