Wear Process Description Based on Acoustic Emission

1990 ◽  
Vol 112 (3) ◽  
pp. 469-476 ◽  
Author(s):  
B. E. Klamecki ◽  
J. Hanchi
Keyword(s):  
Acoustic Emission ◽  
Wear Behavior ◽  
Acoustic Emissions ◽  
Amplitude Distribution ◽  
Wear Process ◽  
Acoustic Emission Count ◽  
Deformation And Fracture ◽  
Emission Activity ◽  
Active Processes ◽  
Insight Into

Since acoustic emissions are generated by fundamental mechanical processes, they can provide insight into the basic processes which determine friction and wear behavior. Descriptions of acoustic emission generated by plastic deformation and fracture were developed, and wear tests were performed, during which acoustic emission activity was measured. This work demonstrates that acoustic emissions can be used to track the wear process in terms of the energy dissipation mechanisms acting. The results show that acoustic emission count rate and amplitude distribution correspond to wear rate and that the amplitude distribution also indicates the active processes contributing to wear.

Acoustic Emission Diagnostics of the Destruction of Welded Joints Stainless Steel Pipes Arising Welding

2015 ◽  
Vol 770 ◽  
pp. 60-65
Author(s):  
A.M. Apasov
Keyword(s):  
Stainless Steel ◽  
Acoustic Emission ◽  
Structural Analysis ◽  
Welded Joints ◽  
Crack Nucleation ◽  
Amplitude Distribution ◽  
Steel Pipes ◽  
Weld Root ◽  
Ae Signals ◽  
Insight Into

It is now possible to formulate the relation of the linear size of cracking arising on welding the cylindrical homogeneous-metal. Mathematical simulation of metal crystallization on welding and micro structural analysis give an insight into the fact that there begins crack nucleation in a weld root. Experimentally, by means of Acoustic Emission (AE), one can study welding and obtain the amplitude distribution of AE signals from cracking against the background of the hindrance accompanying this process. The conditions were found making impossible cracking.

Monitoring Acoustic Emissions from Finger-Joints from Tropical African Hardwoods for Predicting Ultimate Tensile Strength

Holzforschung ◽  
2001 ◽  
Vol 55 (6) ◽  
pp. 652-660
Author(s):  
J. Ayarkwa ◽  
Y. Hirashima ◽  
K. Ando ◽  
Y. Sasaki
Keyword(s):  
Tensile Strength ◽  
Acoustic Emission ◽  
Ultimate Tensile Strength ◽  
Acoustic Emissions ◽  
Tension Test ◽  
Regression Coefficients ◽  
Finger Joints ◽  
Acoustic Emission Count ◽  
Monitoring Procedure ◽  
Species Type

Summary The patterns of acoustic emissions generated during tension test of finger-joints from three tropical African hardwoods, Obeche (Triplochiton scleroxylon), Makore (Tieghemella heckelii) and Moabi (Baillonella toxisperma) were evaluated to assess their potential usefulness for non-destructively predicting ultimate tensile strength. The acoustic emission patterns generated were observed to differ depending on the type of finger profile and the wood species. Regression coefficients from cumulative acoustic emission count versus applied stress squared functions also varied with the profile and species type. When ultimate tensile strength was correlated with these regression coefficients, for stresses applied up to 50% of mean ultimate strength, the logarithmic regression model developed could predict finger-joint strength accurate to ±12%, ±13% and ±18% for Obeche, Makore and Moabi, respectively. The model was also sensitive to the type of finger profile used for all three tropical African hardwoods. The results indicate that this acoustic emission monitoring procedure could be useful for non-destructively predicting ultimate tensile strength of finger-joints from the three tropical African hardwoods.

