A numerical study of indentation using indenters of different geometry

2004 ◽  
Vol 19 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Li Min ◽  
Chen Wei-min ◽  
Liang Nai-gang ◽  
Wang Ling-Dong
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Plastic Material ◽  
Stress And Strain ◽  
The Finite Element Method ◽  
Strain Fields ◽  
Element Simulation ◽  
Single Cone ◽  
Elastic Plastic Material ◽  
Knoop Indenter

Finite element simulation of the Berkovich, Vickers, Knoop, and cone indenters was carried out for the indentation of elastic–plastic material. To fix the semiapex angle of the cone, several rules of equivalence were used and examined. Despite the asymmetry and differences in the stress and strain fields, it was established that for the Berkovich and Vickers indenters, the load–displacement relation can closely be simulated by a single cone indenter having a semiapex angle equal to 70.3° in accordance with the rule of the volume equivalence. On the other hand, none of the rules is applicable to the Knoop indenter owing to its great asymmetry. The finite element method developed here is also applicable to layered or gradient materials with slight modifications.

scholarly journals Relationship Between Rockwell C Hardness and Inelastic Material Constants

2002 ◽  
Vol 124 (2) ◽  
pp. 179-184 ◽  
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.

Large Deformation Modeling Applied to the Sheet Metal Electromagnetic Forming

2008 ◽  
Author(s):  
C. Dumitras ◽  
I. Cozminca
Keyword(s):  
Finite Element ◽  
Deformation Process ◽  
Electromagnetic Forming ◽  
Stress And Strain ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Strain Fields ◽  
The Finite Element Analysis ◽  
History Of ◽  
Free Bulging

The electromagnetic forming has the advantage of a minimum forming time, but this is a major obstacle in determining the process’s history of the forming workpiece. Both experimental and theoretical known analysis methods for this process give a discret array of data (only for the displacements). One considers it is more adequate to use the finite element method in studying this process. The main advantage of the finite element analysis is given by the fact that it shows the stress and strain fields in a continuous way during the deformation process. Also, it offers a model from which one can predict the final shape of the part and the possible crack zones. One present a compared study of the experimental and the simulated results achieved of the free bulging aluminum specimens by electromagnetic impulses.

scholarly journals An Explanation for the Shape of Nanoindentation Unloading Curves based on Finite Element Simulation

1994 ◽  
Vol 356 ◽  
Author(s):  
A. Bolshakov ◽  
W.C. Oliver ◽  
G.M. Pharr
Keyword(s):  
Finite Element ◽  
Plastic Material ◽  
Elastic Half Space ◽  
Simple Explanation ◽  
Axially Symmetric ◽  
Flat Punch ◽  
Element Simulation ◽  
Plastic Hardness ◽  
Elastic Plastic Material ◽  
Indenter Shape

AbstractCurrent methods for measuring hardness and modulus from nanoindentation load-displacement data are based on Sneddon's equations for the indentation of an elastic half-space by an axially symmetric rigid punch. Recent experiments have shown that nanoindentation unloading data are distinctly curved in a manner which is not consistent with either the flat punch or the conical indenter geometries frequently used in modeling, but are more closely approximated by a parabola of revolution. Finite element simulations for conical indentation of an elastic-plastic material are presented which corroborate the experimental observations, and from which a simple explanation for the shape of the unloading curve is derived. The explanation is based on the concept of an effective indenter shape whose geometry is determined by the shape of the plastic hardness impression formed during indentation.

Finite Element Simulation and Experimental Research on the Internal Rolling Connection for Titanium Alloy Tubes

2005 ◽  
Vol 475-479 ◽  
pp. 3287-3290 ◽  
Author(s):  
Yuan Song Zeng
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Material Flow ◽  
Rolling Process ◽  
Fe Analysis ◽  
Stress And Strain ◽  
The Finite Element Method ◽  
Mechanical Method ◽  
Element Simulation ◽  
Distribution Of Stress

In this paper, the internal rolling process is presented to connect the titanium tubes to the tube fitting with the mechanical method. The material flow, the distribution of stress and strain and the connecting mechanics are analyzed by using the finite element method(FEM) for two kinds of the tube fitting structures, the triangle grooves and the rectangle grooves. Rolling experiments and tests for pressure durability, gas-sealing ability, surface finish and contact percent are also introduced. Results show that the tube joints with the triangle grooves has very excellent connecting strength, and the FE analysis agrees well with the experiments.

