Applied Mechanics and Materials Vols. 744-746

Abstract: This paper studies the impact of two rigid bodies considering tangential friction in three dimensional space. It extends Stronge’s spring-based planar contact structure to three dimensions by introducing three orthogonal virtual springs. Impact analysis is carried out using normal impulse rather than time as the only independent variable, unlike previous work on tangential impulse. This makes the algorithm more compact. At last, collision is governed by a system of differential equations. Modularity of the impact model makes it easy to be integrated into a multi-body system.

Abstract: This paper investigates free transverse vibrations of finite Euler–Bernoulli beams resting on viscoelastic Pasternak foundations. The differential quadrature methods (DQ) are applied directly to the governing equations of the free vibrations. Under the simple supported boundary condition, the natural frequencies of the transverse vibrations are calculated, and compared with the results of the complex mode analysis method. The numerical results obtained by using the DQ and the complex mode methods are in good agreement for the first seven order natural frequencies, but with the growth of the orders, the small quantitative differences between them increase. The effects of the foundation parameters on the natural frequencies are also studied in numerical examples.

Abstract: The impact dynamics of spatial multi-link flexible multibody system is studied based on the continuous contact force method (CCFM). According to the rigid-flexible coupling dynamic theory of flexible multibody system, the rigid-flexible coupling continuous dynamic equations of the system are established by using the recursive Lagrange method. The impact dynamic equations of the system are stylized derived on the use of CCFM basing on the nonlinear spring-damper model. The contact separation criterion is given to achieve the conversion and calculation of the dynamic model for the system at different stages. An impact dynamic simulation example for a two-link planar flexible multibody system is given, as well as the global dynamic response. The results show that the impact dynamic solving method based on CCFM can be used for the global impact dynamics of multi-link flexible multibody systems. The dynamic behavior of the system changes dramatically during the impact process. The large overall motion, the small deformation motion and the impact effect are coupled.

Abstract: The structure of castellated beams is complex, using the computation theory of elastic flexural-torsional buckling of H-shaped beams to study the elastic flexural-torsional buckling strength of castellated beams under different loads, based on simplifying the section's eigenvalues. In addition to the theoretical investigation, the finite element analysis of the accurate critical loads of the beams had been done by the ABAQUS software, a comparison has been made between the calculated loads and analyzed results, error is smaller. Analyzing the effects that divergence ratio, depth-span ratio and distance-height ratio has on the elastic flexural-torsional buckling loads of castellated beams and draw out some reduced calculation methods for the section's eigenvalues and elastic flexural-torsional buckling critical load of castellated beams.

Abstract: Using the method of complex analysis and by constructing conformal mapping, the study investigated the antiplane shearing problem of circular holes with 4k periodic cracks in one-dimensional hexagonal quasicrystals. Wherefrom we simulated the problem of antiplane shearing in circular holes of cross-cracks, symmetrical four-cracks, as well as symmetrical eight-cracks, and provided an analytic solution to the crack tip stress intensity factor (SIF).

Abstract: Using the model of stationary white noise excitation, defining the exact analytic method of random response and nearer value of earthquake action about single degree of freedom generalized Maxwell damping, firstly transform the motion equation into standard form, with the Laplace transform and Inverse Laplace transform method, obtained the exact analytical formula of structural response, calculate the response variance by the complex modal method and frequency domain decomposition and make comparisons, The response variance decomposition for the first standard vibrator and second order of the standard vibrator, According to the corresponding relationship between maximum response of the second order vibrator and The design response spectrum, calculated the maximum response by it, base on the maximum response proportion of the first standard vibrator and second, obtained the design of the structural response values and its corresponding earthquake force.

Abstract: The functional relationship between rock and coal permeability and gas adsorption quantity has been determined, based on earlier experimental results. Then, by method of mathematical physics, the authors derived an analytical solution for a gas seepage equation in which the adsorption effect has been considered. This analytical solution could be used for developing the theory of Seepage Mechanics and Computational Fluid Dynamics, and for checking and correcting various numerical solutions as a standard solution, and for inspiring various calculating techniques such as difference schemes, grid generation, and others as well. The analytical solution derived in this paper has extremely important practical significance in conducting the arrangement of gas extraction operation in coal mine and the CBM (coal bed methane) development planning.

Abstract: Real estate mass appraisal is the key preliminary work of imposing real estate tax in urban area.Various methods have been used for real estate mass appraisal,among which geographic information system(GIS) is a powerful method to improve the efficiency due to it’s capacity of spacial analysis and management.This article tries to explore the combination of GIS and Hedonic model,and uses GIS spacial analysis function to quantitative analysis influencing factors of real estate.At last we have a real estate mass appraisal practice on Xi’an,the result shows it is feasible and efficient to apply GIS in urban residential real estate mass appraisal.

Abstract: Two-dimensional electronic chart system can’t intuitively express the various information of 3D navigation environment, and the existing 3D electronic chart system lacks comprehensive display and scientific quantitative analysis. In that context, designed a 3D electronic chart system framework based on GIS and virtual reality technology (VR technology) and studied the key technologies such as visualization of 3D navigation environment, numerical simulation of water current and dynamic ship information display. Consequently, a 3D electronic chart system has been developed for Sutong Bridge section of Yangtze River waterway and it is verified to be feasible and reliable for ensuring safety of navigation.

Abstract: In order to ensure that a satellite navigation receiver is able to work under the navigation warfare environment, a design for dual system anti-jamming satellite navigation receiver is proposed. Space-time anti-jamming technology is analyzed, which takes linearly constrained minimum variance (LCMV) as the optimal criterion, weighted by power inversion, enhanced anti-jamming capability of the receiver. Digital beam forming technology with a stronger anti-jamming performance is realized by feedback of satellite orientation information from baseband. Simulations show that traditional space-time interference suppression technology can realize 70dB anti-jamming capability for an interference, and by introduction of the beam forming technology, the anti-jamming capability for an interference can achieved 85dB.