On the Preliminary Structural Design Strategy of the Wing of the Next-Generation Civil Tiltrotor Technology Demonstrator

Belardo, Marika; Beretta, Jacopo; Marano, Aniello Daniele; Diodati, Gianluca; Paletta, Nicola; Palma, Luigi Di

doi:10.1007/s42405-020-00330-2

Cited by 15 publications

(13 citation statements)

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“…This work is a continuation of a former work by the authors [2]. The previous and the present works represent an overview of a two-level optimization of the composite wing of a tiltrotor.…”

Section: Discussionmentioning

confidence: 74%

“…The work already presented in [2] gives a number of solutions on the Pareto front, which can also be analyzed from a manufacturing point of view. In particular, the solution which guarantees the strength and buckling requirements at minimum mass and is feasible from a manufacturing point of view is selected for flutter analyses, and if cleared (flutter speed VF ≥ 1.15 times the Dive Speed, VD), it is further involved in the second-level optimization performed in this work, which is based on FE models.…”

Section: Results Of the Optimization Process And Flutter Analysis In ...mentioning

confidence: 99%

“…The aim of the first-level optimization is to have, at the very beginning of the project, i.e., at concept design level, a safe structural configuration, which is free from flutter at minimum mass. The second-level optimization is based on a 2D-1D elements Finite Element Model (FEM), built based on the selected first-level structural optimization [2]. The composite parts (skin and spars) of this structural configuration are then subjected to optimization by means of commercial FEM software (OptiStruct ® , ver.…”

Section: Introductionmentioning

confidence: 99%

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Wing Structure of the Next-Generation Civil Tiltrotor: From Concept to Preliminary Design

et al. 2021

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The main objective of this paper is to describe a methodology to be applied in the preliminary design of a tiltrotor wing based on previously developed conceptual design methods. The reference vehicle is the Next-Generation Civil Tiltrotor Technology Demonstrator (NGCTR-TD) developed by Leonardo Helicopters within the Clean Sky research program framework. In a previous work by the authors, based on the specific requirements (i.e., dynamics, strength, buckling, functional), the first iteration of design was aimed at finding a wing structure with a minimized structural weight but at the same time strong and stiff enough to comply with sizing loads and aeroelastic stability in the flight envelope. Now, the outcome from the first design loop is used to build a global Finite Element Model (FEM), to be used for a multi-objective optimization performed by using a commercial software environment. In other words, the design strategy, aimed at finding a first optimal solution in terms of the thickness of composite components, is based on a two-level optimization. The first-level optimization is performed with engineering models (non-FEA-based), and the second-level optimization, discussed in this paper, within an FEA environment. The latter is shown to provide satisfactory results in terms of overall wing weight, and a zonal optimization of the composite parts, which is the starting point of an engineered model and a detailed FEM (beyond the scope of the present work), which will also take into account manufacturing, assembly, installation, accessibility and maintenance constraints.

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“…This work is a continuation of a former work by the authors [2]. The previous and the present works represent an overview of a two-level optimization of the composite wing of a tiltrotor.…”

Section: Discussionmentioning

confidence: 74%

Section: Results Of the Optimization Process And Flutter Analysis In ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Wing Structure of the Next-Generation Civil Tiltrotor: From Concept to Preliminary Design

et al. 2021

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“…This article is a continuation of former works [10,11] in which a two-level optimization of the composite wing of the Next Generation Civil Tiltrotor-Technological Demonstrator (NGCTR-TD) was presented.…”

