Applied Mechanics and Materials Vol. 376

Abstract: The mathematical model for optimal design of a speed reducer is a generalized geometric programming problem that is non-convex and not easy be globally solved. This paper applies a deterministic approach including convexification strategies and piecewise linearization techniques to globally solve speed reducer design problems. A practical speed reducer design problem is solved to demonstrate that this study obtains a better solution than other methods.

Abstract: Robot Gun structure is an efficient way in which multiple welds can be done simultaneously. However mounting several weld guns on a single structure induces a variety of dynamic loads, especially during movement of the robot arm as it maneuvers to reach the weld locations.The primary idea employed in this paper, is to model those dynamic loads as equivalent G force loads in FEA. This approach will be on the conservative side, and will be saving time and subsequently cost efficient. The approach of the paper is towards creating a standard operating procedure (SOP) when it comes to analysis of such structures, with emphasis on deploying various technical aspects of FEA such as Non Linear Geometry, Multipoint Constraint Contact Algorithm, Multizone meshing .

Abstract: The type of Solar panels in photovoltaic power generating system is generally photovoltaic array. On the basis of the photovoltaic array mathematical model for engineering , using the mathematical software MATLAB Simulink tool to build a photovoltaic array simulation model and utilizing monitoring data acquired by the detection system-Sunny Sensor Box-for Donghua University photovoltaic power generating system, the mathematical model of the PV array for engineering is optimized and the optimization includes linear and natural exponential optimization. Furthermore, higher accuracy of the optimized models is validated.

Abstract: Because crosswind affects drivers to control their vehicles safely, the research on flow characteristics in automotive crosswind has a great significance to improve the crosswind stability of the vehicle. By the steady state numerical simulation method, the aerodynamic characteristics of external flow field of Ahmed body in crosswind was investigated. The Ahmed body with 25° slant angle is built in UG NX. The external flow field of the Ahmed body in the wind direction of 0°, 15º, 30° angle is simulated in XFlow software. According to the map of the pressure and velocity distribution, the flow field both before and after, as well as left and right has significant change as the wind direction angle increased, and the trail turbulence intensity also changes. The changes of aerodynamic force and moment affect the driving stability of a motor vehicle.

Abstract: A novel procedure for calculating the dynamic response of elastic solid structures is presented. The ultimate aim of this study is to develop a consistent set of finite volume (FV) methods on unstructured meshes for the analysis of dynamic fluidstructure interaction (FSI). This paper describes a two-dimensional (2D) FV cell-vertex based method for dynamic solid mechanics. A novel matrix-free implicit scheme was developed using the Newmark method and dual time step algorithm and the model is validated with a 2D cantilever test case as well as a 2D plate one.

Abstract: This paper utilized the Improved Particle Swarm Optimization (IPSO) technique for adjusting the gains of PID and the bandwidth of zero-phase Butterworth Filter of an Iterative Learning Controller (ILC) for precision motion. Simulation results show that IPSO-ILC-PID controller without adaptive bandwidth filter tuning have the chance of producing high frequencies in the error signals when the filter bandwidth is fixed for every repetition. However the learnable and unlearnable error signals should be separated for bettering control process. Thus the adaptive bandwidth of a zero phase filter in ILC-PID controller with IPSO tuning is applied to one single motion axis of a CNC table machine. Simulation results show that the developed controller can cancel the errors efficiently as repetition goes. The frequency response of the error signals is analyzed by the empirical mode decomposition (EMD) and the Hilbert-Huang Transform (HHT) method. Errors are reduced and validated by ILC with adaptive bandwidth filtering design.

Abstract: It is on the foundation of theoretical research of fire smoke transfer and mechanical wind –supply to model the bench-scale long channel based on FDS large eddy simulation (LES) model. The result of simulation shows that when the mechanical wind-supply system and the smoke-exhausting system were working together. The air velocity of wind-supply system had an optimum volume. The higher and lower velocity would decrease the efficiency of smoke exhausting and possibility of evacuation.

Abstract: A comprehensive computer simulation has been developed to predict the performance of a twin-rotor piston engine (TRPE) by means of the zero-dimensional thermodynamic model. With the given model, the chamber mass, pressure and temperature are available during a complete engine cycle. The results are consistent with the TRPE’s working cycle trend. By the chamber pressure, the overall engine performance parameters can be calculated. The model can be used as an analytical tool for preliminary design and development of the TRPE.

Abstract: One of the important objectives of lunar exploration is to obtain the lunar soil samples. However, the sampling process is very different from that on the Earth due to special characteristics of the lunar soil and surface environment. In order to ensure that the lunar exploration and sampling are successful, large numbers of ground experiments and computer simulations must be taken. In this paper, the surface lunar soil excavation simulation is investigated by three-dimensional discrete element method (DEM). It is implemented based on the open source LIGGGHTS, which takes the lunar soil as spherical particles. The interaction between the excavation tool and lunar soil is demonstrated. The excavation force and torque have also been calculated in real time. Moreover, the comparison of the excavation in different environments between the Earth and Moon corresponding to their different gravity accelerations was done. This paper shows that three-dimensional discrete element method can be used for the surface lunar soil excavation simulation and can provide important reference results for actual operations.

Abstract: In this paper, a kind of advanced gear body form is proposed, which has the structure characteristics of no weight reducing wholethin spoke platesthick rim and large fillet. The optimization effect is confirmated by comparative analyzing the structure before and after optimization on strengthstiffnessweight and frequency adjustment performance of gear. The results show that the kind of optimization gear body is suitable for application in aviation, for which has the features of high strength, good stiffness and light weight and which is easy to adjust gear frequency.