A New Model of Local Elastic Deflections in Grinding

1984 ◽  
Vol 106 (1) ◽  
pp. 154-163 ◽  
Author(s):  
D. P. Saini
Keyword(s):  
Plastic Deformation ◽  
Mild Steel ◽  
Mathematical Models ◽  
Normal Force ◽  
Tangential Force ◽  
Force Component ◽  
Workpiece Material ◽  
Direct Function ◽  
New Model ◽  
Single Grain

Mathematical models describing the deflection behavior of the wheel-work contact presented so far are based on the assumption that contact deflections are a direct function of the normal force on the wheel or the grains during grinding. This paper presents experimental results showing the evidence of a new mechanism of contact deflections due to the rotation of grain as a result of the tangential force component. In this perspective, a new model which considers the deflections due to both the normal and the tangential force is proposed and developed with the assumption of elasto-plastic deformation of the workpiece material around the grain during cutting. The model is shown to be consistent with experimental deflections obtained from single grain cutting on mild steel and EN25 steel specimens.

Grinding at Very Low Speed

2008 ◽  
Vol 53-54 ◽  
pp. 231-235 ◽  
Author(s):  
Bao Fu Feng ◽  
Lei Zheng ◽  
P. Wang ◽  
Quan Fang Gai ◽  
D. Li ◽  
...  
Keyword(s):  
Normal Force ◽  
Tangential Force ◽  
Grinding Force ◽  
Machining Process ◽  
Grinding Forces ◽  
Low Speed ◽  
Section Area ◽  
Force Ratio ◽  
Single Grain ◽  
Depth Increase

Grinding is a very complex machining process. Single grain grinding methods are useful to study complex grinding action. Very low speed single-grain grinding tests were carried out for 45 steel and 20Cr alloy with 14# ZA grain. The grinding groove width and depth, the grinding force ratio, specific grinding forces, and grain wear and fracture are studied. The plowing decreases with the grinding section area or grinding depth increase. The average tangential force at grain fracture in the experiments is 54.4N; the average normal force at grain fracture is 949.6N. The ratio of tangential-to-normal force varies suddenly when grain fracture.

Elastic Contact of Rough Surfaces Subject to Combined Force and Moment

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Ali Sepehri ◽  
Kambiz Farhang
Keyword(s):  
Half Plane ◽  
Normal Force ◽  
Rough Surfaces ◽  
Tangential Force ◽  
Contact Forces ◽  
Elastic Contact ◽  
Force Component ◽  
Angular Misalignment ◽  
Tangential Contact ◽  
Applied Forces

In this paper we consider the contact between two rectangular rough surfaces that provide normal and tangential contact forces, as well as contact moment, to counteract the net moment imposed by the applied forces. The surfaces are permitted to develop a slight angular misalignment, and thereby contact moment is derived. Through this scheme it is possible to also define elastic contribution to friction, since the half-plane tangential contact force on one side of an asperity is no longer balanced by the half-plane tangential force component on the opposite side. The elastic friction force, however, is shown to be of a much smaller order than the contact normal force.

scholarly journals Effect of Water-Based Nanolubricants in Ultrasonic Vibration Assisted Grinding

2018 ◽  
Vol 2 (4) ◽  
pp. 80 ◽  
Author(s):  
Mir Molaie ◽  
Ali Zahedi ◽  
Javad Akbari
Keyword(s):  
Surface Roughness ◽  
Specific Energy ◽  
Material Removal ◽  
Normal Force ◽  
Tangential Force ◽  
Process Efficiency ◽  
Multiwall Carbon Nanotube ◽  
Ultrasonic Vibrations ◽  
Mql Grinding ◽  
Water Based

