Advanced Materials Research Vols. 199-200

Abstract: Groove parameters in gas film seal with grooved interface make an obvious impact on the performance of seal system. There are many parameters to describe the geometric features of the groove. In general, a big limitation exists in one-dimensional optimization of groove geometry. Based on particle swarm intelligence algorithm, this article proposed and carried out multi-dimensional optimization of groove geometry in gas film seal, regarded the groove geometry parameters as components of the particle, completed numerical solution of the objective function for the seal performance, and obtained better groove geometry parameters. The example showed that the effect that every geometry dimension plays on the steady-state characteristics of cylindrical gas film seal is not independent, and the multi-dimensional optimization method effectively improves the results of the objective function value. The proposed method can be used for the dimensional optimization design of groove geometry in both cylinder and face gas film seal.

Abstract: By studying a typical rectangle PCB, the design parameters affecting natural frequency of PCB are found in the paper. By theoretical deduction and finite element analysis, the sensitivity of the natural frequency of PCB with respect to the design parameters is analyzed, the influence of the design parameters on nature frequency is obtained, and some conclusions for structural optimization of PCB are drawn.

Abstract: This paper proposes a novel parallel mechanism named 3/3-RRRS, and gives a research of direct and inverse solutions to positions of this mechanism. The equations of direct and inverse solutions are proposed by using vector method , and the analytical solutions of the inverse solution are given .There are many factors which influence the workspace, The article analyzes the specific factors that influence the workspace by using the software ADAMS, the workspace will function as a target for agencies to optimize the parameters.

Abstract: The rigidity of the principal axis of a CNC vertical boring-milling machine was analyzed, and the belt tension and end deformation were also calculated. A project was proposed to improve the structure of the principal axis for finish machining. After the discharge belt pulley was applied on the principal axis, the force transmission and the rigidity of principal axle system were improved considerably. The design and process means were proposed for the three added parts of the improved structure. The improved structure is simplified, secure and low-cost. The machining precision was increased, and the fixing was also become convenient.

Abstract: It is well-known that in modern through arch bridges the suspenders are important components since they connect the bridge deck and the arch ribs. When the suspender break happens, the other components of the through arch bridge will be impacted successively. Sometimes, the collapse of bridge deck may be induced by the possible suspender break. In this paper, the impact effect on the remaining components of the through arch bridge due to the suspender break is studied and obtained by appropriate simulation and time-history analysis using the comprehensive commercial software ANSYS, which is based on a real through arch bridge. The study in this paper will be helpful to carry out the reasonable design of the through arch bridge.

Abstract: Along with the shearer's developed in the mining process, especially the rock tunnel boring roadway driving has become a major factor restricting the efficiency of coal, development of a suitable rock tunnel boring machine is very important, this paper use of rock excavation and after the release of stress concentration broken rock rolling theory, inverse problem approach using indirect parameters of the cutting head of, on the cutting head of the energy efficiency and the lowest maximum, minimum tool wear characteristics of multi-objective, were normalized, transformed into single objective problem, a genetic algorithm. The results showed that: the inversion of multi-objective design method is feasible to design a new type of driving hard rock cutting efficiency of institutions to provide 9%, compared with 20% reduction in energy consumption, lower tool wear 55.2% for the rock tunnel excavation needs.

Abstract: This work is devoted to the development of a new type Rollover Protective Structure which absorbs the impact energy using shear energy absorber during a roll-over accident of engineering vehicles. A method is developed for investigate the energy absorption of the shearing processes using the finite element method coupled with the Cockroft-Latham fracture criterion, remeshing and element kill method accounting for nonlinear isotropic and kinematic hardening under the large plastic deformation. Comparing the simulation results with laboratory test results, the proposed method is valid. Using the finite element analysis method, the effects of shearing clearance, cross-section parameters and the shape of the shear edge on shear force and energy absorption of the process are investigated.

Abstract: Guide ways of ultra-precision machine tools always have sufficient stiffness and guiding precision. But guide way rails deformation caused by oil film pressure and slider offset lead to oil film clearance change which affects static stiffness and guiding precision. An inside-slider hydrostatic guide way is designed, and its static characteristics are analyzed. As a result, the effect of slider offset on stiffness and guiding precisions is obtained. A FE model of guide way is established. An elastomer of virtual material properties is used to simulate oil film, so that the relationship between oil film clearance and pressure can be represented in a certain range. Static stiffness and guiding precision are obtained considering deformation of rails.

Abstract: The paper explores, theoretically, vibration reduction analysis of latticed shell equipped with Buckling-Restrained Braces with contact rings. Given the features of the long-span spatial structures, the paper put forward that to replace partial members of latticed shell by BRBs with contact rings results in the changes of stiffness and damp of the structure, which can improve the anti-seismic capability of the structure. Making K8 type lattice shell as the object of study, the paper carries out the seismic analysis under the action of the three-dimensional earthquake ground motion with step-by-step method in the time domain.

Abstract: In order to decrease weight, reduce inertia and dynamic load of a three helical tooth star-wheel and improve its dynamic characteristic, an optimal design model targeting smallest weight of a three helical tooth star-wheel is established in the paper, the geometric parameters of the star-wheel are optimized with the combining methods of ant colony algorithm and finite element method. The weight of the star-wheel reduces by 16.5 %，the load coefficient increases by 20 % and the loading productivity raises by 19 % after optimized, these conclusions lay a foundation for improving the design, determining reasonably the size of the star-wheel loading mechanism, making better the performance of the three helical tooth star-wheel loading mechanism.