AE inspection is a powerful aid to materials testing and the study of deformation and fracture.
It gives an immediate indication of the response and behaviour of a material under stress, intimately connected with strength, damage, and failure.
Because the AE response of a material depends on its microstructure and deformation mode, materials differ widely in their AE response. Brittleness and heterogeneity are two major factors conducive to high emissivity. Ductile deformation mechanisms, such as microvoid coalescence in soft steel, are associated with low emissivity.
In production testing, AE inspection is used for checking and controlling welds, brazed joints, thermocompression bonding, and forming operations such as shaft straightening and punch press operations. In general, AE inspection can be considered whenever the process stresses the material and produces permanent deformation.
In structural testing, AE inspection is used on pressure vessels, storage tanks, pipelines and piping, aircraft and space vehicles, electric utility plants, bridges, railroad tank cars, bucket trucks, and a range of other equipment items.
Typical uses include the detection of cracks, corrosion, weld defects, and material embrittlement.
Often, in NDT there is no one method that can provide the whole solution; for cost effectviness, technical adequacy, or both, it is best to use a combination of methods.
Because Acoustic Emission has features that distinguish it so sharply from other methods, it is particularly useful when used in combination with them.
