Computational Model for Free Abrasive Machining of Brittle Silicon Using a Wiresaw

1999 ◽  
Author(s):  
Milind Bhagavat ◽  
Imin Kao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Large Diameter ◽  
Abrasive Machining ◽  
Element Analysis ◽  
Hydrodynamic Shear ◽  
Representative Model ◽  
Cutting Zone ◽  
Free Body ◽  
Free Abrasive

Abstract The present paper deals with physics based computational modeling of the wiresaw Free Abrasive Machining (FAM). The wiresaw is used to slice large diameter wafers of predominantly brittle semi-conductors such as silicon. The wiresawing model proposed in the present paper involves cutting action by ‘floating’ abrasives. It is proposed that the abrasive carrying slurry forms a film in the cutting zone by an elasto-hydrodynamic action. Finite Element Analysis shows this film to be in general thicker than the average abrasive size. This signifies a ‘float’ machining condition, wherein there is no direct pressing of abrasives by the wire. Typical rolling and indenting of abrasives under such free body abrasion environment is supported by hydrodynamic shear and pressure respectively. The abrasive is assumed to remove material by typical indentation fracture. Finite element analysis of stresses underneath an indenting abrasive shows that cracks leading to chipping occur only during unloading of indented abrasives (during rolling). The volume of the chip removed in a single indentation is proportional to the volume of plastic zone underneath the indenter. We integrate the elasto-hydrodynamic model and the single abrasive indentation model into a complete representative model of wiresawing.

Standardization of Flattening Procedure of Transverse to Pipe Axis Strap Tensile Samples

2018 ◽  
Author(s):  
M. Rashid ◽  
S. Chen ◽  
L. E. Collins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Testing ◽  
Standard Procedure ◽  
Large Diameter ◽  
Spring Back ◽  
Pipe Axis ◽  
Element Analysis ◽  
Line Pipe ◽  
Experimental Approaches

Tensile testing on large diameter line pipe is generally done using strap samples obtained in the transverse to pipe axis (TPA) orientation of a pipe. The strap samples are then flattened and machined prior to testing. Although the standardized tensile testing is well documented, the variability in the reported TPA tensile properties of the same material tested within a lab or at different labs has always been an issue. Recent work conducted at EVRAZ NA research lab has identified flattening as the main source of the variability in reported yield strength (YS) values for line pipe. The lack of a standard procedure for flattening TPA strap samples is a major obstacle to obtaining consistent results. Therefore, the main objective of this current study was to establish a standardized flattening procedure for TPA strap samples. Both finite element analysis (FEA) and experimental approaches were adopted. Various flattening methods and fixtures were studied. Extensive flattening experiments were conducted on TPA samples from different line pipe products. Results showed that the spring back after flattening in a TPA sample is different for pipes with different gauge and grades. It was established that consistent flattening can be achieved using appropriate fixtures for differerent ranges of tubular products defined by grade, diameter and gauges. Evaluation of the flattening fixture designs and experimental results are discussed in this paper.

Design of Ellipsoidal Heads Using Elastic-Plastic Finite Element Analysis

2002 ◽  
Author(s):  
Donald J. Florizone
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
Large Strain ◽  
Large Diameter ◽  
Spherical Shape ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Section Viii ◽  
Design Calculations

