Applied Mechanics and Materials Vols. 789-790

Abstract: A methodology and a procedure for topology optimization of wing structure based on manufacturing constraints were proposed. By the methodology and procedure proposed, topology of thin-box wing structure which is easier manufactured than traditional topology result can be obtained. The manufacturing constraints of draw direction, member size control and inexcusable initial design were introduced into the optimal procedure and executed in Optistruct. Effect and efficiency were analyzed and compared with traditional topology optimization.

Abstract: Global industries nowadays are characterised by market instability and rapid change in customer demand, which consequentially affect the product design and require quick decisions on modification or replacement of the processing and production workstations. Therefore, it has become essential for the world economies to implement an effective industrial strategy that addresses those changes in product design in order to remain competitive. An emerging strategy that might enable industries to cope with the rapidly changing product specifications is based on reconfiguring the manufacturing technologies. A manufacturing strategy that is based on reconfiguration of the workstations may help accommodate those changes at the lowest possible costs by combining certain levels of machine tool flexibility and customised automation. For the last few years, the literature has been enriched with works and publications concerned about the concept of machine tool reconfiguration. Most of these works agreed that a machine tool is considered reconfigurable if it satisfies a number of principles and characteristics. This paper discusses the development of a basic design for a machine tool based on those reconfigurability principles. The design attempts to produce a machine tool having a limited flexibility that is just enough to accommodate all possible modifications and changes, within customised level of automation in the designs of a product family of some automotive products. This work is a part of a project that is aiming on enhancing reconfigurable manufacturing in South Africa.

Abstract: The effects of dynamic forces and elastic contacts in a pair of intermeshing rotors with the gas-induced cyclic loads based on the multibody dynamics simulation have not investigated yet. The comparison of numerical spectra of time and frequency domains of acceleration with the experimental noise spectrum of an oil-injected twin-screw compressor has not also considered. Therefore, this study proposes a new strategy, which combines the fluctuating torques and forces induced by cyclic gas pressure on the screw rotors to numerically predict vibration response in an oil-injected twin-screw compressor.

Abstract: Based on the multi-body dynamics theory, paper builds the virtue prototype of the RV reducer with Adams software. By apply the cycloid gear equation with modification to create the backlash between cycloid gear and the pin gear. Build the backlash model between eccentric shaft and bearing with definition of constraint and function method. By using the MNF file to consider the deformation of the cycloid, pin gear and planet carrier. The dynamic flexible-rigid model of the coupled RV reducer was established. Then output curves of rotation rate, acceleration, force and angle inaccuracy were conducted. Then change the value of the backlash and to study its effect on the transmission error.The simulation results of the RV reducer provides the foundation for the further study of the precision analysis.

Abstract: Established two-dimensional axisymmetric staggered tooth shape labyrinth seal grid model by GAMBIT software, simulated oil-air two-phase mixture flow field within labyrinth seal by fluent software, confirmed the best grid size of numerical calculation, studied the seal mechanism and influence of gap width variation on the leakage. The results show that when fluid flows through the narrow clearance, its velocity increases and pressure decreases. The optimized clearance width within 0.5mm to 1.0mm is preferable.

Abstract: EMU gearbox is a key component of high-speed train, the reliability of the gearbox will directly affect the operational safety of EMU. The box of EMU gearbox is with light alloy materials, bearing structure, so the box is subjected to greater loads and shock and vibration. Designers most take into account the static strength and stiffness of the box, ignore the fatigue failure. Fatigue failure is the leading cause of mechanical structural failure, while the peak load cycle fatigue failure is often far less than estimated in accordance with the static fracture analysis "safe" load, so the EMU gearbox box’s fatigue analysis is needed. Combining high-speed EMU gearbox actual operating conditions, using finite element method to do fatigue analysis of the gearbox box while the analysis result is evaluated and amended by the Smith schematic analysis method.

Abstract: The phenomenon of lubricant cavitation in hydrodynamic bearings and its effect on the stability has been rigorously studied and reported in the literatures. In certain cases, cavitation has significant effect on the dynamic and stability characteristics of the rotor-bearing system. With a proper control of the cavitation condition and groove location, stability can be achieved over a wide range of operating speed, in the case of elliptical journal bearings. On the other hand, the stability is not affected by the presence of vapor cavitation, in the case of multi-lobe journal bearings with the oil supplied at atmospheric pressure. For the unstable, submerged, circular bearings, vapor cavitation phenomena results in a distinctive vibration response observable on the vibration plots. The stability of the elliptical journal bearings under the influence of vapor cavitation erosion was analyzed. It is found that vapor cavitation erosion on elliptical bearings results in instability of the whirling shaft. Collapse of the vapor cavitation bubbles causes erosion wear that falls within the pressure zone of the elliptical bearing, thus causing the instability.

Abstract: A thin corrugated metal gasket had been developed for low pressure work condition. In this study, thin corrugated metal prototype gasket was tested by using water pressure test. A Kyowa T-150N was used as water pressure tester. The experiment was conducted after ensuring that there was no leakage in each joint part. The leak test can only indicate two conditions of leakage which are leak or no leak. Pressure applied in the water pressure test was 200 psi, with 5 minutes of lapse time. The leakage was determined by the presence of liquid from the flange and the change in pressure gauge. Based on leak test results, it can be denoted that thin corrugated metal gasket can be used for 200 psi working pressure and 2.2 – 3.3 kN tightening load.

Abstract: A new design of CAM shaft has been investigated for Campro engine 3.0L V4 engine. The new design adds a modification to Cam profile peak point in the Camshaft to be controllable at different speeds through a hydraulic system. The new design was simulated in CFD for tolerating stresses. The new design promotes Cams to give the exact heights at different engine speed depending on the optimize value valve opening time. At the same time this paper discusses the prediction of power performance of internal combustion engines with the new design. The expected result will significantly improve the engine speed-torque curve, reduce emission gases, and reduce fuel consumption. The new design model predictions need to be tested experimentally for further improvement in the hydraulic system before the commercial use.

Abstract: In the present paper, we have described in-depth numerical study of the basic fluid mechanics problem of yield stress fluid flow with regularization model of Berovier and Engelman in a cylindrical vessel not chicaned equipped with an anchor stirrer by using computational fluid dynamics (CFD) based on the finite volumes method discretization of Navier - Stokes equations formulated in variables (U.V.P). We study the effect of inertia and the yield stress influence by the variation of Hedström number on the flow; we have analyzed also the influence of rheological parameters on the hydrodynamic flow behavior, such as the velocity components and the power consumption.