13 Février – Thesis defense - Paul Van der Sypt

14 h Amphi 3 - IUT Bordeaux (Gradignan)

Analysis and modeling of load paths and damage of the HYPER joints assembly.

Structures need to cope with specifications displaying a rising complexity. Cost and mass budget reduction is no more an option. Optimization of structures occurs through innovative solutions for metal / composite assemblies. The current work focus on a new technology: the HYPER joints. Pins are manufactured on the top of a metallic part using additive manufacturing and then inserted inside a composite laminate while it is still uncured. From an industrial view, designers must be able to determinate the adequate pin pattern on the overlap surface to deal with the mechanical properties required. This work aims to propose a model predicting the failure load and the associated failure mode. To build such tool, a numerical / experimental dialog has been set up. A finite element model is established modeling the failure modes experimentally observed: pin failure and composite failure by ignition and propagation of delamination. Pin failure mode is investigated through three steps: material characterization, pin geometry analysis and finally the implementation of the finite element model integrating an elasto-plastic law. Delamination failure mode is analyzed thanks to cohesive zone modelling (CZM). Under pull-off loading, interface properties are identified using a model based on the linear fracture mechanic. Domain of validity is discussed through two study cases: a mixed mode loading combining pull-off and shear, and a configuration providing a complex load distribution between the pins. Finally, design tools were generated using the finite element model. Those tools are formed by reference curve allowing predicting the failure load and failure mode regarding the pin density and pattern chosen.

Event localization