Applied Mechanics and Materials Vols. 152-154

Abstract: Based on the performance of Vane hydraulic damp O-ring seal ,simulation about the O-ring seal was applied by nonlinear finite element analysis method. The factors influencing sealing performance are considered, such as initial compressibility, sealing materials. Applying the method, the seal structure was designed and optimized. At the same time, the sealing performance was improved, and the contract pressure was increased. The finite element analysis method can be effectively used to solve nonlinear material and sealing failure problem for the seal design, optimization and performance analysis, which provide a new approach and theoretical guidance to the rubber seal research. The seal material and compression ratio are both great influence on the sealing performance , which should be based on working conditions to select the appropriate sealing materials.

Abstract: Mechanism analysis and synthesis commonly used analytic method and graphical method, etc., but the homotopy method has high efficiency in nonlinear analysis of mechanism. This paper applies the homotopy continuation method PHCpack solver to solve mechanism position and orientation, and draws the mechanism configuration according to the results obtained, the relative error of numerical results to exact solutions shows that the homotopy continuation method PHCpack solver can provide sufficient accuracy of mechanism position and orientation analysis, and meet the engineering needs.

Abstract: The robotized aerial systems (RAS) are automated systems whose main characteristic is that can be remotely piloted. This property is especially interesting in those reverse engineering works in which the accuracy of the model is not reachable by common aerial or satellite systems, there is a difficult accessibility to the infrastructure due to location and geometry aspects, and the economic resources are limited. This paper aims to show the research, development and application of a RAS that will generate geo-referenced spatial information at low cost, high quality, and high availability.

Abstract: In this paper, a new Hall sensor’s layout for wheel speed measurement is introduced and the corresponding signal processing system is designed, based on the principle of orthogonal signal subdivision. The system implements the function module of filter, subdivision, gated counter and output interface with FPGA and the simulation results prove its wide measurement range, high measurement precision and stabilization. Compare to the traditional wheel speed measurement, this system has prominent measuring speed under a low speed condition.

Abstract: In this paper, a method for positioning control based on zero phase error tracking controller (ZPETC), optimal control method for plant with dead-time is proposed. A discrete transformed unstable plant is composed of unstable zeros and poles. In the proposed method, we subject stabilization of a plant by optimal control method, compose inverse model of a system with unstable zeros by ZPETC and control a plant with dead-time by predicted-state feedback technique and modified smith predictor composed of a predictor and an observer. In addition, optimal control method achieves good robustness for modeling errors by adjusting the weight of the LQR-scheme. The simulation studies and the experimental result, it is shown that the proposed method is effective for these plants and DC motor.

Abstract: The one cycle AC short-circuit transfer welding method is a new type of low-energy welding method, which could flexible control the welding process on the energy distribution of basement material and wires by changing the time of the polarity of the EN. Tests showed that the 1.0mm thin sheet welding, and welding process stability, beautiful weld bead, and small spatter could be achieved successfully by this one cycle AC short-circuit transfer welding method.

Abstract: This work presents estimates of time histories of pressure coefficients at several taps on the roof of a 1/200 model of a 200 x 100 x 20 ft low-rise building with a 1/24 slope gable roof building. The estimates were obtained by large eddy simulation (LES). The first and second moments as well as peaks for the time histories are compared with those obtained in boundary layer wind-tunnel measurements at the University of Western Ontario. It is noted that the computation times required to obtain records of length comparable to wind tunnel records are at present prohibitively large.

Abstract: Current screen enclosure building codes are based on the experimental wind tunnel studies and, to a smaller extent, full scale open terrain studies conducted at Virginia Tech and Clemson University. There are still widespread wind damages to pool and patio enclosures during wind storms. Experimental studies based on simulation comparison of wind load on a low-rise structure in general, continue to show large discrepancies based on NIST data. Accounting for the many parameters which are essential to achieve an accurate simulation through experimentation is daunting. Reynolds number, spectrum density, large and small turbulent scales, viscous shear layer, and flow intermittency are a few of those parameters. Numerical simulation (CFD) provides an attractive parametric study and offers a richer, higher resolution data output. In this work, flow around a screen enclosure embedded within the atmospheric boundary layer is investigated numerically. The flow is governed by Navier-Stokes equations with a momentum sink that follows Darcy equations and incorporating the eddy viscosity k-ε turbulent closure model. The pressure drop that is computed provides the basis of evaluating wind load on the screen structure. The evaluated load is compared to the Florida Building Code ASCE7 provision and is used to conduct structural analysis on common baseline enclosures to assess their reliability. The structure is analyzed using Bernoulli-Euler beam elements having cross sections according to the code and subjected to forces and moments with 6 (3displacements and 3 rotational) degrees of freedom.

Abstract: In this paper, a delay distribution based stability analysis and synthesis approach for networked control systems (NCSs) of network communication delays is proposed. A bounded delay control model is established to describe the NCSs. Then, delay distribution-dependent NCSs stability criteria are derived in the form of linear matrix inequalities (LMIs). Also, the problem of H_Κ performance analysis for NCSs with time varying delays components is also studied. The results are illustrated by numerical examples.

Abstract: The basic theory of fast multipole virtual boundary element method (VBEM) is discussed through expanding the fundamental solution, and the algorithm can make the complexities of operation and memory about solution of the equations to be of linear proportion to the freedoms of the problem. Numerical examples are presented to demonstrate the feasibility, accuracy and efficiency of the method. At the same time, the relationships between the order for expansion and the storage capacity, computing time, precision are analyzed, and the influence of boundary points in the leaf to the calculation efficiency is discussed. The corresponding reference value is put forward for the convenience of engineering application.