Interior Stress for Axisymmetric Abrasive Indentation in the Free Abrasive Machining Process: Slicing Silicon Wafers With Modern Wiresaw

1999 ◽  
Vol 121 (3) ◽  
pp. 191-195 ◽  
Author(s):  
F. Yang ◽  
I. Kao
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Closed Form Solution ◽  
Local Maximum ◽  
Silicon Wafers ◽  
Machining Process ◽  
Von Mises Stress ◽  
Abrasive Machining ◽  
Von Mises ◽  
Free Abrasive

In wiresaw manufacturing processes, such as those in slicing silicon wafers for electronics fabrication, abrasive slurry is carried by high-speed wire (5 to 15 m/s), which exerts normal load to the surface via hydrodynamic effects and bow of taut wire. As a result, the abrasives carried by slurry are constrained to indent onto and roll over the surface of substrate. In this paper, the axisymmetric indentation problem in the free abrasive machining (FAM) is studied by modeling a rigid abrasive of different shapes pushing onto an elastic half space. Based on the harmonic property of dilatation, the closed-form solution of stress distribution inside the cutting material for three different indentation processes in common FAM process are presented: cylindrical and conical abrasives as well as uniform pressure distribution. Along the symmetrical axis, von-Mises stress is two times larger than that of local maximum shear stress for all three indentation conditions. The von-Mises stress is infinity at the contact point for sharp pointed indentation, a location of crack initiation and nucleation. For indentation by abrasive of flat surface, which also can be provided by the localized effects due to the hydrodynamic pressure acting on the surface, both the von-Mises and local maximum shear stress reach maximum underneath the contact zone.

Poisson Ratio Effects on the Von Mises and Maximum Shear Stresses in Cylindrical Contacts

2005 ◽  
Author(s):  
Itzhak Green
Keyword(s):  
Shear Stress ◽  
Poisson Ratio ◽  
Unit Length ◽  
Maximum Shear Stress ◽  
Critical Force ◽  
Von Mises Stress ◽  
Maximum Pressure ◽  
Shear Stresses ◽  
Wide Range ◽  
Von Mises

This work determines the location of the greatest elastic distress in cylindrical contacts based upon the distortion energy and the maximum shear stress theories. The ratios between the maximum pressure, the von Mises stress, and the maximum shear stress are determined and fitted by empirical formulations for a wide range of Poisson ratios, which represent material compressibility. Some similarities exist between cylindrical and spherical contacts, where for many metallic materials the maximum von Mises or shear stresses emerge beneath the surface. However, if any of the bodies in contact is excessively compressible the maximum von Mises stress appears at the surface. That transitional Poisson ratio is found. The critical force per unit length that causes yielding onset, along with its corresponding interference and half-width contact are derived.

Bending Die Design for a Pre-Formed Sheet Metal with a Golden Finger Feature

2008 ◽  
Vol 594 ◽  
pp. 51-56
Author(s):  
Jinn Jong Sheu ◽  
Sheng Hao Fang
Keyword(s):  
Shear Stress ◽  
Material Flow ◽  
Quality Index ◽  
Design Method ◽  
Maximum Shear Stress ◽  
Die Design ◽  
Von Mises Stress ◽  
Design Parameters ◽  
Profile Design ◽  
Von Mises

In this paper, authors proposed an effective quality index of bending operation and a new punch profile design method to prevent defects. The proposed quality index is presented in terms of distance of fracture location with respect to the topmost plane of blank, the maximum von Mises stress, and the maximum shear stress. The Taguchi method with L18 orthogonal array was adopted to evaluate the effects of design parameters and find out the optimum design of punch profile. A new punch feature called “golden finger” was proposed to control the material flow and move the fracture defects out of the trimming line. The results of this study had demonstrated the optimum die design can be achieved with the proposed golden finger feature to obtain a sound product.

