Structural integrity aspects of a lightweight civil unmanned air vehicle

2016 ◽  
Vol 7 (6) ◽  
pp. 773-787 ◽  
Author(s):  
Efstratios Giannakis ◽  
George Savaidis
Keyword(s):  
Material Properties ◽  
Structural Integrity ◽  
Aircraft Design ◽  
International Standards ◽  
Optimized Design ◽  
Structural Elements ◽  
Safety Factors ◽  
Content Type ◽  
Unmanned Air Vehicle ◽  
Air Vehicle

Purpose The purpose of this paper is to focus on the finite element (FE) analyses undertaken for aerodynamically and structurally optimized design of a modern, lightweight civil unmanned air vehicle (UAV) made fully of composite materials. Design/methodology/approach The FE method has been applied to design and calculate the safety factors of all structural elements of the UAV. Fully parameterized design tools have been developed in the preliminary design phase, allowing automatic reshapes of the skin and the internal structural parts, wherever needed, to achieve optimal structural design, from the point of view of lightweight and structural integrity. Monotonic and fatigue tests have been performed on material specimens with various thicknesses and fibre textures, to verify the material properties used for the FE analyses. The load assumptions were in accordance with the valid international standards. Findings The material tests confirmed the validity of the material properties used within the FE calculations. The calculated safety factors were acceptable for all structural elements and components of the UAV. As a result, a lightweight, structurally optimized design has been achieved, considering the international, standardized specifications assumptions and fulfilling the safety requirements. Practical implications Design engineers may use the outcomes of this work as a guide to achieve optimal lightweight structures ensuring its operational strength using composite, lightweight materials. Originality/value A new, structurally optimized, lightweight aircraft design has been developed, able to accommodate heavy electronic payloads while being able to fly for over ten hours without refuelling. This medium altitude long endurance airplane can overview forests, seas and human trafficking autonomously and economically.

Aerodynamic design and optimization of propellers for multirotor

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Witold Artur Klimczyk
Keyword(s):  
Structural Integrity ◽  
Navier Stokes ◽  
Optimization Approach ◽  
Minimum Thickness ◽  
Design Problems ◽  
Content Type ◽  
Design And Optimization ◽  
Propeller Design ◽  
Unmanned Air Vehicle ◽  
Propeller Blades

Purpose This paper aims to present a methodology of designing a custom propeller for specified needs. The example of propeller design for large unmanned air vehicle (UAV) is considered. Design/methodology/approach Starting from low fidelity Blade Element (BE) methods, the design is obtained using evolutionary algorithm-driven process. Realistic constraints are used, including minimum thickness required for stiffness, as well as manufacturing ones – including leading and trailing edge limits. Hence, the interactions between propellers in hex-rotor configuration, and their influence on structural integrity of the UAV are investigated. Unsteady Reynolds-Averaged Navier–Stokes (URANS) are used to obtain loading on the propeller blades in hover. Optimization of the propeller by designing a problem-specific airfoil using surrogate modeling-driven optimization process is performed. Findings The methodology described in the current paper proved to deliver an efficient blade. The optimization approach allowed to further improve the blade efficiency, with power consumption at hover reduced by around 7%. Practical implications The methodology can be generalized to any blade design problem. Depending on the requirements and constraints the result will be different. Originality/value Current work deals with the relatively new class of design problems, where very specific requirements are put on the propellers. Depending on these requirements, the optimum blade geometry may vary significantly.

Robust design and optimization of UAV empennage

2017 ◽  
Vol 89 (4) ◽  
pp. 609-619 ◽  
Author(s):  
Witold Artur Klimczyk ◽  
Zdobyslaw Jan Goraj
Keyword(s):  
Optimization Problems ◽  
Computational Cost ◽  
Aircraft Design ◽  
Computational Time ◽  
Wing Design ◽  
Surrogate Modelling ◽  
Content Type ◽  
Design And Optimization ◽  
Unmanned Air Vehicle ◽  
Splitting Problem

