Separation and quantification of damage-induced and non-damage-induced vibro-acoustic modulation and the problem of contrary modulations

Vibro-acoustic modulation (VAM) has been exploited over the last three decades to assess and monitor the integrity of structures. One major challenge is the separation of damage-induced and non-damage-induced modulation in the measured system response for reliable structural health monitoring (SHM). Most scientific works on VAM imply that the initiation and growth of structural damage is expected to cause modulation that adds up with non-damage-induced modulation increasing the total amount of modulation. This article unfolds why this assumption can be invalid for standard VAM applications: It is explained analytically why two nonlinearities working in opposite directions (one stiffening the structure under loading, one softening it) cause contrary modulations: The two nonlinear contributions can neutralize each other in the system response. Numerical simulations are then presented that investigate separately one damage-induced nonlinearity and two non-damage-induced nonlinearities in the same aluminum plate. The modulation caused by them individually is quantified and the subsequent comparison demonstrates the occurrence of contrary modulations in this representative VAM setup. It has to be concluded that damage-induced modulation does not necessarily increase the total modulation in the system response. This finding has potential to boost VAM-related research regarding its reliability and sensitivity.

Subjects

Damage detection | Nonlinear acoustics | Structural health monitoring | Vibro-acoustic modulation

DDC Class

620.11: Engineering Materials

530: Physics

Publication version

publishedVersion

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https://creativecommons.org/licenses/by/4.0/

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1-s2.0-S0888327025004091-main.pdf

Type

Main Article

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6.02 MB

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Adobe PDF

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Separation and quantification of damage-induced and non-damage-induced vibro-acoustic modulation and the problem of contrary modulations