Elastic-Plastic Deformation of a Single Grooved Flat Plate Under Longitudinal Shear

1963 ◽  
Vol 85 (4) ◽  
pp. 585-591 ◽  
Author(s):  
Michael F. Koskinen
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Plastic Zone ◽  
Flat Plate ◽  
High Stress ◽  
Longitudinal Shear ◽  
Elastic Plastic ◽  
Semiempirical Equation ◽  
Stress Levels ◽  
Plastic Case

The development of plastic strain is followed from the elastic through the partially plastic to the fully plastic condition for a nonstrainhardening material. Adjacent to the zone of deformation in the fully plastic case is a region of limited plastic deformation. The growth of the plastic zone is compared with predictions based on the elastic-plastic solution for a semi-infinite solid and the elastic solution for a plate. Agreement is good at low stress levels. At high stress levels, a relatively simple semiempirical equation is proposed. Predictions based on elasticity theory alone are shown to be seriously in error.

Correlation between Resilient Modulus and Plastic Deformation for Cohesive Subgrade Soil under Repeated Loading

2008 ◽  
Vol 2053 (1) ◽  
pp. 72-79 ◽  
Author(s):  
Shu-Rong Yang ◽  
Wei-Hsing Huang ◽  
Chi-Chou Liao
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Strain Hardening ◽  
Resilient Modulus ◽  
Cohesive Soil ◽  
Repeated Loading ◽  
Hardening Behavior ◽  
Subgrade Soil ◽  
Stress Levels ◽  
Strain Hardening Behavior

Pavement performance is related to resilient modulus and plastic deformation of pavement materials, which in turn are affected by environmental conditions and traffic loading. A series of triaxial tests was conducted on a residual lateritic soil for 10,000 load repetitions, with some specimens subjected to 100,000 load repetitions, to characterize the behavior of cohesive subgrades under repeated loading, including resilient modulus and plastic deformation. The shakedown concept was used to describe the accumulated plastic deformation and the strain-hardening and softening behavior. Experimental results show that the resilient modulus of cohesive subgrades exhibits strain-hardening behavior under low stress levels. In the meantime, the rate of plastic strain accumulation becomes diminutive. Soil under this condition is in a stable state. Conversely, under high stress levels, cohesive soil tends to soften after a specific number of load applications and accumulates excessive plastic strain and leads to an unstable state. To predict the plastic strain of subgrade soil under repetitive loading, regression models incorporating the strain-hardening behavior for a cohesive soil were used.

Simulation of Plasto-Elastohydrodynamic Lubrication in a Rolling Contact

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Tao He ◽  
Dong Zhu ◽  
Jiaxu Wang
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Rolling Direction ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Surface Plastic Deformation ◽  
Rolling Contact ◽  
Surface Plastic ◽  
Contact Center ◽  
Elastic Plastic

Surface plastic deformation due to contact (lubricated or dry) widely exists in many mechanical components, as subsurface stress caused by high-pressure concentrated in the contact zone often exceeds the material yielding limit, and the plastic strain accumulates when the load is increased and/or repeatedly applied to the surface in a rolling contact. However, previous plasto-elastohydrodynamic lubrication (PEHL) studies were mainly for the preliminary case of having a rigid ball (or roller) rotating on a stationary elastic–plastic flat with a fixed contact center, for which the numerical simulation is relatively simple. This paper presents an efficient method for simulating PEHL in a rolling contact. The von Mises yield criteria are used for determining the plastic zone, and the total computation domain is discretized into a number of cuboidal elements underneath the contacting surface, each one is considered as a cuboid with uniform plastic strain inside. The residual stress and surface plastic deformation resulted from the plastic strain can be solved as a half-space eigenstrain–eigenstress problem. A combination of three-dimensional (3D) and two-dimensional (2D) discrete convolution and fast Fourier transform (DC-FFT) techniques is used for accelerating the computation. It is observed that if a rigid ball rolls on an elastic–plastic surface, the characteristics of PEHL lubricant film thickness and pressure distribution are different from those of PEHL in the preliminary cases previously investigated. It is also found that with the increase of rolling cycles, the increment of plastic strain accumulation gradually approaches a stable value or drops down to zero, determined by the applied load and the material hardening properties, eventually causing a groove along the rolling direction. Simulation results for different material hardening properties are also compared to reveal the effect of body materials on the PEHL behaviors.

