Method for Ultrasonic Inspection of Structure Having Radiused Surface Using Multi-Centric Radius Focusing

An apparatus for inspecting a radiused part, the apparatus comprising:

• an array sensor comprising a multiplicity of transducer elements;
• a probe body that holds the array sensor;
• and
• a pulser/receiver device programmed to perform operations comprising:
• (a) pulsing transducer elements of the array sensor in accordance with a first transmit focal law which is calculated to cause the array sensor to emit a first beam focused at a first focal point located along a centerline of the array sensor;
• (b) after the first beam is emitted, processing transducer output signals from the transducer elements in accordance with a first receive focal law which is calculated to cause the array sensor to derive a first parameter value characterizing a strength of an echo received following impingement of the first beam on a radiused surface of the radiused part;
• (c) pulsing transducer elements of the array sensor in accordance with a second transmit focal law which is calculated to cause the array sensor to emit a second beam focused at a second focal point located along the centerline of the array sensor;
• and
• (d) after the second beam is emitted, processing transducer output signals from the transducer elements in accordance with a second receive focal law which is calculated to cause the array sensor to derive a second parameter value characterizing a strength of an echo received following impingement of the second beam on the radiused surface,
• wherein the first focal point is at a first distance from a center of the array sensor and the second focal point is at a second distance from the center of the array sensor which is different than the first distance.

A method for inspecting a radiused part, the method comprising:

• (a) generating a cross-sectional model of a probe in contact with a radiused part comprising first and second surfaces connected by a radiused surface, the probe comprising an array sensor of transducer elements, the cross-sectional model comprising first and second lines representing respective profiles of the first and second surfaces and a plurality of circular arcs which span an expected range of variation of a radius of the radiused surface of the radiused part, each of the circular arcs terminating at the first and second lines;
• (b) calculating a set of transmit focal laws which, when executed, will cause the array sensor to emit a plurality of beams focused at a plurality of focal points located at different distances from a center of the array sensor, wherein the plurality of focal points correspond to respective centers of the plurality of circular arcs located at different distances from a center of a simulated array sensor of transducer elements;
• (c) calculating a set of receive focal laws which are designed to cause the array sensor to derive a plurality of parameter values characterizing strengths of echoes received following impingement of the plurality of beams on a radiused surface of the radiused part;
• (d) placing the probe in a position relative to the radiused part that conforms to the relative position represented by the cross-sectional model;
• (e) pulsing respective apertures of the transducer elements of the array sensor to transmit a plurality of beams respectively focused at the plurality of focal points in accordance with the set of transmit focal laws;
• and
• (f) after each beam of the plurality of beams is emitted, processing transducer output signals from the transducer elements in accordance with the set of receive focal laws to derive a set of parameter values characterizing strengths of echoes received following impingement of the plurality of beams on the radiused surface of the radiused part.