Simulation of Deep Spherical Indentation Using Eulerian Finite Element Methods

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
D. Anderson ◽  
A. Warkentin ◽  
R. Bauer
Keyword(s):  
Finite Element ◽  
Finite Element Methods ◽  
Large Deformations ◽  
Radial Strain ◽  
Element Model ◽  
Spherical Indentation ◽  
Eulerian Formulation ◽  
Pile Up ◽  
Deep Indentation ◽  
General Material

Simulation of deep indentation, and the associated pile-up effects, requires a robust and accurate finite element model capable of naturally handling the large deformations present. This work successfully demonstrates that the Eulerian formulation is capable of accurately reproducing the forces and general material response of deep indentation. It was found that, in the absence of friction, sink-in dominates at indentation depths less than 1.1% of the indenter radius, there is a transition from sink-in to pile-up from 1.1% to 2.3% of the indenter radius, and pile-up is fully developed at indentation depths larger than 13.2% of the indenter radius for the 4340 steel workpiece and the 0.508 mm radius indenter presented in this work. Friction tended to marginally increase the sink-in and transition depths as well as reduce the material height at the onset of fully developed pile-up due to a reduction in the tensile radial strain directly under the indenter.

Finite element analysis of spherical indentation to study pile-up/sink-in phenomena in steels and experimental validation

2012 ◽  
Vol 54 (1) ◽  
pp. 74-83 ◽  
Author(s):  
V. Karthik ◽  
P. Visweswaran ◽  
Anand Bhushan ◽  
D.N. Pawaskar ◽  
K.V. Kasiviswanathan ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Validation ◽  
Spherical Indentation ◽  
Element Analysis ◽  
Pile Up

Nanoindentation by Multiple Loads Methodology: A Pile Up Correction Procedure

2007 ◽  
Vol 345-346 ◽  
pp. 805-808 ◽  
Author(s):  
Miguel Angel Garrido ◽  
Jesus Rodríguez
Keyword(s):  
Element Model ◽  
Spherical Indentation ◽  
Correction Procedure ◽  
Elastic Plastic ◽  
Multiple Loads ◽  
Plastic Materials ◽  
Wide Range ◽  
Pile Up ◽  
Elastic Plastic Materials

Young’s modulus and hardness data obtained from nanoindentation are commonly affected by phenomena like pile up or sink in, when elastic-plastic materials are tested. In this work, a finite element model was used to evaluate the pile up effect on the determination of mechanical properties from spherical indentation in a wide range of elastic-plastic materials. A new procedure, based on a combination of results obtained from tests performed at multiple maximum loads, is suggested.

SMOOTHED FINITE ELEMENT METHODS FOR THERMO-MECHANICAL IMPACT PROBLEMS

2013 ◽  
Vol 10 (01) ◽  
pp. 1340010 ◽  
Author(s):  
V. KUMAR
Keyword(s):  
Finite Element ◽  
Finite Element Methods ◽  
Large Deformations ◽  
Physical Domain ◽  
Shape Functions ◽  
Mechanical Impact ◽  
Element Approach ◽  
Impact Problems ◽  
Isoparametric Mapping ◽  
Derivatives Of

We present a Smoothed Finite Element Methods (SFEM) for thermo-mechanical impact problems. The smoothing is applied to the strains and the standard finite element approach is used for the temperature field. The SFEM allows for highly accurate results and large deformations. No isoparametric mapping is needed; the shape functions are computed in the physical domain. Moreover, no derivatives of the shape functions must be computed. We implemented a visco-plastic constitutive model and validate the method by comparing numerical results to experimental data.

scholarly journals A Simplified ALE model for finite element simulation of ballistic impacts with bullet splash – development and experimental validation

2021 ◽  
Vol 15 (57) ◽  
pp. 223-245
Author(s):  
Riccardo Andreotti ◽  
Sergio Abate ◽  
Andrea Casaroli ◽  
Mauro Quercia ◽  
Riccardo Fossati ◽  
...  
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Forensic Sciences ◽  
Arbitrary Lagrangian Eulerian ◽  
Aisi 304L ◽  
Simplified Approach ◽  
Ballistic Impacts ◽  
Eulerian Formulation ◽  
Full Metal Jacket ◽  
The Impact

An original simplified finite element model is proposed to simulate the effects of non-penetrating ballistic impacts causing the so-called bullet splash phenomenon (complete bullet fragmentation), while no fragmentation is caused to the target. The model is based on the Arbitrary Lagrangian Eulerian formulation (ALE) and it simulates the impact as a fluid-structure interaction. The bullet splash phenomenon has been tested by experimental analyses of AISI 304L plates impacted by 9x21 FMJ (full metal jacket) bullets. The model has been developed with the aim of creating a simplified approach to be used in the industry and forensic sciences to simulate the non-penetrating interaction of soft impactors with hard targets. Comparisons between evidence and simulation results lead to the conclusion that the proposed approach can be used in a conservative way to estimate both local and global effects of bullet-splash phenomena.

