Abstract: In order to study the non-linear ultrasonic detection and evaluation method of tensile damage extension of composite materials, based on the numerical value and experimental method of nonlinear Lamb wave, the tensile damage extension of orthotropic carbon fiber reinforced epoxy resin composite material was tested. For anisotropic composite laminates, a nonlinear numerical multi-load step model considering the damage evolution of the material under tensile load and the propagation of Lamb waves is established. The Hashin criterion is used to predict the damage evolution of the laminated plate under tension. The propagation of Lamb in the plate is simulated by de-oscillation damping and displacement loads. The time displacement signal is received and the relative nonlinear coefficient is extracted and calculated to evaluate the damage expansion degree of the material. The tensile mechanical properties of the composite material specimens were tested by the tensile testing machine, and the damaged specimens were detected by the RAM-5000 SNAP nonlinear detection system, and the high-order harmonic signals were extracted, and the numerical calculation results were verified. The results show that the propagation of Lamb waves in the plate will produce obvious nonlinear response after the material is tensile damaged. Before macroscopic fracture occurs, the tensile displacement and damage degree are positively correlated with the nonlinear coefficient. The results of experiment and simulation is in good consistency. Therefore, the nonlinear coefficient can be used as an evaluation index for tensile damage detection.

Key words: tension, non-linear Lamb wave, detection, non-linear coefficient, damage area, composites