Currently, because of stricter environmental standards and highly competitive markets, machining operations, as the main part of the manufacturing cycle, need to be rigorously optimized. In order to simultaneously maximize the production quality and minimize the environmental issues related to the grinding process, this research study evaluates the performance of minimum quantity lubrication (MQL) grinding using water-based nanofluids in the presence of horizontal ultrasonic vibrations (UV). In spite of the positive impacts of MQL using nanofluids and UV which are extensively reported in the literature, there is only a handful of studies on concurrent utilization of these two techniques. To this end, for this paper, five kinds of water-based nanofluids including multiwall carbon nanotube (MWCNT), graphite, Al2O3, graphene oxide (GO) nanoparticles, and hybrid Al2O3/graphite were employed as MQL coolants, and the workpiece was oscillated along the feed direction with 21.9 kHz frequency and 10 µm amplitude. Machining forces, specific energy, and surface quality were measured for determining the process efficiency. As specified by experimental results, the variation in the material removal nature made by ultrasonic vibrations resulted in a drastic reduction of the grinding normal force and surface roughness. In addition, the type of nanoparticles dispersed in water had a strong effect on the grinding tangential force. Hybrid Al2O3/graphite nanofluid through two different kinds of lubrication mechanisms—third body and slider layers—generated better lubrication than the other coolants, thereby having the lowest grinding forces and specific energy (40.13 J/mm3). It was also found that chemically exfoliating the graphene layers via oxidation and then purification prior to dispersion in water promoted their effectiveness. In conclusion, UV assisted MQL grinding increases operation efficiency by facilitating the material removal and reducing the use of coolants, frictional losses, and energy consumption in the grinding zone. Improvements up to 52%, 47%, and 61%, respectively, can be achieved in grinding normal force, specific energy, and surface roughness compared with conventional dry grinding.

Plastic Deformation and Pitting Corrosion of Mild Steel in Neutral Media

1978 ◽  
Vol 13 (3) ◽  
pp. 112-117 ◽  
Author(s):  
J. Jelinek ◽  
P. Neufeld ◽  
G. A. Pickup
Keyword(s):  
Plastic Deformation ◽  
Mild Steel ◽  
Pitting Corrosion ◽  
Neutral Media

Experimental Analysis and Crystallographic Model of Plastic Deformation after a Change of Loading Path in Mild Steel Polycrystals

1999 ◽  
Vol 578 ◽  
Author(s):  
T. Hoc ◽  
C. Rey
Keyword(s):  
Plastic Deformation ◽  
Mild Steel ◽  
Strain Localization ◽  
Loading Path ◽  
Slip Systems ◽  
Finite Element Code ◽  
Dislocation Densities ◽  
Dislocation Interactions ◽  
Sequential Tests ◽  
Microstructural Anisotropy

AbstractStrain localization in mild steel submitted to a sequential loading paths is investigated at macroscopic, mesoscopic and microscopic scales. The experimental results demonstrate that the morphology of the localization and the nominal load-displacement curves depend on the microstructural anisotropy. A crystalline model using a finite element code is proposed. The anisotropy is described by a hardening matrix whose terms correspond to dislocation-dislocation interactions and depend on the evolution of the dislocation densities on the activated slip systems during the sequential tests. The strain localization predicted by this model fits with the experimental observation and allows us to assume that localization is correlated to the saturation on the activated slip systems.

An Extension of CEB Elastic-Plastic Contact Model

2007 ◽  
Author(s):  
A. Sepehri ◽  
K. Farhang
Keyword(s):  
Contact Force ◽  
Tangential Force ◽  
Three Dimensional ◽  
Tangential Direction ◽  
Asperity Contact ◽  
Force Component ◽  
Normal Contact ◽  
Elastic Plastic ◽  
Force Components ◽  
Plastic Parts

Three dimensional elastic-plastic contact of two nominally flat rough surfaces is by developing the equations governing the shoulder-shoulder contact of asperities based on the Chang, Etsion and Bogy (CEB) model of contact in which volume conservation is assumed in the plastic flow regime. Shoulder-shoulder asperity contact yields a slanted contact force consisting of both tangential (parallel to mean plane) and normal components. Each force component comprises elastic and elastic-plastic parts. Statistical summation of normal force components leads to the derivation of the normal contact force for the elastic-plastic contact akin to the CEB model. Half-plane tangential force due to elastic-plastic contact is derived through the statistical summation of tangential force component along an arbitrary tangential direction.

