Effect of Hardening Exponent of Power-Law Hardening Elastic-Plastic Substrate on Contact Behaviors in Coated Asperity Contact

The contact between a rigid flat and a coated asperity is studied using the finite element method. The substrate is assumed as the power-law hardening elastic–plastic material. The effect of the hardening exponent of the substrate (n) on the contact behaviors including contact load, area, coating thickness variation and stress in the coating, is investigated. It shows larger hardening exponent results in larger contact loads and larger maximum stresses in the coating at a given interference, and leads to smaller contact area at a specific contact load. The coating thickness becomes smaller monotonically as the interference increases for larger hardening exponents, while it recovers gradually after reaching the minimum value for the smaller n cases. This work will give some universal guidance to improve the contact performance for coatings by adjusting the hardening exponent of the substrate and by optimizing the coatings parameters.

Download Full-text

Elastic–Plastic Multi-Asperity Contact Analysis of Cylinder-on-Flat Configuration

Journal of Tribology ◽

10.1115/1.2540262 ◽

2007 ◽

Vol 129 (2) ◽

pp. 292-304 ◽

Cited By ~ 14

Author(s):

V. Sabelkin ◽

S. Mall

Keyword(s):

Rough Surface ◽

Contact Area ◽

Plastic Material ◽

Material Behavior ◽

Contact Load ◽

Graphical Form ◽

Complex Nature ◽

Asperity Contact ◽

Elastic Plastic ◽

Elastic Plastic Material

The contact interaction between a rough cylindrical body (i.e., with asperities) and a deformable smooth flat was investigated using the finite-element analysis. Analysis included both elastic–plastic deformation and friction. Further, the effects of several parameters of rough surface on the evolution of the contact area with increasing contact load were investigated. These were radius, number, constraint, and placement of asperities. Contact area of rough surface is smaller than its counterpart of smooth surface, and this decrease depends on number, radius, constraint, and placement of asperities. The elastic material behavior results in considerably smaller contact area than that from elastic–plastic material behavior. The evolution of contact area with increasing contact load is of the complex nature with elastic–plastic material deformation since the yielded region widens and/or deepens with increasing load depending on number, radius, and constraint of asperities. The effect of constraint on the asperity depends upon its nature (i.e., from either sides or one side) and radius of the asperity. The effects of these several parameters on the contact area versus applied load relationships are expressed in the graphical form as well as in terms of equations wherever possible.

Download Full-text

A Finite Element Analysis of Mode III Quasi-Static Crack Growth at a Ductile-Brittle Interface

Journal of Applied Mechanics ◽

10.1115/1.2787199 ◽

1996 ◽

Vol 63 (1) ◽

pp. 204-209 ◽

Cited By ~ 2

Author(s):

S. Omprakash ◽

R. Narasimhan

Keyword(s):

Finite Element ◽

Crack Growth ◽

Power Law ◽

Plastic Material ◽

Bimaterial Interface ◽

Mode Iii ◽

Elastic Substrate ◽

Elastic Plastic ◽

Static Crack ◽

Elastic Plastic Material

Steady-state quasi-static crack growth along a bimaterial interface is analyzed under Mode III, small-scale yielding conditions using a finite element procedure. The interface is formed by an elastic-plastic material and an elastic substrate. The top elastic-plastic material is assumed to obey the J2 incremental theory of plasticity. It undergoes isotropic hardening with either a bilinear uniaxial response or a power-law response. The results obtained from the full-field numerical analysis compare very well with the analytical asymptotic results obtained by Castan˜eda and Mataga (1991), which forms one of the first studies on this subject. The validity of the separable form for the asymptotic solution assumed in their analysis is investigated. The range of dominance of the asymptotic fields is examined. Field variations are obtained for a power-law hardening elastic-plastic material. It is seen that the stresses are lower for a stiffer substrate. The potential of the bimaterial system to sustain slow stable crack growth along the interface is studied. It is found that the above potential is larger if the elastic substrate is more rigid with respect to the elastic-plastic material.

Download Full-text

Contact Behaviors of Coated Asperity with Power-Law Hardening Elastic–Plastic Substrate During Loading and Unloading Process

International Journal of Applied Mechanics ◽

10.1142/s1758825118500345 ◽

2018 ◽

Vol 10 (03) ◽

pp. 1850034 ◽

Cited By ~ 4

Author(s):

Xiqun Lu ◽

Fuzhan Huang ◽

Bin Zhao ◽

Leon M. Keer

Keyword(s):

Finite Element Method ◽

Plastic Deformation ◽

Finite Element ◽

Power Law ◽

Coating Thickness ◽

Rapid Decrease ◽

Plastic Substrate ◽

The Finite Element Method ◽

Elastic Plastic ◽

Loading And Unloading

The behavior of a coated asperity contacting with a rigid flat during the loading and unloading processes is investigated using the finite element method. The power-law hardening elastic–plastic substrate is considered, and the effect of the substrate hardening exponent and the coating thickness on the contact behavior is studied. It is shown that in the loading process, the contact load increases more slow and the contact area increases faster as the interference increases for smaller coating thickness and hardening exponent cases, and the coating thickness recovers more obviously after a rapid decrease. In the unloading process, the residual interference and the pileup effect of the asperity surface is larger for smaller coating thicknesses and hardening exponents, and the energy loss due to the plastic deformation is larger accordingly.

