Investigation of the Effect of Cracks on Vibrational Properties of Composite Cylindrical Shells

Document Type : Original Research Paper

Authors

Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran.

10.22084/jrstan.2023.26879.1223

Abstract

Composite structures are prone to reduced performance due to defects occurring over time during the manufacturing and loading process. In this study, the effect of longitudinal and circumferential cracks alone as well as their combined (longitudinal and circumferential together) effect on vibrational properties of composite cylindrical shells was investigated simultaneously using experimental and numerical modal testing. Also, the effect of crack length and depth in longitudinal and circumferential directions on the natural frequencies of composite cylindrical shells was investigated. Initially, in order to validate the finite element (FE) model, an intact shell and a defective shell were modeled and analyzed, and the results were compared with the reference. After validating the FE model, first, modeling and frequency analysis were carried out for a composite cylindrical shell consisting of four layers of woven glass fibers (300 g/m2) impregnated with an epoxy resin with a 0.73-mm thickness for each layer. Then, the defects (cracks) in both longitudinal and circumferential directions in different dimensions and sizes were modeled and after analyzing all samples (intact and defective), natural frequencies and shape modes were obtained. To perform the experimental modal testing (EMT), several shell samples, similar to the simulated samples, were made and the natural frequencies were extracted for all samples. The natural frequencies obtained from the two methods were compared and the estimates show that the results of both methods are in a good agreement. The results also show that longitudinal cracks affect the natural frequencies and the mode shape more than circumferential cracks do. 

Keywords

Journal of Stress Analysis

Articles in Press, Accepted Manuscript
Available Online from 26 June 2023

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