Crystallographic effects during micromachining — A finite-element model

2015 ◽  
Vol 29 (22) ◽  
pp. 1550119
Author(s):  
Shin-Hyung Song ◽  
Woo Chun Choi
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Chip Formation ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Material Behavior ◽  
Face Centered Cubic ◽  
Work Material ◽  
User Material Subroutine ◽  
Crystallographic Orientations

Mechanical micromachining is a powerful and effective way for manufacturing small sized machine parts. Even though the micromachining process is similar to the traditional machining, the material behavior during the process is much different. In particular, many researchers report that the basic mechanics of the work material is affected by microstructures and their crystallographic orientations. For example, crystallographic orientations of the work material have significant influence on force response, chip formation and surface finish. In order to thoroughly understand the effect of crystallographic orientations on the micromachining process, finite-element model (FEM) simulating orthogonal cutting process of single crystallographic material was presented. For modeling the work material, rate sensitive single crystal plasticity of face-centered cubic (FCC) crystal was implemented. For the chip formation during the simulation, element deletion technique was used. The simulation model is developed using ABAQUS/explicit with user material subroutine via user material subroutine (VUMAT). Simulations showed that variation of the specific cutting energy at different crystallographic orientations of work material shows significant anisotropy. The developed FEM model can be a useful prediction tool of micromachining of crystalline materials.

A FINITE ELEMENT MODEL FOR COMPRESSIVE ICE LOADS BASED ON A MOHR-COULOMB MATERIAL AND THE NODE SPLITTING TECHNIQUE

2021 ◽  
pp. 1-33
Author(s):  
Hauke Herrnring ◽  
Søren Ehlers
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Material Behavior ◽  
Double Pendulum ◽  
Strain Rates ◽  
Splitting Technique ◽  
Structure Interaction ◽  
Node Splitting ◽  
Brittle Mode

Abstract This paper presents a finite element model for the simulation of ice-structure interaction problems, which are dominated by crushing. The failure mode of ice depends significantly on the strain rate. At low strain rates the ice behaves ductile, whereas at high strain rates ice reacts in brittle mode. This paper focuses on the brittle mode, which is the dominating mode for ship-ice interactions. A multitude of numerical approaches for the simulation of ice can be found in the literature. Nevertheless, the literature approaches do not seem suitable for the simulation of continuous ice-structure interaction processes at low and high confinement ratios in brittle mode. Therefore, this paper seeks to simulate the ice-structure interaction with the finite element method (FEM). The objective of the here introduced Mohr-Coulomb Nodal Split (MCNS) model is to represent the essential material behavior of ice in an efficient formulation. To preserve mass and energy as much as possible, the node splitting technique is applied, instead of the frequently used element erosion technique. The intention of the presented model is not to reproduce individual cracks with high accuracy, because this is not possible with a reasonable element size, due to the large number of crack fronts forming during the ice-structure interaction process. To validate the findings of the model, the simulated maximum ice forces and contact pressures are compared with ice-extrusion and double pendulum tests. During validation, the MCNS model shows a very good agreement with these experimental values.

Bodner-Partom Constitutive Model and Nonlinear Finite Element Analysis

1990 ◽  
Vol 112 (3) ◽  
pp. 287-291 ◽  
Author(s):  
F. A. Kolkailah ◽  
A. J. McPhate
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Plastic Strain ◽  
Constitutive Model ◽  
Finite Element Model ◽  
Numerical Technique ◽  
Element Model ◽  
Material Behavior ◽  
Model Parameters ◽  
Elastic Plastic

In this paper, results from an elastic-plastic finite-element model incorporating the Bodner-Partom model of nonlinear time-dependent material behavior are presented. The parameters in the constitutive model are computed from a leastsquare fit to experimental data obtained from uniaxial stress-strain and creep tests at 650°C. The finite element model of a double-notched specimen is employed to determine the value of the elastic-plastic strain and is compared to experimental data. The constitutive model parameters evaluated in this paper are found to be in good agreement with those obtained by the other investigators. However, the parameters determined by the numerical technique tend to give response that agree with the data better than do graphically determined parameters previously used. The calculated elastic-plastic strain from the model agreed well with the experimental strain.

Strength Analyses of Sandwich Pipes for Ultra Deepwaters

2004 ◽  
Vol 72 (4) ◽  
pp. 599-608 ◽  
Author(s):  
Segen Farid Estefen ◽  
Theodoro Antoun Netto ◽  
Ilson Paranhos Pasqualino
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Ultimate Strength ◽  
Thermal Insulation ◽  
Research Work ◽  
Element Model ◽  
Material Behavior ◽  
Core Material ◽  
Small Scale ◽  
Mechanical Resistance

Design requirements for pipelines regarding both ultimate strength and flow assurance in ultra deepwater scenarios motivated the development of a new sandwich pipe which is able to combine high structural and thermal insulation properties. In this concept, the annulus is filled with low cost materials with adequate thermal insulation properties and good mechanical resistance. The aim of this research work is to perform small-scale laboratorial tests and to develop a finite element model to evaluate the structural performance of such sandwich pipes with two different options of core material. After calibrated in view of the experimental results, a three-dimensional finite element model incorporating nonlinear geometric and material behavior is employed to perform strength analyses of sandwich pipes under combined external pressure and longitudinal bending. Ultimate strength envelopes for sandwich pipes are compared with those generated for single-wall steel pipes with equivalent collapse pressures. The study shows that sandwich pipe systems with either cement or polypropylene cores are feasible options for ultra deepwater applications.

