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.

Acoustoelastic birefringence effect in wood III: ultrasonic stress determination of wood by acoustoelastic birefringence method

“…For the mechanical calculation, the bending stress σ c and the shear stress τ c were calculated by Eqs. 14…”

“…For the birefringence of a transverse principal wave, the birefringence gives the relation that the velocity difference between two polarized transverse constituents is proportional to the difference between the principal stresses. Imanishi et al 14 and Blinka and Sachse 11 examined experimentally the relation in the acoustical birefringence. Based on their findings, many research studies on stress measurement in metals were carried out using the effect of acoustoelastic birefringence.…”

The influence of stress on the principal polarisation directions of ultrasonic shear waves in textured steel plates

“…It is the purpose of this paper to give a theoretical description of this effect and to report measurements of the principal polarisation directions for steel specimens subjected to an externally applied uniaxial stress. This problem has been investigated previously by Iwashimizu and Kubomura (1973), Okada (1980, 198l), Imanishi et al (1982), Shaikh et a1 (1982), Clark et a1 (1983) and . However the theoretical treatment of these authors gives an incomplete description of the dependence of polarisation direction with stress, as discussed in P 2.…”

On the separation of stress-induced and texture-induced birefringence in acoustoelasticity

“…In Equation (5), the left-hand side is called the total birefringence, B0 is called the texture-induced birefringence, and the term led by Ca the stress-induced birefringence. When Equation (5) was used in the interpretation of experimental data on a variety of weakly anisotropic aluminum and steel sheets, it was found that Ca varied only slightly among the samples of the same material (i.e., aluminum or steel) in those experiments, but B0 could differ considerably from sample to sample [8,9,10]. In a typical ultrasonic measurement, only the total birefringence is determined.…”