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.

A Finite Element Study of Stable Crack Growth Under Plane Stress Conditions: Part II—Influence of Hardening

1987 ◽  
Vol 54 (4) ◽  
pp. 846-853 ◽  
Author(s):  
R. Narasimhan ◽  
A. J. Rosakis ◽  
J. F. Hall
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Plane Stress ◽  
Crack Opening ◽  
Stable Crack Growth ◽  
Small Scale ◽  
Opening Displacement ◽  
Element Analysis ◽  
Critical Crack ◽  
Perfectly Plastic

A detailed finite element analysis is performed to model quasi-static crack growth under plane stress, small-scale yielding conditions in elastic-plastic materials characterized by isotropic power law hardening and the Huber-Von Mises yield surface. A nodal release procedure is used to simulate crack extension. Results pertaining to the influence of hardening on the extent of active yielding and the near-tip stress and deformation fields are presented. Clear evidence of an elastic unloading wake following the active plastic zone is found, but no secondary (plastic) reloading along the crack flank is numerically observed for any level of hardening. A ductile crack growth criterion based on the attainment of a critical crack opening displacement at a small microstructural distance behind the tip, is employed to investigate the nature of the J resistance curves under plane stress. In addition, the same criterion is employed to investigate the influence of hardening on the potential for stable crack growth under plane stress. It is found that predictions based on a perfectly plastic model may be unconservative in this respect, which is qualitatively similar to the conclusions reached in antiplane shear and Mode I plane strain.

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.

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 finite element study of crack growth in WC-Co

1988 ◽  
Vol 36 (4) ◽  
pp. 305-317 ◽  
Author(s):  
L. S. Sigl ◽  
S. Schmauder
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Finite Element Study ◽  
Element Study

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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