Method and apparatus for characterizing surface flaws utilizing ultrasonic surface waves

US4307614A · kind A · utility

Assignee

• Rockwell International Corporation · US

Inventors

• Bernhard R. Tittmann · Thousand Oaks, US
• Gerard Quentin · Colombes, FR
• Frédéric Cohen Tenoudji · Neuilly-sur-Seine, FR
• Alain R. Jungman · Paris, FR
• Etienne M. M. de Crespin de Billy · Paris, FR

Key dates

• Filing date: Jun 11, 1979
• Grant date: Dec 29, 1981
• Expiry date: Jun 11, 1999

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2291/0423
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Disclosed is a method for determining the length of a surface flaw in an object, including the steps of generating a directional beam of ultrasonic waves on the surface of the object toward the flaw and at an angle .theta. with respect to the normal to the direction of the flaw, measuring the intensity of the waves reflected from the flaw, at an angle .theta.' with respect to the normal, as a function of frequency, and calculating the length 1 of the flaw according to the formula 1=n V.sub.R /[f.sub.n (Sin.theta.+Sin.theta.')] where n is a integral number defining the order of the frequency minimu, V.sub.R is the speed of the surface waves in the object, and f.sub.n is the frequency at which a minimum of intensity occurs. Also disclosed is an apparatus for evaluating a surfacae flaw in an object including a transducer for inducing ultrasonic surface waves, a signal generator driving the transducer, a deteactor for responding to reflected waves, an amplifier to boost the detector response, a spectrum analyzer to measure the intensity of the reflected waves as a function of frequency, and a gating device to apply the output of the amplifier to the spectrum analyzer durng a predetermi…