Precision Ultrasonic Thickness Gaging
This paper describes in detail the theory of operation of precision ultrasonic thickness gages. After a review of basic applications, it discusses measurement modes and transducer selection, wave timing methods, factors affecting performance and accuracy, and special situations like high temperature measurements and tests that require use of very long cables. An ultrasonic NDT glossary is also included.
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Detection and Sizing Techniques of ID Connected Cracking
This paper provides a brief summary of advanced detection and sizing techniques for the evaluation of flaws connected to the inner surface of test material. In general, these techniques have found application for the detection, characterization and sizing of intergranular or transgranular stress corrosion cracks and fatigue-type cracks whether inherent, processing or service induced. Examples of interpretation of typical waveforms are provided.
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Elastic Modulus Measurement
Poisson's Ratio, Young's Modulus, and Shear Modulus for rigid, homogeneous materials such as metals, ceramics, and hard plastics can be derived from sound velocity and density information. This paper discusses the mathematical relationships between these material properties and suggests measurement techniques and equipment.
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Multi-mode Adhesive Bond Testing
In applications involving honeycomb composites and certain other adhesively bonded materials, conventional ultrasonic pulse/echo techniques may be of limited use. In such cases alternative acoustic test methods may be appropriate. This paper describes how standing wave resonance, the propagation of plate waves across a pitch/catch probe, and mechanical impedance analysis may be used to categorize bond quality in composites and similar adhesively bonded structures.
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Application Considerations in Specifying High Frequency Ultrasonic Transducers
Very high frequency ultrasonic transducers (50 MHz and above) can be used effectively in certain applications to measure very thin materials or find very small flaws, but in such cases it is necessary to consider several important factors relating to high frequency sound propagation as well as transducer and instrument design. This paper discusses the issues involved in selecting transducers for work at 50 MHz and above.
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Basic Ultrasonic Principles and Transducer Technical Notes
These notes summarize the basic theory of ultrasonic wave propagation and the general principles of transducer design, and provide equations for calculating important beam characteristics such as near field length and focal profile for any transducer.
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Ultrasonic Phased Arrays
Ultrasonic phased arrays are a relatively new method of generating and receiving ultrasound. Phased array testing is a specialized type of ultrasonic testing that uses sophisticated multi-element array probes and powerful software to steer high frequency sound beams through the test piece and map returning echoes, producing detailed images of internal structures similar to medical ultrasound images.
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Eddy Current Probe Tutorial
Selecting an optimum probe is an important part of setting up any eddy current inspection. This paper reviews the advantages and limitations of various types of eddy current probes, including single coil, reflection, and bridge type probes. It also discusses the differences between absolute and differential probes, and the advantages of shielded versus unshielded probes.
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