Effect of Stress Fields on Acoustic Emission during Delayed Fracture of Glass

2020 ◽  
Vol 853 ◽  
pp. 157-161
Author(s):  
Akematsu Yoshiaki ◽  
Tani Takayuki ◽  
Gotoh Hiromitsu
Keyword(s):  
Acoustic Emission ◽  
Stress Field ◽  
Vickers Hardness ◽  
Hardness Test ◽  
Indentation Load ◽  
Stress Fields ◽  
Vickers Indentation ◽  
Delayed Fracture ◽  
Ae Signals ◽  
Vickers Hardness Test

We investigated the effects of the stress field on acoustic emission (AE) during delayed fracture of glass. Delay fracture occurrence was controlled by the Vickers indentation load and kind of glass. Delayed fractures of glass were monitored by an AE method. After the Vickers hardness test, the glass surface was observed and its condition was compared with the AE signals. Characteristic AE signals were identified, and it was shown that the AE method is effective in measurements on the delayed fracture of glass.

scholarly journals Local stress fields in solids estimated by acoustical emission method

2021 ◽  
Vol 2103 (1) ◽  
pp. 012064
Author(s):  
V L Hilarov ◽  
E E Damaskinskaya
Keyword(s):  
Time Series ◽  
Acoustic Emission ◽  
Stress Field ◽  
Estimation Method ◽  
Local Stress ◽  
Stress Fields ◽  
Emission Method ◽  
Macroscopic Fracture ◽  
Stress Estimation ◽  
Kinetic Concept

Abstract Based on the Zhurkov’s kinetic concept of solids’ fracture a local internal stress estimation method is introduced. Stress field is computed from the time series of acoustic emission intervals between successive signals. For the case of two structurally different materials the time evolution of these stresses is examined. It is shown that temporal changes of these stresses’ accumulation law may serve as a precursor of incoming macroscopic fracture.

scholarly journals The effect of various Co contents on the microstructure and properties of Ti(C,N)-TiB2-Co cermets prepared in situ via reactive hot pressing

2020 ◽  
Vol 12 (5) ◽  
pp. 168781402092571
Author(s):  
Xianrui Zhao ◽  
Ze Yu ◽  
Dunwen Zuo ◽  
Qintao Li ◽  
Mengxian Zhang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Relative Density ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Hardness Test ◽  
Reactive Hot Pressing ◽  
Compacting Pressure ◽  
Vickers Hardness Test ◽  
Scanning Electron

Ti(C,N)-TiB2-Co cermets were in situ synthesized, via reactive hot pressing from the Co-Ti-C-BN system, with a Co content ranging from 6 to 22 wt%. The microstructure, relative density, hardness, and fracture toughness of the sintered compacts was investigated by light microscopy, scanning electron microscopy, ceramic densitometry, and Vickers hardness test. The investigations indicate that during hot pressing (compacting pressure = 30 MPa), when the Co content is 14–22 wt%, the metal binder is extruded. Co and Ti are included in the extrudate, breaking the original ratio and deteriorating the properties of the sintered products. As the Co content increases from 6 wt% to 12 wt%, the porosity increases, and the relative density increases from 97.2% to 99.5%. The fracture toughness increases from 6.1 to 6.8 MPa m1/2. The Vickers hardness first increases from 1897 HV10 to the maximum 1960 HV10 and then decreases slightly to 1945 HV10.

Vickers Microhardness Dependence Load and Determining of Tensile Strength of HQ 705 Steel from Microhardness Curves

2016 ◽  
Vol 842 ◽  
pp. 43-52 ◽  
Author(s):  
Viktor Malau ◽  
Latif Arifudin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Alloy Steel ◽  
Vickers Hardness ◽  
Vickers Microhardness ◽  
Hardness Test ◽  
Indentation Load ◽  
Holding Time ◽  
Raw Material ◽  
Vickers Hardness Number

Vickers microindentation hardness test has been applied for a long time to determine the mechanical properties of a small volume of samples. The procedure of this hardness test consists of using a constant load on a rigid indenter and measuring the dimensions of the indenter residual impression (indentation imprint) on the surface of the sample tested after loading and unloading. The objective of this research is to characterize the mechanical properties and material constants of HQ (High Quality) 705 alloy steel mainly its VHN (Vickers Hardness Number) and tensile strength before and after quenching and tempering heat treatments. The characterization is based on Vickers microhardness dependence load curves.Quenching treatment was performed in a furnace by heating the samples at austenite temperature of 850 o C with holding time of two hours and then the samples were rapidly cooled in oil bath. Tempering processes were conducted by heating again the quenching samples to temperatures of 150, 200, 250, 300, 350, 400, 450, 500, 550 and 600 o C with holding time of two hours for each sample. Finally, all samples were slowly cooled in atmospheric temperature. The mechanical properties of samples were characterized by using Vickers microhardness dependence load curves.The results show that VHN (Vickers Hardness Number) depends on indentation load and VHN increases with increment of load for indentation load lower than 5 N. VHN is almost constant for indentation load greater than 5 N. The raw material (without heat treatment) has the VHN and tensile strength of 3413 MPa and 1050.61 MPa respectively and the quenched samples have the VHN and tensile strength of 5407 and 1861 MPa respectively. The Vickers hardness and tensile strength decrease with the increment of tempering temperatures. The higher tempering temperature produces lower hardness and tensile strength. The raw material tensile strength of 1058.8 MPa obtained by tensile test is comparable to its tensile strength of 1050.61 MPa obtained by Vickers indentation. This result indicates that Vickers microindentation is valid to use for evaluating the tensile strength of HQ 705 alloy steel.

Finite Element Method for Simulating the Vickers Hardness Test

2014 ◽  
Vol 555 ◽  
pp. 419-424 ◽  
Author(s):  
Victor Popovici ◽  
Adrian Catalin Pavalache ◽  
Mihai Vasile ◽  
Ionelia Voiculescu ◽  
Elena Manuela Stanciu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Finite Element Modeling ◽  
Vickers Hardness ◽  
Young Modulus ◽  
Hardness Test ◽  
The Finite Element Method ◽  
Simulation Based ◽  
Vickers Hardness Test ◽  
Element Method

The purpose of the present paper is to present a different approach to the finite element modeling of the Vickers hardness test measurement, and to establish a numerical correlation between the Young modulus of a material and its hardness. In order to realize this, calculations were based upon the tensions acquired as a result of the hollow caused in the investigated materials by the indenter the maps of stresses. The present work demonstrates that from the results of the simulation based on the finite element method it is possible to compute a material’s hardness.

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