Experimental studies on impact damage location in composite aerospace structures using genetic algorithms and neural networks

Impact damage detection in composite structures has gained a considerable interest in many engineering areas. The capability to detect damage at the early stages reduces any risk of catastrophic failure. This paper compares two advanced signal processing methods for impact location in composite aircraft structures. The first method is based on a modified triangulation procedure and Genetic Algorithms whereas the second technique applies Artificial Neural Networks. A series of impacts is performed experimentally on a composite aircraft wing�box structure instrumented with low-profile, bonded piezoceramic sensors. The strain data are used for learning in the Neural Network approach. The triangulation procedure utilises the same data to establish impact velocities for various angles of strain wave propagation. The study demonstrates that both approaches are capable of good impact location estimates in this complex structure

Fatigue Crack Detection Using Nonlinear Acoustic-Analysis Of Vibro-Acoustic Modulation

Nonlinear vibro-acoustic is a highly reliable and sensitive method for damage detection. It is a method based on propagation of high frequency acoustic waves in solid structures with low-frequency excitation. Interaction of the acoustic wave with material or geometry properties changes caused wave distortion effects. The causes called nonlinear acoustic effects are amplified with the low frequency excitation. Nonlinear acoustic-acoustic modulations are investigated for fatigue crack detection. The focus is on vibro-acoustic wave moduIations used for crack detection in aluminium. Experimental works are performed to investigate the effect of crack characteristics, i.e. crack lengths and crack modes, on vibro-acoustic effects intensity. Nonlinear acoustic tests are performed for the uncracked and cracked aluminium plates. The analyses results show that there are many nonlinear phenomena (i-e. hysteresis and classical Ist order perturbation) involved in the vibro-acoustic wave modulations. The nonlinear modulations produced by the low-frequency modal excitation and high-frequency ultrasonic excitation can be used effectively for fatigue crack detection

Damage imaging in composites using nonlinear vibro‐acoustic wave modulations

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