Study on Collapse Characteristics and CSRF Method for 45 Deg Cylinder-to-Cylinder Intersections

2012 ◽  
Author(s):  
Takuro Honda ◽  
Shunji Kataoka ◽  
Takuya Sato
Keyword(s):  
Plastic Strain ◽  
High Stress ◽  
Elastic Analysis ◽  
Collapse Pressure ◽  
Elastic Plastic ◽  
Replacement Method ◽  
Inelastic Analysis ◽  
Collapse Strength ◽  
Collapse Characteristics ◽  
Plastic Analysis

It is known that the collapse strength of complex three dimensional structures is hard to evaluate accurately with elastic analysis, and more accurate results require the use of inelastic analysis. A cylinder-to-cylinder acute lateral intersection is one of basic structures of process plants. It is known that a high stress concentration occurs at an acute lateral more than 90 deg-lateral. In general, the area replacement method and the elastic analysis are applied for the design of acute lateral. However, these results may provide overly-conservative designs. In the previous work, the authors proposed CSRF (Collapse Strength Reduction Factor) method. The CSRF was defined as a ratio of the simple cylinder collapse pressure to the cylinder-to-cylinder collapse pressure. The proposed CSRF method provided more reasonable design than the elastic analysis. In this paper, the concept of the CSRF was redefined by using the maximum allowable working pressure. The CSRF were evaluated on the 45 deg and 90 deg-laterals based on the area replacement method, the elastic analysis, the limit load analysis and the elastic plastic analysis to study the collapse characteristics of 45 deg-laterals. The 45 deg-laterals are weaker than 90 deg-laterals, and inelastic analysis provides greater strength of 45 deg-laterals than elastic analysis. The results of elastic plastic analysis showed that overly-large plastic strain occurs on 45 deg-laterals. This plastic strain should be evaluated in addition to the collapse pressure.

Zur Formulierung der Hypothese von der elastischen Formänderungsenergiedichte mit einer Erweiterung auf den elastisch-plastischen Bereich / Formulation of the elastic strain energy theory with an enlargement to the elastic-plastic range

1973 ◽  
Vol 28 (1) ◽  
pp. 35-45 ◽  
Author(s):  
J. Betten
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Elastic Potential ◽  
Plastic Range ◽  
Elastic Case ◽  
Elastic Plastic ◽  
Energy Theory

Contrary to the MISES' theory, the effort of materials under load is discussed in this paper on the base of the elastic potential. This leads to the elastic strain energy theory due to BELTRAMI. This theory is only true for the elastic case. For υ = 1/2 we obtain the MISES' theory, and by changing υ to υep it is possible to enlarge the elastic strain energy theory to the elastic-plastic deformation. υep is the ratio between transverse and longitudinal elastic-plastic strain, and υ is the POISSON's ratio.

Microstructural refinement and deformation twinning during severe plastic deformation of 316L stainless steel at high temperatures

2004 ◽  
Vol 19 (8) ◽  
pp. 2268-2278 ◽  
Author(s):  
G.G. Yapici ◽  
I. Karaman ◽  
Z.P. Luo ◽  
H.J. Maier ◽  
Y.I. Chumlyakov
Keyword(s):  
Plastic Deformation ◽  
Stainless Steel ◽  
Severe Plastic Deformation ◽  
High Temperatures ◽  
High Strain ◽  
High Stress ◽  
Deformation Twinning ◽  
Dynamic Strain ◽  
Microstructural Refinement ◽  
Stress Levels

The present work focuses on the severe plastic deformation and deformation twinning of 316L austenitic stainless steel deformed at high temperatures (700 and 800 °C) using equal channel angular extrusion (ECAE). Very high tensile and compressive strength levels were obtained after ECAE without sacrificing toughness with relation to microstructural refinement and deformation twinning. The occurrence of deformation twinning at such high temperatures was attributed to the effect of high stress levels on the partial dislocation separation, i.e., effective stacking fault energy. High stress levels were ascribed to the combined effect of dynamic strain aging, high strain levels (∈ ∼ 1.16) and relatively high strain rate (2 s−1). At 800 °C, dynamic recovery and recrystallization took place locally leading to grains with fewer dislocation density and recrystallized grains, which in turn led to lower room temperature flow strengths than those from the samples processed at 700 °C but higher strain hardening rates. Apparent tension-compression asymmetry in the 700 °C sample was found to be the consequence of the directional internal stresses.

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.

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