DETERMINATION OF ALL ELASTIC-CONSTANTS OF ORTHOTROPIC PLATE SPECIMENS FROM GROUP-VELOCITY DATA

This paper presents a novel method of nondestructively determining all nine elastic constants of fiber-reinforced orthotropic plate specimens. Group velocities of bulk quasi-longitudinal (QL), pure transverse (PT), and surface skimming pseudo-longitudinal modes are measured in glass-fiber (GF) and carbon-fiber (CF) reinforced Poly Ether Ether Ketone (PEEK) specimens by a point-source/point-receiver (PS/PR) technique. First, the pure index longitudinal moduli C-11, C-22, and C-33, are obtained from the longitudinal (L) group velocities measured in three principal directions. Next, the pure index shear moduli, C-44, C-55, and C-66, are determined by measuring the shear horizontally (SH) polarized PT group velocities in the symmetry planes. Finally, the mixed index elastic constants C-ij (i not equal j) are calculated from QL group velocities measured in the symmetry planes and using analytic formulas.