Applied Mechanics and Materials Vols. 670-671

Abstract: Based on positional finite element method (FEM) and MATLAB platform, program VBEP (Variable cross-section Beam Element based on Positional FEM) is compiled. Flexible spin-up maneuver is calculated. The calculation results show that positional FEM uses fewer elements and gains higher calculation precision and efficiency when compared with traditional nonlinear FEM, and that calculated quantity using lumped mass matrix is less than using consistent mass matrix about properties of materials under the same calculation precision.

Abstract: A numerical study of flow in two-dimensional turbulent boundary layer flow with mass injection through a porous wall is conducted by Reynolds averaged numerical simulation (RANS) in this paper. Numerical results with available experimental data show that Wilcox (2006) k-w turbulence model can give good prediction in this complex flow. The comparison between mass injection and no mass injection for the local frictional resistance coefficient are performed. Numerical investigation indicates that mass injection may reduce the resistance significantly, which is confirmed by comparison of velocity profiles qualitatively.

Abstract: This paper completed the virtual prototype design for a ladder fire truck in ADAMS.After add the joints and motion functions,a dynamic simulation and analysis to the virtual prototype had been carried out.It approved the ladder fire truck could achieve the intended motion with comparatively steady space.The simulation provided a theoretical basis for the further design,which is a reference for the next imporving design.

Abstract: In this work a commercial reverse shoulder prosthesis has been redesigned to improve performances in terms of range of movements of the implant and stability to dislocation. A kinematic and mechanic study has been performed using a realistic solid model of the prothesised shoulder: in particular, all the components of the prosthesis have been acquired via a 3D laser scanner and inserted in a virtual humerus-glenoid system by reproducing the common surgical procedure. The final model has been used to measure the maximum angles of abduction and rotation of the arm and the shear forces that cause dislocation. Modifications proposed to the commercial prosthesis are: a different orientation of the cutting plane of the glenoid component and the interposition of a spacer to move the center of rotation of the arm.

Abstract: Recently, consumers are often dissatisfied with the battery life from even the most advanced lithium-ion rechargeable batteries in mobile phone. A mobile battery was chosen in this study because it is the flat plate of small thin wall which is expected to have some flexing. It is required to be evaluated and designed considering the coupled phenomena. Especially, this paper describes finite element analysis simulation of strength evaluation for epoxy molding compound module using automated FE analysis system.

Abstract: Aimed at cantilever-type foil cylinder film seal system, finite element method analysis model was established to calculate the deformation of cantilever foil under the gas pressure based on the theory of plate bending. The paper proposed a method to solve fluid-solid interaction problems in cantilever-type foil cylinder film seal system based on the numerical analysis method of cylinder gas film seal. The calculation program using the finite element method to solve fluid-solid interaction problems was developed. Calculation simulation of the film mechanical properties and steady-state performance of sealing system was realized which improved the accuracy of the sealing system performance analysis and provided the basis for the multi-parameters matching design of sealing system. The impact of adding cantilever foil support structure to the steady-state performance of sealing system and the influence of flexible support parameters on the steady-state performance of the sealing system was calculated through the method.

Abstract: In order to research and master the effect of surface topography on average film thickness between the end faces for mechanical seals, average film thickness fractal model between the end faces for mechanical seal was established using fractal parameters charactering surface topography characteristics, based on contact fractal model of the end face for mechanical seal, and solving micro-void volume. Effect of surface topography fractal parameters on average film thickness between the end faces for B104a-70 mechanical seal was analyzed by theoretical calculation. The results showed that fractal dimension D and characteristic length scale G of the end face had a great influence on the average film thickness h₀, and h₀ decreased with the increased of D or decreased of G; h₀ decreased rapidly with the increased of D or with the decreased of G when the end face was coarser, however, it decreased slowly with the increased of D or with the decreased of G when the end face was smoother. In normal working parameters and surface topography fractal parameters range, average film thickness between end faces was in the range of 0.27~1.7μm. Studying on the effect of the change of surface topography on average film thickness has an important significance on the predicting of operating characteristics of end faces during actual operating and the design of end faces for contact mechanical seal.

Abstract: For the large air bearing capacity and high rigidity, the author put forward a kind of slit type guide rail which based on gas film clearance throttle,through establishing the guide physical model,fitting the gas film surface ,and building a flotation control equation, refering to the finite difference method and dichotomy,solved the gas film pressure distribution based on Matlab numerical calculation,analysed the bearing capacity of gas floating needle bar under different eccentricity and the stiffness.The results show that: the gas floating guide,if a slit’s width is 0.2 to 0.26,and the cumulative length of the slit for half of the perimeter of the inner surface,the slit intermittently arrange six along circumference,has the best static performance.The larger the needle bar eccentric,the bigger the flotation capacity and stiffness,it is capable of carrying the load of the needle bar,and the air tightness of the structure is good,throttling effect is obvious.

Abstract: The scalability and the efficiency of the OpenFOAM-based parallel viscoelastic solver are greatly restricted by MPI operations. In this work, we proposed a comprehensive strategy of the computation and communication overlap and the hybrid parallelization with MPI and OpenMP to optimize the parallel viscoelastic solver on HPC platforms. Critical simulations based upon 3D contraction benchmark flow show that the efficiency of the parallel viscoelastic solver could be considerably improved, and an extra speedup of 2.20 could be obtained with 8 threads upon 2 MPI processes.

Abstract: In this paper, a research is performed on the tuning strategy for the shape parameter of the RBF to improve accuracy. The shape parameter is an influential factor for the accuracy but the configuration is commonly based on experience. An algorithm is designed to optimize the shape parameter. Three high-order mathematical benchmarks are used to compare the common RBF and the optimized RBF. This paper shows that the optimized RBF is more accurate for various test functions.