Publication Date:
2011-08-24
Description:
The Panel Analysis and Sizing Code (PASCO) was developed for the buckling and vibration analysis and sizing of prismatic structures having an arbitrary cross section. PASCO is primarily intended for analyzing and sizing stiffened panels made of laminated orthotropic materials and is of particular value in analyzing and sizing filamentary composite structures. When used in the analysis mode, PASCO calculates laminate stiffnesses, lamina stress and strains (including the effects of temperature and panel bending), buckling loads, vibration frequencies, and overall panel stiffness. When used in the sizing mode, PASCO adjusts sizing variables to provide a low-mass panel design that carries a set of specified loadings without exceeding buckling or material strength allowables and that meets other design requirements such as upper and lower bounds on sizing variables, upper and lower bounds on overall bending, extensional and shear stiffnesses, and lower bounds on vibration frequencies. Although emphasis in PASCO is placed on flat panels having several identical bays, the only restriction on configuration modeling is that the structure is assumed to be prismatic. In addition, it is assumed that loads and temperatures do not vary along the length of a panel. Because of their wide application in aerospace structures, stiffened panels are readily handled by PASCO. The panel cross section may be composed of an arbitrary assemblage of thin, flat, rectangular plate elements that are connected together along their longitudinal edges. Each plate element consists of a balanced symmetric laminate of any number of layers of orthotropic material. Any group of element widths, layer thicknesses, and layer orientation angles may be selected as sizing variables. Substructuring is available to increase the efficiency of the analysis and to simplify the modeling of complicated structures. The Macintosh version of PASCO includes an interactive, graphic preprocessor called MacPASCO. The main objective of MacPASCO is to make the use of PASCO faster, simpler, and less error-prone. By using a graphical user interface (GUI), MacPASCO simplifies the specification of panel geometry and reduces user input errors, thus making the modeling and analysis of panel designs more efficient. The user draws the initial structural geometry on the computer screen, then uses a combination of graphic and text inputs to: refine the structural geometry, specify information required for analysis such as panel load conditions, and define design variables and constraints for minimum-mass optimization. Composite panel design is an ideal application because the graphical user interface can: serve as a visual aid, eliminate the tedious aspects of text-based input, and eliminate many sources of input errors. The current version of MacPASCO does not implement all the modeling features of PASCO, but has been found to be sufficient for many users. Many difficulties common to text-based inputs are avoided because MacPASCO uses a GUI. First, the graphic displays eliminate syntax errors, like misplaced commas and incorrect command names, because there is no text-based syntax. Second, graphic displays allow the user to see the geometry as it is created and immediately detect and correct any errors. Third, MacPASCO's drawing tools have been designed to avoid modeling errors. Fourth, the graphic displays make revisions to existing structural designs much easier and less error-prone by eliminating the need for the user to conceptualize the text input as geometry. The user can work directly with the geometry displayed on the screen. Finally, MacPASCO automatically generates the correct PASCO input from the geometry displayed on the screen. This input file can be used with any machine version of PASCO to actually perform the analysis and sizing and to output results. The DEC VAX version of PASCO is written in FORTRAN IV for batch execution and has been implemented on a DEC VAX series computer. The Macintosh version of PASCO was developed for Macintosh II series computers with at least 2Mb of RAM running MPW Pascal 3.0 and Language Systems FORTRAN 2.0 under the MPW programming environment. It includes MPW compatible makefiles for compiling the source code. The Macintosh version uses input files compatible with versions of PASCO running on different platforms. MacPASCO is written in Macintosh Programmers Workbench 3.0, MPW Pascal 3.0, and MacAPP 2.0. The Pascal source code is included on the distribution diskette. MacAPP is a development library which is not included. MacPASCO requires a Mac Plus, SE/30, or MacII, IIx, IIcx, IIci, or IIfx running System 6.0 or greater. MacPASCO is System 7.0 compatible. A minimum of 2Mb of RAM is required for execution. The Macintosh version of PASCO is distributed on four 3.5 inch 800K Macintosh format diskettes. The DEC VAX version is distributed on a 9-track 1600 BPI magnetic tape. The PASCO program was developed in 1981, adapted to the DEC VAX in 1983 and to the Macintosh in 1991. MacPASCO was released in 1992.
Keywords:
STRUCTURAL MECHANICS
Type:
LAR-14799
Format:
text
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