scholarly journals Analysis of Large-Strain Extrusion Machining with Different Chip Compression Ratios

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Wen Jun Deng ◽  
Ping Lin ◽  
Zi Chun Xie ◽  
Qing Li
Keyword(s):  
Nanostructured Materials ◽  
Large Strain ◽  
Effective Strain ◽  
Fem Analysis ◽  
Machining Parameters ◽  
Strain And Strain Rate ◽  
Chip Compression Ratio ◽  
High Plastic ◽  
Thrust Forces ◽  
Very High

Large-Strain Extrusion Machining (LSEM) is a novel-introduced process for deforming materials to very high plastic strains to produce ultra-fine nanostructured materials. Before the technique can be exploited, it is important to understand the deformation behavior of the workpiece and its relationship to the machining parameters and friction conditions. This paper reports finite-element method (FEM) analysis of the LSEM process to understand the evolution of temperature field, effective strain, and strain rate under different chip compression ratios. The cutting and thrust forces are also analyzed with respect to time. The results show that LSEM can produce very high strains by changing in the value of chip compression ratio, thereby enabling the production of nanostructured materials. The shape of the chip produced by LSEM can also be geometrically well constrained.

Effect of the Friction Coefficient on Large Strain Extrusion Machining

2013 ◽  
Vol 273 ◽  
pp. 138-142 ◽  
Author(s):  
Ping Lin ◽  
Zi Chun Xie ◽  
Qing Li
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Nanostructured Materials ◽  
Deformation Behavior ◽  
Large Strain ◽  
Effective Strain ◽  
Finite Element Simulations ◽  
Friction Coefficients ◽  
Simulation Results

The present study focused on the influence of the friction coefficient on the deformation behavior in large strain extrusion machining (LSEM). A series of simulation results of effective strain were obtained under different friction coefficients by conducting finite element simulations with a FEM code. The results show that LSEM can produce different effective strains by changing the friction coefficients, thus enabling the fabrication of bulk nanostructured materials. An analysis of the variation of effective strain through the chip demonstrated that the chip deformed much more inhomogeneously when the friction coefficient became larger. The obtained results can offer valuable guidelines for later LSEM studies.

scholarly journals A Finite Element Study of Large Strain Extrusion Machining Using Modified Zerilli–Armstrong Constitutive Relation

2021 ◽  
Vol 143 (10) ◽  
Author(s):  
Muralimohan Gurusamy ◽  
Karthik Palaniappan ◽  
H. Murthy ◽  
Balkrishna C. Rao
Keyword(s):  
Finite Element ◽  
Constitutive Relation ◽  
Compression Ratio ◽  
Inconel 718 ◽  
Strain Distribution ◽  
Large Strain ◽  
Effective Strain ◽  
Machining Process ◽  
Influence Of Process Parameters ◽  
Chip Compression Ratio

Abstract The objective of this work is to study the performance of modified Zerilli–Armstrong constitutive relation proposed in our previous study for the finite element modeling of a severe plastic deformation technique called large strain extrusion machining. The modified Zerilli–Armstrong constitutive relation is implemented in a finite element model of large strain extrusion machining of Inconel 718 to analyze the influence of process parameters, i.e., the chip compression ratio and tool–chip friction, on deformation, effective strain distribution, and hydrostatic pressure distribution along the extruded chip. The predicted strain values for different chip compression ratios were validated by comparison with those obtained through an analytical model. The finite element predictions also served as a guideline in designing the large strain extrusion-machining setup on which experiments were conducted to generate Inconel 718 foils with superior mechanical properties. The predicted limits of chip compression ratio were in close agreement with experimentally realizable values. Furthermore, the predicted strain distribution through the thickness of the chip was validated with the results of hardness measurement tests. Microstructural characterization of the Inconel 718 foils was carried out by using both optical and transmission-electron microscopic studies in order to reveal the presence of fine-grain structures. The validations showed the effectiveness of the modified Zerilli–Armstrong constitutive relation in modeling large strain extrusion machining—a variant of the conventional machining process.

Effect of Machining Parameters on Deformation Field in Machining by Finite Element Method

2011 ◽  
Vol 80-81 ◽  
pp. 942-945
Author(s):  
C.L. Wu ◽  
Z.R. Wang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cutting Force ◽  
Large Strain ◽  
Effective Strain ◽  
High Hardness ◽  
Rake Angle ◽  
Machining Parameters ◽  
Cutting Velocity ◽  
Element Method

Formation of chip is a typical severe plastic deformation progress in machining which is only single deformation stage. The large strain, low temperature and deformation force are the major premises to create significant microstructure refinement in metals and alloys. A finite element method was developed to characterize the distribution of strain, temperature and cutting force. Effects of rake angle, cutting velocity and friction on effective strain, cutting force imposed in the chip are researched and the conditions which lead to the large stain deformation in machining are highlighted. The results of simulation have shown that chip materials with ultrafine grained and high hardness can be produced with negative tool rake angle at some lower cutting velocity.