Finite Element Modeling of Edge Trimming Fiber Reinforced Plastics

2000 ◽  
Vol 124 (1) ◽  
pp. 32-41 ◽  
Author(s):  
D. Arola ◽  
M. B. Sultan ◽  
M. Ramulu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cutting Forces ◽  
Cutting Tool ◽  
Deformable Body ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Tool Geometry ◽  
Reinforced Plastics ◽  
Edge Trimming

A finite element model was developed to simulate chip formation in the edge trimming of unidirectional Fiber Reinforced Plastics (FRPs) with orthogonal cutting tools. Fiber orientations (θ) within the range of 0 deg⩽θ⩽90 deg were considered and the cutting tool was modeled as both a rigid and deformable body in independent simulations. The principal and thrust force history resulting from numerical simulations for orthogonal cutting were compared to those obtained from edge trimming of unidirectional Graphite/Epoxy (Gr/Ep) using polycrystalline diamond tools. It was found that principal cutting forces obtained from the finite element model with both rigid and deformable body tools compared well with experimental results. Although the cutting forces increased with increasing fiber orientation, the tool rake angle had limited influence on cutting forces for all orientations other than θ=0 deg and 90 deg. However, the tool geometry did affect the degree of subsurface damage resulting from interlaminar shear failure as well as the cutting tool stress distribution. The finite element model for chip formation provides a means for optimizing tool geometry over the total range in fiber orientations in terms of the cutting forces, degree of subsurface trimming damage, and the cutting tool stresses.

scholarly journals Dynamic Recrystallization Observed at the Tool/Chip Interface in Machining

2015 ◽  
Vol 651-653 ◽  
pp. 1223-1228
Author(s):  
Yannick Senecaut ◽  
Michel Watremez ◽  
Julien Brocail ◽  
Laurence Fouilland-Paillé ◽  
Laurent Dubar
Keyword(s):  
Finite Element ◽  
Dynamic Recrystallization ◽  
Finite Element Model ◽  
Rheological Behavior ◽  
High Speed ◽  
Orthogonal Cutting ◽  
Element Model ◽  
Numerical Results ◽  
Constitutive Law ◽  
Rheological Models

In numerical approaches for high speed machining, the rheological behavior of machined materials is usually described by a Johnson Cook law. However, studies have shown that dynamic recrystallization phenomena appear during machining in the tool/chip interface. The Johnson Cook constitutive law does not include such phenomena. Thus, specific rheological models based on metallurgy are introduced to consider these dynamic recrystallization phenomena. Two empirical models proposed by Kim et al. (2003) and Lurdos (2008) are investigated in machining modeling. A two-dimensional finite element model of orthogonal cutting, using an Arbitrary Lagrangian-Eulerian (ALE) formulation, is developed with the Abaqus/explicit software. Specific rheological models are implemented in the calculation code thanks to a subroutine. This finite element model can then predict chip formation, interfacial temperatures, chip-tool contact length, cutting forces and chip thickness with also and especially the recrystallized area. New specific experiments on an orthogonal cutting test bench are conducted on AISI 1045 steel specimens with an uncoated carbide tool. Many tests are performed and results are focused on total chip thicknesses and recrystallized chip thicknesses. Finally, compared to numerical results got with a Johnson Cook law, numerical results obtained using specific rheological models to take into account dynamic recrystallization phenomena are very close to experimental results. This work shows also the influence of rheological behavior laws on predicted results in the modeling of high speed modeling.

Finite Element Simulation of Quick – Stop Experiments for Better Understanding of Chip Formation in Grinding

2011 ◽  
Vol 223 ◽  
pp. 764-773 ◽  
Author(s):  
Hans Werner Hoffmeister ◽  
Arne Gerdes
Keyword(s):  
Finite Element ◽  
Chip Formation ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Element Model ◽  
Rake Angle ◽  
Grinding Process ◽  
Workpiece Material ◽  
Element Simulation ◽  
Single Grain

Several authors have previously simulated chip formation and their behaviour at the orthogonal cutting process. In contrast the chip formation for grinding was less investigated. This paper introduces a quick-stop device which allows easy investigation of the chip formation for the grinding process. For this process a workpiece forced by compressed air is shot against a single grain diamond with a large negative rake angle. Cutting forces were measured with a piezo electric sensor and discussed for a cutting speed range from 10m/s up to 30m/s. In Abaqus/Explicit a lagrangian formulation based finite element model was built to describe the chip formation for the grinding process. Chip formation, stress and heat distribution in the workpiece material can be calculated by this simulation model. The material behaviour was described with the Johnson Cook law. The simulation results show a good correlation compared to the quick stop experiments. All in all this simulation leads to a better understanding of the chip formation during grinding.

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