Download Full-text

Near-tip dynamic fields for a crack advancing in a power-law elastic-plastic material: Modes I, II and III

Mechanics of Materials ◽

10.1016/0167-6636(83)90022-4 ◽

1983 ◽

Vol 2 (4) ◽

pp. 305-317 ◽

Cited By ~ 21

Author(s):

Y.C. Gao ◽

S. Nemat-Nasser

Keyword(s):

Power Law ◽

Plastic Material ◽

Elastic Plastic ◽

Elastic Plastic Material

Download Full-text

Structural Integrity Research for Reactor Pressure Vessel Under In-Vessel Retention of a Core Melt

Volume 1: Operations and Maintenance, Aging Management and Plant Upgrades; Nuclear Fuel, Fuel Cycle, Reactor Physics and Transport Theory; Plant Systems, Structures, Components and Materials; I&C, Digital Controls, and Influence of Human Factors ◽

10.1115/icone24-60092 ◽

2016 ◽

Author(s):

Yongjian Gao ◽

Yinbiao He ◽

Ming Cao ◽

Yuebing Li ◽

Shiyi Bao ◽

...

Keyword(s):

Pressure Vessel ◽

Material Properties ◽

Power Plants ◽

Structural Integrity ◽

Plastic Material ◽

Plastic Region ◽

Reactor Pressure Vessel ◽

Elastic Plastic ◽

Elastic Plastic Material ◽

Reactor Pressure

In-Vessel Retention (IVR) is one of the most important severe accident mitigation strategies of the third generation passive Nuclear Power Plants (NPP). It is intended to demonstrate that in the case of a core melt, the structural integrity of the Reactor Pressure Vessel (RPV) is assured such that there is no leakage of radioactive debris from the RPV. This paper studied the IVR issue using Finite Element Analyses (FEA). Firstly, the tension and creep testing for the SA-508 Gr.3 Cl.1 material in the temperature range of 25°C to 1000°C were performed. Secondly, a FEA model of the RPV lower head was built. Based on the assumption of ideally elastic-plastic material properties derived from the tension testing data, limit analyses were performed under both the thermal and the thermal plus pressure loading conditions where the load bearing capacity was investigated by tracking the propagation of plastic region as a function of pressure increment. Finally, the ideal elastic-plastic material properties incorporating the creep effect are developed from the 100hr isochronous stress-strain curves, limit analyses are carried out as the second step above. The allowable pressures at 0 hr and 100 hr are obtained. This research provides an alternative approach for the structural integrity evaluation for RPV under IVR condition.

Download Full-text

On Determining Elastic Modulus from Instrumented Indentation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.668.616 ◽

2013 ◽

Vol 668 ◽

pp. 616-620

Author(s):

Shuai Huang ◽

Huang Yuan

Keyword(s):

Finite Element ◽

Elastic Modulus ◽

Plastic Material ◽

Instrumented Indentation ◽

Computational Simulations ◽

Elastic Plastic ◽

Modified Method ◽

Plastic Materials ◽

Elastic Plastic Material ◽

Elastic Plastic Materials

Computational simulations of indentations in elastic-plastic materials showed overestimate in determining elastic modulus using the Oliver & Pharr’s method. Deviations significantly increase with decreasing material hardening. Based on extensive finite element computations the correlation between elastic-plastic material property and indentation has been carried out. A modified method was introduced for estimating elastic modulus from dimensional analysis associated with indentation data. Experimental verifications confirm that the new method produces more accurate prediction of elastic modulus than the Oliver & Pharr’s method.

Download Full-text

Relationship Between Rockwell C Hardness and Inelastic Material Constants

Journal of Engineering Materials and Technology ◽

10.1115/1.1446863 ◽

2002 ◽

Vol 124 (2) ◽

pp. 179-184 ◽

Cited By ~ 3

Author(s):

Akihiko Hirano ◽

Masao Sakane ◽

Naomi Hamada

Keyword(s):

Finite Element ◽

Friction Coefficient ◽

Strain Hardening ◽

Yield Stress ◽

Plastic Material ◽

Stress And Strain ◽

Material Constants ◽

Elastic Plastic ◽

Elastic Plastic Material ◽

Hardening Coefficient

This paper describes the relationship between Rockwell C hardness and elastic-plastic material constants by using finite element analyses. Finite element Rockwell C hardness analyses were carried out to study the effects of friction coefficient and elastic-plastic material constants on the hardness. The friction coefficient and Young’s modulus had no influence on the hardness but the inelastic materials constants, yield stress, and strain hardening coefficient and exponent, had a significant influence on the hardness. A new equation for predicting the hardness was proposed as a function of yield stress and strain hardening coefficient and exponent. The equation evaluated the hardness within a ±5% difference for all the finite element and experimental results. The critical thickness of specimen and critical distance from specimen edge in the hardness testing was also discussed in connection with JIS and ISO standards.

Download Full-text