Advanced Materials Research Vols. 308-310

Abstract: Besides the three main categories of bistable mechanisms such as latch-lock mechanisms, hinged multisegment mechanisms, and residual-compressive-stress buckled beams, a novel unsymmetrical bistable mechanism with a combined structure of permanent magnets and mechanical beams is proposed, and the bistability of such combined structure is analyzed based on the magnetic-charge model and material mechanics theory. The nonlinear combined force during snap-through procedure is calculated accurately, which is in accordance with that obtained by the experiments. The bistable characteristics such as the threshold snapping force, the traveling range, stable positions, and the elastic reaction force at the stable position can be adjusted freely by changing the magnet structure parameters and the relative distance among the three magnets. Finally, the dynamic response is analyzed theoretically and experimentally, which shows that the bistable structure has a good frequency distinguishing capacity for mechanical shock pulses.

Abstract: The heavy triangular rubber track conversion for the construction machinery has existed the disadvantage for weight oversized. The effective reduced triangular rubber track conversion's weight is essential in the engineering design. This article established one kind of triangular rubber track conversion driving gear wheel axle's three-dimensional model, integrated dynamics analysis has carried on the finite element analysis to it, based on this and carried on the size using Ansys Workbench to optimize for its most superior structure size, finally to optimized the result to carry on the finite element analysis once more. The result contrast indicated that at maintains under the wheel axle stress level basic invariable premise, after the optimized wheel axle weight reduces greatly, enhanced track wheel's performance effectively.

Abstract: A chalcogenide-tellurite composite microstructed optical fiber (MOF) has been proposed and designed in this paper. The fiber has a flattened near-zero dispersion curve around 2.5 μm and has two zero dispersion wavelengths(ZDWs) in close. It also shows low confinement loss and single mode operation properties. Numerical simulation has been used to predict the supercontinuum spectra obtained from the designed fiber. Simulation results show that a widely supercontinuum spectrum covering from 1.8 to 6.0 μm can be generated by pumping pulses of energy below 10pJ/pulse.

Abstract: A virtual platform is developed to support the design of tunnel drilling rigs, which is used to drill holes in underground coalseam for gas drainage. Firstly, a three-layer framework of virtual platform is established, which includes the base layer, platform layer, and application layer to provide data, information and techniques respectively. A virtual design flow of drilling rigs is subsequently defined. Then three key techniques for the virtual design of drilling rigs is proposed, which are digital modelling, digital simulation and digital management. The first is used to support 3-D modelling, the second is used to analyze the dynamic performance, and the third is to manage the design data. Finally, a design case of ZDY6000LDA drilling rig is given to demonstrate the application of this platform.

Abstract: A concept of virtual material was suggested when the flexible joint could be considered as a virtual material with the same cross area. The virtual material is rigidly connected with 2 components situated in two sides of flexible joint. Introducing an element, a complex assembled part including a joint may be equaled as a simple component without any joint in order to simplify the complicated problem about flexible joint. The interaction between normal and tangential characteristics of fixed joint taken into account, a lot of closed-form analytic solutions of elastic modulus, shear modulus, Poisson ratio and density were deduced from virtual material through Hertz contact theory and fractal theory.

Abstract: This paper presents a measurement method of NC machine geometric accuracy. The principle is that a laser tracker is used to collect a lot of target point coordinates on four different locations around the machine during the machine spindle moving. A redundant equations could be established through target point coordinates,then the exact location of each target point coordinates could be determined by the principles of GPS positioning.Through the target point coordinates,the geometric error of machine could be separated. The method has fast measuring speed and low cost.Moreover the measurement precision is higher than direct measurement only using one laser tracker because the GPS positioning principle is used to avoid the angle measurment of laser tracker.

Abstract: An effort is made to give a description of a computer-aided conceptual design system. A novel Function-Action-Behavior-Mechanism (FABM) modeling framework is proposed to realize mapping from the overall function to principle solution according to customer’s requirements. Expansion and modification rules in the demand behavior are developed to extend the innovation of principle solution. A case study on pan mechanism design for cooking robot is presented to show the procedure of how to implement the intelligent reasoning based on the FABM model.

Abstract: Hydrothermal treatment method was proposed to prepare boehmite and the effect of precursors on the morphology of beohmite was investigated. On the coordinate effect of organic and inorganic flower-like AlOOH assembled by nano-plates can be obtained by Al(NO₃)₃ as precursor. 3D urchin-like AlOOH superstructures consisting of nanoribbons were produced from hydrate AlCl₃ as reagents. Dissolution and recrystallinity of intermediate product AlOCl caused this result. Globe and hollow sphere morphologies of beohmite were synthesized by Al₂(SO₄)₃ in a water-alcohol system. The formation mechanism is also because of the dissolution and recrystallinity of intermediate product sodium sulfate aluminum. Beohmite prepared by hydrothermal treatment was transformed to γ- Al₂O₃ at 600°C. The morphologies of γ- Al₂O₃ powders were still kept their original forms.

Abstract: A novel morphing wing structure is designed based on the concept of re–entrant hexagonal cellular structure. The re–entrant hexagonal cellular structure is adopted because of its ability to undergo large overall displacements with limited deformation in spanwise direction. The presented unconventional cellular based morphing wing structure can satisfy the requirements of configuration changing while wing morphing, which can makes the aircraft remain at the most effective state and perform multiple missions effectively and efficiently. Numerical analyses were performed to exploit the presented wing structures using commercial finite element method. It was shown that the morphing wing structure examined here had can change its relative thickness as much as 5%, which can make lift coefficient increase significantly. Therefore, the presented structure can be served as a smart variable wing structure and has much effective and efficient aerodynamic performance.

Abstract: For seepage in unsaturated soil, there are both air flow and water flow, which can be called the water-air two-phase flow. In order to simulate the water-air two-phase flow in soil when there is groundwater, a numerical model of water-air two-phase flow in saturated-unsaturated soil is established in this paper. By the model, the air-flow and water-flow in unsaturated soil are both considered in seepage calculation. And the mass transfer between air-phase and water-phase, change of phase states are considered in calculation. Capillary pressure is the most important factor for the water-air two-phase flow in unsaturated soil, and the calculation method of capillary pressure is also given in the paper. At last examples are given to verify the correctness of the numerical model and the calculation method.