An Experimental Study on the Use of Static Effective Modulus Theories in Dynamic Problems

In a recent paper [1] the effective elastic constants of a [0, ±45,0] 36 graph ite epoxy laminated composite were determined by ultrasonic wave velocity information, and the Young's moduli calculated from these constants were compared to those obtained using a quasi-static loading technique for six different directions. In this article, the previ ously obtained results are compared to those predicted using a three-dimensional static effective modulus theory [2]. It is shown that, if low frequency ultrasonic waves are used, the calculated Young's moduli compare favorably with both the static measurements and those predicted by the effective modulus theory. Comments on the applicability of the various measurement techniques for different purposes are also discussed.