Reflection from an interphase layer modeled as a thin, nonlinear layer. The region of adhesion bonds and defects is best thought of as a layer having physical properties significantly different from either substrate.
Evolution of damage (upper) and stress (lower) during monotonic strain loading for various initial damage states. Here the virgin material was assumed to have an elastic modulus, of , an ultimate strength of and failing slope of .
Interface strain due to a pulse ( ) reflecting from the damaged interphase between dissimilar media. From least to greatest distortion: 0%–75% initial damage. The damage increase calculated for all of these cases is negligible. This would change if the amplitude or length of the toneburst were increased.
Reflected (upper) and transmitted (lower) waves from a damaged interphase between dissimilar media. The nonlinear distortion here is much less obvious than that in Fig. 3 might have suggested; with increasing complexity and additional layers, the situation becomes more difficult to interpret.
Pulse reflected from a damaged interphase between dissimilar media (upper). Phase inversion processing can be used to remove the fundamental (lower), that is, the superposition of two signals reflected from the interface, the direct signal plus the signal with inverse phase.
Normalized harmonic amplitudes for the interphase strain (Fig. 3), reflected and transmitted signals (Fig. 4) for a harmonic wave incident on a boundary with 75% damage.
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