Experimental study on acoustical birefringence in stressed and slightly anisotropic materials

Abstract

The acoustoelastic effect in rolled metals is examined experimentally by the ultrasonic method. The first experiment is concerned with the birefringence due only to the texture-induced anisotropy. In the second experiment, the uni-axial tensile stress is applied to five specimens which are differently inclined from the common rolling direction, and the birefringence due to both the slight orthotropy and stress is examined. Though the experimental results are a little complicated, they are well explained by those theoretical acoustoelastic relations which one of the authors previously proposed for slightly orthotropic materials. This means that, in general, the polarization directions are fairly rotated by the stress, which is explicitly reaffirmed by the third experiment. It is the main conclusion of the present paper that the acoustoelastic relations referred to above are essential for rolled metals. In previous experimental works, slight anisotropies of polycrystalline metals were hardly taken into account, and hence the stress-induced rotation of the polarization directions could not be treated quantitatively.