An Experimental-Numerical Technique for Evaluating the Elastic Constants of Unidirectional Laminates by the Optoacoustic Method: Comparison with Some Theoretical Results

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Abstract
In the present article, the elastic constants for unidirectional transversely isotropic laminated composites are measured using the optoacoustic method. In this method, a laser pulse is used as a standard source of ultrasound. Different three-layer unidirectional laminated specimens with different volume fractions of reinforced graphite 716, Kevlar KS-400, and S-2 glass fibers were prepared. The engineering elastic constants ( E 1 , E 2 , G 12 , x 12 ) were obtained by means of the longitudinal velocity measured in different directions and then fitted in the stress-strain relations for a lamina that is stressed in nonprincipal x - y coordinates. The elastic constants determined with the experimental-numerical technique were compared to different theoretical models reported in the literature, such as Hill's modified model, Hashin and Hashin-Rosen's upper and lower bounds models, and the asymptotic homogenization method. The experimental results obtained in this work show good agreement with those mentioned above.