Non-linear characterization of PP/Twaron laminates based on a model of plasticity with damage

The non-linear stress–strain response of thermoplastic laminates was investigated for a polypropylene matrix composite reinforced with continuous Twaron fibers. Tensile tests were performed on unidirectional composites with a fiber orientation of [0]5, [24]5, [33]5, [45]5 and [90]5 and also on a [±45]2S laminate. The inelastic strains of these materials were described with a modification made to a model of plasticity with damage, originally proposed by Ladeveze (1992). This approach considers the longitudinal plasticity and stiffening behavior of a thermoplastic composite, and models the damaged elastoplastic stress–strain response of the material. The theoretical stress–strain curves and experimental results from the model composites [0]5, [90]5 and [±45]2S were compared, demonstrating that the model can be used as a designing tool for laminated thermoplastic composites.