Characterization of sandwich beams with shear damages by linear and nonlinear vibration methods

• Published in: Journal of composite materials Vol. 52; no. 1; pp. 47 - 60
• Main Authors: Ben Ammar, Imen, El Mahi, Abderrahim, Karra, Chafik, El Guerjouma, Rachid, Haddar, Mohamed
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01-01-2018
• Subjects: Engineering Sciences; nonlinear vibration; linear vibration; Sandwich beams; nonlinear parameters; frequency; loss factor
• ISSN: 0021-9983; 1530-793X
• DOI: 10.1177/0021998317702436

The aim of the present work is to study the vibration behavior of sandwich composites with shear damages on the foams. The effect of the densities of damage on the linear and nonlinear vibration parameters is studied. The sandwich materials used in this study is constructed with glass fiber laminates as skins and with PVC closed-cell foams with density 60 and 100 kg m−3 as core. After a serie of vibration tests, the change of natural frequencies and modal damping due to the damage and the foam densities. For an intact specimen, the resonance frequency was constant when we increase the excitation amplitude. For damaged specimens, the resonance frequencies decrease and the loss factors increase proportionally with the increasing excitation amplitude. The nonlinear parameters corresponding to the elastic modulus and damping were determined for each frequency modes and each damage and foam densities. The results showed that nonlinear dissipative parameters were more sensitive to damage than linear elastic and dissipative parameters.