scholarly journals Modeling of contact stress and tool-based frictional forces considering edge effect through material separation exploration

2021 ◽  
Author(s):  
Weiwei Zhang ◽  
Jian Weng ◽  
Kejia Zhuang ◽  
Cheng Hu ◽  
Xing Dai ◽  
...  
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Stress ◽  
Finite Element Simulations ◽  
Cutting Edge ◽  
Contact Model ◽  
Feature Points ◽  
Normal Contact ◽  
Frictional Forces ◽  
Material Separation

Abstract Cutting tools with round edge can enhance the performance of machining difficult-to-machine materials, while the complex contact mechanism related to micro cutting edge limits the deeper understanding of cutting mechanics. Material separation, which is associate to plough mechanism with formation of dead metal zone (DMZ), also requires the analysis of contact behavior. This study develops a contact model along the round edge together with the illustration of DMZ, with three contact feature points defined to explain the contact situation between workpiece and cutting edge. Among these feature points, two separation points related to DMZ classify the sliding and sticking region considering the dual-zone approach. The stagnation point is the zero shear stress point where a sudden change in shear stress direction happens. Besides, the parabolic stress model obtained from finite element simulations is established to define the normal contact distribution along the round edge. In this basis, the tool-based frictional forces are determined and two contact force components are classified for different contact regions. The proposed contact feature points and contact stress are validated through illustration with finite element simulations. Besides, orthogonal cutting tests ensure the practicality and accuracy of the proposed contact model and predicted cutting forces.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

Measurements and Simulations of Temperature and Deformation Fields in Transient Metal Cutting

2003 ◽  
Vol 125 (4) ◽  
pp. 645-655 ◽  
Author(s):  
Yogesh K. Potdar ◽  
Alan T. Zehnder
Keyword(s):  
Finite Element ◽  
Metal Cutting ◽  
Grid Method ◽  
Finite Element Simulations ◽  
Experimental Measurements ◽  
Force Measurements ◽  
Strain Fields ◽  
Finite Element Software ◽  
Material Separation ◽  
Cutting Experiments

Advanced finite element software makes it possible to perform accurate simulations of orthogonal metal cutting provided all input parameters such as material properties, friction and material separation criteria are known. In principle, such properties can be determined by performing a series of cutting experiments and mechanical property tests, and then iterating the finite element simulations until acceptable agreement is reached. Cutting measurements have generally included only cutting forces and tool-chip temperatures. We hypothesize that by closely coupling simulations to conventional cutting force measurements and with fine scale spatial and temporal experimental measurements of temperature and strain fields, questions related to the choice of parameters in finite element simulations can be resolved. As a step towards that resolution a method for high resolution experimental measurements of temperature and strain fields is presented here. Temperatures of the workpiece and chip are measured during transient metal cutting over areas of 27×27μm and time scales of 200 ns by using infrared detectors. Three different materials, 1018CR steel, Al6061-T6 and Ti-6Al-4V are tested. A grid method is used to measure deformations in steel with a spatial resolution of 50 μm.

scholarly journals Mechanical and Finite Element Analysis of an Innovative Orthopedic Implant Designed to Increase the Weight Carrying Ability of the Femur and Reduce Frictional Forces on an Amputee’s Stump

2019 ◽  
Vol 184 (Supplement_1) ◽  
pp. 627-636 ◽  
Author(s):  
Tejas P Chillale ◽  
Nam Ho Kim ◽  
Larry N Smith
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Weight Bearing ◽  
Contact Forces ◽  
Element Analysis ◽  
Normal Contact ◽  
Fea Modeling ◽  
Significant Difference ◽  
Frictional Forces ◽  
Weight Carrying

Abstract This study was designed to test the hypothesis that: “A properly designed implant that harnesses the principle of the incompressibility of fluids can improve the weight carrying ability of an amputee’s residual femur and reduce the frictional forces at the stump external socket interface.” The hypothesis was tested both mechanically on an Amputee Simulation Device (ASD) and through Finite Element Analysis (FEA) modeling software. With the implant attached to the femur, the FEA and ASD demonstrated that the femur carried 90% and 93% respectively of the force of walking. Without the implant, the FEA model and ASD femur carried only 35% and 77%, respectively, of the force of walking. Statistical calculations reveal three (3) degrees of separation (99% probability of non-random significant difference) between with and without implant data points. FEA modeling demonstrates that the normal contact forces and shear forces are pushed the distal weight-bearing area of the amputee stump, relieving the lateral stump of frictional forces. The ASD mechanical and FEA modeling data validate each other with both systems supporting the hypotheses with confidence intervals of three degrees of separation between with implant and without implant models.

