Advanced Materials Research Vol. 823

Abstract: Fiber Bragg grating sensor is a kind of optical fiber sensor, the sensing process based on fiber grating is through the external physical parameters on fiber Bragg wavelength modulation to obtain sensing information. It is a kind of wavelength modulation type optical fiber sensor. Fiber Bragg grating sensor can realize the direct measurement of temperature, strain and other physical quantities. This paper have the research and analysis on blade tip of mine by using fiber Bragg magnetic coupling sensor, in order to realize long distance and non-contact real-time safety monitoring of blade vibration. The paper first describes the theoretical method of the detection of blade tip timing vibration, then does the dynamic characteristic test. By means of the compare between normal and damaged blade, the method is proved feasible.

Abstract: As for turbine rotor, the simple stress on-line monitoring models of rotors temperature and thermal stress based on Greens function method are obtained. Using perturbation method, the models can deal with nonlinear problems resulting from temperature dependent properties. The working medium temperature change curve and the temperature rising rate curve during the period of startup or shutdown at shortest time for unit can be obtained to reduce fatigue wastage by analyzing the startup or shutdown process of a unit plant with the Pontryagin Maximum Principle of optimal control theory. The temperature rising rate curve thus obtained can be used not only as a guide for operation, but also as a programmable control signal for the startup and shutdown process of generating units, which will improve the economy of a power plant.

Abstract: in order to monitoring connecting rod and crank pin bearings working condition, the PCOT monitoring system which was named crank pin oil temperature monitoring system was developed based on virtual instrument technology. The bearings working condition was estimated by testing oils temperature splashed from the connecting rod and crankshaft. The function, working principle and structure composition were described, and corresponding experimental prototype was researched. After experimental verification, this system could monitoring the crank pin oil temperature in a steady and reliable state, provided technical support for testing bearings faults.

Abstract: Because of the huge lifting weight and complex structure of large-tonnage gantry crane and in order to effectively design and review it, this paper aims to carry out a research on its structural performance based on the method of theoretical calculation and finite element analysis. During the early period of design, the method of theoretical calculations is adopted, and after specific design it comes the finite element analysis, so as to get the results of analysis under a variety of operating conditions, which illustrates that the structural design and review of large-tonnage gantry crane based on theoretical calculations and finite element are feasible, and also verifies that the method of finite element is an effective way to find a real dangerous cross-section, thus providing the basis for the design and manufacture of the crane structure.

Abstract: This paper proposes a simple mechanical CVVA mechanism using a four-bar linkage, a rotating 1st cam and two oscillating 2nd cams in addition to the conventional overhead camshaft valve train system. The fundamental operating principle of the CVVA mechanism is described. A multi-body dynamic model of the CVVA mechanism of single cylinder in ADAMS is developed according to the kinematic design and topological structure of the mechanism. Valve motions and compressive loads of the mechanism are analyzed through the various lift phases and camshaft rotating speeds. The results of the dynamic simulation demonstrate that the CVVA mechanism sustains proper performance in the valve timing and event control through the whole speed range.

Abstract: This article find that one of the effecting the double circular arc gear s running performance is the double circular arc gear tooth profile precision, through analysis to the running-in properties of double arc gear. The problems about tooth profile precision of gear hobs caused by the current profiling theory and approximate design method of gear hobs are analyzed. In the design of circular arc gear hob, use the space engagement theory, can eliminating the tooth error. Acquiring the equation of hobs basic of worm tooth surface by analytical and calculation that the establishment of basic gear rack and worm of hob meshing. The hob not only eliminate the tooth profile error in manufacturing, but also improve the running performance of double circular arc gear, and provides the theory evidence for engineering practice.

Abstract: In order to reduce the effect of hysteresis of piezoelectric ceramic pressure on the system, designed the feedforward compensation adaptive sliding mode control based on Preisach inverse model. The inverse model feed-forward compensation does not depend on the precision of the Preisach model which weakens the hysteresis characteristics, and also can obtain the compensation voltage that combined with adaptive sliding mode controller. This paper proves that the controller can make the system to achieve global asymptotic stability. Simulation in Matlab. The simulation results show that the system can track the desired output, and can get good control effect.

Abstract: In this paper, a new multi-resolution representation (MRR) of a series of intermediate shape models for FTS diamond turning based on mesh simplification is proposed. In this MRR, geometric relations between each resolution model can be controlled so as to avoid overcut and to level the cutting loads. The new control method for MRR is based on an improved Edge Collapse Algorithm with consideration of the curvature factor. In addition, the calculation method of machining allowance and tool path generation method are proposed to support the machining process. The effectiveness of the MRR has been verified through simulation.

Abstract: The long length, light weight, low frequency, flexible joint and link of large space manipulators impact dynamic stability and position accuracy seriously. In this paper, dynamical model of space flexible manipulators system is build base on Lagrange method. With three DOF manipulators as the research object, the impact of flexible link, joint stiffness and clearance on the system frequency and end position accuracy of manipulator is simulated and analyzed. The results indicate that the flexible joint lead to low frequency vibration and flexible link lead to high frequency vibration. Low frequency vibration is the dominant impact of end position accuracy, Flexible joint have greater impact on the dynamic characteristics of system than that of flexible link.

Abstract: A torsional dynamic model of a pair of herringbone gear was presented by using a lumped-mass method, in which the meshing integrated error and time-varying meshing stiffness of the herringbone gear pair were taken into account at the same time. A Rugge-Kutta method was used to solve the dynamic differential equations of the system and the dynamic characteristics of the herringbone gear pair under the action of the external torque and internal excitations were obtained. The study provides a theoretical basis with the future other complex multistage herringbone gear drive system dynamics.