Applied Mechanics and Materials Vols. 55-57

Abstract: Surface quality of bearing ball is one of important factors to improve service performance. It is difficult to detect bearing ball surface defects with high precision and low cost by conventional methods. In this paper one new classification method based on optical fiber sensing technology was put forward from the longitudinal section angle. Inspection mechanism of Y-type and coaxial fiber sensor were analyzed, the mathematical models of the two fiber sensors were established and numerical simulations were realized by Matlab software. Influence of optical fiber parameters on light intensity modulation characteristic regulation was studied. Light intensity modulation characteristic experiments were done with specimens of different reflectivity and processing methods. The results show optical fiber sensing technique is an effective method to separate different surface of steel ball with extracting of two parameters displacement and surface reflectivity.

Abstract: According to the situation that the dual-friction drums on the new type towing machine lack stress analysis when designed, the safety is difficult to test and verify. The pull of wire rope in various positions was derived and calculated, so both compressive stress and tangent friction force generated by the pull of wire rope were calculated. The result made by ANSYS software demonstrates the safety of the left drum which suffers from larger loads, structure improvement measures are put forward for the drum.

Abstract: A modeling methodology based on stacked neural networks by combining several individual networks in parallel is proposed. Stacked neural network as an effective method for modeling of inherently complex and nonlinear systems especially a system with a limited number of experimental data points is chosen for yield prediction. Proper determination of the stacking weights is essential for good stacked neural networks model performance, so determination of appropriate weights for combining individual networks using robust least squares estimation is proposed. Inferential prediction of melt index as the most important characteristic process of polypropylene polymerization has been carried out. The application of the proposed modeling method based on stacked neural networks to the development of melt index soft sensor in an industrial propylene polymerization plant demonstrates its effectiveness.

Abstract: YAG:Ce_0.06,Gd_x phosphors were prepared by solid-state method, and temperature dependence of chromaticity coordinate and correlated color temperature of YAG:Ce_0.06,Gd_x are investigated. Three PL spectra all have broad emission band between 500 nm and 620 nm is assigned to the combination of the lowest energy of 5d bands and the ²F_5/2 and ²F_7/2 states respectively. With increasing temperature, the x values of chromaticity coordinates of YAG:Ce_0.06,Gd_x with Gd concentration increase all increase, but y values all decrease. Differently, z values do not show a clear trend. Moreover, correlated color temperature of YAG:Ce_0.06,Gd_x with Gd concentration increase all decrease with the temperature increase.

Abstract: Polarization analysis method is widely used in the area of target detecting. Compare with the traditional method which based on intensity analysis and spectrum distribution analysis, the polarization analysis is dominant by analyzing the polarization ingredient of optical information. Under normal conditions, polarization analysis method can discern the given targets and determine their characteristic more precisely in a further distance. The validity of polarization analysis depends on the polarization characteristics of the targets. Our experiment indicates that some typical materials have similar scattering characteristics which could fail the traditional analysis method. Further research indicates that there are a few remarkable differences in the scattering characteristics of these kinds of materials based on which a new method of polarization analysis is given in this paper to ensure the validity of polarization analysis under more application conditions.

Abstract: In order to evaluate the dynamic behavior of the buffer of the Seagull 300 aircraft’s main landing gear, a drop model is built to simulate the drop dynamics using the software of LMS Virtual Lab Motion. The fluid damping force of the buffer, the air spring force of the buffer, the tire force of the landing gear and the weight of the fuselage are considered in the model. The simulation results are compared with the results of the Seagull 300 landing gears drop test, which proves the accuracy of the simulation model. Then the buffer performance and its influence factors are computationally discussed. This method gives a new way to study and improve the performance of the buffer system of an aircraft.

Abstract: Kinematic analysis is fundamental for the mechanism synthesis. The kinematic analysis of mechanism is attributed to find the solutions of the nonlinear equations and this process is very difficult. Newton iterative method is an important technique to one dimensional and multidimensional variables and iterative process exhibits sensitive dependence on initial guess point. For the first time, a new method based on utilizing meshed chaos mapping method to obtain locate initial points to find all solutions of the nonlinear questions was proposed. The numerical examples in linkage synthesis and approximate synthesis show that the method is correct and effective.

Abstract: Resistance influence factors of displacement type Deep-vee forms are analyzed with eight hull forms provided. The free surface viscous flow of these forms is calculated by air-water two phases RANS equations with RNG turbulence model and volume of fraction method. Total resistance, pressure distribution and wave profile of bow are presented. Some results can be taken as follows: while maintaining the same tonnage, L/B ratio and draft, the resistance performance of Deep-Vee vessels is excellent at high speed if a large transverse dead rise angle was located from 50%front midship to 25% backward midship; The resistance performance at a lesser L/B and draft is worse if the displacement and dead rise angle is the same; Furthermore, it can be improved by a cigar-shaped bulbous bow. The change of pressure distribution for cigar-shaped bulbous bow is more slightly than that of tobacco pipe-shaped bulbous bow.

Abstract: The purpose of this paper is to determine the unstable points of debris-blocking dam deformation network and to lay the foundation for later accurate monitoring and data processing, for the reason that the affection of earth pressure and water-level-fluctuation lead to increased instability to debris-blocking dam. The author signed one horizontal displacement deformation monitoring network, measured two groups data by changing some point’s horizontal displacement with man, judged the point’s stability of the network by the method of mean gap and obtained the deformation model, and analysis the model sensitivity. The results is that the deformation network stability meet the design requirements through application the method in Fengjie Debris-blocking dam which blocked the stones debris for Shirushan tunnel, the actual displacement amount had been proven similar as the result with the method; It is concluded that this method have some practical value in deformation monitoring because it can construct the approximate model by direct observation data, which is smaller rely on other information.

Abstract: In this paper, the concept and application of virtual prototype technology are simply introduced, and analyses the veracity program in course of complex multi-body system simulation. The rigid-flexible couple virtual prototype model of complex multi-body system including collision is built, and the veracity of virtual prototype simulation is evaluated combining limited test data. Updating some typical system parameters by sensitivity method and perturbation method, it makes the simulation results have better consistency with test results, and improves the simulation precision of virtual prototype model.