Simultaneous Monitoring of Rolling-Element and Journal Bearings Using Analysis of Structure-Born Ultrasound Acoustic Emissions

2010 ◽  
Author(s):  
A. Albers ◽  
M. Dickerhof
Keyword(s):  
Acoustic Emission ◽  
Acoustic Emissions ◽  
Piezoelectric Sensor ◽  
Journal Bearings ◽  
Rolling Element Bearings ◽  
Acoustic Emission Sensor ◽  
Outer Race ◽  
Rolling Element ◽  
Characteristic Values ◽  
Acoustic Emission Technology

The application of Acoustic Emission technology for monitoring rolling element or hydrodynamic plain bearings has been addressed by several authors in former times. Most of these investigations took place under idealized conditions, to allow the concentration on one single source of emission, typically recorded by means of a piezoelectric sensor. This can be achieved by either eliminating other sources in advance or taking measures to shield them out (e. g. by placing the acoustic emission sensor very close to the source of interest), so that in consequence only one source of structure-born sound is present in the signal. With a practical orientation this is often not possible. In point of fact, a multitude of potential sources of emission can be worth considering, unfortunately superimposing one another. The investigations reported in this paper are therefore focused on the simultaneous monitoring of both bearing types mentioned above. Only one piezoelectric acoustic emission sensor is utilized, which is placed rather far away from the monitored bearings. By derivation of characteristic values from the sensor signal, different simulated defects can be detected reliably: seeded defects in the inner and outer race of rolling element bearings as well as the occurrence of mixed friction in the sliding surface bearing due to interrupted lubricant inflow.

Experimental analysis of crack evolution in concrete by the acoustic emission technique

2015 ◽  
Author(s):  
J. Saliba ◽  
A. Loukili ◽  
J.P. Regoin ◽  
D. Grégoire ◽  
L. Verdon ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Fracture Process ◽  
Process Zone ◽  
Mouth Opening ◽  
Acoustic Emissions ◽  
Plain Concrete ◽  
Crack Mouth Opening Displacement ◽  
Notch Depth ◽  
Opening Displacement ◽  
Magnitude Distribution

The fracture process zone (FPZ) was investigated on unnotched and notched beams with different notch depths. Three point bending tests were realized on plain concrete under crack mouth opening displacement (CMOD) control. Crack growth was monitored by applying the acoustic emission (AE) technique. In order to improve our understanding of the FPZ, the width and length of the FPZ were followed based on the AE source locations maps and several AE parameters were studied during the entire loading process. The bvalue analysis, defined as the log-linear slope of the frequency-magnitude distribution of acoustic emissions, was also carried out to describe quantitatively the influence of the relative notch depth on the fracture process. The results show that the number of AE hits increased with the decrease of the relative notch depth and an important AE energy dissipation was observed at the crack initiation in unnotched beams. In addition, the relative notch depth influenced the AE characteristics, the process of crack propagation, and the brittleness of concrete.

scholarly journals Snow Avalanches and Acoustic Emissions

1983 ◽  
Vol 4 ◽  
pp. 271-276 ◽  
Author(s):  
R. A. Sommerfeld ◽  
H. Gubler
Keyword(s):  
Acoustic Emissions ◽  
Limited Range ◽  
Slope Instability ◽  
Type I ◽  
Type Ii ◽  
Noise Levels ◽  
Active Layers ◽  
Differential Movement ◽  
Emission Activity

Analyses of several years of data show that acoustic emission activity is greater from unstable snowpacks than from stable snowpacks. Two types of signals have been identified: type I spikes and type II long-term elevation of the noise level. It is thought that the type I signals originate from macroscopic cracks. The type II signals may originate from differential movement on shearing surfaces, but this is less certain. Increased noise levels of both types correlate well with slope instability, when the slope stability is known. In some climates the limited range of signal detection might be a significant problem. A foam-mounted geophone set into the snow near active layers appears to be the best sensor available at present.

scholarly journals Acoustic Emission in Snow at Constant Rates of Deformation

1973 ◽  
Vol 12 (64) ◽  
pp. 144-146 ◽  
Author(s):  
W. F. St. Lawrence ◽  
T. E. Lang ◽  
R.L. Brown ◽  
C. C. Bradley
Keyword(s):  
Acoustic Emission ◽  
Brittle Fracture ◽  
Uniaxial Compression ◽  
Laboratory Experiments ◽  
Acoustic Emissions ◽  
Snow Sample ◽  
Frequency Range ◽  
Snow Samples

AbstractAcoustic emissions in the audio spectrum are reported from observations of laboratory experiments conducted on snow samples in uniaxial compression. A number of tests show the pattern of acoustic emissions to be a function of the rate of deformation. Over the frequency range 20 to 7 000 Hz acoustic emissions are associated with rates of deformation corresponding to brittle fracture of the snow sample. Though probably present, no acoustic emissions were detected from samples deforming plastically.

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