Study On Correlation Of Basic Parameters Of Acoustic Emission System And Its Impact On The Spatial Prientation

Acoustic emission technology is a new nondestructive testing diagnostic technique can satisfy the real-time dynamic detection, and the judgment and prediction of the development trend of internal damage under the action of external force can be made by this technology. However, many basic problems about acoustic emission technology in the field of rock damage monitoring have not been thoroughly studied. In this paper, four basic problems will be researched:the setting of acoustic emission system hardware parameter, the selection of acoustic emission signal parameters, the selection of probe and the variation of wave velocity in the loading process. Some references will be provided for the further acoustic emission research work.Firstly, in this paper the relevant research results of both domestic and overseas scholars are summarized, the development of acoustic emission in rock field is realized. Secondly, the setting method of the threshold, the PDT, HDT, HLT and wave velocity is determined through the broken lead test and load simulation test. Then, the relevant theoretical analysis and experimental research about the parameters of the simplified waveform is utilized in this paper for analyzing the correlation among these signal parameters. Again, some parameters of probe affecting the three-dimensional positioning are used to be researched. Finally, the changes of wave velocity in the process of loading and the acoustic emission features of rock damage are researched. Through the work mentioned above main conclusions are as follows:(1) In the uniaxial compression test of granite,40dB as the threshold,150μs,30μs,400μs as value of PDT HDT HLT, the test effect is good.(2) An important influence to positioning is made by probes. For this paper, positioning effect is good when the edge of probe and the edge of specimen is at the same level, positioning effect of6probes is better than positioning effect of4probes, and the R6probe is better than NANO-30.(3) In the experiment of acoustic emission three-dimensional positioning, in the case of that sampling rate is satisfied the sampling theorem, the sampling rate is not the bigger the better. At the instant of damage, acoustic emission signals can not be formed located events, that is because the acoustic emission signals at this moment is continuous, so location can not be formed at the instant of damage.(4) The correlation among energy, the absolute power, the signal strength is close to1, the correlation between ringing count and duration is close to1.(5) Essentially, the changing of wave velocity with load is due to the change of the porosity in the process of uniaxial loading.(6) In the process of uniaxial loading, the crack initiation and propagation rule inside the specimens can be reflected by the distribution of acoustic emission events in the spatial orientation.(7) The time crack beginning can be reflected by the curve of acoustic emission events-time in some degree, the turning points of curve as the points of crack beginning, the spurt point of acoustic emission events accumulated curve can be as a precursor of rock failure.