In Situ Analysis of Deformation Mechanics of Constrained Cutting Toward Enhanced Material Removal

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Yang Guo ◽  
Jisheng Chen ◽  
Amr Saleh
Keyword(s):  
Free Surface ◽  
Surface Finish ◽  
Simple Shear ◽  
Chip Formation ◽  
Material Removal ◽  
High Speed ◽  
Image Correlation ◽  
High Speed Imaging ◽  
Chip Flow ◽  
Deformation Mechanics

Abstract Chip formation in conventional cutting occurs by deformation that is only partially bounded by the cutting tool. The unconstrained free surface makes it difficult to determine and to control the deformation of chip formation. The constrained cutting employs a constraining tool in the cutting process to confine the otherwise free surface and enable direct control of the chip formation deformation. The presented work is a study of the deformation mechanics of plane strain constrained cutting using high-speed imaging and digital image correlation (DIC) methods. For different constrained levels (including unconstrained free cutting), the material flow of chip formation is directly observed; the strain rate and strain in the chip as well as the subsurface region are quantified; cutting forces are measured; and surface finish is examined. The study shows that chip formation in constrained cutting can occur in two different deformation modes, i.e., simple shear and complex extrusion, depending on the constrained level. Constrained cutting in the simple shear regime can reduce strain, reduce cutting force and energy, and improve surface finish compared to free cutting; therefore, it is more efficient for material removal than free cutting. Constrained cutting in the extrusion regime imposes a high resistance to the chip flow and causes a significant amount of subsurface deformation, and therefore is not suitable for material removal. Furthermore, the mechanics of chip formation in both free cutting and constrained cutting, especially the roles played by the free surface and the constraining tool, are discussed.

In Situ Analysis of Deformation Mechanics of Constrained Cutting Towards Enhanced Material Removal

2019 ◽  
Author(s):  
Yang Guo ◽  
Jisheng Chen ◽  
Amr Saleh
Keyword(s):  
Free Surface ◽  
Surface Finish ◽  
Simple Shear ◽  
Chip Formation ◽  
Material Removal ◽  
High Speed ◽  
Image Correlation ◽  
High Speed Imaging ◽  
Deformation Mechanics

Abstract Chip formation in conventional cutting occurs by deformation that is only partially bounded by the cutting tool. The unconstrained free surface is a complication in determining the deformation of chip formation. The constrained cutting employs a constraining tool in the cutting process to confine the otherwise free surface and enable direct control of the chip formation deformation. A study has been made on the deformation mechanics of plane-strain constrained cutting using high speed imaging and digital image correlation (DIC) methods. For different constrained levels (including unconstrained free cutting), material flow of chip formation is directly observed; strain rate and strain in the chip as well as the subsurface region are quantified; cutting forces are measured; and surface finish are examed. The study shows that chip formation in constrained cutting can occur in two different deformation modes, i.e., simple shear and complex extrusion, depending on the constrained level. Constrained cutting in simple shear regime can reduce strain, reduce cutting force and energy, and improve surface finish compared to free cutting, therefore it is more efficient for material removal than free cutting. Constrained cutting in the complex extrusion regime imposes a significant amount of surface / subsurface deformation and consumes a very high cutting energy, and therefore is not suitable for material removal. Furthermore, the mechanics of chip formation in both free cutting and constrained cutting, especially the roles played by the free surface and the constraining tool, are discussed.

Experimental Measurement of In-Plane Rolling Nonpneumatic Tire Vibrations Using High-Speed Imaging

2019 ◽  
Vol 47 (3) ◽  
pp. 196-210
Author(s):  
Meghashyam Panyam ◽  
Beshah Ayalew ◽  
Timothy Rhyne ◽  
Steve Cron ◽  
John Adcox
Keyword(s):  
High Speed ◽  
Image Correlation ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
High Speed Imaging ◽  
Correlation Algorithm ◽  
Mode Decomposition ◽  
Series Of Experiments ◽  
Plane Deformations ◽  
Dominant Frequencies

ABSTRACT This article presents a novel experimental technique for measuring in-plane deformations and vibration modes of a rotating nonpneumatic tire subjected to obstacle impacts. The tire was mounted on a modified quarter-car test rig, which was built around one of the drums of a 500-horse power chassis dynamometer at Clemson University's International Center for Automotive Research. A series of experiments were conducted using a high-speed camera to capture the event of the rotating tire coming into contact with a cleat attached to the surface of the drum. The resulting video was processed using a two-dimensional digital image correlation algorithm to obtain in-plane radial and tangential deformation fields of the tire. The dynamic mode decomposition algorithm was implemented on the deformation fields to extract the dominant frequencies that were excited in the tire upon contact with the cleat. It was observed that the deformations and the modal frequencies estimated using this method were within a reasonable range of expected values. In general, the results indicate that the method used in this study can be a useful tool in measuring in-plane deformations of rolling tires without the need for additional sensors and wiring.

scholarly journals Deformation heterogeneity and texture in surface severe plastic deformation of copper

