scholarly journals A Surface Transition Layer Model for Size Effect in T2 Copper Micro-Compression

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 736
Author(s):  
Deng ◽  
Liu ◽  
Wang ◽  
Jin
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Flow Stress ◽  
Sample Size ◽  
Transition Layer ◽  
Strain Curve ◽  
Experimental Results ◽  
Layer Model ◽  
Stress Strain ◽  
Surface Transition

The effects of sample size and grain size on the surface morphology and flow stress of deformed samples were investigated by means of copper micro-cylinder compression experiments at room temperature. The results of SEM showed that when the grain size increased or the sample size decreased, the deformation non-uniformity of samples’ free surfaces increased. Meanwhile, the stress–strain curves showed that during the compression process, the flow stress of the sample also tended to decrease as the grain size increased or the sample size decreased. According to the experimental results of nanoindentation, a surface transition layer model was established on the basis of the surface layer model by considering the mutual constraint of grains and the existence of transition layer grains. The experimental results indicated that the stress–strain curve calculated by the surface transition layer model can more accurately reflect the actual deformation situation of the material compared to the surface layer model.

Fracture Assessment of Pipes Having Multiple Flaws Based on Ramberg–Osgood-Type Stress–Strain Relationships

2011 ◽  
Author(s):  
Hideo Machida ◽  
Tetsuya Hamanaka ◽  
Yoshiaki Takahashi ◽  
Katsumasa Miyazaki ◽  
Fuminori Iwamatsu ◽  
...  
Keyword(s):  
Flow Stress ◽  
Stress Concentration ◽  
Fracture Strength ◽  
Strain Curve ◽  
Assessment Method ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Strain Relationship ◽  
Fracture Assessment

This paper describes a fracture assessment method for a pipe having multiple circumferential flaws. According to Fitness-for-Service (FFS) codes for nuclear facilities published by the Japanese Society of Mechanical Engineers (JSME), the fracture strength of a high-ductility pipe having a circumferential flaw is evaluated using the limit load assessment method assuming the elastic–perfectly-plastic stress–strain relationship. In this assessment, flow stress is used as a proportional stress. However, previous experimental results [1, 2, 3] show that a crack penetrates before the entire flawed pipe section reaches the flow stress. Therefore, stress concentration at a flaw was evaluated on the basis of the Dugdale model [4], and the fracture strength of the crack-ligament was evaluated. This model can predict test results with high accuracy when the ligament fracture strength is assumed to be tensile strength. Based on this examination, a fracture assessment method for pipes having multiple flaws was developed considering the stress concentration in the crack-ligament by using the realistic stress–strain relationship (Ramberg–Osgood-type stress–strain curve). The fracture strength of a multiple-flawed pipe estimated by the developed method was compared with previous experimental results. When the stress concentration in the crack-ligament was taken into consideration, the fracture strength estimated using the Ramberg–Osgood-type stress–strain curve was in good agreement with experimental results, confirming the validity of the proposed method.

Definition of the yield point in plasticity and its effect on the shape of the yield locus

1966 ◽  
Vol 1 (4) ◽  
pp. 331-338 ◽  
Author(s):  
T C Hsu
Keyword(s):  
Yield Point ◽  
Experimental Work ◽  
Strain Curve ◽  
Yield Locus ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Proportional Limit ◽  
Stress Strain ◽  
Small Section ◽  
Definition Of

Three different definitions of the yield point have been used in experimental work on the yield locus: proportional limit, proof strain and the ‘yield point’ by backward extrapolation. The theoretical implications of the ‘yield point’ by backward extrapolation are examined in an analysis of the loading and re-loading stress paths. It is shown, in connection with experimental results by Miastkowski and Szczepinski, that the proportional limit found by inspection is in fact a point located by backward extrapolation based on a small section of the stress-strain curve, near the elastic portion of the curve. The effect of different definitions of the yield point on the shape of the yield locus and some considerations for the choice between them are discussed.

