Platform Design for Characterizing Shear Force Produced by Magnetized Magnetorheological Fluid

In this paper we proposed a platform for measuring shear force of magnetorheological (MR) fluid by which the relationship of yield stress and magnetic flux density of specific material can be determined. The device consisted of a rotatable center tube in a frame body and the magnetic field was provided by two blocks of permanent magnets placed oppositely outside the frame body. The magnitude and direction of the magnetic field were manipulated by changing the distance of the two permanent magnets from the frame body and rotating the center tube, respectively. For determining the magnetic field of the device, we adopted an effective method by fitting the FEM (finite element method) result to the measured one and then rebuilt the absent components to approximate the magnetic field, which was hardly to be measured simultaneously as different device setup were required. With the proposed platform and analytical methods, the drawing shear force and the corresponding yield stress contributed by MR fluid could be evaluated in respect to the magnitude and direction of given magnetic flux density with acceptable accuracy for specific designing purposes without a large, complex, and expensive instrument.

PERANCANGAN DAN ANALISIS RANGKA MESIN DESKTOP CNC MILLING

The need of machine tools is growing in Indonesia every years, this because of the increasing need of high quality product and short product manufacturing time are the answer for the market needed. CNC machine is a numerical method which the computer is used to control the machine tools, in Indonesia itself are increasing its usage from large scale industry to home industry and as well as in education sector. Education sector need to be up to date to the technology to empowering their students in order to catch up in the technology growth. Investment in CNC machine tools is consider as a high investment for education institution, and industrial CNC machine tools also bulky so it difficult to move around which are difficult to bring it in classroom. To overcome the problem in this paper will discuss about design and analysis of prototype CNC milling machine tool which has working area of 328 mm × 245mm × 100mm and can withstand the force of cutting of 0.044Nm. In this paper also discuss about design and analysis of the machine tools frame using finite element method. Result from the frame analysis with the load from Z direction of 10 kg of load shows the maximum displacement is 0.07558mm and maximum stress is 0.09178 Mpa.

Influence of Flexible Bodies in Military Tracked Vehicle Dynamics

Tracked vehicles are meant to be used in the harsh cross country environment. In particular, the military tracked vehicles are highly exposed to severe terrains and critical handling conditions. Yet while carrying out the dynamic studies, the tracked vehicles, in general, are modeled as rigid bodies. Hence in this article, an attempt has been made to understand closely the dynamics of a tracked vehicle with the inclusion of some parts of the tracked vehicle viz., hull side plates and road wheel arms, as flexible bodies in the dynamic analysis using the finite element method. Result of the flexible dynamic simulation is also compared with the tracked vehicle analysis with the same parts modeled as rigid bodies. In this investigation, dimensions of the standard staggered trapezoidal blocks terrain meant for testing the tracked vehicles is used to carry out the dynamic studies on the tracked vehicle. The dynamic simulation result of the flexible tracked vehicle model is also compared with the experimental test result of the actual tracked vehicle conducted in the actual trapezoidal blocks terrain.

FINITE ELEMENT ANALYSIS OF THE MECHANICAL CHARACTERISTICS OF GLAUCOMA

Purpose: Construct a finite element model of the human eye to quantitatively analyze the mechanical characteristics of the human eye, especially the glaucoma damage process of the optic nerve head (ONH). Method: First, the geometry model of the human eye with nonuniform thickness was established based on a reasonable hypothesis and assumptions. Because the ONH is an important factor for glaucoma, we refine the structure of the ONH with lamina cribrosa. Then, mesh division was applied for finite element analysis. To simplify the complexity of the analysis, the materials of the model were assumed to be isotropic linear elastic materials, and physical properties such as Young’s modulus and Poisson’s ratio were set according to published literature. Next, proper constraints and loads were applied to the model and solved with a finite element method. Result: A finite element model of the human eye was created to simulate the mechanical characteristics of the eye structures under high intraocular pressure (IOP). The ONH depressed 1.057[Formula: see text]mm under 0.009[Formula: see text]MPa pressure to simulate high IOP. Conclusion: The constructed model is able to quantitatively simulate excavation of the optic disc and damage of the optic nerve. The result proved Houcheng Liang’s hypothesis about the ONH damage mechanism in glaucoma.