2016 ◽  
Vol 472 (2187) ◽  
pp. 20150486 ◽  
Author(s):  
Saurabh Basu ◽  
Zhiyu Wang ◽  
Christopher Saldana
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Speed ◽  
Surface Deformation ◽  
Image Correlation ◽  
Surface Mechanical Attrition Treatment ◽  
Model Parameters ◽  
Texture Model ◽  
Mechanical Attrition ◽  
Deformation Mechanics

Comprehensive understanding of thermomechanical response and microstructure evolution during surface severe plastic deformation (S 2 PD) is important towards establishing controllable processing frameworks. In this study, the evolution of crystallographic textures during directional surface mechanical attrition treatment on copper was studied and modelled using the visco-plastic self-consistent framework. In situ high-speed imaging and digital image correlation of surface deformation in circular indentation were employed to elucidate mechanics occurring in a unit process deformation and to calibrate texture model parameters. Material response during directional surface mechanical attrition was simulated using a finite-element model coupled with the calibrated texture model. The crystallographic textures developed during S 2 PD were observed to be similar to those resultant from uniaxial compression. The implications of these results towards facilitating a processing-based framework to predict deformation mechanics and resulting crystallographic texture in S 2 PD configurations are briefly discussed.

scholarly journals In situ analysis of flow dynamics and deformation fields in cutting and sliding of metals

2015 ◽  
Vol 471 (2178) ◽  
pp. 20150194 ◽  
Author(s):  
Yang Guo ◽  
W. Dale Compton ◽  
Srinivasan Chandrasekar
Keyword(s):  
Material Removal ◽  
High Speed ◽  
Ductile Failure ◽  
Rake Angle ◽  
Flow Dynamics ◽  
High Speed Imaging ◽  
Image Velocimetry ◽  
Material Forming ◽  
Continuous Chip

The flow dynamics, deformation fields and chip-particle formation in cutting and sliding of metals are analysed, in situ , using high-speed imaging and particle image velocimetry. The model system is a brass workpiece loaded against a wedge indenter at low speeds. At large negative rake angles, the flow is steady with a prow of material forming ahead of the indenter. There is no material removal and a uniformly strained layer develops on the workpiece surface—the pure sliding regime. When the rake angle is less negative, the flow becomes unsteady, triggered by formation of a crack on the prow free surface and material removal ensuing—the cutting regime. The strain on the prow surface at crack initiation is found to be constant. Chip morphologies, such as discrete particle, segmented chip and continuous chip with mesoscale roughness, are shown to arise from a universal mechanism involving propagation of the prow crack, but to different distances towards the indenter tip. The simple shear deformation in continuous chip formation shows small-angle oscillations also linked to the prow crack. Implications for material removal processes and ductile failure are discussed.

scholarly journals Unsteady forces on spheres during free-surface water entry

2012 ◽  
Vol 704 ◽  
pp. 173-210 ◽  
Author(s):  
Tadd T. Truscott ◽  
Brenden P. Epps ◽  
Alexandra H. Techet
Keyword(s):  
Free Surface ◽  
Surface Water ◽  
High Speed ◽  
Accurate Determination ◽  
Water Entry ◽  
High Speed Imaging ◽  
Air Cavity ◽  
Unsteady Forces ◽  
Unsteady Force ◽  
Low Mass

AbstractWe present a study of the forces during free-surface water entry of spheres of varying masses, diameters, and surface treatments. Previous studies have shown that the formation of a subsurface air cavity by a falling sphere is conditional upon impact speed and surface treatment. This study focuses on the forces experienced by the sphere in both cavity-forming and non-cavity-forming cases. Unsteady force estimates require accurate determination of the deceleration for both high and low mass ratios, especially as inertial and hydrodynamic effects approach equality. Using high-speed imaging, high-speed particle image velocimetry, and numerical simulation, we examine the nature of the forces in each case. The effect of mass ratio is shown, where a lighter sphere undergoes larger decelerations and more dramatic trajectory changes. In the non-cavity-forming cases, the forces are modulated by the growth and shedding of a strong, ring-like vortex structure. In the cavity-forming cases, little vorticity is shed by the sphere, and the forces are modulated by the unsteady pressure required for the opening and closing of the air cavity. A data-driven boundary-element-type method is developed to accurately describe the unsteady forces using cavity shape data from experiments.

Chip Formation in High-Speed Milling of Titanium Alloy with PCD Tools

2014 ◽  
Vol 800-801 ◽  
pp. 150-154 ◽  
Author(s):  
An Hai Li ◽  
Jun Zhao ◽  
Hong Guo Zheng ◽  
Yong Hong Lu
Keyword(s):  
Free Surface ◽  
Chip Formation ◽  
High Speed ◽  
End Milling ◽  
Cutting Speed ◽  
Sharp Decrease ◽  
Water Soluble ◽  
Cutting Fluid ◽  
High Speed Milling ◽  
Pcd Tools

This paper presents a detailed analysis of chip morphology through an experimental study of high-speed milling of Ti-6Al-4V alloy with PCD tools. Milling tests were conducted for cutting speed range from 125 m/min to 2000 m/min with water-soluble cutting fluid. The collected chips were firstly examined with a digital cameras and the free surface of the chips was analyzed by a scanning electron microscope (SEM). Geographical parameters of chip morphologies were described in saw-tooth/lamella frequency on the free surface and chip width. Experimental results show that the variation of chips in high-speed end milling of Ti-6Al-4V alloy is as follows, long and straight-shaped → spiral-shaped → curly-shaped → irregular-shaped. The free surface of chips exhibits saw-tooth lamella structures. The lamella becomes clearer and more obvious at higher cutting speeds. Within the same measurement distance, there is a sharp decrease in the lamella number within same measuring range. This should be attributed to the enhancement of the thermal mechanical coupled field applied to the chip formation processes.

