Modelling of laminate composite material structures

In the field of structural design and simulation, long-fiber organic matrix composites (CMO) occupy a special place. Now well known in several pioneering sectors such as space, aeronautics, and naval engineering, these materials are used in complementary sectors such as mobility, energy production and storage, infrastructure, and architecture. Indeed, while at first glance it is their rigidity and strength properties that attract design offices to use them in lightweight structures, today composite materials are used more widely because of their ability to meet various functional requirements set out in specifications. The numerous combinations of fibers, dominated by glass and carbon, thermosetting and thermoplastic polymers, or even mixtures with various materials such as wood, foams, or metals, make them excellent candidates for developing high-performance, durable structures. Their customizable properties make them compatible with extreme conditions of high mechanical loads, cyclic fatigue, or harsh environments (gases, fluids, and exposure to radiation), where their good corrosion resistance extends service life or allows for less frequent inspection and maintenance. Finally, their manufacturing processes also give them other advantages, such as the ability to produce large structures or to adapt to complex shapes that are beneficial for aerodynamics, for example. They are also relevant levers in eco-design initiatives to limit the environmental impact of manufacturing, operation, or potential end-of-life recovery through various innovative technologies that have passed the proof-of-concept stage.

On the other hand, the heterogeneous composition of composite materials, as well as their anisotropic properties that are sensitive to the surrounding environment and time, contribute to their complex behavior, making their design and dimensioning the preserve of specialists. Modeling plays an important role in the development process for composite structures. It enables complex behaviors to be understood, starting with the scale of the elementary coupon used to characterize the laws of behavior, but also the scales of the technological test piece or the structure itself, enabling technical and functional requirements to be validated (e.g., geometric singularities such as holes, curvatures, reinforcements, etc., or composite or hybrid assemblies between components or interface areas with the environment).

The models to be implemented must therefore reproduce each of these behaviors on the scale of the constituents (from 5 to 10 micrometers), through that of the fold (a few tenths of a millimeter) and the laminate (a few millimeters to centimeters), to ultimately describe the behaviors of a complex structure ranging from a few centimeters to several meters....