Behavior and modeling of point assemblies

The article is devoted to tools and methods for analyzing the behavior and failure of point connections. The work is carried out in a context aimed at providing input data for finite element models dedicated to modeling this type of assembly, in simulations of dynamic structural failure. The bibliography shows that the study of assemblies often requires coupled numerical and experimental approaches. The study begins with the mechanical (and possibly thermal or metallurgical) phenomena generated by the industrial implementation of the assembly (welding, riveting, etc.). This implementation leads to changes in material, geometric and structural characteristics, whose influence on the mechanical strength of assemblies in service can be assessed. Numerical 3D modeling is a tool that can be used to study assembly behavior in detail, right up to the point of failure. It makes it possible to evaluate the evolution of a greater number of state variables that are difficult to access through experimentation alone, and to derive macroscopic behavior models and failure criteria at the scale of the structural model. An important issue concerns experimentation on assemblies. Analysis shows that conventional tests only allow partial, and sometimes incorrect, characterization of models. It is difficult to gain access to the intrinsic behavior of fasteners. The latter is often masked in the response of a test specimen, for which many parameters are hidden or poorly understood. The advantage of the new experimental procedures is that they are able to discriminate from the point of view of connection models, behavior and failure criteria used in structural design, and thus contribute to their improvement.