The observed large inelastic deformation, high fracture strain and significant energy dissipation capability as well as high throughput manufacturing and recycling potential makes fibre reinforced thermoplastics a strong candidate in highly structurally loaded components and crash applications in the automotive industry. The large inelastic deformation observed in thermoplastics requires a rethinking of modelling strategies, especially in terms of predicting failure and energy dissipation. In particular, the significant rate sensitivity and non-linearity of the matrix material needs careful consideration when developing constitutive models. This paper compares a complex damage mechanics based constitutive model with a pragmatic plasticity based model to predict the behaviour of glass fibre reinforced thermoplastic materials under impact loading. The models are compared using simple single element simulations as well as impact experiments on novel multi-layered flat-bed weft-knitted fabrics. While the CDM model more accurate predicted the non-linear shear behaviour, the macroscopic response of both modelling approaches was very similar and allowed to correctly reflect the major damage mechanisms observed in impact bending experiments.