Yield strength variation in ring-rolled aluminium

1968 ◽  
Vol 10 (10) ◽  
pp. 749-756 ◽  
Author(s):  
R.M. Caddell ◽  
G. Needham ◽  
W. Johnson
Keyword(s):  
Yield Strength ◽  
Strength Variation ◽  
Yield Strength Variation

scholarly journals The Size Effects of Point Defect on the Mechanical Properties of Monocrystalline Silicon: A Molecular Dynamics Study

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3011
Author(s):  
Wei Wan ◽  
Changxin Tang ◽  
An Qiu ◽  
Yongkang Xiang
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Yield Strength ◽  
Point Defect ◽  
Size Effects ◽  
Constant Strain Rate ◽  
Monocrystalline Silicon ◽  
Dislocation Slip ◽  
Actual Strength ◽  
Yield Strength Variation

The molecular dynamics method was used to simulate the fracture process of monocrystalline silicon with different sizes of point defect under a constant strain rate. The mechanism of the defect size on the mechanical properties of monocrystalline silicon was also investigated. The results suggested that the point defect significantly reduces the yield strength of monocrystalline silicon. The relationships between the yield strength variation and the size of point defect fitted an exponential function. By statistically analyzing the internal stress in monocrystalline silicon, it was found that the stress concentration induced by the point defect led to the decrease in the yield strength. A comparison between the theoretical strength given by the four theories of strength and actual strength proved that the Mises theory was the best theory of strength to describe the yield strength of monocrystalline silicon. The dynamic evolution process of Mises stress and dislocation showed that the fracture was caused by the concentration effect of Mises stress and dislocation slip. Finally, the fractured microstructures were similar to a kind of two-dimensional grid which distributed along the cleavage planes while visualizing the specimens. The results of this article provide a reference for evaluating the size effects of point defects on the mechanical properties of monocrystalline silicon.

Elastic-Plastic Contact Analysis of Materials with Gradient Yield Strength

2006 ◽  
Vol 532-533 ◽  
pp. 881-884
Author(s):  
Qin Xie ◽  
Geng Liu ◽  
Tian Xiang Liu ◽  
Jane Q. Wang
Keyword(s):  
Yield Strength ◽  
Yield Criterion ◽  
Contact Model ◽  
Von Mises Stress ◽  
Stress Distributions ◽  
Initial Stiffness ◽  
Programming Technique ◽  
Elastic Plastic ◽  
Von Mises ◽  
Yield Strength Variation

Reported in the paper is an elastic-plastic contact model developed to analyze the contact performance characteristics of materials with gradient yield strength. Plastic yielding and the strain-hardening properties of the materials are taken into account. The finite element method, the initial stiffness method, and a mathematical programming technique are utilized to solve the contact model. The von Mises yield criterion is used to determine the inception of plastic deformation. Results indicate that nitrided material with appropriate gradient of yield strength may greatly alter the distributions of contact stress, contact pressure as compared with untreated material in contact. The effects of different yield strength variation path of material on von Mises stress distributions are numerically investigated and discussed.

Evaluation of an Alternate Method for Determining Yield Strength Offset Values for Selective Laser Sintered Polymeric Materials

2019 ◽  
Author(s):  
Chelsey Henry ◽  
Keith Rupel ◽  
Charles Park ◽  
Joseph Costanzo ◽  
Cary Kaczowka ◽  
...  
Keyword(s):  
Yield Strength ◽  
Polymeric Materials

Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

2005 ◽  
Vol 10 (2) ◽  
pp. 151-160 ◽  
Author(s):  
J. Kala ◽  
Z. Kala
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Carrying Capacity ◽  
Bending Moment ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Strength Variability ◽  
Hot Rolled ◽  
Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

Regularities and properties of instrumented indentation diagrams obtained by ball-shaped indenter

2020 ◽  
Vol 86 (5) ◽  
pp. 43-51
Author(s):  
V. M. Matyunin ◽  
A. Yu. Marchenkov ◽  
N. Abusaif ◽  
P. V. Volkov ◽  
D. A. Zhgut
Keyword(s):  
Yield Strength ◽  
Ultimate Strength ◽  
Elastoplastic Deformation ◽  
Elastic Limit ◽  
Tensile Tests ◽  
Indentation Load ◽  
International Standards ◽  
Instrumented Indentation ◽  
Indentation Methods ◽  
Special Points

The history of appearance and the current state of instrumented indentation are briefly described. It is noted that the materials instrumented indentation methods using a pyramid and ball indenters are actively developing and are currently regulated by several Russian and international standards. These standards provide formulas for calculating the Young’s modulus and hardness at maximum indentation load. Instrumented indentation diagrams «load F – displacement α» of a ball indenter for metallic materials were investigated. The special points on the instrumented indentation diagrams «F – α» loading curves in the area of elastic into elastoplastic deformation transition, and in the area of stable elastoplastic deformation are revealed. A loading curve area with the load above which the dF/dα begins to decrease is analyzed. A technique is proposed for converting «F – α» diagrams to «unrestored Brinell hardness HBt – relative unrestored indent depth t/R» diagrams. The elastic and elastoplastic areas of «HBt – t/R» diagrams are described by equations obtained analytically and experimentally. The materials strain hardening parameters during ball indentation in the area of elastoplastic and plastic deformation are proposed. The similarity of «HBt – t/R» indentation diagram with the «stress σ – strain δ» tensile diagrams containing common zones and points is shown. Methods have been developed for determining hardness at the elastic limit, hardness at the yield strength, and hardness at the ultimate strength by instrumented indentation with the equations for their calculation. Experiments on structural materials with different mechanical properties were carried out by instrumented indentation. The values of hardness at the elastic limit, hardness at the yield strength and hardness at the ultimate strength are determined. It is concluded that the correlations between the elastic limit and hardness at the elastic limit, yield strength and hardness at the yield strength, ultimate tensile strength and hardness at the ultimate strength is more justified, since the listed mechanical characteristics are determined by the common special points of indentation diagrams and tensile tests diagrams.

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