#### Event Title

The Use of Acoustoelastic Measurements to Characterize the Stress States in Cracked Solids

#### Location

La Jolla, CA

#### Start Date

1980 12:00 AM

#### Description

The theory of acoustoelasticity predicts that a plane longitudinal acoustic wave passing through a solid which is already in a deformed state will propagate with a velocity (v) which is different from the (v_{0}) of the same wave propagating through the undeformed medium. It may be shown that Δv/v_{0} = (v-v_{0})/v_{0} = B(σ_{1}+σ_{2}) where σ_{1} and σ_{2} are the principal stress in the plane normal to the wave propagation direction and B is the acoustoelastic constant. Wave transit time measurements allow the relative velocity change Δv/v_{0} to be determined, so that contours of constant principal stress sum (σ_{1}+σ_{2}) may be mapped by acoustically scanning a stressed solid. We have used the technique described above to characterize the states of stress in cracked and notched aluminum panels. A method for extracting crack stress intensity factors from the acoustic data is proposed and illustrated for center-cracked panel specimens. The results indicate that the technique may offer a promising method for nondestructive testing and evaluation.

#### Book Title

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

#### Chapter

11. Ultrasonics, Material Properties

#### Pages

422-428

#### Language

en

#### File Format

application/pdf

#### Included in

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

The Use of Acoustoelastic Measurements to Characterize the Stress States in Cracked Solids

La Jolla, CA

The theory of acoustoelasticity predicts that a plane longitudinal acoustic wave passing through a solid which is already in a deformed state will propagate with a velocity (v) which is different from the (v_{0}) of the same wave propagating through the undeformed medium. It may be shown that Δv/v_{0} = (v-v_{0})/v_{0} = B(σ_{1}+σ_{2}) where σ_{1} and σ_{2} are the principal stress in the plane normal to the wave propagation direction and B is the acoustoelastic constant. Wave transit time measurements allow the relative velocity change Δv/v_{0} to be determined, so that contours of constant principal stress sum (σ_{1}+σ_{2}) may be mapped by acoustically scanning a stressed solid. We have used the technique described above to characterize the states of stress in cracked and notched aluminum panels. A method for extracting crack stress intensity factors from the acoustic data is proposed and illustrated for center-cracked panel specimens. The results indicate that the technique may offer a promising method for nondestructive testing and evaluation.