Research at PIMM

PIMM research activities fall under the triptych “Processes-Microstructures-Properties” with the central research theme being material processes.

The research actions undertaken in the field of processes concern the polymers, composites and metals processes. The objective of these endeavors, supported, in particular, by the high-power lasers activity, is to: i) understand processes by means of adequate physics which can be highly complex like the laser-matter interaction, ii) model and simulate processes in order to optimize intrinsic process performance as such, but also the end-use properties of the parts produced: mechanical, dimensional, electrical, thermal, sealing quality, optical, and surface quality properties..

Understanding processes and predicting properties require excellent dialog between highly instrumented experimental means and modeling and simulation methods that are adapted to the desired objectives and scales. Thus, a macroscopic scale is sufficient if the aim is to optimize dimensional characteristics, but smaller scales will have to be considered if the focus is on the properties of the material that depend on the induced microstructure. Generally, the simulation of processes requires the implementation and development of modeling methods as well as multiphysics and multiscale calculation methods in space and time. It should be noted that for high strain rate processes, the material behavior and the dynamic behavior of the system making it possible to act on the material are interdependent

The materials, as they result from the forming processes, naturally change over time and conditions of use (mechanical, thermal, chemical, radiative, etc.). Microstructural changes or induced defects at various scales modify and often weaken the characteristics of materials, thereby shortening the lifetime of the parts. These problems relating to the durability of materials are particularly important and must be addressed in the case of organic-matrix polymers and  composites. It is therefore for these kinds of material that the most elaborate methods have been developed, the creation of non-empirical lifetime models, since end-of-life criteria are primarily mechanical. This means that the “chemical-mechanicalinterface must be taken into account to build models that make maximum use of the resources of the physics of polymers in order to predict how their mechanical properties will behave in the future. This research quite naturally leads us to address problems concerning the recycling of plastics. In addition, we analyse metal fatigue for a large and very large number of cycles, in conjunction with the study of microplasticity mechanisms.