Partial Slip Rolling Wheel-Rail Contact With a Slant Rail Crack

2004 ◽  
Vol 126 (3) ◽  
pp. 450-458 ◽  
Author(s):  
Yung-Chuan Chen ◽  
Jao-Hwa Kuang
Keyword(s):  
Stress Intensity ◽  
Contact Stress ◽  
Stress Intensity Factors ◽  
Crack Problem ◽  
Crack Edge ◽  
Contact Model ◽  
Partial Slip ◽  
Stress Distributions ◽  
Intensity Factors ◽  
Normal Contact

This paper investigates the tip characteristics of an oblique crack in the wheel-rail contact problem. The wheel-rail normal contact pressure and interfacial shear stress distributions, and the stress intensity factors (SIF), are studied for oblique cracks of different inclinations, and the variations in both contact stress distributions near the crack edge are simulated under normal and traction loads, respectively. Contact elements are employed to model the interactions between the wheel-rail contact surfaces and the crack surfaces, respectively. The effects of crack orientation, crack length, and contact distance on the contact stress distributions and stress intensity factors, KI and KII, are investigated. The results indicate that a wheel-rail traction force reduces KII significantly as the contact point travels over the crack edge. Furthermore, fluctuations in KI and KII are very significant with regard to early squat propagation of cracks. The results also demonstrate that applying Carter’s contact model or the full slip contact model to the same wheel-rail contact crack problem yields significantly different stress intensity factor values.

Finite Element Simulation of Minimum Cutting Thickness in Micro-Cutting

2016 ◽  
Vol 861 ◽  
pp. 50-55 ◽  
Author(s):  
Pu Zhang ◽  
Hong Tao Zhu ◽  
Chuan Zhen Huang ◽  
Hong Liang Tang ◽  
Yang Yao ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Feed Rate ◽  
Finite Element Simulations ◽  
Cutting Edge ◽  
Workpiece Material ◽  
Micro Cutting ◽  
Cutting Edge Radius ◽  
Element Simulation ◽  
Order Of Magnitude

The cutting edge radius and cutting thickness as well as feed rate are in the same order of magnitude in micro-cutting. So it will appear a situation that the chip cannot be formed when the cutting thickness is less than a certain value which is the minimum cutting thickness. It is possible to find a method that can determine the minimum cutting thickness in the finite element simulation of micro-cutting according. In this paper, a series of finite element simulations of different workpiece materials in micro-cutting are carried out and several different minimum cutting thicknesses are obtained. It is shown that the minimum cutting thickness is related to the workpiece material in micro-cutting. When the workpiece materials are different, the minimum cutting thicknesses obtained are also different in micro-cutting.

COHESIVE FINITE ELEMENT SIMULATIONS OF CONTRACTION AND SHAPE EFFECTS ON CELL DE-ADHESION

2017 ◽  
Vol 17 (06) ◽  
pp. 1750091
Author(s):  
MARGARITA PETROVA ◽  
ZHIWEN GAO ◽  
YAN LIU ◽  
YANFEI GAO ◽  
WEI HE
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Stress Concentration ◽  
Critical Shear Stress ◽  
Finite Element Simulations ◽  
Additional Stress ◽  
Initial Stiffness ◽  
Mode Iii ◽  
Cohesive Interface ◽  
Cell Shapes

Cohesive-interface-based finite element simulations were conducted to investigate the critical shear stress required for cell de-adhesion from extracellular substrates. The interface ligand–receptor bonds are modeled by a cohesive interface model with initial stiffness, interface strength, and fracture energy as the governing parameters. The ratio of the cell modulus to the interface stiffness defines a length scale. If this length is much less than the contact size, the de-adhesion process can be modeled by the linear elastic fracture mechanics, while the opposite limit leads to the concurrent sliding of the cell or, equivalently, debonding of all the interface ligand–receptor pairs. Since it generates additional shear-stress concentration along the interface, cell contraction generally reduces the critical de-adhesion stress. Cell de-adhesion is more prone to take place for three-dimensional irregular cell shapes because of the much easier failure in the anti-plane Mode III shear, as well as the additional stress concentration in these geometric irregularities.

Split Cutter Method for Contact Stresses Research over Flank Surface of a Cutter

2017 ◽  
Vol 743 ◽  
pp. 258-263 ◽  
Author(s):  
Victor Kozlov ◽  
Jia Yu Zhang ◽  
Jian Cui ◽  
Maria Bogolyubova
Keyword(s):  
Cutting Force ◽  
Contact Stress ◽  
Radial Component ◽  
Contact Stresses ◽  
Cutting Edge ◽  
Normal Contact ◽  
Contact Loads ◽  
Orthogonal Turning ◽  
Flank Surface ◽  
Continuous Chip

