Finite Element Modeling of the NASA Langley Aluminum Testbed Cylinder

Abstract

The The finite element models were updated and refined, using physical parameters, to increase correlation with the measured modal data. Excellent agreement, within an average 1.59/; to 2.9%, was obtained between the predicted and measured modal frequencies of the stringer, frame and dome components. The predictions for the modal frequencies &the assembled component Configurations I through V were within an average 2.9% and 9.1%. Finite element modal analyses were performed fbr comparison with 3 psi and 6 psi internal pressurization conditions in Configuration VI. The modal fi'eqnencies were predicted by" applying differential stiNless to the elements with pressure loading and creating reth_ced matrices for beam elements with offisets inside external superelements. The average disagreement between the measured and predicted diffi_rences tbr the 0 psi and 6 psi internal pressure conditions was less than 0.5%. Comparablygood agreement was obtained tbr the diftbrences between the 0 psi and 3 psi measured and predicted internal pressure conditions.

Isogeometric analysis of structural vibrations

“…Figs. [23][24][25] show that the order of convergence of frequencies using NURBS is optimal, that is O(h 2(pÀ1) ). The analytical computation of the discrete spectrum, performed previously for the rod problem, can also be done in the present case.…”

“…Note that there are gaps between the stringer and the ribs in the notch regions. Experimental vibration data have been obtained for a typical isolated stringer, a typical isolated main rib, the frame assembly, and the frame and skin assembly (see [23,9,18] for details and reference computational results). Calculations were performed of each of the corresponding isogeometric models.…”

Analise de sensibilidade vibroacustica de paineis aeronauticos reforçados

“…Pode-se modelar um painel aeronáutico, a partir da montagem de seus componentes, tais como, reforçadores, cavernas, e revestimento ou placas de fechamento (Grosveld, 2002, Buehrle, 2000e Grosveld, 1998.…”

“…A malha de elementos finitos é mostrada na Figura 6.18.b, e as propriedades e dimensões são descritas na Tabela 6.9. As características e condições de contorno adotadas no modelo são consistentes com modelos de fuselagem já estudados (Grosveld, 2002). Assim, as condições de contorno assumidas para este problema consistem na restrições de translação e rotação nos extremos do cilindro.…”