Mechanics of Conventional Spinning

1963 ◽  
Vol 85 (4) ◽  
pp. 346-350 ◽  
Author(s):  
H. C. Sortais ◽  
S. Kobayashi ◽  
E. G. Thomsen
Keyword(s):  
Wall Thickness ◽  
Pure Aluminum ◽  
Tangential Force ◽  
Deformation Energy ◽  
Thickness Variation ◽  
Force Component ◽  
Commercially Pure ◽  
Conventional Spinning ◽  
Wall Thickness Variation ◽  
Experimental Values

In conventional spinning of cones, the cone-wall thickness variation was studied using blanks of 1100-0 commercially pure aluminum sheet of 0.050-in. thickness. The results revealed that the radial stress induced in the unspun flange is the major cause of nonuniform wall thickness of spun cones. The theoretical tangential force component was derived by use of the deformation energy method. Qualitative agreement was found between the theoretical and the experimental values of tangential force component in the underspinning conditions.

Composite Fretting Wear of Aluminum Alloy

2007 ◽  
Vol 353-358 ◽  
pp. 868-873 ◽  
Author(s):  
Min Hao Zhu ◽  
Zhong Rong Zhou
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Relative Motion ◽  
Wear Mechanism ◽  
Normal Force ◽  
Fretting Wear ◽  
Test Results ◽  
Contact Configuration ◽  
Inclined Angle ◽  
Flat Contact

A complex relative motion of fretting combined by dual motions of radial and tangential fretting was achieved on a modified fretting tester. The composite fretting motion was induced by the action of an oscillating normal force in a sphere-on-inclined flat contact (52100 steel ball against 2091 aluminum alloy). Two types of inclined angles (45° and 60°) were used in the tests. Variations of veridical force vs displacement have been recorded and analyzed as a function of cycles. Effects of the cyclic normal force and the inclined angle were discussed. The test results showed that wear, cracking and plastic deformation accumulation with a strong dissymmetry in damage morphology was observed. A transformation of fretting mode from composite to radial fretting mode occurred due to a strong modification at local contact configuration. As a conclusion, a physical model for wear mechanism of composite fretting was presented.

scholarly journals A New Method of Manufacturing Thin-Walled Tube Made of AZ61 Magnesium Alloy Including Direct Extrusion And Corrugated Equal Channel Angular Extrusion

2021 ◽  
Author(s):  
H-J Hu ◽  
Ou Zhang ◽  
Gang Hu ◽  
Hui Zhao ◽  
Zhongwen OU
Keyword(s):  
Plastic Deformation ◽  
Magnesium Alloy ◽  
Large Scale ◽  
Equal Channel Angular Extrusion ◽  
Process Conditions ◽  
Workpiece Material ◽  
Plastic Deformation Behavior ◽  
Angular Extrusion ◽  
Thin Walled Tube ◽  
Thin Walled

Abstract Due to demand of strong toughness of thin walled tube, and good secondary forming properties and high-precision dimension, New plastic forming method should be researched to achieve a complete filling, uniform deformation and microstructure evolution during forming process.To obtain the deformation mechanisms of a new composite extrusion for thin walled tube fabricated by tube corrugated equal channel angular extrusion has been researched which is shorten as “TC-ECAE” in this paper. Finite element DEFORMTM-3D software to investigate the plastic deformation behavior of magnesium billet during TC-ECAE process has been employed. Computed parameters including workpiece material characteristics and process conditions have been taken into consideration. The pridictions of strains distributions and damage distributions and effective stress distributions and flow velocities distributions and microstructures evolutions have been explored. The results proved that the TC-ECAE process is a forming method for magnesium alloy tube which is suitable for large scale industrial application. The TC-ECAE process would cause serve plastic deformation and improve the dynamic recrystallization of magnesium alloy during TC-ECAE process.

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