Section: Introduction: Soa Starting Point and Motivationmentioning

confidence: 89%

Aeroelastic Tailoring of the Next Generation Civil Tiltrotor Technological Demonstrator Composite Wing

et al. 2022

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The tiltrotor wing structure is one of the most critical and heavily investigated structures in design due to the fundamental need to consider the interactions between the wing, pylon, and rotor systems to achieve aircraft aeroelastic stability. Indeed, in high-speed forward flight, wing flexural and torsional stiffness have fundamental roles in pitch-whirl stability. Another specific concern of tiltrotors is dynamic mode placement; it is necessary to properly place wing bending modes away from prop-rotor forcing frequencies. The main aeroelastic stability and dynamics requirements and the wing design process flow for the next generation civil tiltrotor are presented in this work. In this context, the use of composite materials plays a fundamental role in the attempt to satisfy the requirements, with the perpetual aim of minimizing the structural weight. An overview of the idealized and adopted models for strength, aeroelasticity, and whirl flutter analysis is provided. The primary focus was on the aeroelastic tailoring process. To satisfy, at the same time, all of the structural dynamic and aeroelastic stability requirements, the best compromise, with an acceptable weight penalty, was the mixture of two methodological solutions: adding unidirectional tape in the zones of the upper and lower skins for flexural out-of-plane frequency and adding a proper number of ±45° fabric layers at the locations of the skin with the highest value of strain energy for in-plane torsional modes. The results show that the proposed method based on modal strain energy analysis enables a tiltrotor aeroelastic tailored wing design. It can be easily employed in similar applications (e.g., vehicle scale-up/down) with the advantage of using the stiffness requirements derived directly from the aeroelastic ones (i.e., structural frequencies). The specific wing achieved aeroelastic clearance by adding only 2.7% of extra mass.

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“…This aspect has a tremendous impact both on wing design and on the fuel storage system concept. In fact, for the tiltrotor under consideration, the wing has to be able to respect strength, buckling and stiffness requirements [4,5]; under a survivable crash, to break in a defined section in order to alleviate the inertial load on the fuselage; and to allow crew and passenger to safely escape outside the vehicle. On the other hand, the fuel storage system has to be based on the bladder concept and not on the wet-wing concept (which is common practice for fixed wing aircrafts) [6].…”

Section: Introductionmentioning

confidence: 99%

Crashworthiness of a Composite Bladder Fuel Tank for a Tilt Rotor Aircraft

Paciello¹,

Pezzella²,

Belardo

et al. 2021

J. Compos. Sci.

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The fulfilment of the crash is a demanding requirement for a Tiltrotor. Indeed, such a kind of aircraft, being a hybrid between an airplane and a helicopter, inherits the requirements mainly from helicopters (EASA CS 29) due to its hovering ability. In particular, the fuel storage system must be designed in such a manner that it is crash resistant, under prescribed airworthiness requirements, in order to avoid the fuel leakage during such an event, preventing fire and, thus, increasing the survival chances of the crew and the passengers. The present work deals with the evaluation of crashworthiness of the fuel storage system of a Tiltrotor (bladder tank), and, in particular, it aims at describing the adopted numerical approach and some specific results. Crash resistance requirements are considered from the earliest design stages, and for this reason they are mainly addressed from a numerical point of view and by simulations that treat both single components and small/medium size assemblies. The developed numerical models include all the main parts needed for simulating the structural behavior of the investigated wing section: the tank, the structural components of the wing, the fuel sub-systems (fuel lines, probes, etc.) and the fuel itself. During the crash event there are several parts inside the tanks that can come into contact with the tank structure; therefore, it is necessary to evaluate which of these parts can be a damage source for the tank itself and could generate fuel loss. The SPH approach has been adopted to discretise fuel and to estimate the interaction forces with respect to the tank structure. Experimental data were used to calibrate the fuel tank and foam material models and to define the acceleration time-history to be applied. Thanks to the optimized foam’s configuration, the amount of dissipated impact energy is remarkable, and the evaluation of tanks/fuel system stress distribution allows estimating any undesired failure due to a survivable crash event.

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On the Preliminary Structural Design Strategy of the Wing of the Next-Generation Civil Tiltrotor Technology Demonstrator

Cited by 15 publications

References 10 publications

Wing Structure of the Next-Generation Civil Tiltrotor: From Concept to Preliminary Design

Wing Structure of the Next-Generation Civil Tiltrotor: From Concept to Preliminary Design

Aeroelastic Tailoring of the Next Generation Civil Tiltrotor Technological Demonstrator Composite Wing

Crashworthiness of a Composite Bladder Fuel Tank for a Tilt Rotor Aircraft

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