Evidence of dissipative and growing nonlinearity in Lamb waves due to stress-relaxation and material degradation in composites

Subir Patra, Hossain Ahmed, Mohammadsadegh Saadatzi, Sourav Banerjee

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Experimentally observed dissipated nonlinearity in Lamb wave propagation in composites due to stress-relaxation is reported herein. It was found that the stress relaxation in composite is inherently coupled with the second order nonlinear parameter derived from the Lamb wave modes. Due to the combined effect of internal stresses and damage accumulation in composites, the second harmonic frequency was found to be shifted towards the lower frequency with increasing amplitude, which was partially recovered and shifted back during the stress relaxation. A comprehensive fatigue experiment was conducted on ASTM standard composite specimens with fatigue loading sequences and relaxation, while the guided Lamb wave signals were collected using piezoelectric sensors integrated with the specimens. A remarkable ∼27% reduction of acoustic nonlinearity was observed during relaxation. Rate and degree of relaxation were found to be the function of number and frequency of loading cycles and inherently correlated with the remaining strength of the composites.

Original languageEnglish
Pages (from-to)224-231
Number of pages8
JournalUltrasonics
Volume96
DOIs
StatePublished - Jul 2019

Scopus Subject Areas

  • Acoustics and Ultrasonics

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