^^^^^^^^^^^^^^ NASTRAN ^^^^^^^^^^^^^^

oppurePostscript, or PDF

Abstract: AS&M, Inc. performed finite element analysis, with and without discrete damage, of a composite semi-span test article that represents the Boeing 220-passenger transport aircraft composite semi-span test article. A NASTRAN bulk data file and drawings of the test mount fixtures and semi-span components were utilized to generate the baseline finite element model. In this model, the stringer blades are represented by shell elements, and the stringer flanges are combined with the skin. Numerous modeling modifications and discrete source damage scenarios were applied to the test article model throughout the course of the study. This report details the analysis method and results obtained from the composite semi-span study. Analyses were carried out for three load cases: Braked Roll, 1.0G Down-Bending and 2.5G Up-Bending. These analyses included linear and nonlinear static response, as well as linear and nonlinear buckling response. Results are presented in the form of stress and strain plots, factors of safety for failed elements, buckling loads and modes, deflection prediction tables and plots, and strain gage prediction tables and plots. The collected results are presented within this report for comparison to test results.

^^^ '99 Non-Linear Finite Element Modeling of THUNDER Piezoelectric Actuators(NASTRAN) http://wais-gw.larc.nasa.gov:81/techreports.larc.nasa.gov:210/ltrs_index/HTML/2236/1=techreports.larc.nasa.gov%3A210;2=/usr/local/web/waissrc/ltrs_index;3=0%202236%20/usr/local/web/htdocs/ltrs/refer/1999/mtg/NASA-99-6spie-bkt.refer.html;4=techreports.larc.nasa.gov%3A210;5=/usr/local/web/waissrc/ltrs_index;6=0%202236%20/usr/local/web/htdocs/ltrs/refer/1999/mtg/NASA-99-6spie-bkt.refer.html;7=%00; DUE ARTICOLI: marzo PDF MARZO , maggio PDF MAGGIO

^^^ '99 Finite Element Analysis of a Composite Semi-Span Test Article With and Without Discrete Damage (NASTRAN) http://wais-gw.larc.nasa.gov:81/techreports.larc.nasa.gov:210/ltrs_index/HTML/2746/1=techreports.larc.nasa.gov%3A210;2=/usr/local/web/waissrc/ltrs_index;3=0%202746%20/usr/local/web/htdocs/ltrs/refer/2000/cr/NASA-2000-cr210308.refer.html;4=techreports.larc.nasa.gov%3A210;5=/usr/local/web/waissrc/ltrs_index;6=0%202746%20/usr/local/web/htdocs/ltrs/refer/2000/cr/NASA-2000-cr210308.refer.html;7=%00;

^^^ '99 (NASTRAN) DETERMINATION OF NONLINEAR STIFFNESS COEFFICIENTS FOR FINITE ELEMENT MODELS WITH APPLICATION TO THE RANDOM VIBRATION PROBLEM Alexander Muravyov, 1999 MSC Aerospace Users' Conference, Long Beach, California, http://techreports.larc.nasa.gov/ltrs/PDF/1999/mtg/NASA-99-mscauc-aam.pdf

Abstract: In this paper, a method for obtaining nonlinear stiffness coefficients in modal coordinates for geometrically nonlinear finite-element models is developed. The method requires application of a finite-element program with a geometrically nonlinear static capability. The MSC/NASTRAN code is employed for this purpose. The equations of motion of a MDOF system are formulated in modal coordiantes. A set of linear eigenvectors is used to approximate the solution of the nonlinear problem. The random vibration problem of the MDOF nonlinear system is then considered. The solutions obtained by application of two different versions of a stochastic linearization technique are compared with linear and exact (analytical) solutions in terms of root-mean-square (RMS) displacements and strains for a beam structure.

^^^ ' 98 A Unified Micromechanical Model for the Elastic, Elasto-Plastic, and Strength Behaviors of Textile Composites,home

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