دانلود رایگان مقاله عنصر تیر به ستون فضایی برای تحلیل مرتبه دوم از ساختار پوسته شبکه

Abstract

A new method of damping flexural vibrations in plate-like structures based on the ‘acoustic black hole effect’ has been recently developed and investigated. As ‘acoustic black holes’, one-dimensional elastic wedges of power-law profile covered by narrow strips of absorbing layers near sharp edges have been used initially. The addition of such power-law profiled wedges to edges of rectangular plates or strips results in substantial increase in damping of resonant flexural vibrations in such plates or strips due to the more efficient absorption of flexural waves at the tips of power-law wedges. One of the problems faced by this method of damping is having the wedge tips exposed on the outer edges of the plate or strip. One of the solutions to this problem is to move the wedges inside a plate, so that they form edges of power-law slots within the plate. The present paper reports the results of the experimental investigations into the effects of such slots on damping flexural vibrations. The obtained experimental results show that introducing power-law profiled slots within plates represents an effective method of damping flexural vibrations, which is comparable with the method using power-law wedges at plate edges.

6. Conclusions

(1) Considering the coupling effect of axial force, bending moment and shear force, the displacement interpolation functions of the spatial beam-column element under axial tension and axial compression are derived respectively based on the differential equilibrium equations of the deformed member. (2) The different displacement interpolation functions of the tension and compression elements are unified by replacing the stability integration functions with the Maclaurin series, and the unified functions are completely equivalent to those expressed by stability integration functions. The number of series expansion terms in unified displacement interpolation functions is determined from aspects of calculation accuracy and positive definiteness of the structural general stiffness matrixes. (3) The second-order element tangent stiffness matrix considering the effect of axial deformation, shear deformation, biaxial bending and torsion is derived. (4) Numerical calculation results by this element model accord well with the experimental data, and it indicates the accurateness of this element. Different element models are used in the analyses of a single layer lattice shell, and calculation results indicate that the geometrical nonlinearity of the structure is efficiently exhibited by the refined spatial beam-column element proposed in this paper. Acknowledgments Financial supports from National Natural Science Foundation of China (51508557, 91315301), Open Fund of the Airport Engineering Research Base of Civil Aviation University of China (KFJJ2014JCGC05), Research Initial Fund of Civil Aviation University of China (2014QD08X), and Fundamental Research Funds for Central Universities “Seismic Isolation Control Research of Near-Fault Airport Architecture in High Seismic Intensity Region” are gratefully acknowledged.