Crack detection

Modelling of Ultrasonic Crack Detection in Austenitic Welds. 

J. Mattsson., A.J. Niklasson and A. Eriksson, Three-Dimensional Ultrasonic Crack Detection in Anisotropic Materials, Res. Nondestr. Eval. 9 pp.59-79 (1997). 

Simulations about Eddy Current Distributions and Crack Detection Algorithms for a SQUID Based NDE System. 

In this paper we present simulations and measurements of several types of excitation coils, which match the special requirements for a SQUID based eddy current NDE system. We note however that all calculations presented here on penetration depths, current distributions and crack-detecting algorithms are also useful for conventional eddy current testing systems. 

The developed method is used in eddy current defectoscopes like Zond VD used for detecting corrosion spots in the body of the plane through aluminium cover, cracks detecting in helicopter blades under dielectric covers up to 8-10 mm thick, in pipelines under protective covers up to 10 mm thick, etc... 

Cracks detection in welds, mounting hardwares, rivets, on blades and vanes, turbine disks, rotors blades, etc. 

Cracks detection in the compressor equipment and power facilities, assemblies, pipes, separators, metalworks, heating installations and refrigerating plants. 

Crack Detection in Digitized Radiographs with Neuronal Methods. 

Surface Crack Detection Using Magnetic Particle Techniques and Penetrant Inspection Method. 

The normal time to take a picture of the part is 40 ms and the whole crack detection is finished typcally after 200 ms the maximum processing time is about 600 ms for each picture. 

Figure 4 Elements of a Crack Detection Window of an Image Processing Program...

Up to now it was demonstrated, that the probe design enables a fast positioning and that the acoustical parameters of the probe ensure a reliable crack detection implying even a coupling control. Now, the final customer s requirement was the inspection of the blades without demounting them from the engine. 

However, this probe design is dedicated to a special turbine blade type and a special inspection task on this blade. But similar probe types and probe holders can be provided also for other engine types and for other inspection tasks like wall thickness measurement and crack detection in other zones of a blade. 

The intelligent magnetic pig KOD-4M-1420 was developed and passed trials. This system is designed to provide corrosion and cracks detection in the operating underground gas pipelines at the distances up to 150 km. 

Slides Ultrasonic crack detection hydraulic testing. 

Failures of pressure vessels are veiy rare. Many of those that have been reported occurred during pressure test or were cracks detected during routine examination. Major failures leading to serious leaks are hard to find. 

Under development are intelligent vehicles for crack detection. An elastic-wave version (developed by British Gas and the Harwell Laboratory) is currently being evaluated in a test-loop. This vehicle has successfully detected stress-corrosion cracks in the test-loop. The Gas Research Institute (USA) is sponsoring development work with intelligent vehicles at the Battelle Columbus Division (Ohio). Facilities for testing vehicles were commissioned in 1991... 

Kiefner, J. F., Hyatt, R. W. and Eiber, R. J., Metal Loss, Crack Detection Tools Targeted , ibid., 69-71, 24 April (1989)... 

The T) and T2 dependence is described by Eqs. (3.4.3) and (3.4.4) [34] where Qi and q2 are spin-lattice and spin-spin surface relaxivity constants, and S/ Vis the surface-to-volume ratio of the pore. These equations provide the basis of a methodology for crack detection in cement paste specimens [13]. 

The measurement applications of density weighted drying profiles, water ingress, water phase transitions, crack detection, chlorine, sodium and lithium imaging applied to cement-based materials can be easily translated to other porous media. Density weighted MRI will no doubt prove to be a powerful tool in material science research. 

Triboluminescence Mechanical shaking, rubbing or crushing Crack detection in composite materials... 

The crack detection limit for a device that inspects steel structural beams is 3 mm. A structural steel with a fracture toughness of 60 MPa m° has no detectable surface cracks. Assume a geometric factor of unity to determine ... 

To describe the procedure for validation of the ampule crack detection machine to meet the specification other machines available shall be validated accordingly. 

All ampules rejected by the dye-vacuum method must also be rejected on the ampule crack detection machine. 

To compare the effectiveness of the machine with the dye-vacuum method, production batches are passed through the crack detection machine and then through the dye-vacuum chamber. The hnal check after that is carried out again on the crack detection machine. 

The crack detection machine shall recognize more bad ampules than the dye-vacuum method and shall reject an equivalent number of good ampules as the dye-vacuum method. 

To determine the effect of wet or dry product on the outside of the ampule, select 100 good ampules and pass through the machine. The ampules are then wetted (with water) and passed through the machine again. Rewet the ampules (with product solution) allow solution to dry on the outside of the ampules. Pass the ampules again through the crack detection machine. 

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