On the Difference of Subsurface Deformation Obtained by Image Correlation Technique From That of Plane Strain Deformation in Orthogonal Metal Cutting

2016 ◽  
Author(s):  
Dong Zhang ◽  
Xiao-Ming Zhang ◽  
Han Ding
Keyword(s):  
Plane Strain ◽  
Inclination Angle ◽  
Metal Cutting ◽  
Side Surface ◽  
Image Correlation ◽  
Subsurface Deformation ◽  
Plane Strain Deformation ◽  
Orthogonal Metal Cutting ◽  
Angle Method ◽  
Side Flow

Subsurface deformation in orthogonal metal cutting process is nowadays widely determined by image correlation techniques. To get clearer images of the cutting process, two methods were usually adopted to reduce workpiece material side flow in the literature. One is inducing a weak inclination angle of the cutting tool; the other is to restrict material side flow by a piece of thick glass. However, the differences between the subsurface deformation determined by observing the side surfaces in these two methods and that of plane strain deformation has not been studied yet. Therefore, this paper aims to study the differences of subsurface deformation obtained by these two methods quantitatively through numerical methods. It is found that the restrict side flow method surpasses the inducing an inclination angle method; inducing an inclination angle method will produce larger discrepancy than the side surface of typical orthogonal cutting which stands for observing the side surface directly. Besides, restrict material side flow method surpasses inducing an inclination angle method in the aspect of strain distribution across the width direction. To reduce the differences further, a new method called split-workpiece method based on the bonded-interface technique is proposed in this paper. To validate the effectiveness of this method, numerical comparisons between the subsurface deformation produced by the proposed method and that of the plane strain deformation are made. The results show that the subsurface deformation produced by the proposed method is much closer to that of plane strain deformation than the previous two methods.

Subsurface Deformation in Surface Mechanical Attrition Processes

2015 ◽  
Author(s):  
Zhiyu Wang ◽  
Saurabh Basu ◽  
Christopher Saldana
Keyword(s):  
Strain Hardening ◽  
Model Material ◽  
Process Models ◽  
Image Correlation ◽  
Analytical Models ◽  
Subsurface Deformation ◽  
Multi Stage ◽  
Mechanical Attrition ◽  
Dead Metal Zone ◽  
Plane Strain Deformation

A modified expanding cavity model (M-ECM) is developed to describe subsurface deformation for strain-hardening materials loaded in unit deformation configurations occurring in surface mechanical attrition. The predictive results of this model are validated by comparison with unit deformation experiments in a model material, oxygen free high conductivity copper, using a custom designed plane strain deformation setup. Subsurface displacement and strain fields are characterized using in-situ digital image correlation. It is shown that conventional analytical models used to describe plastic response in strain-hardening metals are not able to predict important characteristics of the morphology of the plastic zone, including evolution of the dead metal zone (DMZ), especially at large plastic depths. The M-ECM developed in the present study provides an accurate prediction of the strain distribution obtained in experiment and is of utility as a component in multi-stage process models of the final surface state in surface mechanical attrition.

Further Results on the Friction of Ploughing in the Presence of Bulk Straining

1991 ◽  
Vol 113 (4) ◽  
pp. 789-794 ◽  
Author(s):  
A. Azarkhin ◽  
O. Richmond
Keyword(s):  
Plane Strain ◽  
Frictional Stress ◽  
Subsurface Deformation ◽  
Plane Strain Deformation ◽  
The Mean

Algorithms developed by the authors in previous work (Azarkhin and Richmond, 1990; Azarkhin and Richmond, 1991) have been used here to model friction due to ploughing of rigid, adhesionless, fully embedded asperities through the surface of a material undergoing bulk plane strain deformation. It is shown that the mean frictional stress is influenced by the intensity of the subsurface deformation and by the size of the contacting area relative to asperity dimensions.