Akinetic myocardial infarcts must contain contracting myocytes: finite-element model study

2005 ◽  
Vol 288 (4) ◽  
pp. H1844-H1850 ◽  
Author(s):  
Alan B. C. Dang ◽  
Julius M. Guccione ◽  
Jacob M. Mishell ◽  
Peng Zhang ◽  
Arthur W. Wallace ◽  
...  
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Radial Strain ◽  
Element Model ◽  
Isometric Tension ◽  
Fiber Direction ◽  
Fe Model ◽  
Model Study ◽  
Nonlinear Stress ◽  
Strain Relationship

Infarcted segments of myocardium demonstrate functional impairment ranging in severity from hypokinesis to dyskinesis. We sought to better define the contributions of passive material properties (stiffness) and active properties (contracting myocytes) to infarct thickening. Using a finite-element (FE) model, we tested the hypothesis that infarcted myocardium must contain contracting myocytes to be akinetic and not dyskinetic. A three-dimensional FE mesh of the left ventricle was developed with echocardiographs from a reperfused ovine anteroapical infarct. The nonlinear stress-strain relationship for the diastolic myocardium was anisotropic with respect to the local muscle fiber direction, and an elastance model for active fiber stress was incorporated. The diastolic stiffness ( C) and systolic material property (isometric tension at longest sarcomere length and peak intracellular calcium concentration, Tmax) of the uninfarcted remote myocardium were assumed to be normal ( C = 0.876 kPa, Tmax = 135.7 kPa). Diastolic and systolic properties of the infarct necessary to produce akinesis, defined as an average radial strain between −0.01 and 0.01, were determined by assigning a range of diastolic stiffnesses and scaling infarct Tmax to represent the percentage of contracting myocytes between 0% and 100%. As C was increased to 11 times normal ( C = 10 kPa) the percentage of Tmax necessary for akinesis increased from 20% to 50%. Without contracting myocytes, C = 250 kPa was necessary to achieve akinesis. If infarct stiffness is <285 times normal, contracting myocytes are required to prevent dyskinetic infarct wall motion.

Estimation of Residual Stress and Plastic Properties of a Material without Plastic Plateau by Using Continuous Spherical Indentation

2019 ◽  
Vol 795 ◽  
pp. 409-415
Author(s):  
Zhan Yu Wang ◽  
Jian Ping Zhao
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Model Simulation ◽  
Indentation Test ◽  
Element Model ◽  
Spherical Indentation ◽  
Strain Hardening Exponent ◽  
Unknown Parameters ◽  
Plastic Properties ◽  
Response Parameter

This paper presents a method to allow the measurement of residual stress (), yield strength () and strain hardening exponent () of metal materials through continuous spherical indentation test. Based on the analysis of finite element simulation results, a new fitting equation between the indentation response parameter and the material properties was given. The influence of friction on finite element model simulation was also discussed when the residual stress is included in the material. Only three load values are required at each different indentation depths, and the three unknown parameters (, and ) can be obtained through corresponding dimensionless functions. Finally, the validation of the method presented in this paper was verified by simulating the material (SUS304) with the known material parameters in the literature.

Application of Finite Element Methods for the Analysis of Restitution Coefficients for Golf Club Heads

2015 ◽  
Vol 799-800 ◽  
pp. 589-595
Author(s):  
Ching Hui Tai ◽  
Chun Ho Yin
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Finite Element Methods ◽  
Experimental Testing ◽  
Element Model ◽  
Golf Club ◽  
Finite Element Software ◽  
Ball Flight ◽  
The Finite Element Model

Finite element methods are applied to investigate the coefficient of restitution (COR) for the head of a golf club. ANSYS commercial finite element software is first applied to determine the COR of two different disc-shaped titanium impact surfaces. These values were then experimentally verified to validate the accuracy of the finite element model. Finally, ANSYS was applied to determine the COR for club heads according to USGA specifications to confirm the reliability of the finite element model. The model is then validated by comparison with experimental results. The model can not only reduce time needed for product design and experimental testing, but can serve as a basis for follow-up studies on ball flight trajectory.

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