Papers by Keyword: Pressure Distribution

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Authors: P.S. Rao, Santosh Agarwal
Abstract: This paper presents the theoretical study and analyzes the comparison of porous structures on the performance of a couple stress fluid based on rough slider bearing. The globular sphere model of Kozeny-Carman and Irmay’s capillary fissures model have been subjected to investigations. A more general form of surface roughness is mathematically modeled by a stochastic random variable with non-zero mean, variance and skewness. The stochastically averaged Reynolds type equation has been solved under suitable boundary conditions to obtain the pressure distribution in turn which gives the expression for the load carrying capacity, frictional force and coefficient of friction. The results are illustrated by graphical representations which show that the introduction of combined porous structure with couple stress fluid results in an enhanced load carrying capacity more in the case of Kozeny-Carman model as compared to Irmay’s model.
Authors: Hao Chen, Fang Wang, Jian Guo Zhang, Yan Ping Guo, Hai Yan Song
Abstract: The aim of the present work was to develop a lain-human finite element model for cushion design to prevent bedsore by performing biomechanical analysis on interface pressure. The geometric data of the human was obtained by laser scans. The finite element model was composed of solid hexahedral elements. The material of the bed cushions was obtained according to the mechanical experiment. The human model was validated by comparing the simulation result with the experimental data. The validated finite element model could be used to facilitate, accelerate and economize the process of design of cushion.
Authors: Yong Zhou Li, Xiao Ping Fan, Qiu Yun Zheng
Abstract: Chemical mechanical polishing (CMP) is one of the most effective technologies in modern ultra-precision processing. In this paper, we consider the slurry is ferromagnetic fluid and the influence of the centrifugal force, and then obtain the equations about this slurry in CMP. The slurry pressure distribution, resultant forces and moments acting on the wafer are calculated in typical conditions, and the affects of film thickness, roll and pitch angles are also calculated.
Authors: Jae Hyun Shim, J.H. Ok, Hyoung Jin Choi, H.S. Koo, Beong Bok Hwang
Abstract: Conventional multi-step extrusion processes with solid billet are examined by the rigid-plastic finite element method in order to provide criteria for new process sequence for hollow parts. Two examples are taken for the analyses such as the current three-stage cold extrusion process for a hollow flange part and five-stage process for manufacturing an axle housing. Based on the results of simulation of the current three-stage and five-stage manufacturing processes, new design strategy for improving the process sequences is developed simply by replacing the initial billet from solid to hollow one. The developed new process sequences are applied for simulation by FEM and they are compared with the existing processes to confirm the usefulness of new process sequences with hollow initial billets. The results of simulation show that the newly proposed process sequences with hollow billet instead of solid one are more economical way to manufacture required parts, respectively.
Authors: H.S. Koo, V.R. Jayasekera, K.H. Min, Jung Min Seo, Dong Hwan Jang, J.H. Ok, Beong Bok Hwang
Abstract: This paper is concerned with the pressure distribution along the die-powder interface in long parts. The pressure exerted on the interface at various points on the moving and stationary punch, and also on the sidewall of container was investigated by the finite element method. A plasticity theory describing asymmetric behavior of powdered metals in tension and compression was briefly summarized. The yield criterion applied to the sintered powdered metals had been modified for describing this asymmetric behavior. The material properties of copper powders under compaction were also briefly described for the completeness of the paper. The copper powders were selected as a model material in the present study. The main purpose of this study is to investigate the pressure distribution along the interface of tooling quantitatively by the finite element method so that the results could be applied usefully to the design of tooling, especially container design for powdered metal compaction. Geometrical condition for analysis was confined to the Class II components which is very long parts without steps. It was concluded from the simulation results that the pressure exerted on the moving punch increases sharply near the outer circumference of punch and the pressure on the sidewall decreases at a distance from moving punch to fixed punch. It was also seen from the simulation that the pressure on the stationary punch is not significantly built up and decreases toward outer periphery. These trends were seen amplified with severe frictional conditions imposed on the tooling and powder interface.
Authors: Jing Sun, Guang Jun Yang, Jian Jun Liu
Abstract: To explore the noise suppression effect of mesh on cavity, the wind tunnel experiment is carried out based on the analysis of clean cavity flow characteristics. The meshes are arranged both in the cavity and at the leading edge of the cavity. Through the analysis of pressure distribution on the cavity bottom and the noise spectrum monitored at front and rear walls respectively, noise suppression effects of mesh programs relative to the clean cavity and changes in the flow field are studied, the results show that the mesh inside the cavity has a better noise reduction effect. The work in this paper provides an effective way for cavity noise reduction.
Authors: Ye Bo Liu, Zhi Ming Liu
Abstract: Numerical simulations were carried out to investigate the air flow and pressure distributions beneath high speed trains, based on the three-dimensional Reynolds-averaged Navier-Stokes equations with the SST k-ω two-equation turbulence model. The simulation scenarios were of the high speed train, the CRH2, running in the open air at four different speeds: 200km/h, 250km/h, 300km/h and 350km/h. The results show that, the highest area of pressure is located at the front underbody part of the train whist the pressure for rest of the train is relatively small. Increasing speed does not visibly increase the pressure coefficient, indicating that the pressure increases with the square of the operational speed.
Authors: Ali Parvizi, Karen Abrinia, Mohsen Hamedi
Abstract: In this paper, based on the modified slab method theory, an analytical solution for ring rolling process is presented. The non-uniformity of the normal and shear stresses across the section of the deforming material are considered. The friction factor multiplied by the shear yield strength is used to present friction between the main roll and the ring. Complete expressions for the ring rolling pressure, force and torque are obtained and the position of neutral point is predicted. The influence of the process parameters such as friction factor, main roll rotational speed, feed speed, and others was investigated. Analytical results obtained from the present formulation were compared to previous experimental works and good agreement and improvements were observed.
Authors: Jin Meng, Ping Zhu, Qing Hui Ji, Zhao Liu
Abstract: Radial fatigue life is an important index of automotive wheel. Traditional analysis method neglected the force on flange and confused stable inflation load with dynamic radial load. In this study, a 3D finite element (FE) analysis was executed simulating the inflation and radial press process. Different contact and modeling techniques were adopted to improve the convergence and accuracy. Stable and dynamic pressure on flange and bead seat were distinguished and approximated with different functions. Finally, experiments and comparison were made to ensure the reliability of the method.
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