Panel Flutter Analysis and Optimization of Composite Tow Steered Plates

Abstract

The flutter behavior of tow steered composite panels, in which the fiber placement follow curvilinear trajectory, is evaluated. A simple structural model based on Ritz method combined with supersonic aerodynamic piston theory is used to analyze the aeroelastic behavior. Classical lamination plate theory and symmetric stacking sequence are used and the fiber trajectories are defined by Lagrange interpolation functions. The flutter stability boundaries for optimal conventional (constant stiffness laminates) layups and nonconventional (variable stiffness laminates) steered panels are numerically compared. The effect of in-plane loads is also accounted for in the aeroelastic analyses.

Measurement of sub degree angular carbon fiber tow misalignment

“…2). Calculating the far field distance d f using df =2 (D 2 )/λ ( 1 ) where D is the largest antenna aperture dimension (164 mm,) and λ is the wavelength (144.8 mm at 2.670 GHz), yields d f = 371.4 mm. This establishes that the 510 mm antenna-to-tape distance for this experiment is in the far field.…”

“…Because a side effect of reducing structural weight is an increased susceptibility of wings to enter into flutter conditions, methods of reducing the onset of flutter are concurrently being explored. One method of reducing the probability of flutter onset in a CFRP wing structure is to aeroelastically "tune" the structural characteristics via carbon fiber tow steering [1,2]. Both flutter and gust response can be modified using tow steering methods [3].…”

Aeroelastic panel flutter optimization of tow-steered variable stiffness composite laminated plates using isogeometric analysis

“…Guimaraes et al. 11 studied the flutter behavior of tow-steered flat thin composite panels with curvilinear fiber placements using the Ritz method. The flutter stability boundaries of optimal conventional layups (constant stiffness laminates) and nonconventional steered panels (variable stiffness laminates) were extracted and compared.…”

Optimal design, manufacturing and testing of non-conventional laminates

“…The use of linearly varying fiber angle per bay, for stiffened plates, has also been investigated, and again it has been shown that varying the fiber angles leads to better performance [7,8]. Direct parametrisation of the tow paths using Lagrangian polynomials [9,10,11] Lobatto-Legendre polynomials [12,13], Bezier curves [14,15,16], splines [17,18], B-splines surfaces [19] and NURBS (Non-Uniform Rational B-Splines) [20] have also been used. Constant curvature paths have been extensively applied for flat panels and for cylindrical and conical shells [21,22,23,24,25], as the curvature constraint evaluation is simplified.…”