Analysis of a mathematical model for the heave motion of a micro aerial vehicle with flexible wings having non-local damping effects

In this work we analyze a one dimensional model for a flexible wing micro aerial vehicle which can undergo heaving motion. The vehicle is modeled with a non-local type of internal damping known as spatial hysteresis as well as viscous external damping. We present a rigorous theoretical analysis of the model proving that the linearly approximated system is well-posed and the first order feedback system operators generate exponentially stable C0–semigroups. Furthermore, we present numerical simulations of control designs used on the linearly approximated model to control the associated nonlinear model in two different strategies. The first strategy used to control the system is a target tracking strategy. The second strategy used in this work is morphing the system to a target state over time. The controllers used in this work include Linear Quadratic Regulator, Linear Quadratic Gaussian, and central control. In light of the theory of this work we have incorporated the appropriate Riccati equation solutions into the control design for a system with a mode problem (i.e. zero eigenvalue for stiffness operator). This work remains consistent with the literature that concerns multiple component structures with a mode problem

Performance and Stability of an Agile Tail-less MAV with Flexible Articulated Wings

This paper considers the problems of (a) modelling the ight mechanics of a tail-less MAV equipped with exible articulated wings, and (b) the analysis of its turning performance. The wings are assumed to have two degrees of freedom - heave and twist. They are assumed to be actuated from the root, which is the abstraction of an experimental control mechanism being developed by the authors. The dihedral and twist angles at the wing root are controlled. A novel actuator concept of axial tension to control wing stiffness has been explored in this paper. It is shown that axial tension in the wing has a significant effect on the turning performance of the aircraft, although the effect is not uniformly beneficial in nature. The effect of exibility on the steady state turning performance of the aircraft has been demonstrated by comparing it with that of a rigid aircraft, and with that of a similar aircraft possessing a wing with different elastic properties

Designing Morphing Airfoils for Improving the Aerodynamic Characteristics

Master'sMASTER OF ENGINEERIN

Study of compliant mechanisms and flexible hinges in topology optimization

This thesis presents a comprehensive study on the application of compliant mechanisms and flexible hinges in topology optimization. Compliant mechanisms are a promising approach for achieving desired functionalities and structural flexibility in engineering designs. By exploiting the inherent elasticity of materials, compliant mechanisms offer advantages such as reduced complexity, improved reliability, and enhanced performance. Topology optimization, conversely, allows obtaining compliant mechanisms with reduced weight through the creation of holes, thus achieving an optimized design. In this work, we explore the integration of compliant mechanisms and flexible hinges within the framework of topology optimization, aiming to propose a method of improvement for the design efficiency and performance of structures in the aerospace field. The thesis begins with a thorough literature review of compliant mechanisms and their role in current aerospace applications. Various design principles and analysis techniques are examined to establish a solid foundation for the subsequent chapters. The study then focuses on the implementation of mathematical models and computational algorithms to incorporate compliant mechanisms and flexible hinges into the topology optimization process. To validate the proposed approach, a series of numerical experiments are conducted. Various case studies are considered, including a gripping and inverter mechanisms. The results demonstrate the effectiveness of compliant mechanisms and flexible hinges in enhancing the performance of optimized structures. The compliant mechanisms exhibit improved flexibility, adaptability, and energy absorption capabilities enabling smooth and controlled motion. Overall, this thesis significantly contributes to the understanding and implementation of compliant mechanisms and their integration with topology optimization techniques. The study not only showcases their potential for creating innovative and efficient designs across various engineering disciplines but also emphasizes their particular relevance in the aerospace field. By exploring the application of compliant mechanisms and topology optimization in aerospace engineering, it has been seen that this cutting-edge technology is opened up for new avenues for further research and development

