Analysis Of Large Space Structures Research Articles

Two kinds of tube elements for transient thermal–structural analysis of large space structures

AbstractTwo kinds of thin‐walled tube elements are presented for transient thermal–structural analysis of large space structures by the finite element method. Not only the average temperature, but also the perturbation temperature in the cross‐section of the tube is considered in the present elements. These two temperatures are decoupled in the deduction about the new elements and the non‐linear analysis is restricted to solving the equations of average temperature. Therefore, the magnitude of the non‐linear analysis can be reduced by the presented method. The main difference between the two kinds of thin‐walled tube elements is in the shape functions of the temperature along the circumference of cross‐section. Corresponding to the transient temperature field, quasistatic thermo‐elastic analysis is also introduced. Three examples are shown and the effectiveness of the new elements is discussed. Copyright © 2004 John Wiley & Sons, Ltd.

Design of Large Space Structures with Imperfection Using ANN-Based Simulator

Based on the advanced computational plasticity and an artificial neural network (ANN) simulator, a new design strategy has been presented for large space structures with imperfections. Nonlinear system identification approach has also been greatly spread among the researchers and engineers in the past few years. The neural network simulators as a non-parametric system identification approach present a robust and efficient way to simulate the nonlinear behaviour of engineering systems. In the paper herein an artificial neural network (ANN) simulator, a general back error propagating perceptron, is use to simulate random imperfection for nonlinear dynamic analysis of large space structures. It is also desirable to search for a procedure for wind pressure calculation with accuracy and reliability. In this respect, attention is paid to the advanced computational fluid dynamics (CFD). The use of the advanced CFD analysis can help engineers to estimate the wind pressure for the design of large space structures with complex geometries. The characteristics of the new design method have been shown graphically using a full documented numerical example, which highlights the efficiency of the new simulation method. The purpose of this paper is to present a new design method, which takes into account the effects of imperfection on the resulting dynamic responses of large space structures under gravity, temperature and wind loadings.

Simulation of Impact Effects on Large Space Structures Using Advanced SE Method

One of the important parameters in analysis and design of large space structures is to account for the possible forces induced by flying object impact and the subsequent progressive collapse. Conventional finite element methods have been used successfully in linear and nonlinear dynamic analyses of large space structures. During the past three decades, problems of contact mechanics have also been considered by some authors, and special attention has been devoted to high speed impact. Impact wave propagation in space structures may be analyzed using the conventional finite element method. However, in order to guarantee stability and accuracy of the solution, the number of elements used to model the structure may be very large indeed; more precisely, accurate results can be obtained only after a substantial computational effort. In this respect, the spectral element method (SEM) is developed for analyzing the wave propagation problems in large space structures. Using a computer program, the proposed formulation has been used to derive the impact global dynamic responses of a large dome structure.

Frequency Domain Dynamic Analysis of Large Space Structures with Added Elastomeric Dampers

Modern computer-based computational techniques such as the finite element method enable the structural dynamicist to make precise calculations of the mass and stiffness properties of complex large space structures (LSS). To obtain dissipation analysis up to the same level of sophisitcation as mass and stiffness analysis in damped structures, an equally accurate methodology is required. This paper presents one such methodology for LSS with added elastomeric dampers. Elastomeric dampers have been used in the different parts of LSS to absorb part of the vibrational energy, and to help reduce the damage caused by the dynamic forces. The purpose of this paper is to present the specturally formulated finite element analyses for damped LSS. Using the fractional derivative model, the non-linear damping characteristics of elastomeric dampers have been modelled.

Parallel-Vector Algorithms for Analysis of Large Structures

In analysis of large space structures, the major computational steps are evaluation and assembly of the structure stiffness matrix and solution of the resulting simultaneous linear equations. In this paper we present efficient parallel-vector algorithms for these steps of structural analysis. The goal is to optimize the performance of the algorithms through judicious combination of parallel processing and vectorization. Parallel-vector algorithms are presented for solution of linear simultaneous equations using Cholesky decomposition and preconditioned conjugate gradient approaches. The algorithms are applied to three large space structures modeling the exterior envelope of high-rise and super high-rise building structures in the range of 50–162 stories with up to 6,136 members. Performance results are presented in terms of central-processing-unit time on a Cray Y-MP8/864 supercomputer, MFLOPS (millions of floating point operations per second), and speedup.

Use of load‐dependent vectors for dynamic analysis of large space structures

AbstractStructural models of large space structures have a substantial number of degrees of freedom (DOF) and possess semi‐positive‐definite stiffness matrices. The paper presents an efficient co‐ordinate reduction procedure for structural dynamic analysis of large space structures. The method is based on the superposition of load‐dependent Ritz vectors, which are computed in block form using a shifted stiffness matrix. Comparative transient dynamic analyses are performed on a 2803 DOF model of the space station Freedom using the load‐dependent method (LDM) and the mode‐displacement method (MDM) based on the superposition of eigenvectors. It is shown that the LDM is able to provide convergence of displacements with a small number of vectors. The acceleration response is found to be more sensitive to vector truncation than the displacement response. Error norms based on the representation of the dynamic load by the vector basis are developed to provide an indication of the effect of vector truncation on the structural response.

Dynamic Analysis of Large Space Structures Using Transfer Matrices and Joint Coupling Matrices

Abstract Linear dynamic analysis of lattice structures using transfer matrices and joint coupling matrices is presented. A lattice structure is defined as a network of one-dimensional members that are connected by joints. Two examples are considered to illustrate how transfer matrices and joint coupling matrices may be used to compute natural frequencies of vibration. These two examples indicate that the transfer matrix and joint coupling matrix analysis is numerically accurate over a wide range of frequencies and becomes increasingly efficient, compared to the finite element method, as the frequency increases. Some suggestions for further improvements in computational efficiency and some comments about applicability to numerical analysis of wave propagation problems are given.

Dynamic Response Analysis of Large Latticed Space Structures

In this paper an alternative method for dynamic response analysis of large space structures is presented, for which conventional finite element analysis would require excessive computer storage and computational time. Latticed structures in which the height is very small in comparison to its overall length and width are considered. The method is based on the assumption that the structure can be embedded in its continuum, in which any fiber can translate and rotate without deforming. An appropriate kinematically admissable series function is constructed to descrbe the deformation of the middle plane of this continuum. The unknown coefficients in this function are called the degree-of-freedom of the continuum, which is given the name “super element.” Transformation matrices are developed to express the equations of motion of the actual systems in terms of the degrees-of-freedom of the super element. Thus, by changing the number of terms in the assumed function, the degrees-of-freedom of the super element can be increased or decreased. The super element response results are transformed back to obtain the desired response results of the actual system. The method is demonstrated for a structure woven in the shape of an Archimedian spiral.

Thermal-structural analysis of large space structures - An assessment of recent advances

Recent advances in modeling, analyzing, and understanding the thermal-structural responses of large space structures are reviewed, and uncertainties in the thermal-structural analysis are identified. Typical heat-load, thermal, and structural analyses requirements for large space structures are discussed using a design for a future large spacecraft as an example. The current status of heating, thermal, and structural analyses is then reviewed, and computer programs used in research and design are discussed. The need to develop efficient methods for integrating the interdisciplinary analyses is emphasized.

An Algorithm for Identification and Analysis of Large Space Structures

The identification of the mass, damping and stiffness matrix for the finite-element formulation of a structure will be given. It will be shown that the quadrature integration procedure can be used to find the desired matrices when reasonable assumptions hold. The mass, damping and stiffness matrices of the matrix polynomial are identified by the algorithm.