Applied Mechanics and Materials Vols. 325-326

Abstract: The paper proposes a comparison between two simulation methods of disc brake thermal regime which cause thermal stress. Those methods are the finite element analyses and the thermal image processing using grey level (or the luminosity variation) of disc brake emissivity. The authors consider that the variation of thermal image luminosity, images taken of a disc brake during intensive braking, is similar to one of the finite element analyses modeling the same conditions as the one of the experiment.

Abstract: Despite its intricacy the numerical method applied within the TRANSIT code proved successful in describing discontinuous, non-isentropic flows in rocket engines and solar-gravitational towers for green energy. A number of 0-D approaches are known to render some results in demonstrating the feasibility of the solar tower concept, or in unsteady simulation of transient phases in rocket engines. Computational efficiency is demonstrated by CFD simulation of the starting transients in ADDA solid rocket engines and in the SEATTLER solar mirror tower. The code is exclusively directed to unsteady flow simulations in slender channels. The wave front model scheme covers the dual behavior of fully non-isentropic flow with mass addition and mixing in the thrust chamber or blunt heat addition in a heater and fully isentropic through the exhaust nozzle or gravity draught in a tall tower. Along the tower of the solar-gravity draught power plants small perturbation discontinuous flows are covered. Code robustness is demonstrated during runs on the PC.

Abstract: In this paper, using light-gas propulsion technology, a one-dimensional mathematical model is established and simulated numerically for working process of light-gas launching facility with a piston-compressor type. A 30mm/120mm light-gas launcher is taken for the primary computing model, and lots of data, such as the pressure on pump, the piston velocity, the diaphragm failure pressure, etc. are obtained by computing the model in given geometry parameters and loading conditions. According to the numerical results, it is concluded that the developed mathematical model can provide theoretical references for structure dimension design and loading parameter configuration of light-gas launcher.

Abstract: The transmission of longitudinal vibration (generated by the vibrating platform Brüel & Kjær 4827) in the whole body of ten subjects was investigated. Altogether 200 individual tests were made. Vibration was measured with 356A16 PCB Piezotronics triaxial accelerometers fixed to the toes, ankles, lumbar, cervical, fingers, elbow and shoulder. Vibrations were analyzed with a multiple acquisition vibrations system NetdB. Data were processed using dBFA Suite. Vibration time was 1min and frequency range was between 10-40Hz, because the low frequencies are the resonance frequencies for the human body. Body vibration transmissibility was determined by the ratio of root mean square acceleration signal from accelerometer by the root mean square of acceleration signal from the vibrating platform. It was found that the accelerations at the lumbar level are more attenuated than the accelerations at the ankle level.

Abstract: In the ZB General-purpose Emergency Maintenance Vehicle usability testing, in order to find out the proper selection of test user types, and the best combination of user classification, the author classified the usability testing results by cause, and analyzed the data statistically. Then this paper draws a series of conclusions, and finally draws the theoretically optimal combination of user classification. No experience can be used for reference or comparison in the choice of test samples, so the results can be used as reference and data accumulation for further research.

Abstract: The present work proposes a full campaign of simulation of a Darrieus-type Vertical-Axis Water Turbine (VAWaterT) operating in an open flow-field. After describing the computational model and the relative validation procedure, a complete campaign of simulations based on full RANS unsteady calculations is presented for a three-bladed rotor architecture, characterized by a NACA 0025 blade profile. Flow field characteristics are investigated for several values of tip speed ratio and for a constant unperturbed free-stream water velocity of 2 m/s. Finally, the torque coefficient generated from the three blades is determined for each simulated angular velocity, allowing the calculation of the rotor power-curve. Keywords: Vertical-Axis Water Turbine, hydrokinetic technology, CFD, NACA 0025.

Abstract: This paper introduces the topology optimization theory and mathematical model of the variable density method, to use HyerMesh Optistruct module, designs the structure of the transmission shift fork by topological optimization. First establishes the original three-dimensional model of the fork according to the design requirement, then in the HyerMesh establishes the finite element model of the fork, and sets the fork load constraints and the manufacturing process constraints, finally gets a reasonable distribution of materials, uniform force and can be used for manufacturing the ideal topology configuration, and then by the Ossmooth tool obtains directly optimized three-dimensional model. The topological optimization technique, can effectively guides the design personnel of product structure modification and new product structure design, makes product design structure high reliability, economical.

Abstract: The aeroelastic behavior of high aspect ratio wings in an incompressible flow is investigated. The nonlinear nonplanar bending-bending-twisting motions of beam theory is used for the structural equations assuming large deformations with small strains, small Poisson effects, inextensional beam theory, and linear elastic material characteristics by neglecting warping and shear deformation. An Unsteady nonlinear aerodynamic static stall model based on the Wagner function is introduced and then is used for determination of aerodynamic loading of the wing. In this aerodynamic model, the static lift curve vs. angle of attack is approximated by a piece-wise curve and for each linear part of this curve a corrected Wagner theory is used. Combining these two types of formulation yields fully nonlinear integro-differentials aeroelastic equations of motion. The governing equations will be solved to predict the nonlinear aeroelastic response of a wing in the stall and post stall regions using Galerkin's method and a numerical method without the need of adding any aerodynamic state-space variables and their corresponding equations. The obtained equations are solved for some test cases and the obtained results are compared with the results given in the literature. Also a study is done to show effects of nonlinear aerodynamic static stall model on the limit cycle oscillations.

Abstract: Electrohydrodynamic (EHD) has been applied in many areas, such as EHD atomization, EHD enhanced heat transfer, EHD pump, electrospray nanotechnology, etc. EHD atomization is a promising materials deposition technique as it allows uniform and regular deposition, and offers a range of other advantages, such as low cost compared with other current techniques, easy set-up, high deposition rate, and ambient temperature. Simulation is carried out using ANSYS FLUENT system. The approach in this work was to simultaneously solve the coupled (EHD) and electrostatic equations. The fields of velocities and pressure, as well as electric characteristics of EHD flows, are calculated. The model does not include a droplet break-up model.

Abstract: The paper presents results of analysis of the dynamic behavior of rotating mechanisms and couplings of the main structure of a kinematic chain sharpening machine precision Cugir normal UAS 200. The ultimate goal is to establish diagnostic and maintenance program the car UAS 200. Diagnosis by measurement of vibration and noise, allow a company to monitor faults and machines and equipment, through a system of preventive maintenance, predictive. Diagnosis automatic machinery and equipment is made in order to ensure a higher reliability of these and how to obtain a more extended life cycle without the occurrence of defects. The application of preventive and predictive maintenance management supports enterprise, because it proves effective, the information you provide in making decisions.