Institute for Systems Research

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Author: search.filters.author.Austin, MarkSubject: search.filters.subject.computer aided design

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Now showing 1 - 6 of 6
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    A Systems Approach to Nonlinear Finite Element Analysis of Shell Structures
    (1995) Chen, Xiaoguang; Austin, Mark; ISR
    This report describes a systems approach to the nonlinear finite element analysis of shell structures. The research objective is to understand the structure a small language and computational environment should take so that matrix and nonlinear finite element computations can interact in a seamless manner.

    One four-node-thick shell finite element and one eight-node-thick shell finite element is formulated and implemented in ALADDIN [1]. The finite elements are based on a three-dimensional continuum formulation, and are simplified by assuming a flat element geometry. Numerical experiments are presented for in- plane displacements of a flat plate, and out-of-plane bending of a cantilever structure. In each case, material nonlinearities are modeled with bi-linear and Ramberg-Osgood stress-strain curves. The report concludes with recommendations for further work in the areas of nonlinear finite element solution procedures and enhancements to ALADDIN's problem-solving infrastructure.

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    ALADDIN: A Computational Toolkit for Interactive Engineering Matrix and Finite Element Analysis
    (1995) Austin, Mark; Chen, Xiaoguang; Lin, Wane-Jang; ISR
    This report describes Version 1.0 of ALADDIN, an interaction computational toolkit for the matrix and finite element analysis of engineering systems. The ALADDIN package is designed around a language specification that includes quantities with physical units, branching constructs and looping constructs. The basic language functionality is enhanced with external libraries of matrix and finite element functions.
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    XBUILD: Pre-processor for Finite Element Analysis of Steel Bridge Structures
    (1992) Austin, Mark; Creighton, Steven L.; Albrecht, Pedro; ISR
    Historically, the lack of interactive pre-processors to describe tedious finite element models has hindered the use of the finite element method for bridge analysis. The work performed in the present study mitigates this problem by providing an interactive graphically based pre-processor for the finite element analysis of highway bridges with high-speed engineering workstations. The name of the pre-processor is XBUILD. Version 1 of XBUILD is written in the C programming language, uses Sun View graphics, and runs on SUN SPARCstations. The pre-processor gives engineers the choice of using both keyboard and mouse styles of interaction to describe and edit bridge geometries, set boundary conditions, define sub-structure and highway vehicle objects, and place trucks at desired positions on the bridge. The capabilities of XBUILD Version 1 are demonstrated by working through the step-by- step details of creating a finite element model for the FHWA-AISI test bridge.
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    Structural Optimization in a Distributed Computing Environment
    (1991) Voon, B.K.; Austin, Mark; ISR
    This report presents the formulation and testing of a Feasible Sequential Quadratic Programming (FSQP-DIS) optimization algorithm customized to a Distributed Numerical Computing environment (DNC). DNC utilizes networking technology and an ensemble of loosely coupled processors to compute structural analyses concurrently. Each iterate of the FSQP-DIS is partitioned for concurrent computations in the direction calculation, and the steplength calculation. The prototype environment is tested on three applications; a mathematical programming problem, the design of a two-story planar steel frame, and finally, the optimal design of a two-story three- dimensional steel frame.
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    Solid Modeling of Reinforced Concrete Beams, Part I: Data Structures and Algorithms, Part II: Computational Environment
    (1991) Austin, Mark; Preston, J.L.; ISR
    This 2-part paper describes a solid modeling methodology for the interactive design and analysis of reinforced concrete (RC) beam structures. Part I covers the data structure and algorithms for steel reinforcing bar trajectories, and a three dimensional boundary representation of the concrete beam solid. Algorithms are given for slicing the beam, extracting cross sections, and computing the ultimate strength. Part 2 of this series discuss the design and implementation of an interactive design environment called Beam Tool.
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    Pre-Processor for Finite Element Analysis of Highway Bridges
    (1990) Creighton, Steven L.; Austin, Mark; Albrecht, Pedro; ISR
    Historically, the lack of interactive pre-processors to setup tedious finite element problem descriptions has hindered the use of the finite element method for bridge analysis. The work performed in the present study mitigates this problem via the use of highspeed engineering workstations. This report presents an interactive, graphically based pre-processor for the analysis of highway bridges with the finite element method. With the pre- processor, bridge design engineers can use both keyboard and mouse styles of interaction to describe bridge geometries. The UNIX tool YACC has been used to create a command language for describing and manipulating of structural geometries, material types, loads, and boundary conditions. The pre-processor was successfully used to create input files in a format acceptable to the finite element analysis program ANSYS. In fact, less than 20 minutes was needed to create a finite element model of the prototype bridge tested at the Turner-Fairbanks Laboratory in Langley, Virginia, in a joint FHWA-AISI project. This report describes the development of the pre-processor in words that can hopefully be understood by civil engineers and computer scientists alike.