Applied Mechanics and Materials Vols. 138-139

Abstract: In order to enhance the processing efficency of complex cavity surfaces by using iso-scallop height method, a subdivision method based on the improved image direction information measure is proposed in this paper. According to the relationship between maximum cutting bandwidth and cutting direction in the theory of iso-scallop height, the method constructed an optimal cutting direction angle field image in the u-v system of parameters firstly; and then an improved direction information measure definition which combined with the characters of the angle field image was proposed; Finally, the subdivision boundary for mold cavity surface was identified by using the direction measure as the edge characteristic index. Experimental results indicate that the proposed method demonstrates good performance in distinguishing and extracting boundary points of surface subdivision.

Abstract: Owing to fluid characteristics of hydraulic structure seismic response, analysis method of this problem considering fluid-solid interaction is pointed out. And seismic response of vertical plate in the water was taken as an example to show how to solve this fluid-solid interaction system and analysis the features of it. In the analysis, effects of wave frequency and water depth were considered. The results indicate that incompressible fluid model based on Arbitrary Largrange Elurian description is enough to simulate motion of fluid domain and insure computing convergence in the analysis. It also shows that peak value of structure dynamic response is larger as the consideration of fluid-solid interaction. Water depth has great effect on fluid-solid interaction and has clear nonlinear feature.

Abstract: The movement and deformation of rock stratum occur when the excavation is carries out during the underground mining process. Rock is a continuous-discontinuous material so the continuum mechanics method may not handle the rock problem well. The discontinuous deformation analysis (DDA) method which discretizes the rock mass to block system can describe the large displacement and deformation of rock blocks, especially the rock stratum collapse. The DDA was employed in this paper to analysis a mining excavation process. The displacement field and stress field of rock stratum was computed. The result shows that the DDA can handle the mining excavation and the rock stratum movement and deformation problem well.

Abstract: Because traditional passive suspension system can’t meet with the requirement of ride in all kinds of roads, elastomer damper was designed and installed on the limiting stopper of the suspension system. Two degrees of freedom model of suspension system with elastomer damper was built and its dynamics simulation was done by use of the software Recurdyn. The simulation results show that the application of elastomer damper can improve the ride of tracked vehicle; the striking force apparently decreases when suspension system has broken down and the probability of suspension system breakdown has been obviously reduced, all of which illustrates the elastomer damper has an obvious dampening effect on the tracked vehicle. Keywords: elastomer damper, tracked vehicle, suspension system, dynamics simulation

Abstract: Geometrical parameters of composite laminated plates in engineering structure tend to have stochastic properties. It would be very significant on how to study the random parameter laminated plates, and the parameters optimization analysis of mechanical properties, influencing on the correctly-estimated reliability of structure design. Based on the classical theory advocated by Kirchhoff, which indicates that with spline finite element method, cubic b-spline function constitutes the spline to antisymmetry multi-layer angle laid against laminated plates on the three independent displacement and the interpolation which can deduce composite laminated plate stiffness matrix, quality array type, the damping array type, and the dynamic equations of laminates is derived by Lagrange equation and a characteristic equation established by Rayleigh-Ritz theory. On the basis of Kirchhoff hypothesis, the laminated plates mechanics characteristic analysis with spline collocation method can lead to the resolution of the structural displacement, and dynamic response of velocity and acceleration, further to comparing with Newmark method. As to laminated plates of nonlinear bending, its mechanical properties will be under siscussion. The optimum design of of laying layer of composite laminated plate horn based on the spline finite element analysis will be conducted. The numerical column verifies the effectiveness of the proposed algorithm.

Abstract: By combining modular design with top-down design, a composite design method is proposed in this paper, namely top-down modularization. This design synthesis is achieved based on extensible skeleton model (XSM). XSM is developed oriented to design reuse by integrating traditional skeleton model with useful knowledge, resources, processes, et al. According to the characteristic of multilevel structure of products, a hierarchy framework of XSM is built. In addition, the top-down modular design process based on XSM is established. A design case of a typical two-axis servo mechanism is studied to illustrate as well as to demonstrate the validity of the method.

Abstract: Deeply studying vibration and seismic response characteristics of Beijing Yin-tai Center provided information reflecting its anti-seismic performance based on which seismic response observation array was to be deployed. Time-historic analytical methods on the basis of modal analysis were applied to carry out structural seismic response. Two load cases were mentioned including the responses under minor earthquakes and moderate earthquakes. El-Centro wave, Northridge wave and synthetized time-histories were adopted with contrast analysis under Beijing Hotel time-history recorded in Tangshan Earthquake. Peak inter-story shift ratios and peak accelerations are obtained and analyzed. The inter-story shift ratio determines elastic state of structure under minor earthquakes and elastic-plastic state under moderate earthquakes. Predominant inter-story displacement and acceleration response provides the floors with more remarkable seismic response, which are vulnerable floors for monitoring in earthquakes.

Abstract: Based on the characteristics of blowing control, a new technique was put forward to weaken slat cove separation and reduce noise. The effect of the slat blowing control on lift performance, the flow field and noise with a three-element high lift aerofoil was investigated by using the computational fluid dynamics (CFD) code of Fluent and the Reynolds-averaged Navier-Stokes equations. The blowing apertures were set on the lower surface of the slat. By using the slat blowing technique, the slat cove separation can be controlled efficiently and the lift coefficient increased. The aerodynamic performance varies with different blowing flow rates and angles of attack.

Abstract: During airplane’s take-off, higher lift force should be provided by wing used high lift devices, and the drag should be lower. The design basis of high lift devices with good aerodynamic characteristic is the design of the multi-element airfoil. When a multi-element airfoil is used Gurney flap, lift coefficient can be improved while drag coefficient is also increased, but the lift-to-drag ratio is reduced. In this paper, the numerical simulation method is used to study the aerodynamic characteristic of the multi-element airfoil used Gurney flap with slat in the configuration of take-off. Lift coefficient and drag coefficient of the multi-element airfoil with Gurney flap can be reduced by slat while lift-to-drag ratio of airfoil is increased. Through the comparisons of the multi-element airfoils with Gurney flap with different types of slats, the optimized multi-element airfoil with higher lift coefficient and lower drag coefficient is obtained ultimately.

Abstract: Failure analysis is important for the safety design of the folding umbrella. The failure point is found on certain location after large amount of samples statistics. In order to verify this problem, apply SolidWorks to finish the umbrella framework model, import the model into ADAMS. Then the experiment is conducted, the push force on the umbrella piston which adds to the mechanical model is measured through Gravity Sensor. The dynamic simulation of umbrella framework is discussed by using ADAMS. The simulation result shows the failure point we found is accurate. Since the destructive force on umbrella is diversity and uncertainty, further studies are necessary for this subject.