Structural health monitoring and nondestructive evaluation applications of the stress, vibration, and wave analysis in aerospace composites

This chapter covers the application of stress, vibration, and wave analysis to the structural health monitoring (SHM) and nondestructive evaluation (NDE) of aerospace composites. Numerous practical situations consisting of analytical and finite element method simulations backed up by carefully conducted experiments are presented. Stress and strain monitoring of composite structures includes strain monitoring for delamination detection, strain monitoring for buckling detection, and examples of stress and stress monitoring of actual aerospace vehicles. The chapter continues with the presentation of vibration methods for composite damage detection including model-based vibration SHM, curvature/strain-mode vibration SHM, and an interesting application of the blister-mode method for composite delamination detection. Bulk-wave applications include NDE methods for determination of composite material stiffness properties, delamination NDE, impact-damage NDE, and manufacturing-flaw NDE. The rest of the chapter is dedicated to various SHM and NDE methods utilizing guided-wave propagation in aerospace composites. The use of passive guided-wave monitoring for monitoring impact events is discussed with model-based impact monitoring and directional-sensor monitoring being presented. The discussion of active guided-wave monitoring for damage detection in composites starts with the study of wave-damage interaction coefficients including examples in unidirectional and quasi-isotropic composites. Next, the use of angle beam transducers (ABT) for guided-wave NDE of damage in various composite layups is presented. The ABT angle prediction of the generation of S0 and SH0guided waves in crossply and quasi-isotropic composites of various thickness is predicted and experimentally verified. ABT methods for distinguishing between delaminations and actual impact damage are presented. Finally, acousto-ultrasonic methods and piezoelectric wafer active sensor SHM of composite damage are presented and discussed.