An integrated passive magnetic damping system for high-speed compressor with flexible rotor

To provide a more reliable rotor damping system for high-speed compressor with flexible rotor, a passive magnetic damping integrated with an active axial bearing (PMDAB) system is proposed. The PMDAB system can provide active force in axial direction and also can provide damping force without control system in radial direction. To enhance the damping ability of the system, an analytical model is set up especially for the high-speed vibration rotor, and the relation between resistance of radial coils and the provided damping force is discussed for the first time. The coupling characteristic between passive radial damping coefficient and active axial bearing stiffness is also analyzed; the result shows that the coupling is too small, therefore can be neglected. Finally, a design example for a high-speed compressor is given based on electromagnetic analysis of PMDAB and dynamic analysis of the flexible rotor. The analytical and design results, which are verified by the finite element method result, show that the PMDAB is effective in controlling the first bending vibration of flexible rotor.

Material Analysis and Structural Study on Powering Divider of Herbage Harvester

In order to study stress deformation and distribution of powering divider on 4GH-120 herbage harvester at working time, main materials of the divider were analyzed, and mechanical model of the divider was established by finite element method. Result showed that maximal displacement deformation and stress distribution appeared on the left tooth of divider; stress value decreased from center to edge; Choosing 6 mm tooth thickness and 430r/min rotating speed was the best effect, deformation displacement and equivalent stress are respectively reduced by 53.5% and 54.2% compared with original dates. In 320～400 mm diameter scope, the smaller the divider is, the safer it is.

Numerical Analysis of Thermally-Induced Residual Stresses in Plasma Facing Components for Fusion Reactor

The realization of a fusion reactor is critically dependent on the successful development of high performance materials. Especially, the plasma facing components (PFCs) which basically consist of a direct plasma facing armor material and a heat sinking material. Tungsten (W) and Copper-alloy (CuCrZr) have been considered as the potential candidates for armor materials and heat sinking materials, respectively, due to their attractive nuclear and physical properties. However, due to the incompatibility of the coefficient of thermal expansion and the elastic properties between the W and the Cu-alloy as well as the non-homogeneous temperature distribution in PFCs, one of the crucial issues is the generation of thermally-induced residual stresses in W/CuCrZr PFC on cooling either during fabrication or during operation of fusion reactor. Therefore, the thermo-mechanical response of PFCs under high heat flux from the fusion reactor is a critical issue for the development of fusion technology. In the present work, in order to optimize the thermal and mechanical integrity of PFCs, thermally-induced residual stresses in W/CuCrZr PFCs with a compliant interlayer (OFHC-Cu: Oxygen Free High Conductivity Copper) are analyzed numerically by means of finite element method. Result indicated that the use of interlayer in PFCs could significantly reduce the magnitude and the concentration of thermally-induced stresses in comparison to the PFCs without interlayer. And also the optimum thickness for interlayer was suggested based on the current analysis conditions.

Preparation of Turbulated Cooling Hole for Gas Turbine Blade Using Electrochemical Machining

With the development of high performance of gas turbine engine, there is a tendency to design the ribs in the cooling hole in order to improve the heat transfer and cooling efficiency in a cooling passage. This paper focuses on a machining method of the burbulated cooling hole. The cooling hole is formed by electrochemical machining (ECM) process using a shaped electrode. The ribs on the hole wall form using ECM after the shaped electrode is lowed into the bottom of the straight hole machined in advance. The experimental results indicate that machining efficiency increases obviously. Various parameters affecting the forming of the cooling hole, such as voltages, electrolyte concentrations, and the material of the workpiece, are discussed in detail. Furthermore, the flow field and temperature field of the different type of cooling hole are analyzed using computational fluid dynamics (CFD) model and finite element method. Result shows that the heat transfer coefficient in rib channels could enhances significantly