Applied Mechanics and Materials Vol. 598

Abstract: In this paper, the vehicle driving characteristics are investigated under different Force level of gust wind based on the CFD theory. The distributed pressure acted on the vehicle side surface is equivalent to the six-component force on vehicle gravity center. The six-component force are explored and compared in different Force level of gust wind. The results show that the lateral force Fy and yaw moment Mz vary with v shape and shape under gust wind, respectively. The slopes of the result curves increase with greater Force level of gust wind. Gust wind gives most influence on Fy and Mz while has little effect on other component force. The work will provide a methodology for vehicle stability research under gust wind.

Abstract: The mathematic model of rotor-bearing system coupled with floating raft isolation device is developed and its nonlinear dynamic characteristics are mainly discussed in this paper. First, on the basic assumption theory of short bearing, the nonlinear dynamic motions of the system with 4 DOF is deduced after considering the vertical and horizontal deformation and the nonlinear vibrating behaviors are analyzed such as the steady state response and its spectrum, orbit and its Poincaré map. The results show that the responses at a low speed appear single periodic motion, with increasing the speed it indicates the doubling and quasi periodic motion, etc.

Abstract: In this paper, SimpleC algorithm and Realizable turbulence model are applied to simulate the detailed flow field of oscillator, which is the key component of the vertical drainage jet flowmeter. Based on analyzing the pressure fluctuation of fluid in the feedback channels of the oscillator at different flowrates, the results indicate that there is an obviously linear relationship between velocity and oscillation frequency of static pressure in the vertical feedback channels within a certain range of flowrate. The achievements can be helpful to the optimization the design of vertical drainage jet flowmeter.

Abstract: To fault diagnosis of diesel engine, put forward a fault diagnosis of diesel engine based on EEMD difference energy spectrum of singular value and RBF. Nonstationary original acceleration vibration signal of kinds of diesel engine’s working condition is separated to several IMF and structure a Hankel matrix by the IMF for singular value decomposition, then de-noise and reconstruction one IMF on the basis of the theory of singular value difference spectrum, and use the reconstructed IMF’s energy which include fault information as the income of RBF. This method can judge the kinds of diesel engine’s working condition and fault types accurately in the experiment.

Abstract: This paper demonstrates how to establish the system level requirement set for an aviation piston engine, which is intended to be used for a MALE class UAV and for a Part 23 Normal category airplane. Here, it will be demonstrated, which requirements should be taken into account to construct the system level requirement set. This work is aimed to depict a methodology to create the system level requirement set.

Abstract: This study developed a new hybrid power system which consisted of two continuous variable transmissions (CVT). By matching between the engine, motor, generator, and dual CVT system, this integrated power system can take advantages of components. The hybrid vehicle can be driven by the internal combustion engine (ICE) or electric motor (M) alone, or by these two power sources together when vehicle is driven in hard acceleration or high load. The integrated hybrid system could provide better fuel economy. The energy management of this integrated system controls the power systems based on rule-based control strategy to achieve better fuel economy. When the vehicle driving power demand is low, the ICE which is operating in the low efficiency region. The ICE is shut down, and the vehicle is driven by motor only. When the vehicle driving power demand is high, ICE would operate in the high efficiency region. The vehicle could be driven by ICE. This strategy would operate ICE only in optimal efficiency region to improve the fuel economy. In this research, the vehicle simulation model was built in Matlab/Simulink environment. The model simulation was according with the vehicle dynamics test, and the analysis and discussion of the simulation results was present.

Abstract: Even though actual composition of engine exhaust gases varies across diverse types of engines, such as gasoline, diesel, gas turbine and natural gas engines, engine exhaust temperature is always a major factor with strong impact on emission levels and catalytic converting efficiency. For spark ignition engines, exhaust temperature depends on various engine parameters, such as engine speed, engine load, A/F ratio, intake air temperature, coolant temperature and spark timing, etc. Due to complexity, it is impossible to share a unique analytical model of engine exhaust temperature. Instead, it is mostly modeled as a complicated nonlinear system. The model complexity increases significantly however accuracy cannot be guaranteed. On the other hand, a simple linear model with accurate system identification could serve as a versatile alternative to represent the engine exhaust temperature, while engine parameters are subject to model identification to be adaptable across different types of engines. Combination of linear functions in terms of dominant engine parameters of engine speed and engine load is used for exhaust temperature modeling. To identify optimal parameters, Markov Chain Monte Carlo (MCMC) is applied. The discrete-time Markov chain is introduced where the stationary probability replaces posterior density in Monte Carlo integration for numerical integration. Compared with the high order nonlinear approaches, low computation cost is involved in the simplified model. Good agreement between the model prediction data and testing results is observed. The approach could be easily extended to other types of engines.

Abstract: A topological optimization on the spindle box of a heavy duty lathe was studied. The objective of the work was to seek optimum material distribution and lighter mass of the spindle box, while maintain its original stiffness, strength and natural frequencies. Firstly, static and modal analyses were carried out. Then, the topological optimization was conducted through constraints of spindle hole’s displacement and lower-order natural frequencies, with minimized material volume as objective. Finally, a spindle box with optimized structure was obtained.

Abstract: This article presents the effect of excitation waveforms on the rate of micromixing evaluated using biomimetic cilia-based microfluidic devices (soft cantilever-type, vibrating devices that are excited by the oscillations of the piezoactuator with different trajectories). The main contribution of this article is to experimentally evaluate the mixing excited by different waveforms and to report that (i) the mixing time is significantly decreased through employing the cilia when compared to the case without employing the cilia; (ii) the mixing time in case of employing the cilia is additionally decreased through the application of the symmetric triangular waveform with sharper turnarounds when compared to the case of the symmetric sinusoidal waveform (with smoother turnarounds); (iii) furthermore, the mixing time in case of employing the cilia is reduced further through applying asymmetric excitation waveforms with greater asymmetry when compared to the case of applying asymmetric excitation waveforms with less asymmetry.

Abstract: The performance of the magnetoplasmadynamic thruster is predicted using numerical simulation. The thruster mode is self-induced magnetic field with cylindrical electrodes. The dependence of the thrust level, specific impulse, and the mass flow rate in different total electric currents is investigated. The AUSM⁺ scheme is utilized to develop a numerical procedure and the accurate method is used to simulate the propellant injection rate. Besides the performance curves prediction, the results show the importance of the effect of inlet modeling on the thruster’s actual specific impulse.