Finite Element Simulation of Bending of Steel Bar Including Plasticity

2015 ◽  
Vol 816 ◽  
pp. 182-187
Author(s):  
Ladislav Novotný
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Plastic Material ◽  
Material Model ◽  
Forming Process ◽  
Cold Forming ◽  
Element Simulation ◽  
Steel Bar ◽  
Elastic Plastic Material ◽  
Element Method

The article presents the use of finite element method for the simulation of cold forming process. The numerical simulation of a real technological operation of bending a rod by an industrial bender. Within the simulation, different types of nonlinearities, namely of material nonlinearity, resulting from the flexible plastic material properties of the rod, are considered, geometric nonlinearities result from large displacement and nonlinear contact. This paper briefly describes the elastic – plastic material model. Numerical analysis confirmed the appropriateness of the use of finite element method in the simulation of technological operations and the eventual possible optimization of these processes.

Finite Element Simulation for Residual Stresses in Weling Process

2007 ◽  
Vol 353-358 ◽  
pp. 1915-1918
Author(s):  
He Yu ◽  
Shou Ju Li ◽  
Ying Xi Liu
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Plastic Material ◽  
Yield Criterion ◽  
Welding Process ◽  
Material Model ◽  
Element Simulation ◽  
Elastic Plastic Material ◽  
Von Mises ◽  
Raphson Iteration

Owing to localized heating by the welding process and subsequent rapid cooling, the residual stresses can arise in the weld itself and in the base metals. The prediction procedures of the residual stresses in welding process were presented by using finite element techniques. The bilinear elastic-plastic material model based on Von Mises yield criterion was developed. The material non-linearity of weldment and welding fluid was dealt with using an incremental technique. Inside each step, the Newton-Raphson iteration method was utilized. A fully coupled thermo-mechanical two-dimensional analysis was performed with finite element method. The model applied in this study adopts the technique of element birth and death to simulate the weld filler variation with time in multi-pass welded joints. The effects of welding speed on residual stresses are discussed.

scholarly journals QUASISTATIC STATIONARY GROWTH OF ELASTOPLASTICAL CRACK

2017 ◽  
Vol 20 (7) ◽  
pp. 85-95
Author(s):  
V.A. Nifagin ◽  
M.A. Gundina
Keyword(s):  
Plastic Material ◽  
Plastic Region ◽  
Stress And Strain ◽  
Intermediate Structure ◽  
Stationary Growth ◽  
Strain Fields ◽  
Growing Crack ◽  
Elastic Plastic Material ◽  
Strain Tensors ◽  
Complete Solutions

The boundary value problem with relations to the theory of flow with non- linear hardening in derivatives stress and strain tensors in the parameter loading is formulated to estimate local mechanical properties in the vicinity of crack tip of mode of loading for plane strain of elastic-plastic material at the stage of quasi-static growth. Complete solutions are obtained by the method of asymp- totic decompositions. The redistribution of stress and strain fields in the plastic region at quasi-static growing crack for the intermediate structure is investigat- ed. The form of plastic zones was found in the evolution of fracture process of material. We also obtained direct estimates of errors and diameters of con- vergence when dropping residues of series.

Finite Element Simulation of Compression of Elastomeric Seals in Open Hole Liners

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Khalid Alzebdeh ◽  
Tasneem Pervez ◽  
Sayyad Z. Qamar
Keyword(s):  
Finite Element ◽  
Plastic Material ◽  
Closed Form Solution ◽  
Form Solution ◽  
Element Analysis ◽  
Element Simulation ◽  
The Finite Element Analysis ◽  
Open Hole ◽  
Elastic Plastic Material ◽  
Elastomeric Seals

Control of water flow in open hole wells is an urgent necessity to minimize water production and maximize oil output. Elastomers provide tight seals as they deform against formation during the expansion process of a solid expandable tubular. A better prediction of behavior of elastomers in compression will achieve an effective sealing mechanism. Due to the inherent nonlinearity of tubular expansion and elastomer compression against open hole formation, a closed form solution is extremely difficult to obtain. Finite element modeling provides a viable alternative, as an approximate simulation tool, to determine the seal pressure without significant compromise on the complexity of the problem. The finite element analysis software is employed to model the tubular expansion resulting in compression of elastomer seal to effectively isolate unwanted water producing zones. The formation is modeled as a rigid body or an elastic or elastic-plastic material. Two different boundary conditions, fixed-free and fixed-fixed, are employed depending on prevailing practices of oil operators in such applications. The effect of seal length and thickness, compression ratio and shear resistance at seal-formation interface are determined on the contact pressure between seal and formation.

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