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Foundation ::
Engineering Applications ::
PASCO
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PASCO
Structural Panel Analysis and Sizing Code
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Moderators:
Adopt This Application!
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SOURCE CODE AVAILABLE
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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 textbased
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.
PASCO carries the NASA case number LAR-14799. It was originally released as part of the NASA COSMIC collection.
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