Ultrasonic Non-Destructive Testing Waveguide Design
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Solution Overview
Problem
Ultrasonic non-destructive testing in hostile environments faces challenges due to the limitations of existing transducers and waveguides, including high temperature resistance, dispersion, and energy loss, which hinder precise thickness measurements and defect monitoring.
Innovation Solution
The use of an elongate strip waveguide with a width-to-thickness aspect ratio greater than unity, exciting substantially non-dispersive ultrasonic signals, primarily through lowest order shear or compressional modes, to transmit signals efficiently and flexibly, even in confined geometries, while minimizing energy loss and mode excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intermediary waveguide is used to transmit ultrasonic signals from a non-hostile region to the test object, then the transducer and ancillary components can be protected from hostile environments, but significant energy losses occur due to dispersion, multiple modes, and attenuation
Solution Approach 1:
The patent changes the geometric parameters of the waveguide by using a flat strip configuration with specific width-to-thickness ratios rather than traditional cylindrical rods. This parameter change modifies the dispersion characteristics and mode structure of the waveguide, enabling non-dispersive propagation at higher frequencies and reducing energy losses while still protecting the transducer from hostile environments
Solution Approach 2:
The patent employs composite construction by bonding a thin metallic strip to a rigid support structure or housing. This composite approach allows the flexible strip to transmit ultrasonic signals effectively while the rigid support provides mechanical strength and environmental protection, optimizing both signal transmission and transducer protection
2Measurement precision
If thin rod waveguides are used to minimize dispersion, then signal fidelity is improved, but it is difficult to transfer sufficient energy into the thin rod to produce a strong signal
Solution Approach 1:
The patent transitions from a one-dimensional cylindrical rod to a two-dimensional flat strip geometry. This dimensional change increases the surface area and cross-sectional dimensions available for transducer coupling, enabling more efficient energy transfer while maintaining the thin profile needed for non-dispersive signal propagation and precise timing measurements
3Measurement precision
If the frequency is increased above 1 MHz to obtain good accuracy for ultrasonic thickness gauging, then measurement precision is improved, but more higher order modes may propagate causing dispersion
Solution Approach 1:
The patent changes the geometric parameters of the waveguide (width, thickness, and width-to-thickness ratio) to specifically control the dispersion characteristics. By optimizing these parameters, the waveguide supports non-dispersive propagation modes at higher frequencies (above 1 MHz), enabling both high measurement precision for thickness gauging and stable single-mode propagation without excitation of higher order modes
4Ease of operation
If a thin waveguide is joined to a larger structure, then coupling is achieved, but there is a strong surface reflection and relatively little energy enters the structure
Solution Approach 1:
The patent uses a flat strip geometry with extended width in one dimension, creating a larger coupling surface area when joined to the test structure. This dimensional advantage reduces the impedance mismatch at the interface, minimizing surface reflections and improving energy transfer into the structure compared to thin cylindrical rods
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 enables precise and efficient ultrasonic non-destructive testing in hostile environments by maintaining signal fidelity, reducing energy loss, and allowing deployment in complex geometries, suitable for high-temperature and high-radiation conditions.
Implementation Method 1
The use of ultrasonic signals in the non-destructive testing of materials is known. Thickness measurements may be carried out by sending ultrasonic signals into a test material and measuring their time-of-flight across the sample.
Implementation Method 2
Thickness measurements may be carried out by sending ultrasonic signals into a test material and measuring their time-of-flight across the sample.
Implementation Method 3
Defect monitoring may be performed by sending ultrasonic signals into a test material and observing their reflection from the structure of a defect.
Data Source
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AI summary
An apparatus and method for ultrasonic non-destructive testing provides an elongate strip of ultrasound transmissive material coupled at a proximal end to an object under test. The elongate strip has a transverse cross-section with a width and thickness giving an aspect ratio greater than unity and matched to the ultrasonic transducer such that excitation induces a substantially non-dispersive ultrasonic signal to propagate along the elongate strip to the proximal end and to enter the object under test. These non-dispersive pulses are particularly suited for time-of-flight measurements, thickness measurements, crack measurements and the like. The elongate strip helps to separate the transducer from a potentially hostile environment associated with the object under test. The elongate strip also has a large area of contact with the object under test allowing efficient transmission of energy into the object under test.