Applied Mechanics and Materials Vols. 268-270

Abstract: Modal analysis is a modern method to study structure dynamic characteristics. In this paper, computational modal analysis with Finite Element Method is applied to simulate an aluminum plate with the dimension of 160mm*240mm*1.5mm under different boundary conditions (Including free boundary condition and fixed boundary condition). The results of structure natural frequencies and mode shapes of this plate show obvious difference between the two boundary conditions.

Abstract: This paper aims to research on the sealing capability of rubber seal by utlizing non-linear finite element analysis. After discussion on various types of strain energy functions of rubber like materials, material parameters of Mooney-Rivilin model are determined by curve fitting based on the stress strain curve from the uniaxial tensile experiment. Axis symmetric and isotropic finite element model is developed to analyze the stress field and contact pressue of O-ring seal and lip seal at different medium pressure. Von-mises stress distribution rule and contact stress distribution curve on contact surface are achieved. The results show that maximum Von Mises stress increase with the increases of oil pressure. The maximum contact stress appears on the middle contact zone and the maximum contact stress and contact width increases obviously with the increases of oil pressure. In the meanwhile, the maximum contact stress is greater than midum pressure which can prevent the leakage of midum and achieve the function of sealing. The research results will be a useful technique for predicting the properties of rubber seal and providing reference for engineering design.

Abstract: The impact processes of water and ethanol drops on a rotating horizontal aluminum disk were recorded and analyzed using a high-speed digital camera together with an image analysis program. The angular velocities of the disk were altered to study the effect of surface tension of drops on drop impact processes. The experimental results show that a lower surface tension will result in a higher tangential spread factor and a lower receding rate during the receding stage, for the drop impinging and depositing on a rotating disk. In addition, a lower surface tension of the drop tends to promote the occurrence of splash. The experimental results further verify a proposed correlation of splash-deposition boundary for drops impinging on a rotating disk. Both drops, though they have a quite different surface tension, experience four stages, with two new stages different from those of drops impinging on stationary surfaces. Their tangential spreading factors both increase obviously with the tangential velocity at the impact point, while their radial spreading factors vary a little.

Abstract: To improve the convergence for topology optimization of continuum structure, a new material interpolation model is proposed. This function curve parameterized by certain penalty is similar to solid isotropic microstructures with penalization (SIMP) curve. In static topology optimization problem, the new interpolation function maintains the advantage of robustness and efficiency similar to the SIMP model. In low density, the ratio of density to interpolation function is kept in limited value. Localized mode problem is overcome naturally based on the new interpolation scheme in dynamic topology optimization problem. Two-dimensional numerical examples are used to test the proposed model and method.The results show that the proposed model and method are feasible and robust in topological optimization design of continuum structure.

Abstract: Hamiltonian system used in dynamics is introduced to formulate the three-dimensional problems of the transversely isotropic magnetoelectroelastic solids. The Hamiltonian dual equations in magnetoelectroelastic solids are developed directly from the modified Hellinger-Reissner variational principle derived from generalized Hellinger-Ressner variational principle with two classes of variables. These variables not only include such origin variables as displaces, electric potential and magnetic potential, but also include such their dual variables as lengthways stress, electric displacement and magnetic induction in the symplectic space. Similar to the Hamiltonian formulation in classic dynamics, the z coordinate is treated analogous to the time coordinate so that the method of separation of variables can be used. The governing equations are a set of first order differential equations in z, and the coefficient matrix of the differential equations is Hamiltonian in (x, y).

Abstract: Spiral spring is one of most important components in mechanical systems. According to literatures, there are only few studies on spiral springs. Using the Castiliago’s method and Mohr’s theorem, the mechanic model of spiral spring in elastic deformation is developed. As a typical case, Archimedes spiral spring is studied in details and experiments are also conducted to validate the mechanic model. Experiment shows that the theoretical analysis and experimental result matches very well, therefore the mechanic model can be used to estimate the deformation of spiral spring and to guide and facilitate the design of spiral spring.

Abstract: Aiming at an outbound process of the airship driven by the hydraulic rod and cables, a simulation of the wind-induced displacement for the airframe is conducted. First of all, a spatial three-dimensional flow field including the boathouse and airframe is calculated using fluid dynamics, and a wind pressure distributed on the airframe is equivalent to the forces and moments exerted on the airship head in three directions. Then, a finite element model of the airship structure is modeled and a simulation of the wind-induced displacements for the giant airship is conducted. Finally, a collision possibility between the airship and boathouse is evaluated, which lays a foundation for designing the boathouse structure that meets outbound conditions for the airship.

Abstract: This essay was to build a finite element model to find the influence by oil casing geometric imperfection on anti-collapse strength. Two types of oil casing, Ф177.8×10.36mm/P110 andФ127×9.19mm/ P110, was taken for the calculation, considering the influence on anti-collapse strength by casing with two elements separately, ovality and non-uniformity of wall thickness. The calculation show that the anti-collapse strength of perfect casing perform better than that of imperfect casing. Ovality is an important factor for the anti-collapse strength, and the anti-collapse strength decrease rapidly as the ovality increase. Non-uniformity of wall thickness is the less important factor for anti-collapse strength, and the anti-collapse strength decrease slightly and slowly while the non-uniformity of wall thickness increase.

Abstract: Pore-throat ratio is a significant parameter expressing the characteristics of reservoir pores. It has an apparent influence on viscoelastic polymer solution flow in micro-pores. In this paper, Upper-Convected Maxwell (UCM) equation is applied in describing the viscoelastic polymer behavior. The expansion channel models of different pore-throat ratio are selected in process of simulation. And contours of stream function and velocity of different Weissenberg number (We) are calculated and drawn by Finite Volume Method. Results show that, vortex will occur at the re-entrant corner caused by the sudden expansion of channel, size and intensity of the corner recirculation vortex. The residual oil region is reduced and the mobile oil region is enlarged. Microscopic sweep efficiency is increased relatively. Vortex will be larger and stronger, and the velocity will be increased for We. Vortex will be lager as the bigger pore-throat ratio. Micro-sweep efficiency will be capitalized by viscoelastic polymer solution to the utmost.

Abstract: Through the analysis of force acting on granule in slurry spiral flow and movement characteristics of granules, the granule motion equation, the granule size distribution along radial direction, and distribution of granule concentration on cross section of the pipeline were established. By using computer simulation with FLUENT software for granule concentration distribution on cross section in slurry spiral flow of pipeline, the results of simulation revealed that the granule distribution in slurry spiral flow concentrated in peripheral area of cross section of pipeline, the concentration distribution of granule in center of the cross section area was smaller and more uniform, and the concentration of granule was minimum in pipe wall because of the effect of centrifugal force and circumferential velocity acting granules.