Understanding the failure mechanisms in overmolded composite T-joints via a virtual testing approach

Overmolding discontinuous fiber-reinforced thermoplastic elements on a continuous fibers base laminate enables to speed up composite manufacturing. The performance of such assemblies depends on numerous factors, whose roles are impossible to isolate and clarify in typical experimental tests on T-joint samples, making it difficult to interpret the experimental results and extrapolate them to other configurations or to obtain design allowables. In this work, the mechanical response of T-joint samples is simulated using of a Cohesive Zone Model (CZM) for the laminate/overmold interface and specific numerical tools to handle instabilities and improve convergence. This virtual testing approach enables us to systematically explore and quantify the effect of bond properties, loading conditions and part geometry on the load bearing capacity of the assembly. Clarifying the failure mechanisms of T-joints and their dependence on the different aspects of the structural problem is paramount for interpreting the results of current T-joint tests in the literature, as well as to design improved testing solutions.