指導教授 : 楊國湘 博士 學 生 : 吳孝謙 學 號 : M09304002 ACOUSTIC EMISSION 指導教授 : 楊國湘 博士 學 生 : 吳孝謙 學 號 : M09304002

CONTENTS OVERVIEW SOURCES OF AE AN AE TESTING METHOD THE AE MEASUREMENT CHAIN TRANSIENT AND CONTINUOUS SIGNALS AE PARAMETERS LOCATION CALCULATION BASED ON TIME DIFFERENCES CONCLUSION

OVERVIEW Acoustic Emission (AE) Analysis is an extremely powerful technology of non-destructive testing.

SOURCES OF AE If the elastic limit is exceeded a fracture occurs immediately,or after a certain plastic deformation.This rapid release of elastic energy is what we call an AE event. figure1

AN AE TESTING METHOD The test object must be stressed mechanically in order to have local defects grow and emit the ultrasound pulses under normal conditions.The AE analysis listens to the right defects that are evaluated at the moment of their occurrence.

THE AE MEASUREMENT CHAIN Figure2 (from Vallen-Systeme GmbH, The Acoustic Emission Company )

TRANSIENT AND CONTINUOUS SIGNALS Figure3 (from Vallen-Systeme GmbH, The Acoustic Emission Company )

AE PARAMETERS One has to determine the most important parameters of the waveforms in order to compare the results of the structure under test with a database of defect-free and defect containing test objects. Figure4 (from Vallen-Systeme GmbH, The Acoustic Emission Company )

LOCATION CALCULATION BASED ON TIME DIFFERENCES D=V*T Figure5.6.7 (from Vallen-Systeme GmbH, The Acoustic Emission Company )

CONCLUSION We can detects and interprets events resulting from these crack processes and can identify locate and display a beginning damage within very short time. The AE analysis can offers great potential for use as a continuous monitoring technique, it also showing the good consensus between the men of knowledge.