scholarly journals Determination of tensile strength of concrete and rocks by using the Brazilian test in the confrontation with the failure criteria

2014 ◽  
Vol 13 (2) ◽  
pp. 191-200
Author(s):  
Jakub Gontarz ◽  
Jerzy Podgórski
Keyword(s):  
Tensile Strength ◽  
Stress Field ◽  
Brittle Material ◽  
Critical Stress ◽  
Failure Criteria ◽  
Brazilian Test ◽  
Compression Tests

The paper presents the analysis of the Brazilian compression tests considering the possibilities of determining the proper tensile strength. These analyses include the precise designation of the stress field without singularity at the point of application of force, the evaluation of critical stress in the light of classical and contemporary failure criteria for a brittle material, and determination of the position of the point where the destructive crack is expected to be initiated in the sample.

Determination of the Onset of the Dynamic Recystallization of a 7075 Al Alloy

2013 ◽  
Vol 752 ◽  
pp. 105-114 ◽  
Author(s):  
Tamás Mikó ◽  
Peter Barkoczy
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Critical Stress ◽  
Al Alloy ◽  
Strain Rates ◽  
Compression Tests ◽  
Critical Stresses ◽  
Work Hardening Rate ◽  
Initial States

This paper presents an investigation about the occurrence of the dynamic recrystallization (DRX) during hot forming. Two 7075 aluminum alloy samples in different initial states were examined by compression tests at temperatures between 573 K and 723 K and constant strain rates ranging from 0.002 to 2 (s-1) with the maximum strain of 0.5 mm/mm. The activation energies of the examined aluminium were calculated, being 137.7 kJ/mol and 142.4 kJ/mol. The critical stresses and strains for the initiation of the dynamic recrystallization were determined using a numerical method based on the changes of the work hardening rate (θ) as a function of the flow stress (σ) or a strain (ε), respectively. Based on the micrographs taken after the deformations it was revealed that in some cases only dinamyc recovery (DRV) whereas in others DRX occurred under the applied examination conditions. The critical stress which belongs to the onset of the DRX or the DRV depend on the temperature, the strain rate, and the initial grain size. The critical and maximal stresses and the corresponding strain values at different conditions were determined. In the examined range of deformation, temperature and strain rate, the critical rations are σ_c/σ_p= (0.93-0.99) and εc/ εp = (0.3-0.74), respectively.

Determination of Tensile Strength of Compacted Loess by Double Punch Test

2011 ◽  
Vol 194-196 ◽  
pp. 1176-1179 ◽  
Author(s):  
Xiao Jun Li ◽  
Ying Ran Liu ◽  
Li Hua Jiang ◽  
Yi Chuan Tang
Keyword(s):  
Tensile Strength ◽  
Water Content ◽  
Dry Weight ◽  
Brazilian Test ◽  
Punch Test ◽  
Weight Density ◽  
The Relationship ◽  
Water Contents ◽  
Compacted Loess

Through double punch test, the tensile strength of compacted loess is determined under different water contents and different dry densities, the relationship between tensile strength, water content and the dry weight density is discussed, and their relationship is established. Comparing with Brazilian test, it proved the feasibility of determining tensile strength of compacted loess with double punch tests.

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