TOFD Ultrasonic Testing for Shadow Regions in Rotating Components
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Solution Overview
Problem
Phased array ultrasonic techniques fail to reliably detect flaws in rotationally symmetric components with multiple openings, particularly those located radially below or behind openings, due to shadowing effects, which limits comprehensive non-destructive testing.
Innovation Solution
Employing a time-of-flight diffraction (TOFD) technique with separate transmitter and receiver probes positioned to beam and receive ultrasonic waves from behind openings, allowing detection of flaws in shadow regions, and optionally combining with phased array techniques for comprehensive inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phased array ultrasonic technique is used for non-destructive testing of rotationally symmetric components with multiple openings, then the testing process can be automated and efficiency improved, but reliable detection of flaws in shadow regions behind openings cannot be achieved
Solution Approach 1:
The patent divides the component into different testable regions: visible regions that can be accessed by phased array probes and shadow regions behind openings that require TOFD technique. By segmenting the testing approach based on geometric accessibility, the system achieves comprehensive coverage of all regions including those previously undetectable.
Solution Approach 2:
The patent combines two different ultrasonic testing techniques - phased array technique for visible regions and time-of-flight diffraction (TOFD) technique for shadow regions. This hybrid approach merges the advantages of both methods to achieve complete flaw detection coverage across the entire component surface.
2Reliability
If separate transmitter and receiver probes are positioned to beam ultrasonic waves behind openings using TOFD technique, then flaws in shadow regions can be detected, but device complexity increases
Solution Approach 1:
The patent transitions from single-probe phased array testing to dual-probe TOFD configuration, adding spatial dimensionality by positioning transmitter and receiver probes at specific locations relative to openings. This dimensional change enables ultrasonic waves to propagate through shadow regions that were previously inaccessible to single-probe methods.
Solution Approach 2:
The patent uses the opening structures themselves as intermediaries that facilitate ultrasonic wave propagation into shadow regions. By positioning probes to beam waves through or near the openings, the openings become part of the testing pathway rather than obstacles, enabling detection in previously hidden regions.
3Reliability
If comprehensive testing of all component regions is performed to ensure reliable information about remaining service life, then complete flaw detection is achieved, but testing time and resource requirements increase
Solution Approach 1:
The patent creates a universal testing system that can handle both visible and shadow regions using a standardized dual-probe TOFD approach. This multi-functional capability allows the same testing procedure to comprehensively cover all component regions regardless of their geometric accessibility, eliminating the need for separate specialized procedures.
Solution Approach 2:
The patent performs preliminary identification of shadow regions behind openings and pre-positioning of TOFD probes to cover these areas. By planning the testing sequence to address shadow regions systematically, the system achieves complete coverage without redundant testing passes, optimizing time efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable non-destructive testing of previously inaccessible regions, effectively detecting cracks and other flaws in components with multiple openings, such as those in nuclear power plant shafts, by using TOFD to 'peer' behind openings and correlating results with phased array data for comprehensive flaw detection.
Implementation Method 1
the transmitter probe can beam ultrasonic waves into a shadow region lying behind one of the openings in the component
Implementation Method 2
the receiver probe can receive ultrasonic waves which are diffracted at at least one flaw present in the shadow region
Implementation Method 3
determining, using the time-of-flight diffraction technique, whether one or more flaws are present in the shadow region
Data Source
AI summary
A method for testing a component non-destructively, particularly for internal defects, includes the following steps: a) providing a rotationally symmetrical component having a plurality of preferably cylindrical recesses, which are arranged at one or more hole circles, b) arranging a transmitter probe serving as an ultrasound transmitter and a receiver probe serving as an ultrasound receiver spaced apart from each other outside the component such that ultrasound waves can be irradiated into a shaded area located behind one of the recesses in the component by the transmitter probe and ultrasound waves which are diffracted at least at one defect present in the shaded area can be received by the receiver probe, and c) using time of flight to determine whether one or more faults are present in the shaded area. An apparatus carries out such a method.