Multidisciplinary Design Optimization of the Composite Cooling Structure for Nickel-based Alloy Turbine Blade

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiaoru Qian ◽  
Peigang Yan ◽  
Wanjin Han
Keyword(s):  
Shear Stress ◽  
Flow Field ◽  
Turbine Blade ◽  
Maximum Shear Stress ◽  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Structure Design ◽  
Von Mises Stress ◽  
Von Mises

Abstract A designed method, multidisciplinary coupling computation and multiobjective optimization, has been established for the composite cooling structure of heavy gas turbine blade manufactured with a directionally solidified Ni-based superalloy. The method combines the one-dimensional fluid network gas-thermal coupling computation, three-dimensional flow field coupled with solid stress field, and anisotropic stress calculation based on finite deformation crystal slip. The temperature, flow field, Von-Mises stress and maximum resolved shear stress of the blade before and after optimization were analyzed. The results show that the optimized blade has lower maximum blade temperature, a more uniform temperature distribution, a lower flow resistance of the coolant channel at the leading edge than that of the original blade. The maximum Von-Mises stress of the optimized blade increases by 10.05 % more than the original blade. The maximum shear stress on the suction side and the pressure surface of the optimized blade are improved and slightly deteriorated compared with that of the original blade, respectively. The corresponding relationship of the maximum shear stress distribution with the local temperature gradient reveals further space for the improvement of the composite cooling structure. This paper has a particular guiding significance for the cooling structure design of the turbine blade.

Research Progress of Sawing Mechanism for Free Abrasive Wire Saw

2013 ◽  
Vol 446-447 ◽  
pp. 414-417
Author(s):  
Jin Sheng Wang ◽  
Chao Wang ◽  
Zi Fa Li
Keyword(s):  
Shear Stress ◽  
Hydrodynamic Pressure ◽  
Machining Process ◽  
Research Progress ◽  
Abrasive Machining ◽  
Workpiece Surface ◽  
Wire Saw ◽  
The Wire ◽  
Free Abrasive

The wire saw for slicing wafers process is free abrasive machining process. In this paper, we summarize the sawing mechanism for free abrasive wire saw, and think that the sawing mechanism is mainly rolling-indenting removal. But there are two forms of the force which causing the abrasives to roll and indent in the workpiece surface, one form the force acts on the abrasives by shear stress and hydrodynamic pressure, another form the force acts on the abrasives by wire saw. We design an experiment to verify the form of the force, and think that the second form of the force mainly causes the abrasive to roll and indent in the workpiece surface.

scholarly journals Parametric Study of the Borehole Drilling in Jointed Rock Mass

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yanan Gao ◽  
Yudong Zhang ◽  
Zetian Zhang ◽  
Minghui Li ◽  
Yingfeng Sun ◽  
...  
Keyword(s):  
Shear Stress ◽  
Rock Mass ◽  
Coal Seam ◽  
Coal Mining ◽  
Joint Angle ◽  
Maximum Shear Stress ◽  
Element Model ◽  
Von Mises Stress ◽  
Maximum Displacement ◽  
Von Mises

Gas is associated with coal mining; it commonly exists in the coal seam. It is one of the major dangers during the production because its reaction between the coal masses may induce the gas-coal outburst as well as it being an expositive matter. The gas accident has caused a huge amount of property damage and casualties. Therefore, the primary precaution for coal mining is gas control. At present, drilling and extraction are the main approaches for gas accident prevention. After drilling, the ground pressure will be released; the gas which is in a free state or absorbed in the coal seam will be easy to extract as the migration channel is enhanced. Hence, one of the most concerned problems is the stress redistribution of the coal and rock mass around the borehole. In practical engineering, there are many joints distributed in the coal and rock strata, so it is necessary to investigate the effect of the drilling in the jointed coal and rock mass. In this paper, the boundary element model of the borehole in the jointed coal and rock mass is established to study the influence of joints on the stress and displacement field. The following results can be obtained. The number of joints has a significant effect on the maximum displacement of the coal and rock mass. The maximum displacement increases with the number of the joint. The position of the maximum displacement shifts from the boundary of the borehole to the far field. Meanwhile, it can be found that the displacement may reach a peak value when the joint angle is 30° and if the joint number is less than 4, and the maximum displacement may occur under the joint angle of 45° and if the joints number continuous increases. The von Mises stress has a trend of increasing with the number of joints when the joint angle is less than 30°, while it has a decreasing trend when the joint angle is larger than 30°. The max stress may occur at the joint angle of 15°. The maximum shear stress occurs mostly in the No. 4 joint and the No.7 joint. When the joint angle is 30°, the maximum shear stress occurs in the No. 3 joint and the No. 4 joint. The overlap of the position of the maximum von Mises stress or the maximum displacement with different joint angles or different numbers of joint leads to a reexploration of such positions. The position of the maximum von Mises stress and the maximum displacement o is relatively steady, which locates symmetrically around the borehole. The line between the points that behaves as the maximum von stress is approximately perpendicular to the joint direction.

