The transverse axis assembly (ASM) is an emerging activity that answers to a strong industrial and academic issue. The objective is to optimize the cost and mass of assemblies (bolted, riveted, glued …), by providing a proof of its robustness in its environment.
Given the complexity of these components (few testings, complex processes, multi-material, loss of torque, highly nonlinear models, contact, plasticity, damage), designers have no other choice than using empirical models, simple or highly constrained numerical models. These choices lead to the introduction of safety factors that are often large to avoid problems that may occur throughout the life of the assemblies.
Creating support predimensioning tools
On the one hand, analytical / numerical simplified models for static and fatigue assemblies are developed. These models take into account the non-linear behavior on contact and friction, the effect of single or combined loading and including a possible initial preload. These models are based on physical parameters of the assembly (the axial stiffness and bending parts, materials, friction coefficient…). To do so, the construction of a database of highly instrumented reference tests using techniques such as digital image correlation is required. The idea is ultimately to develop and implement in an commercial FEA software a linear and non-linear connector with high physical content for the early design phases.
The virtual testing applied to assemblies
On the other hand, the definition and implementation of the methodology « Virtual Testing » (virtual experimentation) is to improve the predictability of numerical simulation of the behavior of bolted joints. The challenge is to be able to reliably simulate the whole lifecycle of the component, from the installation (drilling, assembly), up to its behavior under ultimate loads. It also requires to be able to represent the actual conditions of the test, according to certification process of the product. The goal is then to optimize the design of an assembly while remaning robust against accidental events, but also to better understand the mechanisms initiating the destruction of joints. This approach can also improve maintenance processes and improve safety.
Functionalized Multilayers Assemblies (FMA)
Maximizing the mechanical performances while reducing the embedded mass makes sense only if the structural integrity is ensured at acceptable cost. The functionalized multilayers assemblies, which could be obtained by processes such as structural bonding or additive manufacturing, offer the ability to manufacture structures with materials with the right properties at the right place. Both following questions are then induces (i) what about the methodologies for optimal design and predictive modelling at the design office, (ii) what about the manufacturing process quality and control to reach the targeted strength. This theme is addressed through a horizontal approach (design office, manufacturing floor, operations) which involves a large number of parameters, requiring a dialog between real and virtual tests, to ensure the finale reliability of manufacturing parts.
Finally, this theme is adressed in collaboration with the transverse axis named ADHERENCE of CIRIMAT.
Project in progress: S3PAC (French government funding trhrough FUI 21).
Head: Alain Daidié