Italian Aerospace Research Centre

About: Italian Aerospace Research Centre is a other organization based out in Capua, Campania, Italy. It is known for research contribution in the topics: Aerodynamics & Morphing. The organization has 278 authors who have published 400 publications receiving 3563 citations. The organization is also known as: CIRA & Italian Aerospace Research Center.

Crashworthiness of a Composite Wing Section: Numerical Investigation of the Bird Strike Phenomenon by Using a Coupled Eulerian–Lagrangian Approach

Abstract: Crashworthiness is defined as the capability of a structure to guarantee its occupants safety during a crash event. In the present work, the crashworthiness of a composite wing section, subjected to a bird strike event, has been investigated. Indeed, the mechanical behavior of the impacted wing section has been inspected by means of the FE code Abaqus/Explicit. The impact phenomenon has been numerically simulated with a coupled Eulerian–Lagrangian (CEL) approach. The impacted structure has been modeled considering a Lagrangian formulation, while a Eulerian one has been used to model the bird. Moreover, Eulerian–Lagrangian contacts are used for transfer the loads arising from the impact event to the Lagrangian structure. The proposed numerical model, capable to take into account the matrix and fiber traction and compression damages, uses a 3D finite element approach to better predict the deformations and the damages onset and propagation during the impact event. The numerical results, in terms of structural deformation and damage onset and propagation, have been obtained by considering different impact locations and different impact angles.

Enhanced electrical properties of carbon fiber reinforced composites obtained by an effective infusion process

Abstract: Carbon fiber reinforced composites (CFRCs) panels were manufactured with a Resin Film Infusion (RFI) approach by mixing a tetrafunctional epoxy precursor with a reactive diluent which allows to reduce the viscosity of the matrix and facilitate the dispersion in it of 0.5 wt.% multiwall carbon nanotubes (MWCNTs). The proper choice of the viscosity value and the infusion technique allows to obtain high electrical conductivity of panels composed by 7 plies of carbon fiber (crossing at 90°) cloths. The anisotropic electrical behavior is characterized by two in-plane electrical conductivities of 11.34 kS/m (in the direction parallel to the fibers) and 9.57 kS/m (at 45° with respect to the fibers), whereas a value of 1.75 S/m was achieved for the out of plane (through the thickness) value. The DC measurements confirm that the fibers govern the conduction mechanisms in the in-plane direction, whereas the percolating path created by the effective distribution of MWCNTs, favoured by resin formulation and adopted processing approach, leads to a significant enhancement of the overall electrical performance of the CFRCs.

Helicopter blade morphing strategies aimed at mitigating environmental impact

Abstract: The requirement of mitigating the environmental impact of helicopters has been addressed globally within the FRIENDCOPTER Project in the sense that several aspects (such as noise abatement, vibration reduction, fuel consumption)havebeen studied in parallelwith different approachesamong whichthereistheactivebladecontrol.Intheworkathand,attentionispaid on two topics aimed at mitigating helicopter environmentalimpact through a morphing strategy: the aerodynamic optimization of a blade section whose camber can be affected by an actuator and the design of a SMA based static twist concept, aimed at extending the helicopterflight envelope. The latter device is based on a SMA rod which is integrated in the spanwise directionwithin the blade structure at different positions. The actuator,when heated, transmits a torque couple which induces twist onto the blade. The twistvariationduetotheSMAdeviceactivationhasbeenpredictedbyaFE approach(MSC/Marc softwareimplemented with the SMA Brinson model). Finally, rotor performance in hover has been estimated withthe actuator in poweronandoffpositions,highlightingbenefitscomingfromseveralspanwise integrations/distributionsoftheSMA device.

2 – Delamination in the context of composite structural design

Abstract: Publisher Summary Advanced composite materials, due to their high potential in terms of stiffness/weight ratio, are very attractive for structural applications where low weight and high stiffness conditions have to be met. Indeed, the inherent heterogeneity of composites facilitates the design of structures with optimized stiffness and strength in particular locations and directions according to specific requirements. Hence, when designing composite structural elements, additional design variables related to the constituent composites' internal configuration (such as stacking sequence) must be taken into account. However, the heterogeneity of composites is also their main source of weakness, irrespective of the nature of the constituents. In many situations, the most critical damage mechanism for composites design is the delamination between adjacent layers. The delaminations can occur during the manufacturing process of the composite elements or they can arise as a consequence of impact with foreign objects. This chapter provides an overview of the delamination onset phenomenon and focuses on the causes that can lead to delamination initiation in composite laminates.