Free Vibration Study on Edge Cracked Glass Fiber Reinforced Polymer Laminate

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Date

2019

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Addis Ababa University

Abstract

The fiberglass-reinforced polymer is the most widely used composite because of its low cost and easy availability in the market. Fiberglass reinforced polymer is used for structural and semi-structural body parts of the automotive. During services, crack is the most common defect in a structure and cracked composite laminate is subjected to dynamic load and the vibration of the cracked laminate has a significant effect on the failure of the structure. A crack on a laminate reduces the stiffness of the structure and the change of stiffness affects the vibration properties of the laminate. During a change in vibration properties of the laminate resonance will occur and that causes catastrophic failure. In this study, the free vibration analysis, particularly the natural frequency of edge cracked glass fiber reinforced polymer laminate using Analytical, Numerical by using Abaqus software and Experimental analysis was studied. Specimen were prepared using a vacuum bagging assisted hand layup method. ASTM E756 is used for free vibration analysis. Experiments are conducted using unidirectional [04]s and quasi-isotropic [0,90,45, -45]s laminated beam with different crack introduced by a hacksaw. The effect of crack depth and crack location on natural frequencies of unidirectional [04]s and quasi-isotropic [0,90,45, 45]laminated beam investigated for a cantilever beam. Results showed that the natural frequencies were different for unidirectional laminate and quasi-isotropic laminate and it indicates the vibration properties of composite material depend on fiber arrangement. For both UD and QS laminate crack decrease the natural frequency. From the analysis the natural frequency decrease for an increase of crack depth. For both UD and QS laminates the location of the crack affected the natural frequency. The effect of crack depth and crack location on the change of the natural frequency showed the same trend in all the three methods.

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Keywords

Unidirectional laminate, Quasi-Isotropic laminate, edge crack, natural frequency

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