Verification of the EPP Code Case for Strain Limits Evaluations by Inelastic Analysis Method

2017 ◽  
Author(s):  
Mark C. Messner ◽  
T.-L. Sham ◽  
Robert I. Jetter
Keyword(s):  
Finite Element ◽  
Elevated Temperature ◽  
Distinct Advantage ◽  
Analysis Method ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Inelastic Analysis ◽  
Finite Element Technology ◽  
Cyclic Service ◽  
Elastic Perfectly Plastic

An ASME Section III Division 5 code case, N-861, for the evaluation of strain limits based on the elastic-perfectly plastic (EPP) methodology has recently been published. A key feature of the EPP methodology is the application of the EPP finite element analysis method with a pseudo yield stress to bound component response under elevated temperature cyclic service. The simplified inelastic approach in Division 5, Appendix HBB-T that is based on the elastic analysis results is not applicable at the elevated temperature range where creep and plasticity cannot be distinguished and unified viscoplastic model is required to describe the deformation behavior. The EPP strain limits code case overcomes such limitations. It also has the distinct advantage that stress classification, which is required by the simplified inelastic approach, is not needed. Thus, it is ideally suited for modern-day finite element technology. The conservatism of the EPP strain limits code case was verified for some simple geometries. In this paper, a viscoplastic constitutive model calibrated to the experimental data for 316H stainless steel is used to conduct a full inelastic analysis. The calculated strain accumulation is compared with that obtained from using the EPP code case approach.

Elasto-Plastic Coupled Temperature-Displacement Finite Element Analysis of Two-Dimensional Rolling-Sliding Contact With a Translating Heat Source

1991 ◽  
Vol 113 (1) ◽  
pp. 93-101 ◽  
Author(s):  
S. M. Kulkarni ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Finite Element ◽  
Half Space ◽  
Plastic Material ◽  
Element Model ◽  
Rolling Contact ◽  
Two Dimensional ◽  
Element Analysis ◽  
Element Mesh ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

The present paper, describes a transient translating elasto-plastic thermo-mechanical finite element model to study 2-D frictional rolling contact. Frictional two-dimensional contact is simulated by repeatedly translating a non-uniform thermo-mechanical distribution across the surface of an elasto-plastic half space. The half space is represented by a two dimensional finite element mesh with appropriate boundaries. Calculations are for an elastic-perfectly plastic material and the selected thermo-physical properties are assumed to be temperature independent. The paper presents temperature variations, stress and plastic strain distributions and deformations. Residual tensile stresses are observed. The magnitude and depth of these stresses depends on 1) the temperature gradients and 2) the magnitudes of the normal and tangential tractions.

A High Temperature Primary Load Design Method Based on Elastic Perfectly-Plastic and Simplified Inelastic Analysis

2020 ◽  
Author(s):  
M. C. Messner ◽  
R. I. Jetter ◽  
T.-L. Sham
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Creep Damage ◽  
Elastic Analysis ◽  
Allowable Stress ◽  
Perfectly Plastic ◽  
Inelastic Analysis ◽  
Stress Classification ◽  
Elastic Perfectly Plastic ◽  
Primary Load

Abstract The current primary load design provisions of Section III, Division 5 of the ASME Boiler and Pressure Vessel Code, covering high temperature nuclear components, represent an allowable stress methodology using elastic analysis and stress classification procedures to approximate stress redistribution caused by creep and plasticity. This process is difficult to implement and automate in modern finite element frameworks. This paper describes an alternate primary load design approach that uses elastic perfectly-plastic analysis in conjunction with the reference stress concept to eliminate stress classification while retaining a link to the existing Section III, Division 5 allowable stresses. This global, structural allowable stress check is supplemented with a local check to guard against the initiation of creep damage at local stress discontinuities like headers, nozzles, and other stress concentrations. This check is based on a simple elastic-creep analysis with creep damage calculated with the time-fraction approach, using the current ASME minimum-stress-to-rupture values already provided in the current Code. Both the global and local checks are easily implemented in modern finite element analysis software and greatly simplify Section III, Division 5 primary load design when compared to the current design-by-elastic-analysis method. Several examples demonstrate the utility of the new approach and its potential to reduce over-conservatism.

Elevated Temperature Cyclic Service Evaluation Based on Elastic-Perfectly Plastic Analysis and Integrated Creep-Fatigue Damage

2016 ◽  
Author(s):  
T.-L. (Sam) Sham ◽  
Robert I. Jetter ◽  
Yanli Wang
Keyword(s):  
Elevated Temperature ◽  
Fatigue Damage ◽  
Stress And Strain ◽  
Damage Evaluation ◽  
Perfectly Plastic ◽  
Stress Classification ◽  
Plastic Analysis ◽  
Creep Fatigue ◽  
Cyclic Service ◽  
Elastic Perfectly Plastic

