Atomistic Simulations of Nanoindentation on Cu (111) with a Void

2008 ◽  
Vol 33-37 ◽  
pp. 919-924
Author(s):  
Chung Ming Tan ◽  
Yeau Ren Jeng ◽  
Yung Chuan Chiou
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Indentation Depth ◽  
Equilibrium Configuration ◽  
Complete System ◽  
Internal Surface ◽  
Atomistic Simulations ◽  
Element Formulation ◽  
Variable Parameters ◽  
Deformed State

This paper employs static atomistic simulations to investigate the effect of a void on the nanoindentation of Cu(111). The simulations minimize the potential energy of the complete system via finite element formulation to identify the equilibrium configuration of any deformed state. The size and depth of the void are treated as two variable parameters. The numerical results reveal that the void disappears when the indentation depth is sufficiently large. A stress concentration is observed at the internal surface of the void in all simulations cases. The results indicate that the presence of a void has a significant influence on the nanohardness extracted from the nanoindentation tests.

Mechanical Behavior of Laminated Composites with Circular Holes

2013 ◽  
Vol 550 ◽  
pp. 1-8 ◽  
Author(s):  
Habib Achache ◽  
Benali Boutabout ◽  
Djamel Ouinas
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Composite Structures ◽  
Laminated Composites ◽  
Three Dimensional ◽  
Laminated Composite ◽  
Element Formulation ◽  
Composites Materials ◽  
Circular Holes ◽  
Fibers Orientation

This paper presents a numerical method for the evaluation of the stress concentration factor (SCF) in three dimensional laminated composites under mechanical loads. The proposed method uses the finite element formulation. The composites materials based on the epoxy matrix and reinforcing fibers are extensively used in aircraft structures due to their high specific characteristics. However, the withstanding of composite structures can be significantly reduced by the addition of geometric singularities, such as perforations or notches. To Analyses the stress concentration around geometrical notches, several studies as analytical, numerical and experimental techniques are available. The stress distribution in a laminated composite plate with the presence of a circular hole was investigated using the finite element method. In order, the results obtained by this study are compared with those reported in literature. The aim of this analysis is to evaluate numerically the factor of stress concentration under the influence of several parameters such as fibers orientation, the mechanical characteristics of composites and the distance between notches of cross-laminated.

Static Atomistic Simulations of Nanoindentation and Determination of Nanohardness

2005 ◽  
Vol 72 (5) ◽  
pp. 738-743 ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Chung-Ming Tan
Keyword(s):  
Finite Element ◽  
Nonlinear Finite Element ◽  
Deformation Mechanisms ◽  
Finite Element Formulation ◽  
Atomistic Simulations ◽  
Element Formulation ◽  
Indentation Size ◽  
Plastic Deformations ◽  
Nanoindentation Testing

This paper develops a nonlinear finite element formulation to analyze nanoindentation using an atomistic approach, which is conducive to observing the deformation mechanisms associated with the nanoindentation cycle. The simulation results of the current modified finite element formulation indicate that the microscopic plastic deformations of the thin film are caused by instabilities of the crystalline structure, and that the commonly used procedure for estimating the contact area in nanoindentation testing is invalid when the indentation size falls in the nanometer regime.

scholarly journals The reduction of stress concentration in a uni-axially loaded infinite width rectangular isotropic/orthotropic plate with central circular hole by coaxial auxiliary holes

2012 ◽  
Vol 12 (6) ◽  
Author(s):  
Dr. Nitin Jain
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Circular Hole ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Orthotropic Plate ◽  
Maximum Stress ◽  
Element Formulation ◽  
Smooth Flow ◽  
Axially Loaded

A comprehensive plane stress finite element study is made for reduction of stress concentration factor (SCF) in a uni-axially loaded infinite width rectangular isotropic/orthotropic plate with central circular hole. The finite element formulation was carried out by the analysis section of the package ANSYS. With the help of present work, stress concentration can be reduced up to 24.4 % in an isotropic and 31 % in an orthotropic plate by introducing four coaxial auxiliary holes on either side of main hole. The study reveals that the introduction of these holes helps to smooth flow of the tensile stress past the main hole and result a reduction in stress concentration factor. With such reduction in maximum stress levels, the improvement in fatigue life of a component can be significant.

The Analysis of Stress Concentration in Piezoelectric Ceramic Multilayer Actuators

2006 ◽  
Vol 45 ◽  
pp. 1117-1123
Author(s):  
Hai Tao Wang
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Piezoelectric Ceramic ◽  
Numerical Procedure ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Displacement Fields ◽  
Electrical Loads ◽  
Electromechanical Field ◽  
Multilayer Actuators

This paper concerns the determination of stress concentration in piezoelectric ceramic multilayer actuators when they are subjected to electrical loads. A full numerical procedure is developed here to evaluate the strength of the stress concentration at the tip of electrodes. The whole procedure consists of two steps: (1) a 1D finite element formulation is proposed to determine the eigensolution of the singular electromechanical field; (2) a hybrid-Trefftz element is constructed to determine the strength of the singular electromechanical field. The independently assumed stress and electrical displacement fields are extracted from the eigensolution obtained from previous 1D finite element formulation. Then, the proposed procedure is used to study stress concentration in piezoelectric ceramic multilayer actuators.

INVESTIGATION OF DEPENDENCE IMPACT OF TOOL GEOMETRICAL PARAMETERS AND CUTTING SPEED UPON SHAPING EFFORT AT HELICAL GROOVE CUTTING ON INTERNAL SURFACE OF CYLINDRICAL SHELL

2020 ◽  
Vol 2020 (10) ◽  
pp. 22-28
Author(s):  
Vadim Kuc ◽  
Dmitriy Gridin
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cylindrical Shell ◽  
Contact Interaction ◽  
Cutting Speed ◽  
Internal Surface ◽  
Geometrical Parameters ◽  
Software Complex ◽  
Helical Groove ◽  
Groove Cutting

The work purpose was the investigation of dependence impact of tool geometrical parameters upon shaping effort during internal groove cutting. As a realization for the fulfillment of the helical groove processing investigation there was used a software complex based on a finite element method and a computer mathematic system. As a result of the investigations carried out there was obtained a regression equation manifesting the dependence of factors impact upon axial force falling on one tooth of the tool in the set scale of factor parameters. The scientific novelty consists in that in the paper there is considered a new method for helical groove cutting in which a shaping motion is carried out at the expense of the contact interaction of a tool and a billet performing free cutting. The investigation results obtained allowed determining the number of teeth operating simultaneously, that can be used further at cutting mode setting, and also as recommendations during designing tool design.

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