Applied Mechanics and Materials Vols. 152-154

Abstract: Missile-borne measuring device needs to be installed in the missile body. When projectiles running in trajectory, they are in a high temperature, high pressure, high g value of the overload conditions, therefore whether reasonable of the mechanical shell design or not has important implications for the entire test system anti-overloading performance. According to the test environment characteristics and compatibility with the principles of the PCB, Mechanical protection shell takes cylindrical structure. According to strength theory, calculates the design parameters of the cylinder and make structure design、strength analysis、limited simulation calculation. Simulation results show that, the strength of missile-borne measuring device designed meet the requirements of gun in high chamber pressure when fired.

Abstract: For the numerical prediction on motion responses and performances of trimaran in regular wave, this paper solves two special problems for trimaran, which include abnormal numerical oscillation for the high frequency motion and obvious stem rising and stern falling due to large variation of navigation posture. On one hand, the authors introduced an artificial viscous force on the free surface between main and side sections to restrain the abnormal numerical oscillation. On the other hand, in order to consider the influence of navigation posture, the authors revised wet surface in motion prediction. Finally, some test cases were calculated and simulated to validate the present method. Compared with experimental data, the results of trimaran model with transom stern show that artificial viscous force has obvious effect on the heave response and small influence on the pitch motion. Furthermore, navigation posture plays a very important role on pitch and little action on heave movement. Especially, for trimaran model with low speed, viscous force and navigation posture basically have no effect on the results of motion prediction.

Abstract: To enhance the accuracy of stabilization, this paper presents a design of two-axis horizontal stabilization platform system, which is based on the combination of gyroscope and inclinometer sensors. The self-correction control method is put forward to solve the system error caused by gyroscope zero drift in traditional gyro stabilized platform, which works in the way of revising the gyroscope zero coefficient, according to the real-time attitude information feed backed by inclinometer sensors fixed in objective platform.

Abstract: This research aims to investigate the types of thin film coating for the evaluation of coefficient of friction using ring compression test. Ring compression test was used to evaluate the coefficient of friction of contact between die coating surface and workpiece material, brass grade C3771. Specimen was machined by CNC to the standard size with ratio of the outer diameter [25.4mm] to inner diameter [12.7mm] and thickness [8.5 mm] is 6:3:2. The dies were made from tool steel grade JIS SKD11 hardened to 60±2HRC then polished die surface at Ra= 0:07 to0:09 microns. Tool surface conditions selected for this research were non-coated, PVD coated DLC, AlCrN, TiCN and TiAlN.The Experiments were carried without lubricant. Experiments were reduced height of the specimen at 50 percent. It was found that Non coated condition had shown lower coefficient of friction than DLC, AlCrN, TiAlN and TiCN due to influence of surface roughness. Furthermore, thin film coated die had shown durable and high resistance scratch of die surface more than non coated die.

Abstract: Image presents the basic physical features of an object. Geometry, on the other hand, provides us a powerful way to quantify the information reflected by images or their shapes. Traditional geometry however finds limitation in describing the differences between highly irregular objects，which requires us to find new approaches to measure an object and quantify its difference from another. In this paper, we define some scalars in two dimensions to meet this demand. These approaches, grounded on circularity, convexity and cavity, describe the geometry of shapes in statistic sense, and they can also be applied to qualify the differences of shapes.

Abstract: Abstract. Truck cab mounting bracket is one of very important connecting elements. With the aid of Hyper Works software topology optimization and shape optimization techniques, the article elaborates that after realizing the cab mount bracket, the suspension support reduces weight leading to optimization design of the process. Meanwhile, it unifies the actual stress situation which has made the finite element validation comparison analysis comparing traditional optimization with the topology optimization design. The final results indicate that after weight loss optimized stent significantly reduce stress and the stress distribution is evener. Also, the relatively primary structure quality has obvious reduction which could satisfy the product the operational performance and the foundry technique performance requirement.

Abstract: The research of the large branches grinder is based on the requirements of China's biomass power generation to branches timber local processing. According to China's specific national conditions, the design of the existing branches grinder has been improved. By increasing the wooden grasping manipulator improves feeding efficiency and automation. The transmission mode of branches grinder has been changed. Switching to big diesel engine to drive it overcame the existing branches grinder’s dependence on electricity. Increasing the trailer chassis make it moved freely, which made the branches grinder crush the branches local.

Abstract: The flow field of car exhaust pipe using ethanol gasoline has been researched, the continuity equation of a mixed two-phase model have been established by means of the mathematical model of two-phase flow field, and the simulation for the velocity distribution of droplets radial slipping in exhaust gas have been achieved. By using the divided grid and setting these four boundary conditions as conditions of the entrance, flow conditions at the end of the export, overflow conditions of the export, solid-wall boundary conditions, the iterative steps of calculation process and the relationship among the residuals of various parameters have been obtained. State of exhaust flow have been calculated using algebraic slip model (ASM) ,obtaining the distribution rule of the internal flow field in exhaust pipe for the disconnection of steam-water ,and the characteristics relationship of separation for two-phase flow field of steam-water. The characteristic relationship among flow, split ratio and separation efficiency have been numerically simulated. The existence of the best range of split ratio for a particular exhaust pipe has been confirmed.

Abstract: In the present work the temperature fluctuations in a mixing tee were simulated on FLUENT platform using the large-eddy simulation (LES) turbulent flow model with three kinds of sub-grid scale (SGS) models such as Smagorinsky-Lilly (SL) model, Wall-adapted Local Eddy-viscosity (WALE) model, and Kinetic-energy transport (KET) model. The normalized mean and root mean square temperatures were predicted and analyzed with consideration of buoyancy. The numerical results showed that buoyancy greatly influences the mixing flow and the thermal striping phenomena were quite obvious. These three SGS models have somewhat similar accuracies for prediction of the temperature fluctuation and thermal stripping in a tee of mixing hot and cold fluids.

Abstract: Velocity fluctuations in a mixing T-junction were simulated in FLUENT using large-eddy simulation (LES) turbulent flow model with sub-grid scale (SGS) Smagorinsky–Lilly (SL) model. The normalized mean and root mean square velocities are used to describe the time-averaged velocities and the velocities fluctuation intensities. Comparison of the numerical results with experimental data shows that the LES model is valid for predicting the flow of mixing in a T-junction junction. The numerical results reveal the velocity distributions and fluctuations are basically symmetrical and the fluctuation at the upstream of the downstream of the main duct is stronger than that at the downstream of the downstream of the main duct.