Publication Date:
2011-08-24
Description:
The Iterative DEsign of Antenna Structures (IDEAS) program is a finite element analysis and design optimization program with special features for the analysis and design of microwave antennas and associated sub-structures. As the principal structure analysis and design tool for the Jet Propulsion Laboratory's Ground Antenna and Facilities Engineering section of NASA's Deep Space Network, IDEAS combines flexibility with easy use. The relatively small bending stiffness of the components of large, steerable reflector antennas allows IDEAS to use pinjointed (three translational degrees of freedom per joint) models for modeling the gross behavior of these antennas when subjected to static and dynamic loading. This facilitates the formulation of the redesign algorithm which has only one design variable per structural element. Input data deck preparation has been simplified by the use of NAMELIST inputs to promote clarity of data input for problem defining parameters, user selection of execution and design options and output requests, and by the use of many attractive and familiar features of the NASTRAN program (in many cases, NASTRAN and IDEAS formatted bulk data cards are interchangeable). Features such as simulation of a full symmetric structure based on analyses of only half the structure make IDEAS a handy and efficient analysis tool, with many features unavailable in any other finite element analysis program. IDEAS can choose design variables such as areas of rods and thicknesses of plates to minimize total structure weight, constrain the structure weight to a specified value while maximizing a natural frequency or minimizing compliance measures, and can use a stress ratio algorithm to size each structural member so that it is at maximum or minimum stress level for at least one of the applied loads. Calculations of total structure weight can be broken down according to material. Center of gravity weight balance, static first and second moments about the center of mass and optionally about a user-specified gridpoint, and lumped structure weight at grid points can also be calculated. Other analysis outputs include calculation of reactions, displacements, and element stresses due to specified gravity, thermal, and external applied loads; calculations of linear combinations of specific node displacements (e.g. to represent motions of rigid attachments not included in the structure model), natural frequency eigenvalues and eigenvectors, structure reactions and element stresses, and coordinates of effective modal masses. Cassegrain antenna boresight error analysis of a best fitting paraboloid and Cassegrain microwave antenna root mean square half-pathlength error analysis of a best fitting paraboloid are also performed. The IDEAS program is written in ATHENA FORTRAN and ASSEMBLER for an EXEC 8 operating system and was implemented on a UNIVAC 1100 series computer. The minimum memory requirement for the program is approximately 42,000 36-bit words. This program is available on a 9-track 1600 BPI magnetic tape in UNIVAC FURPUR format only; since JPL-IDEAS will not run on other platforms, COSMIC will not reformat the code to be readable on other platforms. The program was developed in 1988.
Keywords:
COMMUNICATIONS AND RADAR
Type:
NPO-17783
Format:
text
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