Papers by Keyword: Local Stability

Abstract: In this paper the questions of local stability of castellated beams with openings of rhombic shape were considered. The studies were performed numerically on the finite-element models including investigation of castellated beam openings, flanges and a web thickness on critical load influence. The obtained results were verified by experimental data received from the tests performed on the 4-meters steel beams with different parameters of perforation. It was a changing relative width of web-posts under constant height of openings. The experiments confirmed reliability of stability calculations by FEM and show that, in fact, the critical load corresponding to buckling of web-posts determines bearing capacity of castellated beams. It was defined that under the fixed height of openings the critical load of beam with rhombic openings is almost independent on relative width of web-posts.

Abstract: The influence of local buckling on the bearing capacity of light steel thin-walled profiles is a hot topic today. In this paper we evaluated the effect of the thickness of the elements of the cross section on bearing capacity the profile in a transverse bending.

Abstract: Local buckling and accounting of the geometric nonlinearity of light steel thin-walled profiles is an important topic. The authors assesses the influence of geometric nonlinearity on the bearing capacity profile in transverse bending conditions.

Abstract: Work is devoted to the actual topic - local buckling of light steel thin-walled sections. Method of calculating stability in thin-walled structures described in the work. The mechanisms of local buckling under transverse bending considered by authors.

Abstract: Most methods for calculating bearing capacity profiles section of complex shape local buckling (LPA) are ignored. The problem of LPA rod is reduced to the problem of overall sustainability. At the design stage constructions of thin-walled beams, it is important to have a simple method for estimating the bearing capacity and the potential loss of local and general stability of the structure.

Abstract: In order to solve the problems of local stability of telescopic boom of truck crane in practical engineering, considering the initial geometric imperfection and the welding residual stress, the nonlinear local stability analysis of telescopic boom was studied by ANSYS software. APDL command flow was used for controlling the analytical process. Firstly, the foundational theories of the nonlinear finite element method were introduced. Secondly, the influence of the initial geometric imperfection and the welding residual stress on the nonlinear buckling of the boom was studied. Finally, the nonlinear buckling critical stress value of the curved cross section boom for an example was obtained, and it was used to compare with the rectangle, hexagon and dodecagon boom, consequently, a conclusion was drawn that the ability to resist bucking of curved cross section boom was stronger.

Abstract: Through the finite element simulation to study the local stability of the circle-castellated beams, reasonable finite element model was established using finite element software and in-depth analysis of the local stability of the circle-castellated beams on the basis of the castellated beams shear performance test. The same span of the circle-castellated beams, deformation stability performance under two point loads simulation, got deformation form of castellated beams under different pitch of holes, opening ratio, stiffener thickness, depth-thickness ratio. The local stability properties of the same span of the circle-castellated beams are directly related to opening ratio and web depth-thickness ratio changes, which has little effect with the change of hole spacing, stiffener thickness. Using the appropriate opening ratio, web depth-thickness ratio plays an important role on improving the local stability of web under the shear force and the bending moment.

Abstract: Checking the global and local stability of cooling towers during construction is very important to construction safety and reasonable construction process. On the basis of existing researches and by combining the checking method of global and local stability of cooling towers in operation period given in the present design code, this paper presents a method with implementation steps to check the global and local stability of cooling towers during construction. The method is verified to be simple and effective by a cooling tower example. The example analysis indicates that the global stability of cooling towers decreases with the construction height and achieves the minimum when the topmost layer is just built, though it increases bit when all concrete layers reach the design strength. The local stability of cooling towers during construction is poor in the range of 1/5 to 3/5 tower height and should be paid great attention during construction.

Abstract: A method to find the optimized parameter values of passive dynamic walking biped is presented. The effects of biped physical parameters on the stability property of passive gaits are studied by simulation experiments. The chosen parameters include the mass distribution, length of leg and slope angle. The stability property of passive walking limit cycles is used as criterion of optimization calculation, including the orbital stability described by eigen-values of linearized Poincaré map and the global property described by size of attraction region. The simulation results show how the stability of limit cycle varies when physical parameters of the passive biped change. The work is useful to explore the inherent property of passive dynamic walking and can be used as an important instruction in the mechanical design of biped robots based on principle of passive dynamic walking.

Abstract: The chaotic behaviors of the Arneodo’s system are investigated in this paper. Based on the Arneodo's system characteristic equation, the equilibria of the system and the conditions of Hopf bifurcations are obtained, which shows that Hopf bifurcations occur in this system. Then using the normal form theory, we give the explicit formulas which determine the stability of bifurcating periodic solutions and the direction of the Hopf bifurcation. Finally, some numerical examples are employed to demonstrate the effectiveness of the theoretical analysis.