Effect of design parameters on the mass of a variable-span morphing wing based on finite element structural analysis and optimization

In the past years, the development of morphing wing technologies has received a great deal of interest from the scientific community. These technologies potentially enable an increase in aircraft efficiency by changing the wing shape, thus allowing the aircraft to fly near its optimal performance point at different flight conditions. However, these technologies often present an undesired mass increase due to their inherent complexity. Therefore, the aim of the current work is to ascertain the influence of geometrical and inertial parameters on the structural mass of a Variable-span Wing (VSW). The structural mass prediction is based on a parametric study. A minimum mass optimization problem with stiffness and strength constraints is implemented and solved, being the design variables structural thicknesses and widths, using a parametric Finite Element Model (FEM) of the wing. The study is done for a conventional fixed wing and the VSW, which are then combined to ascertain the VSW mass increment, i.e., the mass penalization of the adopted morphing concept. Polynomials are found to produce good approximations of the wing mass. The effects of the various VSW design parameters in the structural mass are discussed. On one hand, it was found that the span and chord have the highest impact in the wing mass. On the other hand, the VSW to fixed wing mass ratio proved that the influence of span variation ratio in the wing mass is not trivial. It is found that the mass increase does not grow proportionally with span variation ratio increase and that for each combination of span and chord, exists a span variation ratio that minimizes the mass penalty. In the future, the developed polynomials could be used to create a mass prediction model to aid the design of morphing wings during the conceptual design phase

Technologies to develop technology: the impact of new technologies on the organisation of the innovation process.

Companies are under increasing pressure to develop new product more effectively and efficiently. In order to meet this challenge, the organisation of the new product development process has received ample attention both in the academic literature and in the practitioner literature. As a consequence, a myriad of methods to design new products has been developed. These methods aim at facilitating concurrent product design and engineering. However, it is only recently, through the advent of families of new design technologies, that concurrency really becomes possible. In this paper, research on the impact of new design technologies on the product development process is reported and discussed. It is demonstrated that these technologies can have a significant impact on the organisation of innovation processes.Processes;

Demonstrator for Selectively Compliant Morphing Systems with Multi-stable Structures

The field of morphing wings presents significant potential for increasing the efficiency of aircraft. Conventional designs used in the industry limit the adaptability of aerodynamic surfaces to address an engineering trade-off between load-carrying and compliance. This same trade-off remains a factor in morphing wings, which must also balance weight considerations while attempting to remain competitive with conventional designs. The current state-of-the-art in morphing wings is briefly described in this work. This is followed by an investigation into a new application of the principle of selective stiffness, by which local changes in stiffness may be applied to affect the global structural characteristics. In this manner, this trade-off is addressed by providing the ability to allow a deformation mode when undergoing shape change and restrict it when sustained load-carrying is required. This principle has previously been explored using pre-stressed composite laminates to produce a bi-stable structure with unique curvature in each stable state. Geometrically bi-stable structures are explored for the same purpose in this research. Three types of bi-stable element are explored and presented. The last of these is then embedded in a simple airfoil concept. The placement and geometry of this element are optimized, and a physical model is produced using additive manufacturing. This physical model is finally mechanically tested to assess the stiffness in each stable state of the embedded element

STEM KIT: Teachers’ Notebook

info:eu-repo/semantics/publishedVersio

Design and engineering methods for open-rotor nacelle shaping

Due to the growing transport needs in emerging economies and recent success of the low-cost airlines, the demand for short/medium-haul aeroplanes is increasing. Within the next twenty years, the existing single-aisle aircraft are likely to be replaced by new models mounting new propulsion systems. One promising con- figuration being considered is the open-rotor, which is a revision of the propfan. However, further progress has to be done in order to transform propfan engines, whose technology dates back to the 1980s, into viable and feasible open-rotor con- cepts. Among the aspects yet to be investigated in su ficient depth is the de finition of a methodology for the open-rotor nacelle design. The aim of the present research is to help enhance the knowledge in this area. Even if there are a number of important fields of investigation for open-rotor designs, this work is limited to the analysis of the pusher architecture with no exhaust impingement through rotors. The research is initially performed combining both a graphical and a compu- tational approach, investigating the mathematical and physical aspects involved in the de finition of appropriate nacelle pro files, boundary conditions for the CFD analysis and simplifi ed rotor modelling. The first simulations are mainly focused on a typical propfan nacelle, which is taken as a reference model: the computations provide useful results for evaluating its aerodynamic features ... [cont.]

A Cooperative Approach for Autonomous Landing of UAVs

This dissertation presents a cooperative approach for the autonomous landing of MRVTOL UAVs (Multi Rotor-Vertical Take-off and Landing Unmanned Aerial Vehicles). Most standard UAV autonomous landing systems take an approach, where the UAV detects a pre-set pattern on the landing zone, establishes relative positions and uses them to perform the landing. These methods present some drawbacks such as all of the processing being performed by the UAV itself, requiring high computational power from it. An additional problem arises from the fact most of these methods are only reliable when the UAV is already at relatively low altitudes since the pattern’s features have to be clearly visible from the UAV’s camera. The method presented throughout this dissertation relies on an RGB camera, placed in the landing zone pointing upwards towards the sky. Due to the fact, the sky is a fairly stagnant and uniform environment the unique motion patterns the UAV displays can be singled out and analysed using Background Subtraction and Optical Flow techniques. A terrestrial or surface robotic system can then analyse the images in real-time and relay commands to the UAV. The result is a model-free method, i.e independent of the UAV’s morphological aspect or pre-determined patterns, capable of aiding the UAV during the landing manoeuvre. The approach is reliable enough to be used as a stand-alone method, or be used along traditional methods achieving a more robust system. Experimental results obtained from a dataset encompassing 23 diverse videos showed the ability of the computer vision algorithm to perform the detection of the UAV in 93,44% of the 44557 evaluated frames with a tracking error of 6.6%. A high-level control system that employs the concept of an approach zone to the helipad was also developed. Within the zone every possible three-dimensional position corresponds to a velocity command for the UAV, with a given orientation and magnitude. The control system was tested in a simulated environment and it proved to be effective in performing the landing of the UAV within 13 cm from the goal

