Applied Mechanics and Materials Vol. 724

Abstract: s:Aiming at circumferential arc spring dual mass flywheel (CSDMF), this paper carries out analysis on the piecewise linear model and calculates the frequency response of damped model under sinusoidal excitation. Being combined with the calculate results, the research respectively analyzes the value of inertia ratio, torsional stiffness and damping parameters. The analysis results show that the greater the damping, inertia ratio of primary and secondary flywheels are, the torsional stiffness, the more obvious vibration damping of the dual mass flywheel would be. To meet the vibration damping requirements, the detail design of the three parameters need to be combined with power train and the torsion characteristic of CSDMF.

Abstract: The tamping maintenance of railway ballast is employed to restore the geometry of railway track distorted by train traffics. In this paper, based on the analysis of tamping principle, the three dimensional analysis model of railway ballast is created using the discrete element method, numerical simulations are performed to study the micro mechanical behavior of railway ballast under tamping operation. This paper presents the evolution of force chains inside railway ballast under tamping operation. The obtained results are showed that the contact force inside railway ballast is enhanced by tamping, so as to improve the carrying capacity and stability of railway track.

Abstract: In this paper, the defect sheet was captured coincidentally. According to the defective product’s characteristics, we suspected to be caused by the vertical vibration of the roll. When the rolling speed reached a certain value, the vibration of the fourth stand can be feel. The experiment of the vibration data collection was taken to compare the vibration parameters of rolling operating side with those of drive side by wavelet analysis. The result states that the abnormal vibration signal features can be extracted in a special frequency segment of wavelet decomposition, and the vibration frequency to the roll is confirmed which appeared product defects.

Abstract: Tamping operation is an important work of railway maintenance. There are many factors that can influence the tamping effect. This paper mainly studies the influence of vibration frequency and amplitude on the porosity of railway ballast. In order to obtain the minimal porosity, the response surface method was used to seek the optimal vibration parameters. Using an optimization method, the optimum vibration parameters were obtained that gives the minimal porosity. The obtained results are consistent with those of other similar studies, which mean that the response surface method is an effective analysis method of multi-parameter optimization problem under tamping operation.

Abstract: Typical hydraulic systems with inertia executive components like hydraulic cylinders are generally low in damping and lack of stability. Adding DPD to systems is an easy and effectual method to solve these problems. The performance of a mechanical dynamic pressure feedback DPD applied in a common hydraulic system was simulated while the influences of the structure and system parameters on DPD and the system were analyzed. Further research on characteristic optimization was carried out by adding accumulators to DPD. It shows that the DPD can practically improve the system stability and contain the pressure impact. The accumulators should be set appropriately before the damping orifices and have a certain ability to absorb pressure impact.

Abstract: In order to measure capture performance of the seeker in the typical terminal guidance scene under HPM damage effect, the paper proposes a new method to model the dynamic capture state in different ballistic position. The proposed missile-target geometry count can be used to process multiple data generated in multiple Monte Carlo simulations under the same scene, which facilitates capture performance comparative analysis between different scenes. Simulations validate proposed counting measure, so that it can be applied for measuring the performance of missile capture.

Abstract: This paper presents the development of a flight simulator for a fixed-wing propeller-driven UAV. A new architecture for UAV low-level functional units is presented. The work involves modeling main low-level units of the UAV, which includes modeling of aircraft lateral and longitudinal dynamics and controlling of flight-path states holding. Key characteristics for aerodynamics and propulsion properties are calculated. A nested PID loops are used to provide a low-level control necessary for intelligent control and mission planning and execution. Simulation results are demonstrated in order to validate the effectiveness of the flight simulator and thereby providing an infrastructure low-level abstraction platform that can be used for various multi-level algorithms testing.

Abstract: From the urgent needs of storage life evaluation in missile storage management, combining the characteristics of long-term use of missile and characteristics of different level products of the system, a complete set of overall solution of the life prediction and life extension of missile was proposed. First, through the use of missiles long-term use historical information, the reliability function model of the missile storage was established, and the life conclusions of missiles were estimated. Secondly, by conducting accelerated life or accelerated degradation test of missile, the life of missile was estimated. And by conducting environmental test and simulation test, the environmental adaptability indexes were verified. Thirdly, by carrying out the life feature detection analysis of the circuit board, the microscopic defects in the circuit board were detected, and the guidance for life extension work was raised. Finally, by conducting accelerated degradation of the key components and materials, the life conclusions of them were estimated. Combining the storage life information of missiles, board-level circuits, components and materials, a complete set of overall solution of the life prediction and life extension of missile was proposed.

Abstract: The method of satellite orbit determination on real time was proposed based on star sensor and sun sensor. According to the wireless net composed by star sensor and sun sensor, the kinematics orbit data of satellite will be generated. With the restriction of kinematics model, the parameters in dynamic model such as atmosphere index and sunlight radiation index could be estimated accurately with appropriate algorithm. For the non-linear characteristic of the dynamic model, the UKF estimator was put forward to restrain the interceptive error. The simulation experiment results shown that the method of satellite orbit determination based on UKF method and wireless net data system based on star sensor and sun sensor was excellent to adapt the complex space circumstance, and can generate high precise orbit.

Abstract: Combination of conflicting evidence usually resulted in illogical outcome. In order to solve this problem, an approach to acquire evidence reliability based on relative entropy was proposed by researching the evidence theory and relative entropy. Firstly, the weights of evidences were calculated by evidence distance, reference evidence was obtained by weighting and meaning. Then relative reliabilities were achieved by calculating the relative entropy between original evidence and reference evidence. In the end, final outcome was achieved by D-S composition. This method can commendably extract information in the conflict evidences. The result of the simulation proves it well.