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65 lines
3.3 KiB
65 lines
3.3 KiB
2 years ago
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\chapter{Introduction}
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The \numbers\ program is a shell program which reads and stores data
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from a finite element model described in the \exo\ database
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format~\cite{EXODUS}.
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Within this shell program are several utility routines which calculate
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information about the finite element model. The utilities currently
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implemented in \numbers\ allow the analyst to determine:
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\begin{itemize}
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\item the volume and coordinate limits of each of the materials in the model;
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\item the mass properties of the model;
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\item the minimum, maximum, and average element volumes for each material;
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\item the volume and change in volume of a cavity;
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\item the nodes or elements that are within a specified distance from a
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user-defined point, line, or plane;
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\item an estimate of the explicit central-difference timestep for each
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material;
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\item the validity of contact surfaces or slidelines, that is, whether
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two surfaces overlap at any point; and
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\item the distance between two surfaces.
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\end{itemize}
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These utilities have been developed to automate and simplify some of the
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tasks normally performed during an analysis. The \numbers\ program
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reads the finite element model and results from a file written in the
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\exo\ binary file format which is used in the Engineering
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Analysis Department at \SNLA.
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The capabilities of \numbers\ have evolved during the past eighteen
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months. Originally, it was written solely to calculate the mass
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properties of a body. However, once the basic function of reading and
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storing an \exo\ database was in place, it was realized that several
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tasks that were usually performed manually could easily be implemented
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in \numbers. Tasks such as determining node and element numbers,
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verifying contact surfaces, and others, are now performed more
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efficiently and, hopefully, more accurately since the code performs the
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repetitive calculations automatically.
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Although the original reason for developing \numbers\ was to simply
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calculate mass properties, the code now functions as an \exo\ shell that
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can be easily extended by analysts who require specific calculations or
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need to create information not currently available. The analyst can
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simply write a subroutine to perform their function, and insert it into
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\numbers\ without worrying about the details of reading an \exo\
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database and providing a user interface. For most cases, adding a
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function to \numbers\ requires only writing the function subroutine,
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adding the command name to the table of valid commands, and adding a few
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statements to call the routine.
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The remainder of this report is organized as follows.
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Chapter~\ref{c:numerics} describes the numerical algorithms used by the
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utility functions in \numbers. A list of the commands and the command
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syntax are presented in Chapter~\ref{c:commands}.
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Chapter~\ref{c:examples} gives several examples of the use of the
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utilities, and Chapter~\ref{c:conclude} concludes the report. Three
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appendixes are included. Appendix~\ref{a:cmdsum} is a summary of the
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command syntax for each of the commands.
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The descriptions in the following chapters assume that the reader is
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familiar with the \gen\ and \exo\ file formats and with the analysis,
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preprocessing, and postprocessing codes used in the Engineering Analysis
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Department at \SNLA. Readers not familiar with these can check the
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references at the end of this report for a list of the documentation for
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these codes and file formats.
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