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Design Spectrum Analysis in NASTRANThe utility of Design Spectrum Analysis is to give a mode by mode characterization of the behavior of a design under a given loading. The theory of design spectrum is discussed after operations are explained. User instructions are taken up here in three parts: Transient Preface, Maximum Envelope Spectrum, and RMS Average Spectrum followed by a Summary Table. A single DMAP ALTER packet will provide for all parts of the design spectrum operations. The starting point for getting a modal break-down of the response to acceleration loading is the Modal Transient rigid format. After eigenvalue extraction, modal vectors need to be isolated in the full set of physical coordinates (P-sized as opposed to the D-sized vectors in RF 12). After integration for transient response the results are scanned over the solution time interval for the peak values and for the times that they occur. A module called SCAN was written to do this job, that organizes these maxima into a diagonal output matrix. The maximum amplifier in each mode is applied to the eigenvector of each mode which then reveals the maximum displacements, stresses, forces and boundary reactions that the structure will experience for a load history, mode by mode. The standard NASTRAN output processors have been modified for this task. It is required that modes be normalized to mass.
Document ID
19840024799
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Butler, T. G.
(Butler Analyses Towson, MD, United States)
Date Acquired
August 12, 2013
Publication Date
August 1, 1984
Publication Information
Publication: COSMIC Twelfth NASTRAN (R) Users' Colloq.
Subject Category
Structural Mechanics
Accession Number
84N32870
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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