Method and apparatus for characterizing surface flaws utilizing ultrasonic surface waves

A method of determining the length of a surface flaw in an object, comprising the steps of:

• (a) generating a broadband directional beam of ultrasonic waves on the surface of the object toward the flaw and at an angle .theta. with respect to a normal to the direction of the flaw;
• (b) 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
• (c) calculating the length l of the flaw according to the formula
• l=n V.sub.R /[f.sub.n (Sin .theta.+Sin .theta.')]
• where:
• n=an integral number defining the order of the frequency minimum;
• V.sub.R =the speed of the surface waves in the object;
• and
• f.sub.n =a frequency at which a minimum of intensity occurs.

A method of determining the length of a surface flaw in an object, comprising the steps of:

• (a) generating a broadband directional beam of ultrasonic waves on the surface of the object toward the flaw and at an angle .theta. with respect to a normal to the direction of the flaw;
• (b) measuring the intensity of the waves reflected from the flaw, at an angle .theta. with respect to the normal, as a function of frequency;
• (c) calculating the length l of the flaw according to the formula
• l=n V.sub.R /[f.sub.n (Sin .theta.+Sin .theta.')]
• where:
• n=an integral number defining the order of the frequency minimum;
• V.sub.R =the speed of the surface waves in the object;
• and
• f.sub.n =a frequency at which a minimum of intensity occurs;
• (d) repeating step (c) for a plurality of frequency minima f.sub.n ;
• (e) repeating steps (a)-(d) for a plurality of incident angles .theta..