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