Representative stiffened panels are optimized such that multiple buckling modes and failure (using open hole allowables) occur within a range of 10% of the lowest buckling load. This implies the panels cannot be loaded up to the buckling load without risking failure, hence vibrational correlation testing was used to estimate the buckling loads and modes. At the same time, a finite element model was created using the Carrera Unified Formulation. This model was validated using the tests and a good correlation between both was observed. Three panels were manufactured and each panel was put in place for testing twice. Each time a panel was put in place, the test was repeated three times. This allowed us to get a ballpark estimate for the variation due to replicas of the panel, the test set-up and repeating the tests. @en

The present paper deals with the buckling and post-buckling analysis of a multilayered composite reinforced panel. The panel, design for aeronautical applications, results in a complex stacking sequence, and the development of a refined model able to describe its geometrical nonlinear behavior is mandatory to avoid the usage of highly computational effort-required 3D finite elements. The proposed approach is a finite element analysis based on the Carrera Unified Formulation (CUF). Thanks to CUF, a 1D model of the composite panel can be formulated and complicated stress fields within the structure can be evaluated, so the nonlinear behavior is fully described. A refined Equivalent Single Layer (ESL) technique is employed, making use of Lagrange polynomials for the description of the stacking sequence. The results clearly demonstrate the reliability of this approach, comparing the linearized buckling and nonlinear post-buckling solutions with those from Nastran (1D, 2D and 3D) and experiments. @en

This research work deals with the buckling load prediction of reinforced laminated composite panels of aeronautical interest. Being subjected to pure compression, these panels are characterized by stable post-buckling. Thus, the vibration correlation technique (VCT) is utilized herein as an effective nondestructive means to extrapolate critical loads from free vibration measurements. A hierarchical design of experiments, making use of nested multifactors (i.e. panel replicas, test setups, and measurement repetitions), is employed to estimate components of variance. The experimental outcomes are compared with the results of an advanced finite element model with layer-wise kinematics and based on the Carrera Unified Formulation (CUF). The results show that, although obtained with a low number of tests and specimens, the VCT experiments are repeatable and provide a good validation of the numerical simulations, which are demonstrated to be accurate and reliable.

@en

This paper presents the main outcomes of the preliminary development of the Anuloid, an innovative disk-shaped VTOL aircraft. The Anuloid has three main features: lift is provided by a ducted fan powered by a turboshaft; control capabilities and anti-torque are due to a system of fixed and movable surfaces that are placed in the circular internal duct and the bottom portion of the aircraft; the Coanda effect is exploited to enable the control capabilities of such surfaces. In this paper, results from flight mechanics are presented. The vertical flight dynamics were found to be desirable. In contrast, the horizontal flight dynamics of the aircraft shows both dynamic instability, and more importantly, insufficient pitch and roll control authority. Some recommendations and guidelines are then given aimed at the alleviation of such problems.@en