Open AccessAeroelastic Behavior of Low Aspect Ratio Metal and Composite Blades
Author(s) -
Judith White,
Oddvar O. Bendiksen
Publication year - 1986
Publication title -
volume 1: turbomachinery
Language(s) - English
Resource type - Conference proceedings
DOI - 10.1115/86-gt-243
Subject(s) - aeroelasticity , flutter , torsion (gastropod) , supersonic speed , structural engineering , airfoil , materials science , composite number , mach number , rayleigh–ritz method , bending , aerodynamics , composite material , mechanics , engineering , physics , finite element method , medicine , surgery
The aeroelastic stability of titanium and composite blades of low aspect ratio is examined over a range of design parameters, using a Rayleigh-Ritz formulation. The blade modes include a plate-type mode to account for chordwise bending. Chordwise flexibility is found to have a significant effect on the unstalled supersonic flutter of low aspect ratio blades, and also on the stability of tip sections of shrouded fan blades. For blades with a thickness of less than approximately four percent of chord, the chordwise, second bending, and first torsion branches are all unstable at moderately high supersonic Mach numbers. For composite blades, the important structural coupling between bending and torsion cannot be modeled properly unless chordwise bending is accounted for. Typically, aft fiber sweep produces beneficial bending-torsion coupling that is stabilizing, whereas forward fiber sweep has the opposite effect. By using crossed-ply laminate configurations, critical aeroelastic modes can be stabilized.