Traditional design techniques result in excess material being required for ellipsoidal heads. The 2001 ASME Boiler and Pressure Vessel Code Section VIII Division 1, UG-32D and Section VIII Division 2, AD-204 limit the minimum design thickness of the heads. ASME Boiler and Pressure Vessel Code Case 2261 provides alternate equations that enable thinner head design thickness. VIII-2 Appendix 3 and 4 methods potentially could be used to further optimize the head thickness. All the equations in the code use one thickness for the entire head. On large diameter thin heads the center or spherical area is often thicker than the knuckle area due to the method of manufacture. Including this extra material in the design calculations results in an increase of the MAWP of large diameter thin heads. VIII-2, AD-200 of the code permits localized thinning in a circumferential band in a cylindrical shell. Applying these same rules to elliptical heads would permit thinning in the knuckle region as well. Engineers have powerful finite element analysis tools that can be used to accurately determine levels of plastic strain and plastic deformed shapes. It is proposed that VIII-2 Appendix 4 and 5 methods be permitted for the design of elliptical heads. Doing so would permit significant decreases in thickness requirements. Different methods of Plastic Finite Element Analysis (PFEA) are investigated. An analysis of a PVRC sponsored burst test is done to develop and verify the PFEA methods. Two designs based on measurements of actual vessels are analyzed to determine the maximum allowable working pressures (MAWP) for thick and thin heads with and without local thin regions. MAWP is determined by limit analysis, per VIII-2 4-136.3 and by two other proposed methods. Using Burst FEA, the calculated burst pressure is multiplied by a safety factor to obtain MAWP. Large deflection large strain elastic perfectly plastic limit analyses (LDLS EPP LL) method includes the beneficial effect of deformations when determining the maximum limit pressure. Elliptical heads become more spherical during deformation. The spherical shape has higher pressure restraining capabilities. An alternate design equation for elliptical heads based on the LDLS EPP LL calculations is also proposed.

Two-Dimensional Finite Element Analysis for Large Diameter Steel Flanges

2004 ◽  
Vol 126 (3) ◽  
pp. 399-403 ◽  
Author(s):  
Abdulmalik A. Alghamdi ◽  
Muhsen S. Al-Sannaa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Elasticity Modulus ◽  
Large Diameter ◽  
Two Dimensional ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Gasket Material ◽  
Clamping Pressure

This paper presents numerical results obtained using Finite Element Analysis (FEA) in studying large diameter welded neck steel flanges under different loading conditions. Obtained FEA results show the effect of the clamping pressure, internal pressure, axial end load, temperature effect, gasket elasticity modulus on the contact pressure between the gasket and the steel flange. As expected clamping pressure is a determinate factor for the sealing condition. Gasket material is another primary factor in designing flanged joints.

Use of Finite Element Analysis for Stud Pre-Tension Determination of Large Diameter Integral Flanges With Ring Joint Gaskets

2010 ◽  
Author(s):  
Upali Panapitiya ◽  
Haoyu Wang ◽  
Syed Jafri ◽  
Paul Jukes
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Oil And Gas ◽  
Large Diameter ◽  
Three Dimensional ◽  
Oil And Gas Industry ◽  
Element Analysis ◽  
Axial Forces ◽  
Three Dimensional Finite Element

Large diameter integral steel flanges are widely used in many applications in the oil and gas industry. The flanges of nominal pipe sizes, 26-inch and above with ring-joint gaskets as specified in ASME B 16.47 Standard, are used in the offshore applications for the transportation of oil and gas from production facilities. These pipelines require flanged connections at end terminations, mid-line tie-ins and expansion loops. The conventional design of large diameter steel flanges is based on one-dimensional analytical methods similar to the procedure in ASME VIII Boiler and Pressure Vessel Code, Division 1 Appendix 2. The effects of axial forces and bending moments are approximated by calculating an equivalent pressure. This usually results in conservative designs for the large flanges because it estimates the required stud pre-tension based on the assumption that the gasket will be unloaded entirely to a minimum stress, whereas only a small section of the gasket is subjected to low stress. This technical paper presents the quasi-static, nonlinear, and three-dimensional finite element models of large diameter steel flanged joint for the determination of stud pre-tension and change of stud tension under various loading conditions. The finite element analysis results are compared with the results obtained by using the equivalent pressure method and flange “Joint Diagram”.