Design optimisation of shape memory alloy linear actuator applications

Shape memory alloy (SMA) actuators have drawn much attention and interest in recent decades due to their unique properties; and, are expected to be increasingly integrated within commercial automotive applications. Key advantages of SMA actuators include: potentially simplified construction, whereby the SMA can act as both sensor and actuator simultaneously; compatibility with Joule heating and convective ambient cooling; and, potential mass advantages over competing actuation technologies. These attributes potentially allow for the development of simpler, more reliable and cost effective actuation systems with significant reduction in mechanical complexity and size. SMA is readily available in commercial quantities and exhibits high wear resistance and durability, which make it an ideal candidate for application in automotive grade applications. Despite these identified advantages, SMA actuators are subject to a series of technical challenges associated with:  - Relatively small strain (displacement or stroke)  - Achievable frequency (actuation speed)  - Controllability (and stability)  - Positional accuracy  - Energy efficiency These technical challenges contribute to a relatively low success rate of commercial SMA actuator applications; and, provide motivation for this program to generate relevant research outcomes that enhance the commercialisation of SMA actuators. An extensive literature review of over 500 journal and patent documents was conducted to provide a clear roadmap for the commercial imperatives for SMA design. The formulated research methodology identifies milestones required for achieving the research objectives, which were addressed as research themes. Based on this literature review, the following research themes were identified:  - Design methods to resolve SMA actuator limitations  - Development of simple and practical numerical models for SMA actuator response  - Data for SMA linear actuator design Specific research contributions within these themes are presented within the thesis, with the objective of enhancing the commercial application of shape memory alloy (SMA) linear actuators, and include:  - A comprehensive analysis of SMAs: history, commercial applications, strength and limitations, design challenges and         opportunities.  - A novel investigation of transient heat transfer scenarios for cylindrical systems associated with their crossover and critical radii.  - Development of novel latent heat models for analytical and numerical applications, and proposal of readily applied activation and deactivation charts compatible with the requirements of SMA actuator designers.  - A novel investigation of the morphological effects of SMA-pulley systems (i.e. pulley diameter, SMA and lagging diameter) on structural and functional fatigue

IMPROVED PREDICTION OF FLAPPING WING AERIAL VEHICLE PERFORMANCE THROUGH COMPONENT INTERACTION MODELING

Flapping wing aerial vehicles offer the promise of versatile performance, however prediction of flapping wing aerial vehicle performance is a challenging task because of complex interconnectedness in vehicle functionality. To address this challenge, performance is estimated by using component-level modeling as a foundation. Experimental characterization of the drive motors, battery, and wings is performed to identify important functional characteristics and enable selection of appropriate modeling techniques. Component-level models are then generated that capture the performance of each vehicle component. Validation of each component-level model shows where errors are eliminated by capturing important dynamic functionality. System-level modeling is then performed by creating linkages between component-level models that have already been individually validated through experimental testing, leading to real-world functional constraints that are realized and correctly modeled at the system level. The result of this methodology is a system-level performance prediction that offers the ability to explore the effects of changing vehicle components as well as changing functional properties, while maintaining computational tractability. Simulated results are compared to experimental flight test data collected with an instrumented flapping wing aerial vehicle, and are shown to offer good accuracy in estimation of system-level performance properties

12th EASN International Conference on "Innovation in Aviation & Space for opening New Horizons"

Epoxy resins show a combination of thermal stability, good mechanical performance, and durability, which make these materials suitable for many applications in the Aerospace industry. Different types of curing agents can be utilized for curing epoxy systems. The use of aliphatic amines as curing agent is preferable over the toxic aromatic ones, though their incorporation increases the flammability of the resin. Recently, we have developed different hybrid strategies, where the sol-gel technique has been exploited in combination with two DOPO-based flame retardants and other synergists or the use of humic acid and ammonium polyphosphate to achieve non-dripping V-0 classification in UL 94 vertical flame spread tests, with low phosphorous loadings (e.g., 1-2 wt%). These strategies improved the flame retardancy of the epoxy matrix, without any detrimental impact on the mechanical and thermal properties of the composites. Finally, the formation of a hybrid silica-epoxy network accounted for the establishment of tailored interphases, due to a better dispersion of more polar additives in the hydrophobic resin