AbstractIn the field of composites, welding of lightweight structures consisting of metal/fibre‐reinforced polymers is a very seminal issue, concerning for example the automotive industry. The theoretical and numerical modelling as well as the simulation of the mentioned composites is a crucial and integrating subarea. By using various material laws in a traction‐separation context, different experimental and analytical methods must be consulted to verify the mesomechanical models. In this contribution we discuss a characterisation of interfacial elasto‐plasticity with Lemaitre‐damage, which has been applied to model thermal impact welded single lap tensile specimens. Then, numerical and experimental results are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)