Objectives and general principles
Dynamic tests on composites - Low-frequency characterization

The most general composite material exhibiting elastic behavior is determined by the knowledge of 21 independent moduli, the number of elasticity moduli being reducible depending on the degree of material symmetry of the materials.

In the field of composite materials, the lowest degree of symmetry encountered is that of the orthotropic material to which we shall confine ourselves: three orthogonal planes of symmetry and nine independent elastic moduli. Let's briefly recall the formulation of linear elastic behavior