The Micromechanics Analysis Code Post-Processing (MACPOST) computer program is designed primarily to serve as an improved means of processing the output of the Micromechanics Analysis Code With Generalized Method of Cells (MAC/GMC) computer program. [MAC/GMC was described in "Comprehensive Micromechanics-Analysis Code (MAC/GMC)" (LEW-16870) NASA Tech Briefs, Vol. 24, No. 6 (June 2000), page 38. To recapitulate MAC/GMC is a comprehensive, user-friendly, efficient program that predicts the elastic and inelastic thermomechanical responses of continuous and discontinuous composite-material structures that have arbitrary internal microstructures and reinforcement shapes and are subjected to complex thermomechanical load histories.]

MACPOST operates within MSC/PATRAN — a commercial package of preprocessing and postprocessing software. MACPOST is written in the Patran Command Language (PCL), which is the programming language embedded in PATRAN. MACPOST establishes a direct link between the analysis capabilities of MAC/GMC and the postprocessing capabilities of MSC/PATRAN. MACPOST enables the graphical display of results of a MAC/GMC analysis in the following ways:

  • Contour plots of spatially and/or temporally localized results can be generated. For example, such a plot could indicate the spatial variation of stress or strain over a composite-material unit cell (that is, on a microscopic scale) at a specific time step of the analysis. Alternatively, one can require that local results be displayed at a point where a specified stress or strain on the macroscopic (average or global) level is indicated by the analysis.
  • The user can require the generation of two-dimensional (X-Y) plots of such quantities as temporal variations of stress, strain, and/or other specified quantities at the macroscopic or microscopic level (even within individual subcells of a composite-material unit cell).

The user provides input through a series of menus and forms. MACPOST checks for input errors. From the user input, MACPOST automatically carries out the MSC/PATRAN commands needed to generate the desired graphical displays. As a result, a user who is familiar with MAC/GMC but has only minimal knowledge of MSC/PATRAN can obtain useful results.

MACPOST enables the user to examine the MAC/GMC output more thoroughly. For example, by examining X-Y plots of results on the macroscopic scale, the user can identify spatial and/or temporal regions of particular interest; for example, the time when a stress-vs.-strain plot becomes nonlinear. Through the contour-plot option, the user can then examine graphically the variation of such quantities such as effective stress over the unit cell at the point of interest. By examining the contour plots, the user can determine what microscopic effects (for example, matrix-material stresses reaching the yield point) caused the trend observed in the macroscopic results.

This program was written by Robert K. Goldberg and Steven M. Arnold of Glenn Research Center and Brett A. Bednarcyk of Ohio Aerospace Institute. For further information, access the Technical Support Package (TSP) free on-line at  under the Software category.

Inquiries concerning rights for the commercial use of this invention should be addressed to

NASA Glenn Research Center
Commercial Technology Office
Attn: Steve Fedor
Mail Stop 4—8
21000 Brookpark Road
Ohio 44135.

Refer to LEW-16945.

NASA Tech Briefs Magazine

This article first appeared in the January, 2001 issue of NASA Tech Briefs Magazine.

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