The goal of the Elastic-Perfectly Plastic (EPP) combined integrated creep-fatigue damage evaluation approach is to incorporate a Simplified Model Test (SMT) data based approach for creep-fatigue damage evaluation into the EPP methodology to avoid the separate evaluation of creep and fatigue damage and eliminate the requirement for stress classification in current methods; thus greatly simplifying evaluation of elevated temperature cyclic service. The EPP methodology is based on the idea that creep damage and strain accumulation can be bounded by a properly chosen “pseudo” yield strength used in an elastic-perfectly plastic analysis, thus avoiding the need for stress classification. The original SMT approach is based on the use of elastic analysis. The experimental data, cycles to failure, is correlated using the elastically calculated strain range in the test specimen and the corresponding component strain is also calculated elastically. The advantage of this approach is that it is no longer necessary to use the damage interaction, or D-diagram, because the damage due to the combined effects of creep and fatigue are accounted in the test data by means of a specimen that is designed to replicate or bound the stress and strain redistribution that occurs in actual components when loaded in the creep regime. The reference approach to combining the two methodologies and the corresponding uncertainties and validation plans are presented. Results from recent key feature tests are discussed to illustrate the applicability of the EPP methodology and the behavior of materials at elevated temperature when undergoing stress and strain redistribution due to plasticity and creep.

scholarly journals Use of shakedown maps to assess plastic flow in railway curves

2019 ◽  
Vol 234 (4) ◽  
pp. 417-425
Author(s):  
SJ Hawksbee ◽  
GJ Tucker ◽  
M Burstow
Keyword(s):  
Finite Element Analysis ◽  
Plastic Deformation ◽  
Finite Element ◽  
Plastic Flow ◽  
Material Model ◽  
Element Analysis ◽  
Contact Conditions ◽  
Effective Measure ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Plastic deformation of rails can occur on tight curves, which can significantly reduce the rail life. This paper investigated the phenomena of gross plastic deformation, or plastic flow, using multibody vehicle–track interaction and simplified finite element analysis. The focus is on understanding the contact conditions on the low rail of curves and how these differ from those in shakedown maps. To this end, two trial sites are simulated using multibody vehicle–track software. The contact conditions are then compared against several criteria assumed in the derivation of the shakedown maps. A further assumption implicit in the shakedown maps is also investigated by a non-linear finite element analysis. In this case, a more realistic Chaboche material model is used as opposed to the simple linear elastic–perfectly plastic model in the shakedown theory. The results of the finite element analysis are combined with a bespoke indicator of plastic flow to assess the influence of distance to shakedown limits on the likely plastic flow. Finally, a simple interpolation scheme is used to map the finite element results back to the trial sites. The interpolated results for the sites are used to evaluate the influence of running speed and different levels of wheel profile wear. Results suggest that the bespoke indicator defined in this work can be used as an effective measure of plastic flow; this measure is then used to quantify the influence of cant excess on the rates of plastic flow.

An Elastic-Plastic Finite Element Model of Rolling Contact, Part 1: Analysis of Single Contacts

1985 ◽  
Vol 52 (1) ◽  
pp. 67-74 ◽  
Author(s):  
V. Bhargava ◽  
G. T. Hahn ◽  
C. A. Rubin
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Rolling Contact ◽  
Stress And Strain ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Contact Width ◽  
Elastic Perfectly Plastic

This paper describes a two-dimensional (plane strain) elastic-plastic finite element model of rolling contact that embodies the elastic-perfectly plastic, cycle and amplitude-independent material of the Merwin and Johnson theory, but is rigorous with respect to equilibrium and continuity requirements. The rolling contact is simulated by translating a semielliptical pressure distribution. Both Hertzian and modified Hertzian pressure distributions are used to estimate the effect of plasticity on contact width and the continuity of the indentor-indentation interface. The model is tested for its ability to reproduce various features of the elastic-plastic indentation problem and the stress and strain states of single rolling contacts. This paper compares the results derived from the finite element analysis of a single, frictionless rolling contact at p0/k = 5 with those obtained from the Merwin and Johnson analysis. The finite element calculations validate basic assumptions made by Merwin and Johnson and are consistent with the development of “forward” flow. However, the comparison also reveals significant differences in the distribution of residual stress and strain components after a single contact cycle.

Elasto-Plastic Finite Element Analysis of Repeated, Two-Dimensional Rolling-Sliding Contacts

1988 ◽  
Vol 110 (1) ◽  
pp. 44-49 ◽  
Author(s):  
G. Ham ◽  
C. A. Rubin ◽  
G. T. Hahn ◽  
V. Bhargava
Keyword(s):  
Finite Element ◽  
Tangential Force ◽  
Element Model ◽  
Sliding Contact ◽  
Two Dimensional ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Pure Rolling ◽  
Tangential Surface ◽  
Elastic Perfectly Plastic

The stresses, strains, and deformations produced by repeated, two-dimensional rolling-sliding contact are analyzed using a modified finite element model developed by Bhargava et al. [1]. Rolling and sliding are simulated by translating an appropriate set of normal and tangential surface tractions across an elastic-perfectly plastic half space. The study examines a peak-pressure-to-shear strength ratio of po/k = 4.5 and normal to tangential force ratios of T/N = 0.20 and T/N = 0.17. The calculations describe the residual stresses, displacements and the continuing cyclic radial, shear and equivalent strains generated at various depths in the rim. The results are compared with previous calculations by Johnson and Jefferis [2] of rolling-sliding contact and with pure rolling. The present work predicts much higher deformations than previously calculated.