scholarly journals Finite Element Analysis of Composite Repair for Damaged Steel Pipeline

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 301
Author(s):  
Jiaqi Chen ◽  
Hao Wang ◽  
Milad Salemi ◽  
Perumalsamy N. Balaguru
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Hoop Stress ◽  
Pipe Wall ◽  
Von Mises Stress ◽  
Repair System ◽  
Composite Repair ◽  
Steel Pipeline ◽  
Von Mises ◽  
Infill Material

Carbon fiber reinforced polymer (CFRP) matrix composite overwrap repair systems have been introduced and accepted as an alternative repair system for steel pipeline. This paper aimed to evaluate the mechanical behavior of damaged steel pipeline with CFRP repair using finite element (FE) analysis. Two different repair strategies, namely wrap repair and patch repair, were considered. The mechanical responses of pipeline with the composite repair system under the maximum allowable operating pressure (MAOP) was analyzed using the validated FE models. The design parameters of the CFRP repair system were analyzed, including patch/wrap size and thickness, defect size, interface bonding, and the material properties of the infill material. The results show that both the stress in the pipe wall and CFRP could be reduced by using a thicker CFRP. With the increase in patch size in the hoop direction, the maximum von Mises stress in the pipe wall generally decreased as the maximum hoop stress in the CFRP increased. The reinforcement of the CFRP repair system could be enhanced by using infill material with a higher elastic modulus. The CFRP patch tended to cause higher interface shear stress than CFRP wrap, but the shear stress could be reduced by using a thicker CFRP. Compared with the fully bonded condition, the frictional interface causes a decrease in hoop stress in the CFRP but an increase in von Mises stress in the steel. The study results indicate the feasibility of composite repair for damaged steel pipeline.

Analysis of Loads and Stresses for a Sewing Needle

2002 ◽  
Author(s):  
Yuan Mao Huang
Keyword(s):  
Shear Stress ◽  
Personal Computer ◽  
Failure Modes ◽  
Von Mises Stress ◽  
Bending Stress ◽  
Principal Stresses ◽  
Acceptable Accuracy ◽  
Von Mises ◽  
Von Mises Stresses ◽  
The Cost

This study analyzes the loads of a needle by using singularity functions and determines the Von-Mises stresses to predict the failure modes of needles by using a personal computer. After principal stresses are calculated from the bending stress, compressive stress and shear stress, predicted failure modes of needles based on the Von-Mises stress coincide with practical existing failure modes reported by a manufacturer. These calculated stresses are also compared with the results obtained by using the software ABAQUS in the mainframe, and the deviation between the results calculated by these two methods is also investigated. Using this methodology can obtain loads, stresses and failure modes of a needle with acceptable accuracy while reducing the cost of using the commercial software in the mainframe.

