A Finite Element Study of Elasto-Plastic Hemispherical Contact

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.

A Finite Element Study of Elasto-Plastic Hemispherical Contact Against a Rigid Flat

Journal of Tribology ◽

10.1115/1.1866166 ◽

2005 ◽

Vol 127 (2) ◽

pp. 343-354 ◽

Cited By ~ 372

Author(s):

Robert L. Jackson ◽

Itzhak Green

Keyword(s):

Finite Element ◽

Yield Strength ◽

Surface Characteristics ◽

Constant Factor ◽

Current Work ◽

Asperity Contact ◽

Normal Contact ◽

Finite Element Study ◽

Wide Range ◽

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), although micro-scale surface characteristics such as grain boundaries are not considered. The material is modeled as elastic-perfectly plastic. The numerical results are compared to other existing models of spherical contact, including the fully plastic truncation model (often attributed to Abbott and Firestone) and the perfectly elastic case (known as the Hertz contact). This work finds that the fully plastic average contact pressure, or hardness, commonly approximated to be a constant factor of about three times the yield strength, actually varies with the deformed contact geometry, which in turn is dependent upon the material properties (e.g., yield strength). The current work expands on previous works by including these effects and explaining them theoretically. Experimental and analytical results have also been shown to compare well with the current work. The results are fit by empirical formulations for a wide range of interferences (displacements which cause normal contact between the sphere and rigid flat) and materials for use in other applications.

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

Journal of Tribology ◽

10.1115/1.4038984 ◽

2018 ◽

Vol 140 (4) ◽

Cited By ~ 5

Author(s):

Huaidong Yang ◽

Itzhak Green

Keyword(s):

Finite Element ◽

Plane Strain ◽

Tangential Force ◽

Ductile Material ◽

Finite Element Study ◽

Perfectly Plastic ◽

Von Mises ◽

Von Mises Stresses ◽

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 Stable Crack Growth Under Plane Stress Conditions: Part I—Elastic-Perfectly Plastic Solids

Journal of Applied Mechanics ◽

10.1115/1.3173126 ◽

1987 ◽

Vol 54 (4) ◽

pp. 838-845 ◽

Cited By ~ 12

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 ◽

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.

Finite element study of an interface crack between an elastic-perfectly plastic solid and a rigid substrate

International Journal of Fracture ◽

10.1007/bf00032324 ◽

1994 ◽

Vol 68 (1) ◽

pp. 35-44

Author(s):

Y. Huang ◽

H. W. Zhang

Keyword(s):

Finite Element ◽

Interface Crack ◽

Rigid Substrate ◽

Finite Element Study ◽

Perfectly Plastic ◽

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

MRS Proceedings ◽

10.1557/proc-731-w7.1 ◽

2002 ◽

Vol 731 ◽

Cited By ~ 8

Author(s):

Antonios Zavaliangos

Keyword(s):

Finite Element ◽

Powder Compaction ◽

Inhomogeneous Deformation ◽

Finite Element Discretization ◽

Element Discretization ◽

Perfectly Plastic ◽

Interparticle Friction ◽

Individual Particles ◽

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.

A finite element study of the pressuremeter test in sand using a nonlinear elastic model: Discussion

Canadian Geotechnical Journal ◽

10.1139/t94-095 ◽

1994 ◽

Vol 31 (5) ◽

pp. 797-799

Author(s):

J.M.O. Hughes ◽

R.G. Campanella ◽

R.P. Cunha

Keyword(s):

Finite Element ◽

Elastic Model ◽

Pressuremeter Test ◽

Finite Element Study ◽

Nonlinear Elastic ◽

The Influence of Chord Yield-to-Tensile Stress Ratio on the Static Strength of Unstiffened CHS K-Gap Joints under Static Axial Loading

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.204-208.4702 ◽

2012 ◽

Vol 204-208 ◽

pp. 4702-4715

Author(s):

Chisanga Kaluba ◽

M. Mulife Tawana

Keyword(s):

Finite Element ◽

Statistical Analysis ◽

Yield Strength ◽

Tensile Stress ◽

Joint Strength ◽

Stress Ratio ◽

Axial Loading ◽

Static Strength ◽

Finite Element Study ◽

The yield strength-to-tensile stress ratio (fy/fu) is considered to be an important material factor in the design of welded tubular joints. For instance CIDECT (2008) has set a limitation on fy of 0.8fu and for steels with nominal fy greater than 355Mpa and a reduction factor of 0.9 on all joint strength formulae to account for the relatively larger deformations that take place for joints with nominal fy of 450Mpa[1]. In this study a statistical analysis of an experimental database was carried in order to determine the influence of the chord fy/fu ratio on joint strength. A finite element study was also carried out in order to quantify this influence and a yield strength function was proposed. Results from the statistical analysis and finite element study both show that the static strength of unstiffened circular hollow section (CHS) K-gap joints under static axial loading is inversely proportional to the chord fy/fu ratio.

Finite Element Based Plastic Loads for Elbows With Local Wall Thinning

Volume 6: Materials and Fabrication ◽

10.1115/pvp2007-26219 ◽

2007 ◽

Author(s):

Jong-Hyun Kim ◽

Chang-Sik Oh ◽

Joon-Hyuk Ahn ◽

Yun-Jae Kim ◽

Chi-Yong Park ◽

...

Keyword(s):

Finite Element ◽

Large Strain ◽

Three Dimensional ◽

Geometry Effect ◽

Perfectly Plastic ◽

Wall Thinning ◽

Plastic Materials ◽

Wide Range ◽

Local Wall Thinning

Based on systematic three-dimensional (3-D), large strain FE limit analyses using elastic-perfectly plastic materials, this paper quantifies the effect of local wall thinning on plastic behaviors and TES (twice-elastic-slope) plastic loads for 90° elbows under in-plane bending. The thinning geometry is assumed to be rectangular rather than circular, but the nonlinear geometry effect is fully considered. Results from systematic analyses lead to simple approximations for TES plastic loads, covering a wide range of elbow and thinning geometries.

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

Journal of Materials Research ◽

10.1557/jmr.1998.0147 ◽

1998 ◽

Vol 13 (4) ◽

pp. 1059-1064 ◽

Cited By ~ 85

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 ◽

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.