A coupled experimental and numerical approach was developed to overcome the limits of integrative simulation methods in the case of short glass fibre-reinforced thermoplastics. On the one hand, laboratory X-ray computed tomography and finite element modelling were combined to assess local mechanical properties in strongly anisotropic zones where weld lines potentially form. On the other hand, an original experimental protocol was developed to monitor damage evolution during continuous tensile loading. The experimental results open new perspectives to formulate more physically based local damage criteria.