Inverse Identification of Johnson-Cook Material Parameters from Machining Simulations

2011 ◽  
Vol 223 ◽  
pp. 277-285 ◽  
Author(s):  
Aviral Shrot ◽  
Martin Bäker
Keyword(s):  
Error Function ◽  
Chip Morphology ◽  
Material Model ◽  
Element Model ◽  
Machining Process ◽  
Model Parameters ◽  
Strain Rates ◽  
Machining Processes ◽  
Material Parameters ◽  
Marquardt Algorithm

A material model is a prerequisite to the modelling of machining processes. Owing to its versatility, the Johnson-Cook model is commonly used for machining simulations. Determination of the model parameters from experiments is challenging due to the large variations of strains, strain-rates and temperatures which lead to several problems. State-of-the-art experimental methods have to rely on data obtained from much lower strains and strain-rates than those encountered during machining. In this paper, an inverse method of identifying Johnson-Cook parameters from machining experiments is described. A fnite-element model of the machining process was created and a particular Johnson-Cook parameter set was taken from literature for the simulation. The Levenberg-Marquardt Algorithm was used to re-identify the material parameters by looking at the Chip-morphology and the Cutting force evolution. It is shown that the optimisation parameters and error function must be chosen carefully in order to achieve better solutions at lower computational expense.

scholarly journals Analysis of Forces in Vibro-Impact and Hot Vibro-Impact Turning of Advanced Alloys

2011 ◽  
Vol 70 ◽  
pp. 315-320 ◽  
Author(s):  
Riaz Muhammad ◽  
Agostino Maurotto ◽  
Anish Roy ◽  
Vadim V. Silberschmidt
Keyword(s):  
Finite Element ◽  
Cutting Forces ◽  
Three Dimensional ◽  
Element Model ◽  
Machining Process ◽  
Strain Rates ◽  
Machining Processes ◽  
Machined Surface ◽  
Cutting Zone

Analysis of the cutting process in machining of advanced alloys, which are typically difficult-to-machine materials, is a challenge that needs to be addressed. In a machining operation, cutting forces causes severe deformations in the proximity of the cutting edge, producing high stresses, strain, strain-rates and temperatures in the workpiece that ultimately affect the quality of the machined surface. In the present work, cutting forces generated in a vibro-impact and hot vibro-impact machining process of Ti-based alloy, using an in-house Ultrasonically Assisted Turning (UAT) setup, are studied. A three-dimensional, thermo-mechanically coupled, finite element model was developed to study the thermal and mechanical processes in the cutting zone for the various machining processes. Several advantages of ultrasonically assisted turning and hot ultrasonically assisted turning are demonstrated when compared to conventional turning.

scholarly journals Experimental and Numerical Study of Viscoelastic Properties of Polymeric Interlayers Used for Laminated Glass: Determination of Material Parameters

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2241 ◽  
Author(s):  
Tomáš Hána ◽  
Tomáš Janda ◽  
Jaroslav Schmidt ◽  
Alena Zemanová ◽  
Michal Šejnoha ◽  
...  
Keyword(s):  
Vinyl Acetate ◽  
Shear Stiffness ◽  
Ethylene Vinyl Acetate ◽  
Material Model ◽  
Polyvinyl Butyral ◽  
Experimental Program ◽  
Model Parameters ◽  
Laminated Glass ◽  
Material Parameters ◽  
Lap Shear

An accurate material representation of polymeric interlayers in laminated glass panes has proved fundamental for a reliable prediction of their response in both static and dynamic loading regimes. This issue is addressed in the present contribution by examining the time–temperature sensitivity of the shear stiffness of two widely used interlayers made of polyvinyl butyral (TROSIFOL BG R20) and ethylene-vinyl acetate (EVALAM 80-120). To that end, an experimental program has been executed to compare the applicability of two experimental techniques, (i) dynamic torsional tests and (ii) dynamic single-lap shear tests, in providing data needed in a subsequent calibration of a suitable material model. Herein, attention is limited to the identification of material parameters of the generalized Maxwell chain model through the combination of linear regression and the Nelder–Mead method. The choice of the viscoelastic material model has also been supported experimentally. The resulting model parameters confirmed a strong material variability of both interlayers with temperature and time. While higher initial shear stiffness was observed for the polyvinyl butyral interlayer in general, the ethylene-vinyl acetate interlayer exhibited a less pronounced decay of stiffness over time and a stiffer response in long-term loading.

Verification of the Charpy Impact Test Capability to Determine the Constants of the Johnson-Cook Model

2016 ◽  
Vol 250 ◽  
pp. 197-202 ◽  
Author(s):  
Michal Stopel Stopel ◽  
Dariusz Skibicki
Keyword(s):  
Experimental Test ◽  
Impact Test ◽  
Charpy Impact ◽  
Material Model ◽  
Charpy Impact Test ◽  
Feasibility Analysis ◽  
Model Parameters ◽  
Strain Rates ◽  
Split Hopkinson

Feasibility analysis of replacing split Hopkinson bars test by Charpy impact test for determination of Johnson-Cook’s material model parameters. The results show that the Charpy impact test may, due to the strain rates achieved, successfully replace the mentioned experimental test. Moreover the results shows that some further studies should be conducted to improve efficiency of the proposed method.

