Accelerometers - KISTLER - #51

Acoustic Emission (AE) is transient elastic waves during the rapid release of energy from localized sources within a material. AE waves range in frequency from a few kHz to several MHz.

The source of these emissions in metals is closely associated with the dislocation movements accompanying plastic defor­mation and the initiation and extension of cracks in a structure under stress. Sources of AE include melting, phase transformation, thermal stresses, cool down cracking, fric­tion mechanisms and stress build up.

The AE sensor can be used to monitor pro­cesses such as:

• Stamping

• Grinding

• Deep drawing

• Cutting tool breakage

• Fracture of metal or composite pressure vessels

• Fracture of stressed structures/bridges

• Detecting loose parts in an electronic assembly

• Detecting, locating and evaluating flaws in materials

• Steam valve leaks

• Partial discharge in transformers

AE sensors can warn of faults as the faults actually occur, not just whether or not they exist like traditional nondestructive text methods, i.e. x-ray, dye penetrants, eddy current, ultrasonic transmission or micro­scopic inspection. Detectable AE signals are emitted before visual signs of fracture or cracking appear.