Advanced Materials Research Vols. 156-157

Abstract: The clock synchronization is the key technology in distributed control system. This paper investigates the method to adjust computer clock frequency and time in embedded control system based on Ethernet. This paper also analyses the basic working principle of the IEEE 1588 Precision Time Protocol. In particular, it outlines the working principle of the free PTPd that is the software only implementations of the IEEE 1588 Precision Time Protocol. In the ARM-Linux environment, it presents a clock synchronization method to achieve high precise clock synchronization in distributed control system using PTPd. The results indicate that it is able to synchronize distributed clocks with the accuracy less than 500 microseconds using PTPd without the support of specialized hardware.

Abstract: In order to reduce the work of repeated nad iterative of process model for manufacturing system, the paper proposed the establishment of three-dimensional "product - process - property" of the modeling methods with matrix mapping technology and mapped products, function, performance, process to model of production system according to the steps. Production system modeling of light-box as a case to detail description of production systems and process modeling. The modeling method with convenience, comprehensive, integrated, inheritable, and sometimes with large amount of calculation.

Abstract: Generally speaking, the flexible manufacturing systems can be classified into two main groups: open-loop and closed-loop systems. In this investigation, a recursive formulation is developed for the dynamic analysis of open-loop flexible manufacturing systems. The nonlinear generalized Newton-Euler equations are developed for rigid and deformable bodies that undergo large translational and rotational displacements. These equations are formulated in terms of a set of time invariant scalars, vectors and matrices that depend on the spatial coordinates as well as the assumed displacement fields, and these time invariant quantities represent the dynamic coupling between the rigid body motion and elastic deformation. The method to solve equations of motion for open-loop systems consisting of interconnected rigid and deformable bodies is presented in this paper. This method applies recursive method with the Newton-Euler method for deformable bodies to obtain a large, loosely coupled system equations of motion. The solution techniques used to solve for the system equations of motion can be more efficiently implemented in the modern computer systems. The algorithms presented in this paper are demonstrated by using cylindrical joints that can be easily extended to revolute, slider and rigid joints. The recursive formulation developed in this investigation is illustrated by a practical numerical example.

Abstract: The manufacture of complex components was always the difficult point in manufacturing field. According to superposition principle, the manufacture of complex components could accomplish by geometry division, machining and assembling. A complex component was divided into several simple portions based on its geometry characteristics, to ensure relative position among each subassembly, the unilateral centricity method was adopted to fix the reference point, anchor surface and anchor sign and to complete the design of anchor structure. As soon as the design of assembly structure was completed, the NC processes were generated and the assembly structure would be scrabbled up immediately. In the end, an instance of profile bracket of human’s ear gave credence to the feasibility of manufacture of complex components by segmental manufacturing.

Abstract: To solve the rapidly increasing of complexity and uncertainty and inappropriate solving space of innovative with the complex product using the traditional combination manufacturing mode, this paper proposed modular manufacturing theory by separating the need of function, performance, structure, and size in the manufacturing process into the external modules and internal modules. The theory of generalize modularize decomposition, modules solving and optimize, modularize integrated are systematical represented. To reduce the complexity and uncertainty by the way of separate the business with internal model and external model. An example of installed and calibrated system of Laser device is given to illustrate the theory and methodology of modular manufacturing.

Abstract: The dynamic responses of the standard charpy impact machine are experimentally studied using the relevant data acquisition system in order to obtain the impact response. The numerical analysis by means of the finite element method has been used to obtain the findings. The standard charpy modelling using the aluminium 6061 material and low carbon steel 1050 were used for extracting strain responses on the striker during the impact simulation. A power spectrum density (PSD) approach is then applied to convert a signal from the time domain to the frequency domain using the fast Fourier transform (FFT) method. Related parameters of different frequencies, different material, strain signals, power spectrum density (PSD) and the relationship between them were finally correlated and discussed. It was found that the modulus elasticity of materials and frequencies (sample rates) were proportional to the strain signals and PSD during impact simulation.

Abstract: Li+ and Ta5+ modified lead-free piezoelectric ceramics [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 have been prepared by an ordinary sintering technique. Effect of Li+ and Ta5+ on microstructure and piezoelectric properties of the ceramics was systematically studied. A morphotropic phase boundary between orthorhombic and tetragonal phases is identified in the composition range of (0.02≤x≤0.04, 0.15≤y≤0.25), which can enhance electrical properties of [(K0.5Na0.5)1-xLix](Nb1-yTay)O3 ceramics. The Curie temperature TC of these ceramics is lower than that of pure (K0.5Na0.5)NbO3 ceramics, but the temperature of orthorhombic to tetragonal phase transition TO-T of the former is higher than that of the latter. TC and TO-T both decrease as the content of Ta5+ increases. With the addition of Li+ increasing, TC increases. The optimal piezoelectric properties are obtained at (x, y)=(0.03, 0.20): piezoelectric constant d33 is 192pC/N; the electromechanical coefficient of the planar mode kp is 44%; room temperature dielectric constant εr is 1049, and the corresponding mechanical quality factor Qm is 49.

Abstract: With malefic anhydride chose as coupling agent, Wheat straw and recycled Polypropylene (PP) was used as the main row material and compounded by isocyanate resin though the hot press technics. The effects of coupling agent on mechanical property of wheat straw/PP composite were studied by orthogonal experiments. The results showed that, if only coupling agent was used, it may have effects on composite, but the properties of composite were poor. If both of MDI and coupling agent were used, it would decrease the effects of MDI resin.

Abstract: The application of advanced composites on the aerocraft structure can significantly reduce the weight, and improve the aerodynamic and flight performances. In this work, optimization design of a composite wing structure of a minitype unmanned aerial vehicle (UAV) is implemented. The parametric finite element model is established using parametric modeling technique for stress and stain analysis. The global optimal solution is guaranteed by the proposed two-step optimization search strategy combing genetic algorithm (GA) and sequential quadratic programming (SQP).

Abstract: In order to suppress the periodic interference of continuous rotary electro-hydraulic servo motor, make the motor tracking periodic signals more accurate, and improve the influence of friction interference on the performance of continuous rotary electro-hydraulic servo motor, mathematic model of continuous rotary motor electro-hydraulic position servo system was established, and the compound control method based on the discrete sliding mode controller was adopted to suppress the friction interference. Through the simulation, the result confirms that the discrete sliding mode controller decreases the tracking error of the system, increases the system robust performance and improves performance of continuous rotary electro-hydraulic servo motor. This method is simple and feasible.