Proposal of a methodology for the design of the installation of turrets on aircrafts – the approach on the aerodynamic influences

The present work has its origin on the necessity of enabling a design certified company, or DOA (Design Organization Approval), to perform a modification; this modification is the installation of EO/IR (Electro-optical infrared) sensors on aircrafts. The subject of interest in this dissertation lies on the aerodynamic impact of the modification on the aircraft. The primary purpose of the present thesis is the creation of a methodology that regards the design stage of the modification. This methodology serves as guidance to the DOA design team that is assigned to the design of the modification. The methodology includes a recommendation to the certification of the modification; it contains a method intended to decide the location of the installation of the sensors on the aircraft; it also comprises of a design structure specifically adapted to the modification in study. Regarding the aerodynamic impact, it is studied the aerodynamic analysis’ tools, which allows one to relate the different stages of design to the most suited tools to each stage. A case study is performed with the purpose of not only validating the methodology which was created but also to giving a first approach to the preliminary design of the modification. As example, there are used the Lockheed Martin C-130 aircraft and the FLIR Star Safire III sensor

Aeroelastic Stability Assessment Of a CS-25 Category Aircraft Equipped With Multi-Modal Wing Morphing Devices

Morphing wing structures have the greatest ambition to dramatically im-prove aircraft aerodynamic performance (less fuel consumption) and reduce aerodynamic noise. Several studies in the literature have shown their potential for increased aerodynamic efficiency across nearly all flight conditions, en-hanced aircraft maneuverability and control effectiveness, decreased take-off/landing length, reduced airframe noise, etc. However, despite a long herit-age of research, morphing wing technology has yet to be approved by the Euro-pean Aviation Safety Authority (EASA) for use in commercial aviation. Models and approaches capable to predict the aeroelastic impact of a morphing wing still need to be matured to safely alter design and operation of future genera-tions of aircraft. Additionally, a number of practical challenges remain to be addressed in the suitable materials, systems reliability, safety and maintenance. Due to the reduced stiffness, increased mass and increased Degree Of Freedom (DOF) with respect to conventional wings, these mechanical systems can cause significant reduction of aircraft flutter margins. This aspect requires dedicated aeroelastic assessments since the early stages of the design process of such an innovative wing. Flutter boundaries predictions need sensitivity anal-yses to evaluate bending/torsional stiffness and inertial distribution variability ranges of the aircraft wing equipped with the morphing wing devices. In such a way, aeroelastic assessments become fundamental to drive a balance between weight and stiffness of the investigated adaptive systems. Furthermore, in pseu-do rigid-body mechanisms-based morphing structures, the inner kinematics is so important that its faults may compromise the general aircraft-level functions. Similarly to the demonstration means of safety compliance, commonly applied to aircraft control surfaces, the novel functions resulting from the integration of adaptive devices into flying aircraft thus impose a detailed examination of the associated risks. In the framework of Clean Sky 2 Airgreen 2 project, the author provides advanced aeroelastic assessments of two adaptive devices enabling the camber morphing of winglets and flaps, conceived for regional aircraft integration (EASA CS-25 category). Segmented ribs architectures ensure the transition from the baseline (or un-morphed) shape to the morphed ones, driven by em-bedded electromechanical actuators. Some of the advantages resulting from the combination of the two aforementioned morphing systems are wing load con-trol, lift-over-drag ratio increase and root bending moment alleviation. The aircraft aeroelastic model was generated by means of the proprietary code SANDY 3.0. Then, the same code was adopted to solve the aeroelastic stability equa-tions through theoretical modes association in frequency domain. To carry out multi-parametric flutter analyses (P-K continuation method), the actuation lines stiffness and winglet/flap tabs inertial parameters were considered in combina-tion each other. Nominal operative conditions as well as systems malfunction-ing or failures were examined as analyses cases of the investigated morphing devices, together with actuators free-play conditions. Proper design solutions were suggested to guarantee flutter clearance in accordance with aircraft stabil-ity robustness with respect to morphing systems integration, evaluated through a combination of “worst cases” simulating the mutual interaction among the adaptive systems. The safety-driven design of the morphing wing devices required also a thorough examination of the potential hazards resulting from operational faults involving either the actuation chain, such as jamming, or the external interfaces, such as loss of power supplies and control lanes, and both. The main goal was to verify whether the morphing flap and winglet systems could comply with the standard civil flight safety regulations and airworthiness requirements (EASA CS25). More in detail, a comprehensive study of systems functions was firstly qualitatively performed at both subsystem and aircraft levels to identify poten-tial design faults, maintenance and crew faults, as well as external environment risks. The severity of the hazard effects was thus determined and then ranked in specific classes, indicative of the maximum tolerable probability of occurrence for a specific event, resulting in safety design objectives. Fault trees were final-ly produced to assess the compliance of the system architectures to the quanti-tative safety requirements resulting from the FHAs