Nonlinear ultrasonic scanning to detect material defects

US5736642A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• William T. Yost · Newport News, US
• John H. Cantrell · Williamsburg, US

Key dates

• Filing date: Jan 8, 1997
• Grant date: Apr 7, 1998
• Expiry date: Jan 8, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2291/104
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and system are provided to detect defects in a material. Waves of known frequency(ies) are mixed at an interaction zone in the material. As a result, at least one of a difference wave and a sum wave are generated in the interaction zone. The difference wave occurs at a difference frequency and the sum wave occurs at a sum frequency. The amplitude of at least one nonlinear signal based on the sum and/or difference waves is then measured. The nonlinear signal is defined as the amplitude of one of the difference wave and sum wave relative to the product of the amplitude of the surface waves. The amplitude of the nonlinear signal is an indication of defects (e.g., dislocation dipole density) in the interaction zone.