10,041 research outputs found
A three-dimensional rigid-plastic finite element analysis of bevel gear forging by using a remeshing technique
No full textA three-dimensional remeshing scheme implemented by using a modular concept is proposed for the finite element analysis of a complicated forging process. In order to show the effectiveness of the scheme, forging of a bevel gear is simulated by using several basic modules in the general rigid-plastic finite element code (Yoon and Yang, Int. J. Mech. Sci. 30, 887, 1988; Yang et al., Int. J. Mech. Sci. 31, 145, 1989) developed for cold forging. Criteria for remeshing as well as a scheme for the mapping of state variables are proposed for three-dimensional remeshing. The computational results are compared with experimental data in order to check the validity of the simulation. The computational results show that the computation can be effectively carried out by using the proposed remeshing scheme and that it can be extended to other more complicated product geometry. © 1990
JH-induced phosphorylation of aPKC and Par3 as well as zonula adherens disassembly.
No full text(A) The levels of phosphorylated aPKC (p-aPKC) and Par3 (p-Par3) in the follicular epithelium of adult females during the first gonadotropic cycle. (B) Phosphorylation of aPKC and Par3 in cultured follicular epithelia of 7-day-old females treated by JH at 0.1 μM for 5–30 min. (C) Suppression of ACPD on JH-induced aPKC and Par3 phosphorylation in cultured follicle cells of 7-day-old females. ACPD was applied at 0.1 μM prior to JH treatment. (D) Distribution of p-aPKC in cultured follicular epithelium from adult females on day 8 and treated with DMSO, JH and ACPD+JH, respectively. Blue: nuclei. Green: F-actin. Arrow heads indicate patency. Scale bars: 5 μm. (E) Distribution of p-Par3 in cultured follicular epithelia from adult females on day 8 and treated with DMSO, JH and ACPD+JH, respectively. Arrow heads indicate patency. Scale bars: 5 μm. (F) Immunoprecipitation (IP) and Western blotting (WB) showing inhibition of ACPD on JH-induced disassociation of p-Par3 and β-Cat. (G) Distribution of β-Cat in the follicular epithelium treated with DMSO, JH and ACPD+JH. Arrow heads indicate patency. Scale bars: 5 μm.</p
A study on an open architecture CNC system with a NURBS interpolator for WEDM
No full textThis paper deals with the design and implementation of an open architecture CNC system for wire electrical discharge machining (WEDM) with a consideration of the differences between WEDM and NC cutting machines. Work using open architecture controllers (OACs) has focused mainly on metal cutting machines. WEDM has many aspects similar to milling machines. However, there are differences in the machining processes and control strategies. To close the gap between previous general work on OAC and the WEDM specific needs, an open architecture NC model for WEDM comprised of a synchronisation kernel and an NC functional module is proposed. The proposed CNC system is applied to an existing commercial WEDM system by a retrofitting method. A precise NURBS interpolation function is implemented and sample runs are conducted with a NURBS interpolator that is added to the proposed system
Preparation of high surface area CaCO3 by reacting CO2 with aqueous suspensions of Ca(OH)(2): Effect of the addition of sodium polyacrylate
No full textTREATMENT OF CONTACT TRACTION AT THE DIE - WORKPIECE INTERFACE FOR THE ELASTIC ANALYSIS OF DIE DEFORMATION
No full textA method to calculate the contact traction on the die-workpiece interface is proposed. A systematic method for performing the elastic finite element analysis of the die deformation by using the information obtained from the finite element analysis of the workpiece deformation is proposed. The proposed method can be applied to both the two-dimensional and three-dimensional analyses of die deformation independently of the friction modelling and the constitutive equations. A rigid-plastic finite element analysis of workpiece deformation is carried out for the upsetting of a cylindrical workpiece. In order to check the validity of the present method for both flat and curved contact surfaces, the elastic finite element analysis of die deformation is then performed for flat square block forging as well as for a bevel gear forging (Yoon and Yang, Int. J. Mech. Sci. 32, 277-291, 1990) [8]. From the computation it is shown that the error due to the transfer of data from the workpiece mesh to the die mesh does not influence appreciably the elastic deformation of the die. The proposed method can be applied to arbitrarily curved die geometries in three-dimensional metal forming problems
Finite element analysis of filling stage in die-casting process using marker surface method and adaptive grid refinement technique
No full textThe marker surface method and the adaptive grid refinement technique have been applied to the three-dimensional (3-D) finite element analysis of the filling stage in the die-casting process. Especially, the marker surface plugging technique and the marker surface regeneration technique incorporated in the marker surface method have been proposed for the efficient analysis of 3-D practical problems. Through the marker surface plugging technique, new parts of marker surface are effectively created in order to eliminate the gaps between the parts of marker surface or between the edge of marker surface and cavity wall. By using the marker surface regeneration technique, the marker surface including a great number of marker elements is recreated on the basis of its original shape in order to decrease the number of marker elements and computational time. A 3-D example used as the benchmark test and a typical industrial problem of the die-casting process have been analysed. The numerical results have been in good agreement with the experimental results and the efficiency of the adaptive grid refinement technique has been verified. It has been shown that the proposed techniques incorporated in the marker surface method and the adaptive grid refinement technique can be effectively applied to general industrial problems. Copyright (C) 2004 John Wiley Sons, Ltd
Rigid-plastic finite element analysis of three-dimensional forging by considering friction on continuous curved dies with initial guess generation
No full textA method of measurement for determination of relative density in the axisymmetric forming of sintered porous material
No full textA new method for the determination of relative density is proposed in this work. Density is one of the most important variables in the forming of sintered porous materials. In the proposed method, the distribution of relative density is obtained experimentally from the grid patterns of the deformed specimen. The nodal coordinates and the tangential slopes of the end-points of each segment of a grid element are measured by use of an optical projector. The measured data are curve-fitted using an appropriate interpolating equation, the relative density then being obtained by means of numerical integration on the basis of mass conservation. The validity of the proposed method is checked for the axisymmetric forward extrusion process through a curved die. The indirectly measured values of relative density distribution are compared with those obtained by the rigid-plastic finite-element method, the comparison showing that there is a good agreement between the two results considering the numerical errors involved in the two methods. It is thus shown that the proposed method can be utilized further in other forming processes for sintered materials. © 1992
An analysis of upset forging of square blocks considering the three-dimensional bulging of sides
No full textA simple kinematically admissible velocity field for three-dimensional deformation in upset forging of square blocks is proposed which considers not only the sidewise spread but also bulging along thickness. From the derived velocity fields the upper bound load andt he deformed configuration are determined by optimizing some given parameters. Experiments are carried out with annealed AISI 1015 steel billets at room temperature for different thickness and lubrication conditions. The theoretical estimates both in forging load and the deformed configuration are in good agreement with the experimental results. It is shown that the velocity field proposed in this work can be used conveniently for the prediction of forging load and deformation in upset forging of square blocks. © 1985
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