EVALUATION OF INPLANE SHEAR MODULUS OF COMPOSITE LAMINATES USING HOLOGRAPHIC-INTERFEROMETRY

A test method for the evaluation of the in-plane shear modulus of comp osite laminates is presented. The method is essentially a resonance te st on a cantilevered rectangular orthotropic laminate using laser holo graphic interferometry. Based on Rayleigh's quotient, a simple formula is derived to determine the in-plane shear modulus using the resonanc e frequency of the first torsional vibration. An appropriate value of the length-to-width (aspect) ratio of the specimen is suggested to eva luate the in-plane shear modulus accurately. The results show that the measured in-plane shear moduli by the present method agree well with the modulus obtained by a +/-45-deg off-axis tensile test. (C) 1997 So ciety of Photo-Optical Instrumentation Engineers.