Applied Mechanics and Materials Vols. 52-54

Abstract: The problem of radially symmetric motion is examined for a pre-existing micro-void in the interior of a sphere under a suddenly applied outer surface tensile load, where the sphere is composed of a homogeneous incompressible hyper-elastic material. Through qualitatively analyzing the second-order ordinary differential equation that describes the motion of the pre-existing micro-void with time, some interesting conclusions are proposed. For any given values of surface tensile loads, it is proved that the motion of the pre-existing micro-void with time presents a nonlinear periodic oscillation, however, in certain cases, the oscillation amplitude increases discontinuously with the increasing values of surface tensile loads. Finally, based on the known transversely isotropic incompressible Gent-Thomas material model as an example, numerical simulations are carried out.

Abstract: Biopsy precious research has an important relationship with treatment efficiency and side effect complication. Most of the investigation is focus on the non-creatural material which is used to substitute creatural soft tissue for precious research. The aim of this paper is to develop a prescription that can be used for opaque and transparent PVA making which has similar mechanics property to the creatural tissue. The preparation, characteristics, and the results of PVA hydrogel on the composite material are studied as the key investigation. Porcine liver tissue property is also tested as a consultant for PVA material preparation. Comparing with the liver tissue test result, certain component ratio and freezing-thaw circle are determined. This PVA hydrogel material shows big potential in the creatural material substitution application. This research will benefit others who are interested in using non-creatural material to do experiment or surgical technology training.

Abstract: Based on interior trajectory calculation of the missile capsule in underwater launching tube，the hydrodynamic pressure distributions of the capsule surface at different moments are simulated carefully by using Flotran module in Ansys software. The results provide some theoretical basis for main body structure design and performance optimization of the underwater capsule.

Abstract: A rheological analysis has been performed to evaluate the characteristics and behaviors of Microminiature Powder Injection Molding (μPIM) feedstocks. The feedstocks comprised of 316L stainless steel powder and water-based binder components. Feedstocks formulations with powder loading of 59% to 63% were prepared and investigated. In these formulations, the binder system consists of 65% Polyethelena Glycol (PEG), 25% Polymethyl Methacrilate (PMMA) and 10% Cellulose Acetate Butyrate (CAB) based on the weight fraction. The influences of rheological behaviors such as flow activation energy (E), Power-Law exponent (n), viscosity (η) and temperature (T) of the SS316L/PEG/PMMA/CAB feedstocks are analyzed and discussed. Results show that all of the feedstocks exhibited the pseudo-plastic flow behavior. The homogenous feedstock at 61 vol. % demonstrated the most satisfactory rheological properties for μPIM with the lowest flow activation energy, Power-Law exponent, n < 1 and moderate viscosity values. It was chosen to perform the injection molding process. Micro components have been replicated successfully by using this selected feedstock.

Abstract: Optimization of injection parameters in Micro Metal Injection Molding (μMIM) was described in this study. Stainless steel powder was mixed with Polyethelena Glycol (PEG), Polymethyl Methacrilate (PMMA) and Cellulose Acetate Butyrate (CAB) to produce feedstock. Design of Experiments (DOE) of Taguchi L-27 (313) orthogonal array technique has been used to investigate the significance and optimal injection molding parameters. The signal-to-noise ratio and analysis of variance (ANOVA) are applied to study the optimum levels and effects of process parameters. Simultaneous optimization to obtain the highest green density and excellent surface appearance was discussed. The result concluded that the mold temperature (D) is the most statistically significant process parameter and its contribution to the best appearance and density is the highest.

Abstract: To improve the overall performance of the VM cycle pump. Based on the mixture with nitrogen (including N2 - Ne, N2 - Ar, and N2 - Kr) by working in the regenerator of flow and heat transfer in performance is analyzed and calculated, different mix of refrigerant regenerator performance impact. To enhance the VM cycle pump overall performance study provides new ideas.

Abstract: The paper analyses CO2 trans-critical two stage compression refrigeration cycle with vortex tube expansion by thermodynamics method. And compare with CO2 trans-critical two stage compression refrigeration cycle with expansion value. The results show that in the calculated conditions of the paper, the performance of the cycle with vortex tube improves 2.4%~16.3% than the cycle with expansion value. The optimal discharge pressure maximizing COP of the cycle with vortex tube exists. With lower evaporating temperature or higher gas cooler exit temperature, COP of system decreases and COP improvement increases. The effect of cold fluid mass fraction on COP is not significant, but COP improvement increases more quickly with cold gas mass fraction increasing.

Abstract: The Dynamics Analysis & Simulation of the Rocket Sled were done based on the Multibody System Dynamics and Finite Element Analysis Theory. The most difficult work in the analysis is how to establish the boundary conditions of the rocket sled. This paper makes this kind of attempt. Then the relevant postprocessing figures and data were obtained，thereby providing the designer and manufacturer with detailed and reliable data. The conclusion is the simulation method is more effective than those before and the boundary conditions are acceptable.

Abstract: This paper aims to understand influence of the obliquity of fin ray on its motion performance. An environment-friendly propulsion system mimicking undulating fins of stingray had been built. Investigations were presented by using three-dimensional unsteady Computational Fluid Dynamics (CFD) method. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive remeshing was used to compute the unsteady flow around the fin through twenty complete cycles. The pressure distribution on fin surface was computed and integrated to provide fin forces which were decomposed into lift and thrust. Vortex contour maps of the fin with different obliquity of fin ray were displayed and compared. Finally, we draw a conclusion that the generated propulsion force of the biomimetic propulsor is gradually increase with the obliquity of the fin ray from 0 degree till a certain angle and then gradually decrease with the obliquity of the fin ray from the certain angle till 90 degree. The results provide valuable information for the optimization of robotic underwater undulating propulsor design.

Abstract: Focusing on the application technique of the phase testing techniques in cell identification, the analysis to the morphological structures of the leucocytes is done, and the physical models with nucleus of white blood cells are built. Based on the VirtualLab and numerical simulation techniques to systematic study on the distribution of the phase of the the leucocytes, the inside and outside morphological structures of the leucocytes and the main characteristics of the models are found. Thus, the phase testing application has been expanded. The light phase distribution analysis of biological cell is expected to become a new tool to detect the biological cell.