Crack-induced Changes in Divergence and Flutter of Cantilevered Composite Panels

Abstract

The aeroelastic characteristics of a cantilevered composite panel of large aspect ratio and with an edge crack are investigated. The panel consists of several fiber-reinforced composite plies, and is modeled with a one-dimensional beam vibrating in coupled bending and torsion. The fundamental mode shapes of the cracked cantilever are used to study the interaction between a crack and aerodynamic characteristics by employing Galerkin’s method. Variation of the divergence/flutter speed with respect to the crack ratio, its location as well as the fiber angle is investigated. The divergence/flutter speed is more sensitive to the bending-torsion coupling parameter than to the presence of the crack. The crack may or may not reduce the divergence/flutter speed, depending on the fiber orientation. The qualitative analysis may help the development of an online prognosis tool for an aircraft with large aspect-ratio unswept composite wings.

Aeroelastic assessment of cracked composite plate by means of fully coupled finite element and Doublet Lattice Method

“…Modal analysis is performed to validate the procedure used in this work. The benchmark results of vibration modes are compared with the results presented by Wang et al [14]. In Table 3, the results of the modal analysis for a unidirectional composite of θ = 0 using the presented method are shown and are compared with the results established in [14].…”

“…All eight vibrations modes (four bending modes and four torsion modes) that are presented in Table 3 are plotted in Fig 10. It is a different modelling technique in observing the modal vibration modes. Thus, in this case, the finite element modelling has been applied to the unidirectional cracked composite panel instead of a cracked beam presented in [14]. In the reference, an analytical model was used to determine the natural frequencies/ mode shapes.…”

“…The flutter speed, V F is determined for several cases of crack ratio, η = a/b which are 0.2, 0.25, 0.4, 0.5, 0.6 and 0.75. The normalized flutter speeds of V F /V R versus the crack ratio which are compared with results in [14] as shown in Fig. 13.…”

“…Based on the overview, it can be seen that there is a lack of publication on the flutter of cracked composite. Moreover, at subsonic regime, to the authors knowledge, only Wang et al [14] studied it by means of analytical/semi-computational model. As most transport and light aircrafts are operating in subsonic regime, thus it is considered a great benefit to investigate the flutter effect on cracked composite within this airspeed regime.…”

Developing an integrated structural health monitoring and damage prognosis (SHM-DP) framework for predicting the fatigue life of adhesively-bonded composite joints

“…; qg. In particular, the wing skin-to-spar adhesive joints are recognized as the most fatigue-sensitive structural elements of a lightweight composite UAV because the progressive debonding, evolving from the wing-root along these joints, can compromise the global aeroelastic performance of the vehicle (Bauchau & Loewy, 1997;Styuart, Demasi, Livne, & Lin, 2008;Styuart, Demasi, Livne, & Mor, 2011;Styuart et al, 2007;Wang, Inman, & Farrar, 2005). All probabilistic information necessary to fully embed and execute this analysis step within the proposed SHM-DP framework are contained in the joint PDF of the load intensity measure vector denoted as f IM (im).…”