Dislocation Detection Through Harmonic Generation
Abstract
A fundamental goal of ultrasonic nondestructive evaluation is to characterize material defects before failure. During material fatigue, dislocations tend to nucleate, becoming sources of stress concentration. Eventually, cracks start to form and lead to material failure. Recent research has indicated that nonlinear harmonic generation can be used to distinguish between materials of high and low dislocation densities. This research reports nonlinear harmonic generation measurements to distinguish between those areas of high and low dislocation densities in copper bars. The copper bars were subjected to flexural fatigue. Periodic scans were taken in order to track dislocation development during the fatigue life of the material. We show that this technique provides improved early detection for critical components of failure.
- Publication:
-
Review of Progress in Quantitative Nondestructive Evaluation Volume 29
- Pub Date:
- February 2010
- DOI:
- 10.1063/1.3362230
- Bibcode:
- 2010AIPC.1211.1391R
- Keywords:
-
- nondestructive testing;
- nonlinear acoustics;
- harmonic generation;
- shear modulus;
- dislocation interactions;
- 43.40.Le;
- 43.25.Ts;
- 42.65.Ky;
- 81.40.Jj;
- 61.72.Ff;
- Techniques for nondestructive evaluation and monitoring acoustic emission;
- Nonlinear acoustical and dynamical systems;
- Frequency conversion;
- harmonic generation including higher-order harmonic generation;
- Elasticity and anelasticity stress-strain relations;
- Direct observation of dislocations and other defects