Investigation of the Transition From Plane Strain to Plane Stress in Orthogonal Metal Cutting

2004 ◽  
Author(s):  
Vasant Pednekar ◽  
Vis Madhavan ◽  
Amir H. Adibi-Sedeh
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Plane Stress ◽  
Metal Cutting ◽  
Chip Thickness ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Orthogonal Machining ◽  
Strain And Strain Rate ◽  
Plane Strain Deformation

It is widely known that in practical orthogonal machining experiments, interior sections of the deforming material undergo plane strain deformation whereas material near the side faces of the workpiece undergoes plane stress deformation. This study is aimed at investigating the plane strain to plane stress transition using 3D coupled thermo-mechanical finite element analysis of orthogonal machining. The temperature, stress, strain and strain-rate distributions along different planes of the workpiece are analyzed to obtain estimates of the fraction of material undergoing plane strain deformation for different widths of cut. While it is found that the deformation in the mid-section of the workpiece is close to that observed in 2D plane strain simulations, the deformation along the side faces is quite different from that observed in 2D plane stress simulations, due to the constraint imposed upon the material along the sides by the material in the middle. Though the chip thickness along the sides is smaller than the chip thickness in the middle, the strain, strain-rate, and temperature fields along the side face and mid-section are quite similar. This study confirms that accurate maps of temperature, strain and strain-rate in plane strain deformation can be obtained by observing the side faces. It is found that for the cutting conditions used, a width to depth-of-cut ratio of twenty (not ten, as is commonly assumed) results in a close approximation to plane strain deformation through more than 90% of the width of the work material. For a width to depth-of-cut ratio of ten, significant deviations are observed in the stresses, with respect to their corresponding values in plane strain. Recommendations for the width of cut to depth of cut ratio to be used in experiments for other cutting conditions can be developed based upon similar studies.

A Finite Element Model of Orthogonal Metal Cutting

1985 ◽  
Vol 107 (4) ◽  
pp. 349-354 ◽  
Author(s):  
J. S. Strenkowski ◽  
J. T. Carroll
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Residual Stresses ◽  
Finite Element Model ◽  
Metal Cutting ◽  
Element Model ◽  
Effective Plastic Strain ◽  
Orthogonal Metal Cutting ◽  
Chip Separation ◽  
Chip Geometry

A finite element model of orthogonal metal cutting is described. The paper introduces a new chip separation criterion based on the effective plastic strain in the workpiece. Several cutting parameters that are often neglected in simplified metal-cutting models are included, such as elastic-plastic material properties of both the workpiece and tool, friction along the tool rake face, and geometry of the cutting edge and workpiece. The model predicts chip geometry, residual stresses in the workpiece, and tool stresses and forces, without any reliance on empirical metal cutting data. The paper demonstrates that use of a chip separation criterion based on effective plastic strain is essential in predicting chip geometry and residual stresses with the finite element method.

Exact determination of gravity stresses in finite elastic slopes: Part I. Theoretical considerations

1983 ◽  
Vol 20 (1) ◽  
pp. 47-54 ◽  
Author(s):  
V. Silvestri ◽  
C. Tabib
Keyword(s):  
Plane Strain ◽  
Half Plane ◽  
Inclination Angle ◽  
Complex Variable ◽  
Earth Pressure ◽  
Exact Distributions ◽  
Exact Determination ◽  
Upper Half Plane ◽  
Theoretical Considerations

The exact distributions of gravity stresses are obtained within slopes of finite height inclined at various angles, −β (β = π/2, π/3, π/4, π/6, and π/8), to the horizontal. The solutions are obtained by application of the theory of a complex variable. In homogeneous, isotropic, and linearly elastic slopes under plane strain conditions, the gravity stresses are independent of Young's modulus and are a function of (a) the coordinates, (b) the height, (c) the inclination angle, (d) Poisson's ratio or the coefficient of earth pressure at rest, and (e) the volumetric weight. Conformal applications that transform the planes of the various slopes studied onto the upper half-plane are analytically obtained. These solutions are also represented graphically.

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