Performances and Limitations of Three Ultra High-Speed Imaging Cameras for Full-Field Deformation Measurements

2011 ◽  
Vol 70 ◽  
pp. 81-86 ◽  
Author(s):  
Fabrice Pierron ◽  
Rachid Cheriguene ◽  
Pascal Forquin ◽  
Raphael Moulart ◽  
Marco Rossi ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Grid Method ◽  
Image Correlation ◽  
High Speed Imaging ◽  
Full Field ◽  
Ultra High Speed ◽  
Ultra High Speed Imaging ◽  
Deformation Measurements

This paper compares the technology and the performances of three ultra high speed cameras for full-field deformation measurements with Digital image correlation or the grid method. The three cameras are based on multiple CCD sensors (Cordin 550-62, with rotating mirror or DRS IMACON 200 with gated intensified CCDs) or dedicated chip (Shimadzu HPV). The advantages and limitations of these cameras are critically reviewed.

Incipient Plastic Strain Fields in Material Removal Processes

2014 ◽  
Author(s):  
F. Du ◽  
C. Moreno ◽  
Z. Wang ◽  
C. Saldana
Keyword(s):  
Flow Field ◽  
Chip Formation ◽  
Material Removal ◽  
Transient Flow ◽  
Surface Texturing ◽  
Shear Plane ◽  
Image Correlation ◽  
Removal Processes ◽  
Mechanical Surface

Knowledge of the plasticity associated with the incipient stage of chip formation is important for understanding the flow field underlying transient material removal processes. The transition from an incipient state of strain to steady-state was investigated in chip formation of copper. Characterization of the flow field was made by image correlation, hardness mapping and microstructure measurement. A framework for describing the incipient straining length in chip formation as a function of process parameters was established and explained by effects of the deformation on shear plane morphology. The present results are potentially useful for enabling better informed design of processing configurations wherein transient flow fields contribute significantly to the overall deformation process, such as in grain refinement methods for bulk materials and micro-mechanical surface texturing methods based on machining.

Investigations on the Nature of Surface Finish and Its Variation With Cutting Speed

1964 ◽  
Vol 86 (2) ◽  
pp. 134-140 ◽  
Author(s):  
K. L. Chandiramani ◽  
N. H. Cook
Keyword(s):  
Surface Finish ◽  
Chip Formation ◽  
High Speed ◽  
Orthogonal Cutting ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Relative Importance ◽  
Cutting Mechanism ◽  
Low Speed

An attempt has been made to investigate the nature and cause of the variation of surface finish with cutting speed during orthogonal cutting operations. It is found that the variation of cutting speed alone is sufficient to give rise to the three different mechanisms of chip formation, conventionally known as discontinuous, continuous without “bue” (built-up-edge) and continuous with bue. The transition from low-speed, nonbue cutting to high-speed, bue cutting is found to greatly influence the surface finish and in fact the entire cutting mechanism. Photomicrographs of the cutting zones, the chips, and the profiles of the finished surfaces have been taken to observe these changes closely. Tests have also been carried out to determine the relative importance of cutting speed and cutting temperature in affecting the surface finish of the workpiece being machined.

Effect of Low-Frequency Modulation on Deformation and Material Flow in Cutting of Metals

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Ho Yeung ◽  
Yang Guo ◽  
James B. Mann ◽  
W. Dale Compton ◽  
Srinivasan Chandrasekar
Keyword(s):  
Frequency Modulation ◽  
Chip Formation ◽  
Material Flow ◽  
High Speed ◽  
Surface Deformation ◽  
Low Frequency ◽  
High Speed Imaging ◽  
Machining Processes ◽  
Asperity Contacts ◽  
2D System

The deformation field, material flow, and mechanics of chip separation in cutting of metals with superimposed low-frequency modulation (<1000 Hz) are characterized at the mesoscale using high-speed imaging and particle image velocimetry (PIV). The two-dimensional (2D) system studied involves a sharp-wedge sliding against the workpiece to remove material, also reminiscent of asperity contacts in sliding. A unique feature of the study is in situ mapping of material flow at high resolution using strain fields and streaklines and simultaneous measurements of tool motions and forces, such that instantaneous forces and kinematics can be overlaid onto the chip formation process. The significant reductions in specific energy obtained when cutting with modulation are shown to be a consequence of discrete chip formation with reduced strain levels. This strain reduction is established by direct measurements of deformation fields. The results have implications for enhancing sustainability of machining processes and understanding surface deformation and material removal in wear processes.

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