scholarly journals A connexion between the criterion of yield and the strain ratio relationship in plastic solids

1947 ◽  
Vol 191 (1027) ◽  
pp. 441-446 ◽  
Keyword(s):  
Plastic Strain ◽  
Yield Stress ◽  
Principal Stress ◽  
Strain Differences ◽  
Strain Ratio ◽  
Stress Criterion ◽  
Small Plastic ◽  
Maximum Work ◽  
Work Done ◽  
Small Plastic Strain

The assumption that the work done during a small plastic strain is a maximum as the yield - stress criterion is varied is shown to give rise to a connexion between the yield-stress and the strain-ratio relationship. The strain-ratio relationship is that which exists between the ratios of principal stress differences and the ratios of the corresponding strain differences. It is common to assume that this relationship is one of simple proportionality. Experiments, however, show that this assumption is not true in metals. The observed strain-ratio relationship is used in conjunction with the assumption of maximum work during a given strain to calculate the criterion of yield. It is found that this is very close to, but not identical with, the Mises-Heneky criterion.

A round robin EBSD measurement for quantitative assessment of small plastic strain

2020 ◽  
Vol 170 ◽  
pp. 110662
Author(s):  
Masayuki Kamaya ◽  
Yohei Sakakibara ◽  
Rika Yoda ◽  
Seiichi Suzuki ◽  
Hirobumi Morita ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Quantitative Assessment ◽  
Round Robin ◽  
Ebsd Measurement ◽  
Small Plastic ◽  
Small Plastic Strain

scholarly journals FATIGUE PERFORMANCE OF THE BUCKLING-RESTRAINED BRACE IN THE SMALL PLASTIC STRAIN AMPLITUDE

2016 ◽  
Vol 22 (50) ◽  
pp. 115-119 ◽  
Author(s):  
Kazuhisa KOYANO ◽  
Shuichi KOIDE ◽  
Tadao NAKAGOMI ◽  
Mitsumasa MIDORIKAWA ◽  
Mamoru IWATA
Keyword(s):  
Plastic Strain ◽  
Strain Amplitude ◽  
Plastic Strain Amplitude ◽  
Fatigue Performance ◽  
Buckling Restrained Brace ◽  
Small Plastic ◽  
Small Plastic Strain

Elastic-Plastic Pull-In Strength and Damage Analyses of Steel Catenary Risers in Deepwater

2011 ◽  
Author(s):  
C. H. Luk ◽  
S.-H. Mark Chang
Keyword(s):  
Aspect Ratio ◽  
Plastic Strain ◽  
Plastic Zone ◽  
Bend Radius ◽  
Elastic Plastic ◽  
Low Aspect Ratio ◽  
Small Plastic ◽  
Surface Flaws ◽  
Plastic Analysis ◽  
Small Plastic Strain

This paper presents the strength and damage results based on elastic-plastic analysis to address the design feasibility of pulling in a steel catenary riser (SCR) through a pull tube with various bend configurations in a Spar. The example riser system contains an SCR of typical size, a tapered stress joint, a vertical pull tube with multiple bend sections, guide supports for the pull tube, and the associated pull head and pull chain connected to the top of the riser. The design methods discussed in the paper include: (1) Modeling of riser and pull tube in ABAQUS for strength analysis of the SCR; (2) Strain-based strain-life method to assess the associated fatigue damage; and (3) Strain-based Level 3B ECA design method to derive the critical surface flaw sizes for weld qualification of the SCR inside the pull tube. Comparisons are also presented between results derived from elastic and elastic-plastic analysis methods. The pull-in load on the example SCR increases with the water depth as well as the number and curvature of the bends on the pull tube. Calculated riser pull-in loads are about 11% to 51% higher than the submerged weight of the SCR. The elastic-plastic analysis shows small plastic zone and also small plastic strain on the example SCRs passing through pull tubes of a large bend radius of 125 ft. It also shows large plastic zone but small plastic strain on the SCR in a triple-bend pull tube with a small bend radius of 70 ft. The overall fatigue damage caused by cyclic plastic straining on the example SCRs due to pull in is lower than 3.3%. The allowable surface flaw sizes for the example SCRs are on the order of a × 2c = 8 × 10mm and 2.5 × 40mm for low aspect-ratio and high aspect-ratio surface flaws, respectively. Critical flaw sizes determined by Level 2A ECA are about 25% smaller than the flaw sizes based on Level 3B ECA for low aspect-ratio surface flaws. The specified maximum allowable flaw sizes are not very sensitive to the pull tube configuration and the water depth under the present study. The strength and damage analyses of SCR from other installation methods such as reeling are not included in this paper.

Creep of a Hollow Sphere

1990 ◽  
Vol 57 (2) ◽  
pp. 276-281
Author(s):  
T. Sakaki ◽  
T. Kuroki ◽  
K. Sugimoto
Keyword(s):  
Thermal Stress ◽  
Plastic Strain ◽  
Hollow Sphere ◽  
Strain Range ◽  
Steady Creep ◽  
Steady State Creep Rate ◽  
Plastic Strain Range ◽  
Small Plastic ◽  
Numerical Calculation Method ◽  
Small Plastic Strain

Using internal stress arising from a spherically symmetric, finite plastic strain, creep of a hollow sphere subjected to inner and outer pressures, and also thermal stress, is discussed. If computer-aided numerical calculation method is used, creep is easily followed up to a finite plastic strain range including initial transient creep, whatever type of creep law is employed. If assumed in a steady state, creep rate, stress, small plastic strain leading to a stress state in steady creep, and another small plastic strain relaxing thermal stress are analytically obtained. Numerical method is also applicable to creep relaxation. Further, the origin of residual stress after unloading is clarified.

A Modified Peric Model for Al-Mg Alloy Sheet with Rate-Independent Initial Yield Stress at Warm Temperatures

2019 ◽  
Vol 287 ◽  
pp. 3-7
Author(s):  
Yong Zhang ◽  
Qing Zhang ◽  
Yuan Tao Sun ◽  
Xian Rong Qin
Keyword(s):  
Flow Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
Yield Stress ◽  
Constitutive Models ◽  
Mg Alloy ◽  
Initial Yield Stress ◽  
Initial Yield ◽  
Rate Dependent ◽  
Dependent Flow

The constitutive modeling of aluminum alloy under warm forming conditions generally considers the influence of temperature and strain rate. It has been shown by published flow stress curves of Al-Mg alloy that there is nearly no effect of strain rate on initial yield stress at various temperatures. However, most constitutive models ignored this phenomenon and may lead to inaccurate description. In order to capture the rate-independent initial yield stress, Peric model is modified via introducing plastic strain to multiply the strain rate, for eliminating the effect of strain rate when the plastic strain is zero. Other constitutive models including the Wagoner, modified Hockett–Sherby and Peric are also considered and compared. The results show that the modified Peric model could not only describe the temperature-and rate-dependent flow stress, but also capture the rate-independent initial yield stress, while the Wagoner, modified Hockett–Sherby and Peric model can only describe the temperature-and rate-dependent flow stress. Moreover, the modified Peric model could obtain proper static yield stress more naturally, and this property may have potential applications in rate-dependent simulations.

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