Sheet forming analysis of woven FRT composites using the picture-frame shear test and the nonorthogonal constitutive equation

Abstract

This study investigates the validity of a nonorthogonal constitutive equation that has been developed for simulating the deformation behaviour of woven fabric thermoplastic (FRT) composites. The model incorporates shear material properties measured from picture-frame shear testing into the constitutive model. Two different types of single layer materials were investigated; a commingled woven fabric (preform) and a consolidated form of the preform. Picture-frame testing at elevated temperatures was conducted on the consolidated samples and experimental test data was used to determine the relationship between shear stress and shear strain. Experimental validation of the model was conducted utilising a stamp thermo-hydroforming press without the use of the counteracting fluid. To address an important issue in utilising picture-frame shear testing, a virtual test was performed with experimentally determined data in an implicit finite element solver. The stamping forming simulation was also performed by the constitutive equation with the shear material properties, showing good agreement with experimental results.