Acoustic Emission (AE) technique has distinguished itself as an active NDT technique and therefore its unique application where active defects/discontinuities are encountered, particularly in the case of fracture prone pressurised systems - both metallic and Fibre Reinforced Plastics (FRP). AE monitoring is carried out either during their acceptance testing as in the case of aerospace pressure chambers or during their operation also as in the case of pressure vessels used in nuclear and chemical industries. Whilst the AE technique has satisfactorily demonstrated its capability for the location of active flaws and its severity on a qualitative basis, the technique suffers from limitations in characterizing the defects or quantifying the severity of the defects. Besides, AE being material specific, it requires separate comprehensive studies of signatures and generation of criteria for any application. Nevertheless the importance of certain common standards and guidelines with respect to any general application cannot be less stressed especially in the context of different AE equipment manufactures following their own calibration standards etc. The paper reviews the AE application attempted by several users beginning with its well known maiden application in the aerospace industry almost three decades ago. The guide lines or criteria, if any, followed for the qualitative or quantitative evaluation are discussed. The efforts to characterize the defects and the severity along with their limitations are brought out. The difficulties experienced by the users when it come to application of lab scale results to large pressure chambers are highlighted. The paper makes a critical study of the technique which offers many promises especially in the background of the aforesaid limitations. The possible refinements that would bring out the best from the technique for its effective application to pressurized systems is outlined. The paper also attempts to dispel the panacea syndrome' attached to the technique by many of the enthusiastic users.
Publication Source: Trends in NDE Science & Technology; Proceedings of the 14th World Conference on Non-Destructive Testing, New Delhi, 8-13 December 1996.full paper not received Publisher:Ashgate Publishing Company
NDTnet
