#### Event Title

#### Location

La Jolla, CA

#### Start Date

1981 12:00 AM

#### Description

Third order elasticity theory may be used to show that a longitudinal acoustic wave normally incident on a sample in a state of plane deformation experiences a relative velocity shift given by [*equation*] where B is the acoustoelastic constant, σ_{1} and σ_{2} are the principal stresses normal to the direction of wave propagation, and V_{0} is the wave velocity in undistorted material. Hence, wave transit time measurements may be used to ascertain the sum σ_{1} + σ_{2} in the deformed state. We use a double pulse-echo technique to provide an accurate measure of transit time through the thickness of aluminum discs produced by hydrostatic extrusion (25% area reduction). The residual stress state produced during extrusion is axi-symmetric and we are able to separately determine residual radial and hoop stresses by a single longitudinal wave measurement at points on the disc face. The technique is extremely rapid and accurate, and the acoustic results are cross-checked by both x-ray measurements and finite element simulation of the extrusion process.

#### Book Title

Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE

#### Chapter

9. Acoustic Emission and Material Property Measurements

#### Pages

263-264

#### Language

en

#### File Format

application/pdf

#### Included in

Acoustics, Dynamics, and Controls Commons, Engineering Mechanics Commons, Mechanics of Materials Commons

Non-Destructive Acoustic Determination of Residual Stresses in Hydrostatically Extruded Aluminum Rods

La Jolla, CA

Third order elasticity theory may be used to show that a longitudinal acoustic wave normally incident on a sample in a state of plane deformation experiences a relative velocity shift given by [*equation*] where B is the acoustoelastic constant, σ_{1} and σ_{2} are the principal stresses normal to the direction of wave propagation, and V_{0} is the wave velocity in undistorted material. Hence, wave transit time measurements may be used to ascertain the sum σ_{1} + σ_{2} in the deformed state. We use a double pulse-echo technique to provide an accurate measure of transit time through the thickness of aluminum discs produced by hydrostatic extrusion (25% area reduction). The residual stress state produced during extrusion is axi-symmetric and we are able to separately determine residual radial and hoop stresses by a single longitudinal wave measurement at points on the disc face. The technique is extremely rapid and accurate, and the acoustic results are cross-checked by both x-ray measurements and finite element simulation of the extrusion process.