Acoustic Emissions

Acoustic Emission (EA) is a Non-Destructive Testing Method (NDT) that is used to detect and locate leaks and defects such as cracks or corrosion in pressure equipment, machines, facilities, cranes, bridges, among others. This method is based on the physical phenomenon that takes place inside the materials. Acoustic Emission is defined as the spontaneous energy emitted by a material, in the form of transient elastic waves. The application of stress, severe environmental conditions on a metallic material, can produce changes in its internal structure, such as: the growth of cracks, local plastic deformation, corrosion or phase changes that are normally accompanied by the emission of elastic waves. inside.

These waves, therefore, contain valuable information about their internal behavior. An AE test is useful to monitor the formation of defects in a material by detecting and analyzing the acoustic emission waves generated. This type of test differs from the rest of the NDT in two fundamental aspects: The first lies in the origin of the AE signal, since it is a passive method, it detects the energy that is released in the material itself, while The other methods require artificial energy input to detect defects (for example: X-rays, gamma rays, ultrasound, thermal energy or microwaves). The second is that it reveals dynamic phenomena, this characteristic is especially relevant, since during the test only active phenomena are detected, such as the growth of cracks, and not geometric discontinuities as the rest of the NDT methods do. The EA test is effective in detecting fracture and fatigue behavior in a variety of materials such as metals, advanced composite materials, plastics, concrete, wood, among others.

In this sense, the test is useful for monitoring the integrity of structures in a non-invasive way, as well as for the characterization of materials subjected to deformation and/or fracture. Some applications in which the use of this test is common are the detection of failures and/or leaks in pressure vessels, piping systems, storage tanks, control of welds, detection of corrosion processes, inspection of structures or machinery.