Damage imaging in Composites by means of Nonlinear Time-reversed Elastic Waves

Fiber reinforced polymers (or composites) have excellent specific stiffness and strength as well as corrosion resistance, which makes them very attractive for high-tech applications in aerospace, renewable energy … Though, composites are also known for their high susceptibility to internal defects (introduced during manufacturing cycle, or during in-service loading) which could compromise their structural integrity. Accurate and time-efficient non-destructive detection and assessment of these internal defects is a crucial, yet challenging task. This is especially true for composite materials considering their (i) heterogeneous structure, (ii) anisotropic mechanical behavior, (iii) multi-layer characteristic and (iv) broad variety of defect types (delamination, void, porosity, matrix cracks, dry fiber zone, matrix pocket, fiber wrinkling …).

The goal of this project proposal is to develop a fast and precise non-destructive inspection technique based on nonlinear vibrations. The project will merge aspects and techniques related to (i) nonlinear wave/defect interactions, (ii) time reversed vibrations, and (iii) vibro-thermal heating phenomena, in order to selectively activate defects in an optimal way. Doing so, the defect itself will become a strong secondary nonlinear vibrational and thermal source. By searching for the presence of these secondary sources, defects can be efficiently found and assessed.