3D Simulation of Laser Assisted Side Milling of Ti6Al4V Alloy Using Modified Johnson-Cook Material Model

2013 ◽  
Vol 554-557 ◽  
pp. 2054-2061 ◽  
Author(s):  
Hassan Zamani ◽  
Jan Patrick Hermani ◽  
Bernhard Sonderegger ◽  
Christof Sommitsch
Keyword(s):  
Tool Wear ◽  
Laser Beam ◽  
Cutting Forces ◽  
Three Dimensional ◽  
Material Model ◽  
Element Model ◽  
Milling Process ◽  
Machining Processes ◽  
Side Milling ◽  
Three Dimensional Finite Element

During machining of hard materials, one approach to reduce tool wear is using a laser beam to preheat the material in front of the cutting zone. In this study, a new concept of laser-assisted milling with spindle and tool integrated laser beam guiding has been tested. The laser beam is located at the cutting edge and moving synchronously with the cutter. In experiment, a reduction in the resulting process cutting forces and tool wear has been observed in comparison to milling without laser. A three-dimensional finite element model in DEFORM 3D was developed to predict the cutting forces in the milling process with and without an additional laser heat source, based on a Johnson-Cook-type material constitutive model adapted for high strains and strain rates. Both in experiment and simulation, the deformation behavior of a Ti-6Al-4V workpiece has been investigated. The comparison of the resulting cutting forces showed very good agreement. Thus the new model has great potential to further optimize laser assisted machining processes.

On the Flow Stress Model Selection for Finite Element Simulations of Machining of Ti6Al4V

2014 ◽  
Vol 611-612 ◽  
pp. 1274-1281 ◽  
Author(s):  
Stano Imbrogno ◽  
Giovanna Rotella ◽  
Domenico Umbrello
Keyword(s):  
Finite Element ◽  
Flow Stress ◽  
Chip Morphology ◽  
Experimental Tests ◽  
Finite Element Method Simulation ◽  
Machining Process ◽  
Stress Model ◽  
Machining Processes ◽  
Flow Stress Model ◽  
Materials Flow

Numerical simulation of machining processes represents a promising tool able to reproduce the cutting conditions without the need to perform a large number of experimental tests. In order to obtain reliable results from the finite element method simulation, is then necessary to properly set up the simulation conditions and to implement the most suitable materials behavior according to the real workpiece characteristics. These data are available in commercial softwares libraries but often they have difficulties to properly represent the machined workpiece behavior. Thus, advanced model are implemented in the software to improve the simulations performance and to obtain realistic results. In this work, the more suitable materials flow stress, within those proposed in literature, is sought to simulate the machining process of Ti6Al4V. The results of the simulations have been compared with those obtained experimentally in terms of temperature, chip morphology and cutting force. The results confirm the need to properly select the materials flow stress model according to the physical sample.

Identification and Validation of Marusich’s Constitutive Law for Finite Element Modeling of High Speed Machining

2014 ◽  
Author(s):  
Walid Jomaa ◽  
Monzer Daoud ◽  
Victor Songmene ◽  
Philippe Bocher ◽  
Jean-François Châtelain
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Chip Morphology ◽  
Material Model ◽  
Element Model ◽  
Contact Length ◽  
Constitutive Law ◽  
High Speed Machining ◽  
Orthogonal Machining ◽  
Deform 2D

This study aims to identify the coefficients of Marusich’s constitutive equation (MCE) for the aluminum AA7075-T651. Material constants were identified inversely form orthogonal machining tests and from dynamic tests. The proposed material model was successfully implemented in a finite element model (FEM) to simulate the high speed machining of the aluminum AA7075-T6. Deform 2D® software was used. A reasonable agreement between predictions and experiments was obtained. The comparison was based on cutting forces, chip morphology, and tool/chip contact length.

scholarly journals Shear Wave Propagation and Estimation of Material Parameters in a Nonlinear, Fibrous Material

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Zuoxian Hou ◽  
Ruth J. Okamoto ◽  
Philip V. Bayly
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Shear Waves ◽  
Material Model ◽  
Model Parameters ◽  
Single Family ◽  
Wave Speeds ◽  
Material Parameters ◽  
Hgo Model

Abstract This paper describes the propagation of shear waves in a Holzapfel–Gasser–Ogden (HGO) material and investigates the potential of magnetic resonance elastography (MRE) for estimating parameters of the HGO material model from experimental data. In most MRE studies the behavior of the material is assumed to be governed by linear, isotropic elasticity or viscoelasticity. In contrast, biological tissue is often nonlinear and anisotropic with a fibrous structure. In such materials, application of a quasi-static deformation (predeformation) plays an important role in shear wave propagation. Closed form expressions for shear wave speeds in an HGO material with a single family of fibers were found in a reference (undeformed) configuration and after imposed predeformations. These analytical expressions show that shear wave speeds are affected by the parameters (μ0, k1, k2, κ) of the HGO model and by the direction and amplitude of the predeformations. Simulations of corresponding finite element (FE) models confirm the predicted influence of HGO model parameters on speeds of shear waves with specific polarization and propagation directions. Importantly, the dependence of wave speeds on the parameters of the HGO model and imposed deformations could ultimately allow the noninvasive estimation of material parameters in vivo from experimental shear wave image data.

