An Elastoplastic Finite Element Study of Displacement-Controlled Fretting in a Plane-Strain Cylindrical Contact

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Huaidong Yang ◽  
Itzhak Green
Keyword(s):  
Finite Element ◽  
Plane Strain ◽  
Tangential Force ◽  
Ductile Material ◽  
Finite Element Study ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Element Study

This work presents a finite element study of a two-dimensional (2D) plane strain fretting model of a half cylinder in contact with a flat block under oscillatory tangential loading. The two bodies are deformable and are set to the same material properties (specifically steel), however, because the results are normalized, they can characterize a range of contact scales (micro to macro), and are applicable for ductile material pairs that behave in an elastic-perfectly plastic manner. Different coefficients of friction (COFs) are used in the interface. This work finds that the edges of the contacting areas experience large von Mises stresses along with significant residual plastic strains, while pileup could also appear there when the COFs are sufficiently large. In addition, junction growth is investigated, showing a magnitude that increases with the COF, while the rate of growth stabilization decreases with the COF. The fretting loop (caused by the tangential force during the fretting motion) for the initial few cycles of loading is generated, and it compares well with reported experimental results. The effects of boundary conditions are also discussed where a prestressed compressed block is found to improve (i.e., reduce) the magnitude of the plastic strain compared to an unstressed block.

A fretting finite element investigation of a plane-strain cylindrical contact of Inconel 617/Incoloy 800H at room and high temperatures

2018 ◽  
Vol 233 (4) ◽  
pp. 553-569 ◽  
Author(s):  
Huaidong Yang ◽  
Itzhak Green
Keyword(s):  
Finite Element ◽  
Plane Strain ◽  
Room Temperature ◽  
Tangential Force ◽  
Alloy 800H ◽  
Incoloy 800H ◽  
Inconel 617 ◽  
Von Mises ◽  
Von Mises Stresses ◽  
Two Bodies

This work presents a finite element study of a 2D plane strain fretting model of a half-cylinder in contact with a flat block under oscillatory tangential loading. The two bodies are deformable and are set to Inconel 617 and Incoloy 800H at room temperature (20 ℃) and 800 ℃. However, because the results are normalized, they can characterize a range of contact scales (micro to macro). Different coefficients of friction are used at the interface. This work finds that the edges of the contacting areas experience large von Mises stresses along with significant residual plastic strains, while pileup could also appear when the coefficients of friction are sufficiently large. In addition, junction growth is investigated, showing that the direction of the growth is in the same direction of the tangential force that the weaker material (Incoloy alloy 800H) experiences. The fretting loop (caused by the tangential force during the fretting motion) for the initial few cycles of loading is generated, and it compares well with the reported experimental results. The different extents of damage at room temperature and 800 ℃ are also compared.

A Finite Element Study of Elasto-Plastic Hemispherical Contact

2003 ◽  
Author(s):  
Robert L. Jackson ◽  
Itzhak Green
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Constant Factor ◽  
Elastic Model ◽  
Asperity Contact ◽  
Finite Element Study ◽  
Perfectly Plastic ◽  
Wide Range ◽  
Elastic Perfectly Plastic ◽  
Element Study

This work presents a finite element study of elasto-plastic hemispherical contact. The results are normalized such that they are valid for macro contacts (e.g., rolling element bearings) and micro contacts (e.g., asperity contact). The material is modeled as elastic-perfectly plastic. The numerical results are compared to other existing models of spherical contact, including the fully plastic case (known as the Abbott and Firestone model) and the perfectly elastic case (known as the Hertz contact). At the same interference, the area of contact is shown to be larger for the elasto-plastic model than that of the elastic model. It is also shown, that at the same interference, the load carrying capacity of the elasto-plastic modeled sphere is less than that for the Hertzian solution. This work finds that the fully plastic average contact pressure, or hardness, commonly approximated to be a constant factor (about three) times the yield strength, actually varies with the deformed contact geometry, which in turn is dependant upon the material properties (e.g., yield strength). The results are fit by empirical formulations for a wide range of interferences and materials for use in other applications.

Physically nonlinear analysis of metal beams in the context of GBT

2019 ◽  
Author(s):  
Miguel Abambres ◽  
Dinar Camotim ◽  
Nuno Silvestre
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Normal Stresses ◽  
Simply Supported ◽  
Perfectly Plastic ◽  
Transverse Normal Stress ◽  
Shell Finite Element ◽  
Elastic Perfectly Plastic ◽  
Von Mises ◽  
Von Mises Stresses

A GBT formulation for 1st order elastoplastic analysis is presented and its application illustrated for a elastic-perfectly plastic simply supported I-setion beam subjected to point loads at mid-span. GBT results were validated against ABAQUS by means of shell finite element models. There is an excellent agreement in that comparison, particularlly regarding equilibrium paths and deformed configurations. With respect to stress diagrams, GBT results are very satisfactory for axial, shear and von Mises stresses, but distinct with respect to transverse normal stresses. However, the transverse normal stress 3D contours are qualitatively similar between GBT and ABAQUS in the whole beam domain.

