Location

Williamsburg, VA

Start Date

1-1-1988 12:00 AM

Description

The use of ultrasonic waves to measure stress is an old technique whose extensive application has been retarded by the fact that texture or preferred orientation in the grain structure within the material introduces anisotropy that cannot be distinguished from the effects of stress. During the past few years, a new approach to this problem has emerged since a technique based on the use of shear horizontal (SH) waves has been demonstrated to overcome the effects of texture. In particular, it has been shown that the symmetry of the stress tensor demands that in a stress free solid the velocity of propagation of a shear wave along a principal symmetry axis is the same when the polarization and propagation directions are interchanged no matter how much anisotropy may be present due to texture. More important, if there is a difference in these two velocities, its magnitude is a direct measure of any uniaxial stress that may be present. Thus, it appears that one can measure the level of stress in a body by finding the principal symmetry axes of the material and then measuring the difference in wave velocities of two properly chosen shear waves.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

7B

Chapter

Chapter 7: Characterization of Materials

Section

Acoustoelasticity, Stress, and Texture

Pages

1399-1404

DOI

10.1007/978-1-4613-0979-6_62

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Measurement of Stress in Steel Structures with SH Wave EMATS

Williamsburg, VA

The use of ultrasonic waves to measure stress is an old technique whose extensive application has been retarded by the fact that texture or preferred orientation in the grain structure within the material introduces anisotropy that cannot be distinguished from the effects of stress. During the past few years, a new approach to this problem has emerged since a technique based on the use of shear horizontal (SH) waves has been demonstrated to overcome the effects of texture. In particular, it has been shown that the symmetry of the stress tensor demands that in a stress free solid the velocity of propagation of a shear wave along a principal symmetry axis is the same when the polarization and propagation directions are interchanged no matter how much anisotropy may be present due to texture. More important, if there is a difference in these two velocities, its magnitude is a direct measure of any uniaxial stress that may be present. Thus, it appears that one can measure the level of stress in a body by finding the principal symmetry axes of the material and then measuring the difference in wave velocities of two properly chosen shear waves.