Papers by Author: Yi Sun

Abstract: The current mainstream security systems are independent existence. They are too complex to achieve for the average families.The networking technology and smart home technology has been developed mature.And the home automation and intelligent basically achieved.It's low-cost and low-hanging to integrate Home security into smart home. Scheme of Adding the home system based on the current smart security module was proposed.The MCU is CC430F5137 produced by TI,and the monitored is finished by the temperature sensor MAX6662,humidity sensor HS1101, smoke sensor MQ-2 detector and camera and other hardware equipments. And complete the interaction with the server through the RF433MHz wireless communication mode, the server finish background analysis and notify the user by the client software.

Abstract: In this paper, different amounts of fluoropropyl polyhedral oligomeric silsesquioxanes (FP-POSS) were incorporated into the poly (vinylidene fluoride) (PVDF) matrix by the solvent evaporation method. Influence of FP-POSS on morphology and mechanical properties of PVDF matrix was investigated. Good dispersion between FP-POSS and PVDF was achieved up to 8 wt% of nanofiller. The mechanical testing and dynamic mechanical analysis showed that low FP-POSS content induced a positive reinforcement effect on mechanical property in the formed composites. The results also indicated the existence of the optimal formula for producing POSS polymer composites, and POSS owning to its unique organic-inorganic structure can act as a plasticizer or as a reinforcing agent on the basis of interactions between filler and polymer.

Abstract: The expressions of the effective elastic constants of composite material with cylindrical inclusions are derived based on M-T method, and it can be used in discussing the approximate range of effective elastic constant of air. Moreover, it is possible to homogenize tube-sheet by making use of the expression. The numerical result obtained is in good agreement with effective elastic constant adopted by the ASME code. It demonstrates that the approach is effective and accurate. At the last, the relationship between effective elastic and thickness of the tube-sheet is discussed.

Abstract: In this paper, we investigate the mechanical properties of ceria and gadolinia doped ceria by molecular dynamics simulations. The doped concentrations and temperature dependence of yield stress and elastic modulus have been evaluated via uniaxial compression. Simulation results reveal that such properties decrease dramatically with higher temperature and doped content. In addition, the attenuated effect of doped content is more significant than that of temperature.

Abstract: The objective of this study was to incorporate POSS-MA into the polymeric matrix to develop a new kind of nanocomposite. The effect of different weight percentage of POSS incorporated into the matrix on the mechanical properties was also evaluated. Infrared spectroscopic technique and X-ray diffraction were used to characterize their microstructures and double bond conversion. With only 2wt% POSS added, the nanocomposite’s flexural strength increased 15%, compressive strength increased 12%, hardness increased 15% and uncommonly, even the toughness of resins obviously increased. With 5wt% POSS polymerized, compressive strength increased from 192MPa to 251MPa and compressive modulus increased from 3.93GPa to 6.62GPa, but flexure strength began to decline from 87MPa to 75MPa. The nanocomposites incorporated with POSS showed greatly improved mechanical properties, and increased wear resistance and service life. The mechanism of reinforcement was also discussed.

Abstract: The deformation and damage process of POSS nanocomposite is investigated by molecule mechanics (MM) simulation. Firstly, the nano-scale models of two kinds of homopolymers, pure polystyrene (PS) and polystyrene attached with 5 mol% propyl-POSS (P-POSS-PS) were built. Then the mechanical behaviors of these two kinds of hybrid materials under focused uniaxial tensile loading and the remote uniaxial tensile loading are examined by MM simulations. It is found that a small quantity of POSS can observably increase the tensile modulus of the normal polymers. During tensile loadings, micro voids appear in the polymer matrix. With the increase of deformation, the micro voids become bigger and then connect to form the damage in bigger area. The POSS monomers prevent these micro voids from coalescence and thus retarding the formation of the damage. This would be helpful in understanding the reinforcement mechanism of POSS and provide important referential message for the applications of POSS.

Abstract: In the present paper, the relation between fatigue crack growth threshold and material’s cyclic saturation behavior is investigated. The dislocation-free zone (DFZ) model is used to determine the dislocation distribution ahead of the crack tip. A cohesive zone model is developed to determine the stress field of the DFZ under cyclic loading. The effect of cyclic loading makes the plastic zone hardening (or softening), which raises the stress level in DFZ, and may lead to fracture. It is found that the near threshold characteristics are mostly determined by the cyclic deformation behavior of the material, and might be theoretically determinable from the standard cyclic loading test.

Abstract: The influences of the polyhedral oligomeric silsesquioxane (POSS) on the mechanical properties of the polystyrene (PS) under tensile strain loading were studied using the atomistic finite element simulations. Firstly, the nano scale pole-like atomistic models and the micro scale pole-like finite element models of two kinds of homopolymers, the pure PS and the polystyrene attached with 5 mol% propyl-POSS (P-POSS-PS), were built, after which the atomistic finite element models were built by connecting the carbon and silicon atoms on the boundaries of the atomistic models to the corresponding nodes in the finite element ones. Then the mechanical behaviors of the two kinds of homopolymers under different tensile strains were investigated. The results show that, when the tensile strain of PS reaches 0.05 the micro voids appear. The tensile stresses of PS approximatively keep increasing with the increasing strain before the tensile strain of 0.07, after which the stresses declines. And the corresponding tensile modulus of PS is 4.52GPa. By contrast with PS, when the tensile strain of P-POSS-PS reaches 0.06 the micro voids appear. The tensile stresses of P-POSS-PS are almost keeping increasing before the tensile strain of 0.08, and the corresponding tensile modulus is 5.32GPa. Conclusions can be made from this work that the tensile strength of homopolymers can be observably improved by POSS. A small quantity of POSS can even improve the toughness of homopolymers slightly. This work has realistic theoretical significance to understand the reinforcement mechanism of POSS and provides important referential message to the applications of POSS.

Abstract: Magnetorheological (MR) fluids are suspensions of micron sized ferromagnetic particles dispersed in varying proportions of a variety of non-ferromagnetic fluids. MR fluids exhibit rapid, reversible and significant changes in their rheological (mechanical) properties while subjected to an external magnetic field. In this paper, a double-plate magneto-rheological fluid (MRF) clutch with controllable torque output have been designed. Electromagnetic finite element analysis is used to optimize the design of the clutch by using the commercial FEA software ANSYS.