scholarly journals Elasto-thermoviscoplastic finite element analyses of cold upsetting and forging processes of S25C steel with dynamic strain aging considered

2021 ◽  
Vol 2047 (1) ◽  
pp. 012001
Author(s):  
S M Ji ◽  
M K Razali ◽  
K H Lee ◽  
W J Chung ◽  
M S Joun
Keyword(s):  
Finite Element ◽  
Flow Stress ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Large Strain ◽  
Flow Behavior ◽  
Cold Forging ◽  
Dynamic Strain ◽  
Strain Effect ◽  
Strain And Strain Rate

Abstract A practical methodology is presented to characterize the thermoviscoplastic flow stress at larger strain over the temperature range of cold metal forming using tensile and compression tests. Its importance is emphasized for non-isothermal finite element (FE) analysis of automatic multi-stage cold forging (AMSCF) process where maximum strain and strain rate exceed around 3.0 and 200/s, respectively. The experimental compressive flow stress is first characterized using traditional bilinear C-m model with high accuracy. It is employed for describing the closed-form function model to extrapolate the experimental flow stress over the experimentally uncovered ranges of state variables. The strain effect on the flow stress is then improved using the experimental tensile flow stress accurately calculated at large strain and room temperature. A complicated flow behavior of S25C characterized by its dynamic strain aging features is expressed by the presented methodology, which is utilized to analyze the test upsetting and AMSCF processes by the elasto-thermoviscoplastic finite element method for revealing the effects of flow stresses on the process.

Comparison of Two Complete Solutions in an Axisymmetric Extrusion With Experiment

1969 ◽  
Vol 91 (3) ◽  
pp. 543-548 ◽  
Author(s):  
A. H. Shabaik ◽  
E. G. Thomsen
Keyword(s):  
Strain Rate ◽  
Effective Strain ◽  
Cone Angle ◽  
Low Friction ◽  
First Approximation ◽  
Strain And Strain Rate ◽  
Conical Die ◽  
Stream Lines ◽  
Half Cone ◽  
Half Cone Angle

An upper-bound and a potential solution to a forward extrusion problem were compared with experimental results obtained by the visioplasticity method. The process consisted of extruding a 2-in-dia billet of preforged lead through a conical die having a half-cone angle of 45 deg under the condition of relatively low friction. The comparison was made for steady state stream lines, velocities, strain rate components, effective strain and strain rate, grid distortion, and stress distribution. It was found that the curves were generally of similar shape and that some differences existed in magnitude only. It is suggested that the theoretical solutions can be used to advantage to a first approximation in predicting all important variables.

Research of Formation Mechanics on Nanostructured Chips by Multi-Deformations Based on Finite Element Method

2014 ◽  
Vol 989-994 ◽  
pp. 352-355
Author(s):  
C.L. Wu ◽  
Z.R. Wang ◽  
Wen Zhang
Keyword(s):  
Finite Element Method ◽  
Plastic Deformation ◽  
Finite Element ◽  
Large Strain ◽  
Effective Strain ◽  
Longitudinal Section ◽  
Rake Angle ◽  
Governing Parameter ◽  
Cutting Velocity ◽  
Mean Strain

Formation of chip is a typical severe plastic deformation progress in machining which is only single deformation stage. The rake angle of tool is governing parameter to create large strain imposed in the chip. Effect of rake angle and deformation times on effective strain, mean strain, strain variety and strain rate imposed in the chip are researched respectively. The result of simulation have shown that the chip with large strain and better uniform of strain along the longitudinal section of chip can be produced with negative rake angle at some lower cutting velocity by multi-deformations in large strain machining.

scholarly journals Experimental and FEM Analysis of Void Closure in the Hot Cogging Process of Tool Steel

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 538 ◽  
Author(s):  
Marcin Kukuryk
Keyword(s):  
Hydrostatic Stress ◽  
Effective Strain ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Fem Analysis ◽  
Experimental Tests ◽  
Reduction Ratio ◽  
Compression Process ◽  
Void Closure ◽  
Axial Defects