A Study on the Large-Diameter Seamless Gas Cylinder Dimensional Accuracy of Rotary Expanding Process with Finite Element Analysis

2011 ◽  
Vol 328-330 ◽  
pp. 136-142
Author(s):  
Shun Yao Jin ◽  
Zhong Guo Huang ◽  
Zong Ke Shao ◽  
Ming Xiang Li ◽  
Hui Lai Sun ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Wall Thickness ◽  
Large Diameter ◽  
Dimensional Accuracy ◽  
Steel Tube ◽  
Element Analysis ◽  
Thickness Uniformity ◽  
Gas Cylinder ◽  
Roll Gap

This paper expounds the application of rotary expanding process to manufacture the large-diameter hot-rolled seamless gas cylinder. Through analytic geometry method, an equation is established among the tail roll gap, roll distance and the plug protrusion distance. 3D drawing software CATIA-V5 is applied to build 3d models of steel tube and rolling tools. The rolling process is simulated by MSC.Marc FEA (finite element analysis) software. Marc’s second development function and FORTRAN software’s extracting finite element node coordinates function are applied to calculate the wall thickness uniformity. A novel method to calculate the wall thickness uniformity after finite element analysis is proposed. The wall thickness uniformity of steel tube after rolling is well simulated and compared by MSC.Marc FEA software, which can help the technologist to predict and choose the best rolling parameter. For gas cylinder rolling, the tail roll gap should be set to 17mm. The roller distance and the plug protrusion distance should be set as 342mm and 78mm separately.

The Finite Element Analysis of the Large-Diameter Composite Slurry Valve Gate

2014 ◽  
Vol 989-994 ◽  
pp. 3149-3152
Author(s):  
Jie Wu ◽  
Zhao Meng Yang ◽  
Dong Zheng Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Large Diameter ◽  
Optimization Method ◽  
Vital Role ◽  
Manufacturing Cost ◽  
Long Distance ◽  
Element Analysis ◽  
Valve Gate ◽  
Composite Slurry

In a long distance slurry pipeline transport system, pulp valve plays a vital role, which combined the pulp valve application is more, ram is one of the important components of composite slurry valve. This article mainly aims at gate has carried on the design and analysis, finite element modeling, and study the corresponding constraints, in the process of loading method, large diameter combination valve gate stress and strain distribution are obtained, combined with the optimization method and finite element analysis software for its structure optimization research, realize the lightweight of the gate. To reduces the manufacturing cost of the gate, as to provide theoretical basis for design.

scholarly journals Finite element analysis of the initial stability of arthroscopic ankle arthrodesis with three-screw fixation: posteromedial versus posterolateral home-run screw

2020 ◽  
Author(s):  
Sen Wang ◽  
Jian Yu ◽  
Dahang Zhao ◽  
Xiang Geng ◽  
Jiazhang Huang ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Articular Surface ◽  
Large Diameter ◽  
Ankle Arthrodesis ◽  
Joint Surface ◽  
Element Analysis ◽  
Tibiotalar Joint ◽  
Initial Stability ◽  
The Impact

Abstract Objective: Arthroscopic ankle arthrodesis (AAA) is a standard surgical method for the treatment of advanced traumatic ankle arthritis and has become more popular due to its advantages. To fix the tibiotalar joint, the use of three percutaneous screws is considered to have better mechanical stability than the use of two screws. However, it is sometimes difficult to insert three screws because they might block each other due to the small area of the tibiotalar joint surface and the large diameter of the screws; few articles illustrate how to insert three screws without the screws disturbing each other. The purpose of this study is to explore possible screw configurations of tripod fixation in arthroscopic ankle arthrodesis that avoid the collision of screws and yield better biomechanical performance.Methods: We used the finite element method to examine the impact of different screw positions and orientations on the biomechanical characteristics of a three-dimensional (3D) ankle model. Maximum and average micromotion, pressure on the articular surface, and von Mises stress values of the tibia and the talus were used to evaluate the initial stability of the ankle.Results: Five kinds of three-screw configurations were identified, and finite element analysis results suggested that configurations with the posteromedial home-run screw presented lower micromotion (maximum: 17.96 ± 7.49 μm versus 22.52 ± 12.8 μm; mean: 4.88 ± 1.89 μm versus 5.19 ± 1.92 μm) (especially configuration 3) and better screw distributions on the articular surface than those with the posterolateral home-run screw.Conclusion: Screw configurations with the posteromedial home-run screw avoid collision and are more biomechanically stable than those with the posterolateral home-run screw. Thus, inserting the home-run screw through the posteromedial approach is recommended for clinical practice.

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