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Buckling Load (buckling + load)
Selected AbstractsVibration of a space arc subject to a critical dynamic loadINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 4 2005Lazarus Teneketzis Tenek Abstract The present study concerns the dynamic behaviour of a space arc subject to a midarc vertical buckling load dynamically applied. The arc is discretized with a set of three-dimensional beam finite elements and the non-linear dynamic equation (large displacements) is solved by means of an unconditionally stable time-dependent scheme over time. The vertical excitation gives rise to a very fast and erratic horizontal wave as the structure begins to vibrate in all directions. This horizontal wave has chaotic characteristics as its attractor indicates. Time,displacement curves are obtained for all components of the midarc point. Although the time algorithm was executed here for 2000 time steps, simulation over longer periods of time can reveal the vibration characteristics and even simulate structural failure under the imposed dynamic buckling load for the space arc structure. Copyright © 2004 John Wiley & Sons, Ltd. [source] Critical buckling load of paper honeycomb under out-of-plane pressure,PACKAGING TECHNOLOGY AND SCIENCE, Issue 3 2005Li-Xin Lu Abstract Two out-of-plane buckling criteria for paper honeycomb are proposed by analysing the structure properties and the collapse mechanism of paper honeycomb: these are based on the peeling strength and ring crush strength of the chipboard wall. Taking into account the orthotropic, initial deflection and large deflection properties of the chipboard wall, the two new mechanical models and the calculation methods are developed to represent the out-of-plane critical load of paper honeycomb. Theoretical calculations and test results show that the models are suitable for describing the collapse mechanism of paper honeycomb. The peeling strength and ring crush strength determine the critical buckling load of paper honeycomb in different stretch phases. The out-of-plane critical buckling load can be predicted when the two models are integrated. Copyright © 2005 John Wiley & Sons, Ltd. [source] Mechanical properties of auxetic tubular truss-like structuresPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2008F. Scarpa Abstract The mechanical properties of cellular tubular structures made of centresymmetric cells are evaluated using analytical and numerical simulations. A theoretical model based on bending stiffness of the single ribs composing the unit cell of the tubes is developed, providing estimations for the Poisson's ratios and uniaxial stiffness of the tubular grid-like structures, as well as their Eulerian buckling load. Full 3D Finite Element models in linear elastic regime are used to validate the theoretical results. A continuum nonlinear tube bending model is also presented to show the dependence of the curvature-bending moment versus the Poisson's ratio of the core. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Initialization Strategies in Simulation-Based SFE Eigenvalue AnalysisCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2005Song Du Poor initializations often result in slow convergence, and in certain instances may lead to an incorrect or irrelevant answer. The problem of selecting an appropriate starting vector becomes even more complicated when the structure involved is characterized by properties that are random in nature. Here, a good initialization for one sample could be poor for another sample. Thus, the proper eigenvector initialization for uncertainty analysis involving Monte Carlo simulations is essential for efficient random eigenvalue analysis. Most simulation procedures to date have been sequential in nature, that is, a random vector to describe the structural system is simulated, a FE analysis is conducted, the response quantities are identified by post-processing, and the process is repeated until the standard error in the response of interest is within desired limits. A different approach is to generate all the sample (random) structures prior to performing any FE analysis, sequentially rank order them according to some appropriate measure of distance between the realizations, and perform the FE analyses in similar rank order, using the results from the previous analysis as the initialization for the current analysis. The sample structures may also be ordered into a tree-type data structure, where each node represents a random sample, the traverse of the tree starts from the root of the tree until every node in the tree is visited exactly once. This approach differs from the sequential ordering approach in that it uses the solution of the "closest" node to initialize the iterative solver. The computational efficiencies that result from such orderings (at a modest expense of additional data storage) are demonstrated through a stability analysis of a system with closely spaced buckling loads and the modal analysis of a simply supported beam. [source] Block diagonalization of Laplacian matrices of symmetric graphs via group theoryINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2007A. Kaveh Abstract In this article, group theory is employed for block diagonalization of Laplacian matrices of symmetric graphs. The inter-relation between group diagonalization methods and algebraic-graph methods developed in recent years are established. Efficient methods are presented for calculating the eigenvalues and eigenvectors of matrices having canonical patterns. This is achieved by using concepts from group theory, linear algebra, and graph theory. These methods, which can be viewed as extensions to the previously developed approaches, are illustrated by applying to the eigensolution of the Laplacian matrices of symmetric graphs. The methods of this paper can be applied to combinatorial optimization problems such as nodal and element ordering and graph partitioning by calculating the second eigenvalue for the Laplacian matrices of the models and the formation of their Fiedler vectors. Considering the graphs as the topological models of skeletal structures, the present methods become applicable to the calculation of the buckling loads and the natural frequencies and natural modes of skeletal structures. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||