Behavior of oil-based modeling clay at medium strain rates

2021 ◽  
pp. 154851292110497
Author(s):  
Camilo Hernandez ◽  
Mario F Buchely ◽  
Juan P Casas-Rodriguez ◽  
Alejandro Maranon
Keyword(s):  
Element Model ◽  
Strain Rates ◽  
Material Parameters ◽  
Expansion Theory ◽  
The Difference ◽  
Cavity Expansion Theory ◽  
Good Concordance ◽  
Constitutive Parameters ◽  
Penetration Profile ◽  
Modeling Clay

The modeling clay is an oil-based soft, flowable, and pliable material made from waxes and oils. Besides its primary use for making sculptures, the modeling clay is commonly used to evaluate bulletproof vests and simulate metal manufacturing processes by conformation. In ballistic tests, the clay is used to retain the deformation of the rear face of body armors; and in the study of metal forming processes, it is used as a physical model to provide information on the plastic flow. However, its mechanical dynamic behavior is not entirely understood. In this study, Plastilina Roma No. 1 modeling clay was mechanically characterized using the power-law constitutive model at medium strain rates [Formula: see text]. The material parameters were determined using a penetration model based on the Cavity Expansion Theory and an inverse technique involving the comparison of the model with experimentation. The optimum set of constitutive parameters was found by reducing the difference of the calculated penetration profile and the measurements from a drop test. This optimization process was programmed on the MATLAB–Simulink environment. The determined material parameters were validated by comparing the results from a computational model with three test set-ups. Finite element model results show good concordance with experimental measurements.

Measuring of Equibiaxial Tension of Rubber-Like Materials by Optical Method

2010 ◽  
Vol 659 ◽  
pp. 289-294
Author(s):  
Attila Bojtos ◽  
Antal Huba ◽  
Lena Zentner ◽  
Uwe Risto
Keyword(s):  
Optical Measurement ◽  
Material Model ◽  
Model Parameters ◽  
Biaxial Test ◽  
Testing Methods ◽  
Material Parameters ◽  
Inner Pressure ◽  
Short Summary ◽  
Definition Of ◽  
Test Result

For the simulations of elastic constructions actuated by inner pressure we need for the definition of the material model parameters, the data originating from the biaxial test. The paper reviews the biaxial material testing methods, especially the bubble inflation methods. It contains a short summary of the stress analysis of the rotation ellipsoid shells in association with the bubble inflation. The paper shows a developed equibiaxial inflating test using optical measurement method. Two different methods using image processing are showed. The test result of an examined silicone rubber (MED-4930) is presented with it’s material parameters.

Rapid Finite Element Prediction on Machining Process

2013 ◽  
Author(s):  
Long Meng ◽  
Xueping Zhang ◽  
Anil K. Srivastava
Keyword(s):  
Finite Element ◽  
Programming Model ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Machining Process ◽  
Fe Model ◽  
Machining Processes ◽  
Machined Surface ◽  
Element Analysis ◽  
Python Language

Finite Element Analysis (FEA) is widely used to simulate machining processes. However, in general, it is time consuming, error-prone, and requires repeated efforts to establish a verified successful Finite Element (FE) model. To rapidly investigate the effects of parameters such as tool angle, feed rate, cutting speed, and temperatures generated during the machining process, an efficient approach is proposed in this paper. The technique has been used to achieve rapid FF simulation during turning and milling processes using Python language programming of Abaqus. Sub-model 1 is programmed to simulate the chip formation process in Abaqus/Explicit. Sub-model 2 is programmed to simulate the cooling spring-back process by importing the machined surface into Abaqus/Implicit. The proposed method is capable of simulating the chip morphology, stress, strain and temperature of the machining process with different parameters immediately. The established FE models are automatically solved in batch by programming script. Post-processing is programmed by Abaqus script to easily achieve and evaluate the simulation results. The Programmed FE models are validated in terms of the predicted chip morphology, cutting forces and residual stresses. This method is extraordinarily efficient saving more than 33% simulation time in comparison to existing FEA approach used for machining processes. Moreover, the script is concise, easy to debug, and effectively avoiding interactive mistakes. The rapid programming model provides a novel, efficiency and convenient approach to thoroughly investigate the effects of a large number of parameters on machining processes.

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