A Finite Element Study of Stable Crack Growth Under Plane Stress Conditions: Part I—Elastic-Perfectly Plastic Solids

1987 ◽  
Vol 54 (4) ◽  
pp. 838-845 ◽  
Author(s):  
R. Narasimhan ◽  
A. J. Rosakis ◽  
J. F. Hall
Keyword(s):  
Finite Element ◽  
Plastic Zone ◽  
Crack Growth ◽  
Plane Stress ◽  
Stable Crack Growth ◽  
Small Scale ◽  
Finite Element Study ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Element Study

A detailed finite element study of stable crack growth in elastic-perfectly plastic solids obeying an incremental plasticity theory and the Huber-Von Mises yield criterion is performed under plane stress, small-scale yielding conditions. A nodal release procedure is used to simulate crack extension under continuously increasing external load. It is found that the asymptotic angular extent of the active plastic zone surrounding the moving crack tip is from θ = 0 deg to about θ = 45 deg. Clear evidence of an elastic unloading region following the active plastic zone is found, but no secondary (plastic) reloading is numerically observed. The near-tip angular stress distribution inside the active plastic zone is in good agreement with the variation inside a centered fan, as predicted by a preliminary asymptotic analysis by Rice. It is also observed that the stress components within the plastic zone have a strong radial variation. The nature of the near-tip profile is studied in detail.

Analytical Solutions of Crack Tip Plasticity Zone Shape for a Semi-Infinite Crack

2003 ◽  
Author(s):  
Peihua Jing ◽  
Tariq Khraishi ◽  
Larissa Gorbatikh
Keyword(s):  
Plane Strain ◽  
Plane Stress ◽  
Analytical Solutions ◽  
Yield Criterion ◽  
Plasticity Zone ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Classical Plasticity ◽  
Elastic Perfectly Plastic ◽  
Von Mises

In this work, closed-form analytical solutions for the plasticity zone shape at the lip of a semi-infinite crack are developed. The material is assumed isotropic with a linear elastic-perfectly plastic constitution. The solutions have been developed for the cases of plane stress and plane strain. The three crack modes, mode I, II and III have been considered. Finally, prediction of the plasticity zone extent has been performed for both the Von Mises and Tresca yield criterion. Significant differences have been found between the plane stress and plane strain conditions, as well as between the three crack modes’ solutions. Also, significant differences have been found when compared to classical plasticity zone calculations using the Irwin approach.

A limit load solution for a thick-walled cylinder with a fully circumferential crack under axial tension

2009 ◽  
Vol 44 (6) ◽  
pp. 407-416 ◽  
Author(s):  
P J Budden ◽  
Y Lei
Keyword(s):  
Finite Element ◽  
Plastic Material ◽  
Yield Criterion ◽  
Limit Load ◽  
Cylinder Wall ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Von Mises ◽  
Inside Radius ◽  
Walled Cylinder

Limit loads for a thick-walled cylinder with an internal or external fully circumferential surface crack under pure axial load are derived on the basis of the von Mises yield criterion. The solutions reproduce the existing thin-walled solution when the ratio between the cylinder wall thickness and the inside radius tends to zero. The solutions are compared with published finite element limit load results for an elastic–perfectly plastic material. The comparison shows that the theoretical solutions are conservative and very close to the finite element data.

A Multiparticle Simulation of Powder Compaction Using Finite Element Discretization of Individual Particles

2002 ◽  
Vol 731 ◽  
Author(s):  
Antonios Zavaliangos
Keyword(s):  
Finite Element ◽  
Powder Compaction ◽  
Inhomogeneous Deformation ◽  
Finite Element Discretization ◽  
Element Discretization ◽  
Perfectly Plastic ◽  
Interparticle Friction ◽  
Elastic Perfectly Plastic ◽  
Individual Particles ◽  
Element Study

AbstractDiscrete element studies of powder compaction have become popular recently. A disadvantage of this technique is the need for simplification of the inter-particle contact behavior which limit the applicability of DEM to small relative densities. To overcome this problem, we analyze the compaction of powder by a 2-D finite element study of the compaction of 400 particles, each of which is discretized at a sufficient level to provide adequate detail of the interparticle interaction. The material is modeled as elastic-perfectly plastic. Simulations show that: (a) there is an effect of interparticle friction on the macroscopic response in the earlier stages of compaction, (b) there is significant rearrangement even in highly constrained compaction modes, (c) the absence of friction promotes inhomogeneous deformation in the compact, and (d) conditions for fragmentation develop in particles with loose lateral constrains.

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