Bending damage evolution from micro to macro level in CFRP laminates studied by high-frequency acoustic microscopy and acoustic emission

This work presents the results of the experimental investigation of the bending damage evolution in the volume of laminate with a stacking sequence of [0 degrees /90 degrees ]4S and thickness of 4.32 mm. Damage formation under the stepby-step loading (three iterations) was detected by acoustic emission (AE) and was visualized by high-frequency acoustic microscopy. The acoustic emission method revealed the moments of the fiber breakage, formation of cracks and delaminations in the process of bending. AE activity and the energy of AE pulses were related to drops and slope of the loading curves, which corresponded to the damage in the composite volume. The layer-by-layer ultrasound imaging revealed the location of matrix cracking, fiber fracture and interlayer delaminations. We presented the scheme of the step-by-step damage development in the laminate volume, based on experimental data.

Automated summary

This work presents the experimental investigation of bending damage evolution in a laminated structure. The damage formation was detected and visualized using acoustic emission and high-frequency acoustic microscopy. The study reveals the relationship between AE activity, energy of AE pulses, and the loading curves, providing insights into the damage evolution in composite materials.