Acoustic Emission and Force Drop in Grain Crushing of Carbonate Sands

2019 ◽  
Vol 145 (9) ◽  
pp. 04019057 ◽  
Author(s):  
Yang Xiao ◽  
Lei Wang ◽  
Xiang Jiang ◽  
T. Matthew Evans ◽  
Armin W. Stuedlein ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Grain Crushing ◽  
Force Drop

Effect of Loading Path and Porosity on the Failure Mode of Porous Rocks

1992 ◽  
Vol 45 (8) ◽  
pp. 281-293 ◽  
Author(s):  
Teng-fong Wong ◽  
Hiram Szeto ◽  
Jiaxiang Zhang
Keyword(s):  
Acoustic Emission ◽  
Strain Hardening ◽  
Yield Locus ◽  
Loading Path ◽  
High Porosity ◽  
Porous Rocks ◽  
Stress Space ◽  
Pore Collapse ◽  
Clastic Rocks ◽  
Grain Crushing

Grain crushing and pore collapse are the dominant compaction mechanisms in high porosity clastic rocks. These micromechanical processes control the evolution of strain hardening during cataclastic flow, and they can also result in embrittlement of the rock. The mechanics of the transition from brittle fracture to homogeneous cataclastic flow for the Berea and Kayenta sandstones were investigated in the laboratory. The mechanical data show that the transition is sensitively dependent on the stress state as well as the porosity. In the stress space, the complete locus for brittle failure by shear localization can be determined by tests on normally consolidated and overconsolidated samples along different loading paths. Using porosity as the hardening parameter, the evolution of the inelastic yield locus with strain hardening can be mapped out in the stress space. This yield locus expands with decreasing porosity. Scanning electron microscope and acoustic emission measurements were used to elucidate the micromechanics. The onset of grain crushing and pore collapse was marked by a surge in acoustic emission activity. A Hertzian fracture mechanics model was formulated to analyze the roles of porosity, grain size and fracture toughness in controlling the onset of hydrostatic and shear-enhanced compaction. Stereological measurements of the microcrack density show that significant stress-induced anisotropy was induced by shear-enhanced compaction, with preferred orientations of the stress-induced microcracks subparallel to the maximum compression direction.

Propagation of acoustic emission signals in metallic fuselage structure

2001 ◽  
Vol 148 (4) ◽  
pp. 169-177 ◽  
Author(s):  
R.P. Dalton ◽  
P. Cawley ◽  
M.J. Lowe
Keyword(s):  
Acoustic Emission

Comparison of random field strengths in (1-x)SrTiO3-xBiFeO3 and (1-x)SrTiO3-xBaTiO3 relaxor ferroelectrics by means of acoustic emission

2020 ◽  
Vol 92 (2) ◽  
pp. 20401
Author(s):  
Evgeniy Dul'kin ◽  
Michael Roth
Keyword(s):  
Acoustic Emission ◽  
Random Field ◽  
Electric Fields ◽  
Bias Field ◽  
Relaxor Ferroelectrics ◽  
External Bias ◽  
Field Strengths

In relaxor (1-x)SrTiO3-xBiFeO3 ferroelectrics ceramics (x = 0.2, 0.3 and 0.4) both intermediate temperatures and Burns temperatures were successfully detected and their behavior were investigated in dependence on an external bias field using an acoustic emission. All these temperatures exhibit a non-trivial behavior, i.e. attain the minima at some threshold fields as a bias field enhances. It is established that the threshold fields decrease as x increases in (1-x)SrTiO3-xBiFeO3, as it previously observed in (1-x)SrTiO3-xBaTiO3 (E. Dul'kin, J. Zhai, M. Roth, Phys. Status Solidi B 252, 2079 (2015)). Based on the data of the threshold fields the mechanisms of arising of random electric fields are discussed and their strengths are compared in both these relaxor ferroelectrics.

Sign in / Sign up

Export Citation Format

Share Document