Elastic Stresses Below Asperities in Lubricated Contacts

1986 ◽  
Vol 108 (3) ◽  
pp. 394-400 ◽  
Author(s):  
E. Ioannides ◽  
J. C. Kuijpers
Keyword(s):  
Maximum Shear Stress ◽  
Hertzian Contact ◽  
Stress Fields ◽  
Von Mises Stress ◽  
Near Surface ◽  
Elastic Stresses ◽  
Lubricated Contacts ◽  
Deep Groove ◽  
Surface Distress ◽  
Von Mises

The presence of contacting asperities in lubricated rolling bearings modifies the subsurface stress field strongly in the neighborhood of the surface and, to a lesser extent, at larger depths where the maxima of the shear or von Mises stress of a smooth Hertzian contact normally exist. The near surface stresses are of importance because they may result in micropitting, a mode of surface distress which leads to the eventual fatigue failure of the contacting surfaces. A mathematical method is presented in this paper which allows the statistical calculation of important parameters (maximum von Mises stress or maximum shear stress amplitude) of the stress fields generated under elastically deforming asperities during their passage through a lubricated contact. The asperities themselves are modelled using estimates of the surface spectral moments obtained from single-profile trace measurements. The method is applicable to both isotropic and anisotropic rough surfaces. Moreover, the important effect of the shear surface tractions, including tractions over the asperities, is contained in the analysis. Computed examples are presented for different surface textures and film thicknesses in the case of a deep groove ball bearing. Finally, a qualitative attempt is made to correlate features of these stress fields with the presence of surface pitting, and the limitations of the analysis are discussed.

Shear stress and von Mises stress distributions in the periphery of an embedded acetabular cup implant during impingement

2017 ◽  
Vol 62 (3) ◽  
Author(s):  
Christoph Arndt ◽  
Alexandra Görgner ◽  
Carsten Klöhn ◽  
Roger Scholz ◽  
Christian Voigt
Keyword(s):  
Shear Stress ◽  
Von Mises Stress ◽  
Shear Stresses ◽  
Periprosthetic Bone ◽  
Worst Case ◽  
Bone Interface ◽  
Numerical Predictions ◽  
Von Mises ◽  
Acetabular Implant ◽  
Interface Distance

AbstractAs literature implies, daily activities of total hip arthroplasty (THA) patients may include movements prone to implant-implant impingement. Thus, high shear stresses may be induced at the acetabular implant-bone interface, increasing the risk of implant loosening. The aim of the current study is to determine whether or not impingement events may pose an actual risk to acetabular periprosthetic bone. An existing experimental workflow was augmented to cover complete three-dimensional strain gage measurement. von Mises and shear stresses were calculated from 1620 measured strain values, collected around a hemispherical cup implant at 2.5 mm interface distance during worst-case impingement loading. A shear stress criterion for acetabular periprosthetic bone was derived from the literature. At the impingement site, magnitudes of von Mises stress amount to 0.57 MPa and tilting shear stress amount to -0.3 MPa at 2.5 mm interface distance. Conclusion can be drawn that worst-case impingement events are unlikely to pose a risk of bone material failure in the periphery around fully integrated cementless acetabular hip implants in otherwise healthy THA patients. As numerical predictions in the literature suggested, it can now be confirmed that impingement moments are unlikely to cause acetabular implant-bone interface fixation failures.

An Evaluation of Chip Separation Criteria for the FEM Simulation of Machining

1996 ◽  
Vol 118 (4) ◽  
pp. 545-554 ◽  
Author(s):  
J. M. Huang ◽  
J. T. Black
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Fem Simulation ◽  
Shear Plane ◽  
Machining Process ◽  
Stress And Strain ◽  
Machined Surface ◽  
Average Maximum ◽  
Chip Separation ◽  
Chip Geometry

Different chip separation criteria for the FEM simulation of machining were examined. Criterion based on distance between the tool tip and the node located immediately ahead, criterion based on maximum shear stress in the element ahead of the tool tip, criterion based on average maximum shear stress in the shear plane, and criterion based on a combination of distance and stress were investigated. Under conditions of smooth separation of chip from workpiece, simulation results showed that, during steady-state cutting, the type of chip separation criteria did not greatly affect chip geometry, nor distributions of stress and strain. The magnitude of the chip separation criteria also did not significantly affect chip geometry and distributions of stress in the chip but it did affect the chip separation process, distributions of stress in the machined surface, and distributions of effective plastic strain both in the chip and in the machined surface. During the initiation of cutting, neither the geometrical nor physical criteria simulate the machining process correctly. A combination of geometric and physical criteria was also recommended in this study.

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