In the present study, a new complex methodology for the analysis the closure of voids and a new forging system were developed and tested. The efficiency of the forging parameters and the effective geometric shapes of anvils to improve void closure were determined. A new cogging process provided a complete closure of an ingot’s axial defects, as confirmed by experimental tests. The evolution behavior of these defects with different sizes was investigated during the hot cogging process by means of the professional plastic forming software Deform-3D. A comprehensive procedure was developed using the finite-element method (FEM) for the three-dimensional cogging process and laboratory experimentation to predict the degree of void closure. The hot multi-pass cogging process was used to eliminate void defects in the forgings so as to obtain sound products. In the compression process, the effects of the reduction ratio and forging ratio, the void size, and the types of anvil were discussed to obtain the effective elimination of a void. For the purpose of the assessment of the effectiveness of the void closure process, the following indices were introduced: the relative void volume evolution ratio, the relative void diameter ratio, and the internal void closure evaluation index. Moreover, the void closure process was assessed on the basis of stress triaxiality, hydrostatic stress, forging ratio, value of local effective strain around the void, and critical reduction ratio. The results of this research were complemented by experiments predicting the formation of fractures in the regions near the void and in the volume of the forging in the course of the cogging process. The comparison between the predicted and the experimental results showed a good agreement.

Failure assessment of a woven E-glass/vinyl ester composite subjected to large deformation loading

2012 ◽  
Vol 19 (2) ◽  
pp. 183-193 ◽  
Author(s):  
David R. Hufner ◽  
Liqun Xing ◽  
Michael L. Accorsi
Keyword(s):  
Large Deformation ◽  
Large Strain ◽  
Micromechanical Model ◽  
Image Correlation ◽  
Woven Composites ◽  
Linear Behavior ◽  
Failure Assessment ◽  
Strain Components ◽  
Deformation Kinematics ◽  
Very High

AbstractWoven polymer-based composites exhibit highly non-linear behavior, which often results in very high strains to failure. A micromechanical model is developed to represent the large deformation kinematics of woven composites, and develop predictions for failure strain components in specific cases of multiaxial loading. Failure functions are proposed for macromechanical analyses of arbitrary cases of large deformation loading. The approach is validated against basic tension experiments performed using both digital image correlation and with specially designed instrumentation for large strain measurement. Predicted failure strains correspond well with experimental observations. The proposed failure functions are well suited for finite element applications involving user-defined material models.

Finite Element Simulation of Cyclic Channel Die Compression with Route A

2010 ◽  
Vol 44-47 ◽  
pp. 1300-1304
Author(s):  
Feng Jian Shi ◽  
Tao Xu ◽  
Sheng Lu ◽  
Lei Gang Wang
Keyword(s):  
Finite Element ◽  
Large Strain ◽  
Effective Strain ◽  
Central Zone ◽  
Peripheral Zone ◽  
Linear Increase ◽  
Rigid Plastic ◽  
Compression Load ◽  
Fine Grained ◽  
Two Stages

In this paper, effective strain and load were simulated by rigid-plastic finite element method (FEM) during cyclic channel die compression (CCDC) with route A, and the optical microstructure was observed. The results show that large strain can be accumulated in the material by CCDC. The load variation includes two stages, slowly linear increase and rapid increase. At the end of the CCDC, the compression load rises rapidly. Apart from the edges of the specimen, the effective strain is higher in the central region and lower at the surrounding region. The effective strain gradient increases with the number of compression. Grain refinement at the central zone is faster due to the strain inhomogeneity. But the peripheral zone is also refined with the number of CCDC. This illustrates CCDC is a promising method for producing bulk ultra-fine grained materials.

Deformation Mechanics Associated with Formation of Ultra-Fine Grained Chips in Machining

2006 ◽  
Vol 503-504 ◽  
pp. 379-384 ◽  
Author(s):  
Michael Sevier ◽  
Seongeyl Lee ◽  
M. Ravi Shankar ◽  
Henry T.Y. Yang ◽  
Srinivasan Chandrasekar ◽  
...  
Keyword(s):  
Large Strain ◽  
Rake Angle ◽  
Image Sequences ◽  
Deformation Field ◽  
Machining Parameters ◽  
The Finite Element Method ◽  
Fine Grained ◽  
Image Velocimetry ◽  
Cutting Velocity ◽  
Deformation Mechanics

The deformation field associated with chip formation in plane strain (2-D) machining has been simulated using the finite element method (FEM), with the objective of developing 2-D machining as an experimental technique for studying very large strain deformation phenomena. The principal machining parameters are the tool rake angle, cutting velocity and the friction at the toolchip interface while the deformation field parameters are strain, strain rate and temperature. The relation between rake angle and the shear strain in the deformation zone is studied for the low-speed cutting of lead. This correspondence is validated by comparison with measurements of the deformation parameters made by applying a Particle Image Velocimetry (PIV) technique to highspeed photographic image sequences of the deformation. It is shown that plastic strains in the range of 1-15 can be realized in a controlled manner by appropriate choice of the rake angle. The unique capabilities offered by 2-D machining for studying micro- and nano- mechanics of large strain deformation, and the creation of ultra-fine grained materials are highlighted in the context of these results.

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