Ferromagnetic Wall Testing with Higher Order Shear Waves
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Solution Overview
Problem
Existing non-destructive testing methods for ferromagnetic component walls, such as pipes and panels, are inadequate in detecting cracks and defects like stress crack corrosion without increasing construction and energy expenditure, particularly in efficiently exciting and detecting shear waves of higher order for effective defect detection.
Innovation Solution
The configuration of transducers is optimized based on wall thickness to excite horizontal shear waves of higher order at a slant angle relative to the magnet orientation, with the receiving transducer positioned laterally and oriented towards the testing area, enhancing sensitivity and reducing direct signal interference, allowing for effective detection of surface-near defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shear waves of higher order are excited to enhance surface-near defect detection, then sensitivity to surface-near defects is improved, but mode dispersion increases leading to diverging wave packages
Solution Approach 1:
The patent applies local quality by orienting the sending transducer at a specific slant angle (10-60 degrees) relative to the magnetization direction to locally optimize shear wave excitation. This angular orientation concentrates the wave energy in a specific propagation direction, reducing mode dispersion while maintaining sensitivity to surface-near defects. The receiving transducer is also positioned laterally and oriented toward the testing area to locally maximize detection capability in the desired direction.
2Ease of manufacture
If the sending transducer is oriented parallel to the magnet orientation, then excitation is simplified, but multiple oscillation components including lamb waves are generated reducing testing clarity
Solution Approach 1:
The patent employs asymmetry by deliberately orienting the sending transducer at a slant angle (10-60 degrees) rather than parallel to the magnetization direction. This asymmetric angular orientation selectively excites horizontal shear waves while suppressing other oscillation components like lamb waves. The asymmetric angle creates a directional wave propagation pattern that improves signal clarity and reduces interference from unwanted wave modes.
3Power
If the receiving transducer is positioned to detect direct signals from the sending transducer, then signal strength is improved, but direct signals interfere with defect detection
Solution Approach 1:
The patent applies dimensionality change by positioning the receiving transducer laterally offset from the sending transducer and orienting it at a specific angle toward the testing area. This spatial and angular configuration in multiple dimensions allows the receiving transducer to detect shear waves that have propagated through the wall thickness and reflected from defects, while minimizing detection of direct signals from the sending transducer. The lateral positioning and angular orientation create a geometric separation between direct and reflected signal paths.
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
This approach improves the sensitivity and reliability of defect detection in ferromagnetic components by utilizing shear waves of higher order, particularly effective for cracks penetrating partially into the wall, while maintaining efficient energy use and construction simplicity.
Implementation Method 1
excitation of acoustic waves in the wall can be realized from the exterior by means of electromagnetic-acoustic transducers
Implementation Method 2
EMAT (electromagnetic-acoustic transducer) enables the contactless excitation of acoustic lamb waves
Implementation Method 3
the excitation of acoustic waves in the wall can be realized from the exterior by means of electromagnetic-acoustic transducers
Implementation Method 4
shear waves that must be excited by a suitable frequency for generating a useable excitation with a high frequency induction coil
Implementation Method 5
ultrasound waves, in particular shear waves, that are excited by a high frequency induction coil
Data Source
AI summary
A device for destruction-free testing of ferromagnetic component walls with respect to elongate defects has a sending transducer that excites ultrasound waves in a wall area of a ferromagnetic component wall magnetized in a predetermined direction of magnetization. The ultrasound waves propagate on a path oriented by the sending transducer. A receiving transducer receives the ultrasound waves at a spacing from the sending transducer. The configuration of the sending transducer and a high frequency emitted by the sending transducer, which high frequency is to be determined based on a thickness of the ferromagnetic component wall, are selected so as to effect excitation of horizontal shear waves of higher order. The path orientation is selected at a slant angle to the predetermined direction of magnetization. The receiving transducer is positioned lateral to the path and is oriented toward a predetermined testing area of the wall section in the path.