Elastic-Plastic Stress Distribution in a Compressed Ring

1968 ◽  
Vol 90 (4) ◽  
pp. 435-440
Author(s):  
K. T. Chang ◽  
P. M. Leopold
Keyword(s):  
Stress Distribution ◽  
Strain Curve ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Strain Gages ◽  
Stress Strain ◽  
Theoretical Predictions ◽  
Strain Relationship ◽  
Plastic Stress

This investigation was conducted to define the plastic stress distribution at a section 90 degrees from the point of load application on a ring. The elastic and plastic stress distribution was determined experimentally by using postyield strain gages and the stress-strain relationship obtained from a uniaxial tensile test. The experimental results in the elastic range were found to agree with presently available theoretical predictions. A theoretical plasticity analysis of the ring was made by assuming that it deforms to the shape of an ellipse and that plane sections remain plane. The strains determined in this manner were used to calculate stresses off the tensile stress-strain curve. The experimental results indicated that this initial analysis gave a good approximation of the stress distribution for large deflections of the ring.

scholarly journals Constitutive Model of 30CrMoA Steel with Strain Correction

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1214
Author(s):  
Song Zhang ◽  
Xuedao Shu ◽  
Jitai Wang ◽  
Yingxiang Xia
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
High Speed ◽  
Strain Curve ◽  
Material Constant ◽  
Test Machine ◽  
Experimental Stress ◽  
High Speed Train ◽  
Stress Strain Curve ◽  
Stress Strain

It is necessary to establish a constitutive model of 30CrMoA steel to optimize the forming shape and mechanical properties of high-speed train axles. The experimental stress–strain curve of 30CrMoA steel was obtained by an isothermal compression test on a Gleeble-3500 thermal simulation test machine under temperature of 1273~1423 K and strain rate of 0.01~10 s−1. Considering the effect of strain on the material constant, an empirical constitutive model was proposed with strain correction for 30CrMoA steel. In addition, the material constant in the constitutive model is determined by linear regression analysis of the experimental stress–strain curve. Comparing the theoretical value and experimental value of flow stress, the correlation R is 0.9828 and the average relative error (ARRE) is 4.652%. The constitutive model of 30CrMoA steel with strain correction can reasonably predict the flow stress under various conditions. The results provide an effective numerical tool for further study on accurate near-net forming of high-speed train axles.

scholarly journals Scientifically substantiated definition of quality optimum parameters for surface layer low-rigid shafts at centrifugal runningin

2016 ◽  
Vol 1 (6) ◽  
pp. 28-34
Author(s):  
С. Зайдес ◽  
S. Zaides ◽  
А. Горбунов ◽  
A. Gorbunov
Keyword(s):  
Grain Size ◽  
Surface Layer ◽  
Experimental Results ◽  
Cold Hardening ◽  
Layer Depth ◽  
Optimum Parameters ◽  
A Value ◽  
Basic Parameters ◽  
Definition Of

A surface layer and a cold-hardening depth as basic parameters ensuring quality of low-rigid shafts are analyzed. A value of an interference area depending on a grain size which is a criterion for the definition of strengthened layer depth is established. The experimental results on the definition of quality basic parameters for a surface layer at the strengthening for the depth of an interference area are shown.

Experimental Research on Stress-Strain Curve of Carbon Fiber Reinforced Concrete

2013 ◽  
Vol 668 ◽  
pp. 640-644 ◽  
Author(s):  
Xiao Chu Wang ◽  
Jun Wei Wang ◽  
Hong Tao Liu
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Strain Curve ◽  
Fiber Reinforced Concrete ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Fiber Volume ◽  
Stress Strain

In order to further investigate the stress-strain curve of carbon fiber reinforced concrete, the curve of stress-strain is used segmentation tabulators on the basis of the existing tests. Based on the axial compression experiments of 9 carbon fiber concrete reinforced samples filled with different carbon fiber admixture amounts, the theoretical calculating formula of the stress-strain curve with different admixture amounts was proposed, and the theoretical formula of calculation parameters and carbon fiber volume fraction was putted forward. The experimental results show that the calculation parameters of the stress-strain curve increases with the increase of the carbon fiber admixture amounts. The theoretical calculating formula of the peak strain and carbon fiber volume fraction, the compressive strength, and the calculated results agreed well with the experimental results.

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