On the characterisation of transverse tensile properties of molten unidirectional thermoplastic composite tapes for thermoforming simulations

The development of Finite Element (FE) thermoforming simulations of tailored thermoplastic blanks, i.e. blanks composed of unidirectional pre-impregnated tapes, requires the characterisation of the composite tape under the same environmental conditions as forming occurs. This paper presents a novel approach for the characterisation of transverse tensile properties of unidirectional thermoplastic tapes using a Dynamic Mechanical Analysis (DMA) system in a quasi-static manner. The relevance of the presented method is assessed by testing, under the same environmental conditions, a control material with both a universal testing machine and a DMA system. For simulation purposes, a unidirectional thermoplastic tape is characterised under environmental forming conditions using the presented test method. Experimental results, which include stress-strain behaviour and transverse viscosity, are eventually used to identify, via an inverse approach, simulation parameters of a thermo-visco-elastic composite material model (MAT 140, PAM-Form, ESI Group). Comparisons between simulated and experimental results show good agreement.