Effect of stress on energy flux deviation of ultrasonic waves in GR/EP composites

Ultrasonic waves suffer energy flux deviation in graphite/epoxy because of the large anisotropy. The angle of deviation is a function of the elastic coefficients. For nonlinear solids, these coefficients and thus the angle of deviation is a function of stress. Acoustoelastic theory was used to model the effect of stress on flux deviation for unidirectional T300/5208 using previously measured elastic coefficients. Computations were made for uniaxial stress along the chi /sub 3/ axis (fiber axis) and the chi /sub 1/ axis for waves propagating in the chi /sub 1/ chi /sub 3/ plane. These results predict a shift as large as three degrees for the quasi-transverse wave. It is noted that the shift in energy flux offers a new nondestructive technique for evaluating stress in composites.<<ETX>>