Advanced Materials Research Vols. 308-310

Abstract: Hydraulic poppet valve often works in fluid-solid coupling state. It is necessary to comprehensively consider the multidisciplinary coupling effects in the design and optimization of poppet valves. This paper presents the fluid-solid coupling model for the optimization of a poppet valve, and the actual flow performance of the poppet valve is analyzed by numerical method. By coordinating the conflicting requirements at the system level, the MDO model of the poppet valve is built. The Multiple-island Genetic Algorithm is employed to solve the optimization problem, and an optimum design of the poppet valve is obtained. The optimization results show that the optimum poppet valve has a better performance on the flow characteristics.

Abstract: According to the structural characteristics of floor standing air-conditioner，three dimensional numerical model of air duct system for a certain floor standing air-conditioner is developed to simulate aerodynamic characteristic of the air duct. Flow characteristics and deficiency of air duct for original floor standing air-conditioner are analyzed, and the optimal schemes of air duct are raised and numerical simulation has been carried on to obtain aerodynamic characteristic of the new air duct. The numerical results show that the volume flow rate of air-conditioner with new air duct is increased by 6.1%. The experimental results of air-conditioner with new air duct show the volume flow rate of new air duct is promoted by 5.6% at the same approximate noise level. The numerical results agree well with the previous experiment.

Abstract: Product tolerance is one of the important factors which affect the quality and cost of product. However, influenced by many complicated factors, there are still many problems which need to be resolved compared with other research works in CAD field. How to determine tolerances of product effectively is still a big problem. Based on exponent model of tolerance-cost, the relationships between tolerance and other characteristics influencing processing cost are studied in this paper. A relational model of tolerance-cost is come up with based on the above relationships. And then, internal relation between tolerance and lifetime is discussed. Meanwhile, along with the lifetime converted into the cost, the compensated relational model of tolerance-lifetime is presented. Finally, the method on the decision of tolerance grade is analyzed. This paper realizes the organic combination of tolerance, lifetime and cost, and effectively decides how to generate tolerance grades.

Abstract: Thinking of the characteristics of the human visual system, proposed a target detection model of attention mechanism which was based on dynamic saliency map. This method improved classical visual attention calculation model, extracted the static characteristics of intensity, color and orientation, and selected different parameters to fuse into a static saliency map which was based on different target on scenarios. Using differential filter method to extract the dynamic features of two images, and fused different scales feature maps into the dynamic saliency map. At the end, with modified factor modify two saliency map, and fused into the basic image with which detected the moving targets. This method simulated human’s attention mechanism, extracted different scales features with strong processing and analysis capacity. Experimental results show that the method can quickly and accurately detect moving target, can effectively meet the single target detection and multi-target detection.

Abstract: In CNC machine tools servo feed system, there are many uncertain parameters, it is difficult to establish accurate mathematical model of the Servo feed system. The parameters of conventional PID controller can’t adjust immediately to the controlled object. Fuzzy PID controller [1], which has the advantages of conventional PID control and fuzzy control, can solve these problems. We apply it in numerical control machine servo feed system. The simulation in MATLAB shows that the fuzzy auto-tuning PID controller improve the dynamic performance of the servo feed system and has better robustness.

Abstract: Molecular dynamics simulation is performed on the inter-tube friction force and energy dissipation of double-walled carbon nanotube oscillators with vacancy defects. It is found that there are vacancy defect-size and temperature dependences of the friction force between the inner tube and the defective outer tube. The original distance between the “hole” formed by the vacancy carbon atoms and the inserted end of the core has a significant influence on the oscillation profile.

Abstract: The plane supporting spring, the radial stiffness of which is considered as one of the most significant parameters in design process and application, is commonly used in the isolation instruments in the fields of aeronautics, astronautics, auto industry, etc. Proposed in this paper is a force-based theoretical method for computing the radial stiffness of multi-spiral supporting spring, which is obtained by solving the component force and radial displacement of each spiral line using the force and energy approaches respectively. Finite element analysis (FEA) of Archimedes spiral-plane supporting springs with 1 to 6 spiral lines is made via speedy modeling by ANSYS parameter design language (APDL). Validity of the theoretical method has been verified by comparison of its calculation results and our numerical analysis. And the relationship between the radial stiffness of plane supporting spring and the key geometrical parameters has been confirmed by our study, which can surely provide insights into the optimal design of plane supporting spring.

Abstract: The mechanism innovative design plays a quite important role in mechanical product processing. In this paper, a systematic method is proposed, in which restructuring based on the link number, the adding and subtracting links, the topological evaluation and isomeric mechanism are all contained, improving Yan’s Creative Mechanism Design Methodology. More probable, simple, lightweight mechanisms are obtained. An example is cited to illustrate the proposed method.

Abstract: Activated starch was prepared by ball milling before used. Graft copolymerization of acrylamide onto activated starch was carried out in inverse emulsion using a redox initiation system of ammonium persulfate and sodium bisulfite. The effects of ball-milling time, reaction temperature, initiator concentration and weight ratio of acrylamide to starch on the conversion of monomer, grafting percentage and grafting efficiency were studied. The structure and properties of the graft copolymer and activated starch were characterized by FT-IR, XRD and SEM. The results showed that ball milling could progressively destroy the crystalline structure of starch and improve the chemical reactivity. The monomer conversion, grafting percentage and grafting efficiency of grate copolymerization were 96.6%、62.4%、85.49%, respectively.

Abstract: Based on Solid Isotropic Microstructure with Penalization (SIMP) method, a mathematical model for topology optimization of EV is proposed, which has design objective as minimizing compliance, with volumetric and geometric constraints. To make results more engineering value, the BIW optimization of EV takes into account not only the static loads, but also the torsion load in turning and moment load in braking process of EV. A number of implementation aspects in solving the numerical instability problem generated in optimization process are discussed, including checkboard patterns and mesh-dependency. Topology optimization of EV body in white with geometry and volumetric constraints is conducted, showing effectiveness of the proposed model.