The paper presents a method for of contact load (stress) research over a flank land of a cutter by a “split cutter” (sectional cutter) method which is more preferable in cutting steels and durable materials in industrial cutting mode. The research of contact stresses distribution over surfaces of a cutter must be carried out on the special rigid four-component dynamometer for the “split cutter” with inspection of total components of cutting force Pz and Py. However, the investigation of contact loads distribution over the flank land faces the problem due to elastic deformation of measuring elements and penetration of work material into a slit between the two parts of the “split cutter”. The research of contact stresses distribution over a face of a cutter should be carried out on a lathe with horizontal radial feed, while the research of contact stresses distribution over a flank land should be done on a horizontal-milling machine with vertical radial feed of a table. The distributions of contact stresses over the flank land of the cutter in free orthogonal turning of a disk made from ductile brass (63Cu-37Zn), brittle brass (57Cu-39Zn-1Al-3Mn) are described. In machining ductile brass with formation of a continuous chip, extreme pattern of normal σh and tangential τh contact stresses epures (curves of distribution) over a flank land is observed, i.e. the highest contact stress is at some distance from the cutting edge. In machining brittle brass with formation of a discontinuous chip, the highest contact stress is observed, on the contrary, near the cutting edge. The character of normal contact stresses over a flank-land depends on the type of the chip formation due to a sag of the transient surface under the act of a radial component of the cutting force on the rake surface.

scholarly journals Influence of Cutting Tool Wear on Contact Stresses and Temperature Distribution in Titanium Alloy Machining

2017 ◽  
Vol 743 ◽  
pp. 252-257 ◽  
Author(s):  
Victor Kozlov ◽  
Jia Yu Zhang ◽  
Ekaterina Letshiner ◽  
Wen Ze Zhao
Keyword(s):  
Titanium Alloy ◽  
Temperature Distribution ◽  
Experimental Research ◽  
Contact Stress ◽  
Cutting Tool ◽  
Flank Wear ◽  
Contact Stresses ◽  
Cutting Edge ◽  
Normal Contact Stress ◽  
Normal Contact

This paper analyses the results of experimental research of contact stresses distribution over an artificial flank wear-land and temperature distribution in a cutting wedge in a free orthogonal turning of the disk made from titanium alloy (Ti-6Al-2Mo-2Cr) by a cutter with a sharp-cornered edge and with a rounded cutting edge. The investigation was carried out by the method of “split cutter” (sectional tool) and method of variable length of an artificial flank wear land. Experiments with variable feed rate and cutting speed show that in titanium alloy machining with a sharp-cornered cutting edge, the highest normal contact stress over the flank land (σh max = 3400…2200 MPa) is observed immediately at the cutting edge, and the curve has a horizontal region with a length of 0.2…0.6 mm. At larger distance from the cutting edge, the value of normal contact stress is dramatically reduced to 1100…500 MPa. The character of normal contact stresses for a rounded cutting edge is different: it is uniform and its value is approximately 2 times smaller as compared to machining with sharp-cornered cutting edge. In author’s opinion it is connected with generation of a seizure zone in chip formation region and explains working capacity of very worn-out cutting tools in machining titanium alloys. The results of experimental research of temperature distribution in the cutting tool wedge show that temperature reaches 1000 °С at essential wear over the flank surface. Such high value of temperature on the contact surface causes softening of work material, and explains the small value of tangential contact stresses (τh = 800…200 MPa) and reduction of normal contact stresses σh far from the cutting edge for a sharp-cornered cutting edge.

Optimization of a Triangular Slot Shape in a Tire Tread Block by Using the Finite Element Analysis and MPSO

2012 ◽  
Vol 505 ◽  
pp. 424-428
Author(s):  
T. Dolwichai ◽  
J. Limtragool ◽  
S. Bureerat
Keyword(s):  
Finite Element ◽  
Tensile Test ◽  
Contact Stress ◽  
Hyperelastic Material ◽  
Design Parameters ◽  
Element Analysis ◽  
Normal Contact Stress ◽  
Normal Contact ◽  
Axial Tensile ◽  
Planar Shear

The work of this paper presents the use of MPSO which is an evolutionary optimizer. The work objective is finding the optimal shape of triangular slot in a tire tread block. The numbers of design parameters with triangular slot are 9. They are used to characterize size and position of the triangular slot in a tire tread block. The optimization methods are implemented to solve two objectives. First, the normal contact stress at contact patch region must be lowest and second, the friction contact stress at the same region must be highest. Therefore, the problem type is bi-objective optimization. The finite element analyses are simulated by modeling of tire tread block contacting to the friction surface with commercial finite element program (ANSYS). The models are simulated as compressing and sliding or braking situation. The tire tread block is modeled as hyperelastic material which used the three basic tests, i.e., uni-axial tensile test, planar shear test and equal bi-axial tensile test. The best fitted of hyperelastic material model for the work is Ogden Hyper Foam order 3th. The results of work are present as the mean of design parameters which are accepted for two objectives.

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