scholarly journals Application of Finite Element Analysis in Modeling of Bionic Harrowing Discs

Biomimetics ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 61
Author(s):  
Benard Chirende ◽  
Jian Qiao Li ◽  
Wonder Vheremu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Dung Beetle ◽  
The Body ◽  
Soil Deformation ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Three Dimensional Finite Element

Ansys software was used to carry out three-dimensional finite element analysis (FEA) for biomimetic design of harrowing discs based on the body surface morphology of soil burrowing animals like dung beetle (Dicranocara deschodt) which have non-smooth units such as convex domes and concave dips. The main objective was to find out the effects of different biomimetic surface designs on reducing soil resistance hence the horizontal force acting on the harrowing disc during soil deformation was determined. In this FEA, soil deformation was based on the Drucker–Prager elastic–perfectly plastic model which was applied only at the lowest disc harrowing speed of 4.4 km/h which is within the limits of model. The material non-linearity of soil was addressed using an incremental technique and inside each step, the Newton–Raphson iteration method was utilized. The model results were analyzed and then summation of horizontal forces acting on the soil-disc interface was also done. An experiment was then conducted in an indoor soil bin to validate the FEA results. The FEA results are generally in agreement with those of the indoor experiment with a difference of less than or equal to the acceptable 10% with an average difference of 4%. Overall, convex bionic units gave the highest resistance reduction of 19.5% from 1526.87 N to 1228.38 N compared to concave bionic units.

A theoretical model for the contact of elastoplastic bodies

2001 ◽  
Vol 216 (4) ◽  
pp. 421-431 ◽  
Author(s):  
L-Y Li ◽  
C-Y Wu ◽  
C Thornton
Keyword(s):  
Finite Element ◽  
Theoretical Model ◽  
Contact Problems ◽  
Rigid Sphere ◽  
Element Analysis ◽  
Normal Contact ◽  
Perfectly Plastic ◽  
Static Contact ◽  
Elastic Perfectly Plastic ◽  
Force Displacement

The paper presents a theoretical model for the normal contact of a rigid sphere with an elastic-perfectly plastic half-space or an elastic-perfectly plastic sphere with a rigid wall. Formulae describing the force-displacement relationship for static contact problems and the coefficient of restitution for dynamic impact problems are derived. The present model can be considered as a modification of Johnson's model by using a more detailed pressure distribution function which is based on finite element analysis (PEA) results and considering the variation in the curvature of the contact surface during the contact interaction. In order to verify the theoretical model, finite element analyses are also conducted, and results are compared with those predicted by the model for both contact force-displacement relations and restitution coefficients. Good agreements between the model predictions and the FEA results are found.

scholarly journals Further analysis of indentation loading curves: Effects of tip rounding on mechanical property measurements

1998 ◽  
Vol 13 (4) ◽  
pp. 1059-1064 ◽  
Author(s):  
Yang-Tse Cheng ◽  
Che-Min Cheng
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Yield Strength ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Conical Indentation

The effects of indenter tip rounding on the shape of indentation loading curves have been analyzed using dimensional and finite element analysis for conical indentation in elastic-perfectly plastic solids. A method for obtaining mechanical properties from indentation loading curves is then proposed. The validity of this method is examined using finite element analysis. Finally, the method is used to determine the yield strength of several materials for which the indentation loading curves are available in the literature.

scholarly journals Nonlinear Finite Element Analysis of Fiber Reinforced Concrete Slabs

2021 ◽  
Vol 39 (3A) ◽  
pp. 426-439
Author(s):  
Saad A. Al-Taan ◽  
Ayad A. Abdul-Razzak
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Plastic Material ◽  
Fiber Reinforced Concrete ◽  
Concrete Slabs ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Reinforced Concrete Slabs ◽  
Elastic Perfectly Plastic

This paper presents a study on the behavior of fiber reinforced concrete slabsusing finite element analysis. A previously published finite element program is used for the nonlinear analysis by including the steel fiber concrete properties. Concrete is represented by degenerated quadratic thick shell element, which is the general shear deformable eight node serendipity element, and the thickness is divided into layers. An elastic perfectly plastic and strain hardening plasticity approach are used to model the compression behavior of concrete.The reinforcing bars were smeared within the concrete layers and assumed as either an elastic perfectly plastic material or as an elastic-plastic material with linear strain hardening. Cracks initiation is predicted using a tensile strength criterion. The tension stiffening effect of the steel fibers is simulated using a descending parabolic stress degradation function, which is based on the fracture energy concept. The effect of cracking in reducing the shear modulus and the compressive strength of concrete parallel to the crack direction is considered. The numerical results showedgood agreement with published experimental results for two fibrous reinforced concrete slabs.

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