Purpose This paper aims to address the issue of designing aerodynamically robust empennage. Aircraft design optimization often narrowed to analysis of cruise conditions does not take into account other flight phases (manoeuvres). These, especially in unmanned air vehicle sector, can be significant part of the whole flight. Empennage is a part of the aircraft, with crucial function for manoeuvres. It is important to consider robustness for highest performance. Design/methodology/approach Methodology for robust wing design is presented. Surrogate modelling using kriging is used to reduce the optimization cost for high-fidelity aerodynamic calculations. Analysis of varying flight conditions, angle of attack, is made to assess robustness of design for particular mission. Two cases are compared: global optimization of 11 parameters and optimization divided into two consecutive sub-optimizations. Findings Surrogate modelling proves its usefulness for cutting computational time. Optimum design found by splitting problem into sub-optimizations finds better design at lower computational cost. Practical implications It is demonstrated, how surrogate modelling can be used for analysis of robustness, and why it is important to consider it. Intuitive split of wing design into airfoil and planform sub-optimizations brings promising savings in the optimization cost. Originality/value Methodology presented in this paper can be used in various optimization problems, especially those involving expensive computations and requiring top quality design.

Improved efficiency of an unmanned air vehicle IC engine using computational modelling and experimental verification

2017 ◽  
Vol 89 (1) ◽  
pp. 184-192 ◽  
Author(s):  
Peter Hooper ◽  
Tarik Al-Shemmeri
Keyword(s):  
Experimental Test ◽  
Computational Simulation ◽  
Computational Modelling ◽  
Dynamic Modelling ◽  
Ic Engine ◽  
Engine Operation ◽  
Content Type ◽  
Unmanned Air Vehicle ◽  
Air Vehicle ◽  
Stroke Cycle

Purpose This paper aims to present experimental results of gasoline-fuelled engine operation of a crankcase-scavenged two-stroke cycle engine used for unmanned air vehicle (UAV)/unmanned air system application and to cross correlate with computational fluid dynamic modelling results. Design/methodology/approach Computational modelling of the engine system was conducted using the WAVE software supported by the experimental research and development via dynamometer testing of a spark ignition UAV engine to construct a validated computational model exploring a range of fuel delivery options. Findings Experimental test data and computational simulation have allowed an assessment of the potential advantages of applying direct in-cylinder fuel injection. Practical implications The ability to increase system efficiency offers significant advantages in terms of maximising limited resources and extending mission duration capabilities. The computational simulation and validation via experimental test experience provides a means of assessment of possibilities that are costly to explore experimentally and offers added confidence to be able to investigate possibilities for the development of similar future engine designs. Originality/value The software code used has not been applied to such crankcase-scavenged two-stroke cycle engines and provides a valuable facility for further simulation of the twin cylinder horizontally opposed design to offer further system optimisation and exploration of future possibilities.

Preliminary design of a box-wing VTOL UAV

2019 ◽  
Vol 92 (5) ◽  
pp. 737-743
Author(s):  
Giuseppe Palaia ◽  
Vittorio Cipolla ◽  
Vincenzo Binante ◽  
Emanuele Rizzo
Keyword(s):  
Mechanical Design ◽  
Design Procedure ◽  
General Aviation ◽  
Preliminary Design ◽  
Content Type ◽  
Unmanned Air Vehicle ◽  
Vtol Uav ◽  
Air Vehicle ◽  
Aerodynamic Performances ◽  
Vtol Aircraft

Purpose This paper aims to present a preliminary study on a disruptive vertical take-off and landing (VTOL) configuration based on the best wing system concept by L. Prandtl. Design/methodology/approach A preliminary design has been addressed from several points of views: a conceptual design has been carried out thanks to in-house optimization tool; aerodynamic performances, propulsion design and mechanical design have been addressed to make the first prototype for preliminary vertical flight tests. Findings The study shows the feasibility of box-wing configuration for VTOL aircraft. Practical implications The work shows a general design procedure for box-wing unmanned air vehicle (UAV) configuration. The study of this configuration can be easily adopted in wider range, from UAV to general aviation. In the last category, it can be a promising configuration for the future of urban air mobility. Originality/value This work lays the foundation for studying and testing box-wing configuration for unmanned VTOL aircraft. The design procedure can be scaled to manned aircraft belonging to general aviation aircraft.

Unmanned Air Vehicle Interdisciplinary Design Project

2016 ◽  
Author(s):  
Ioannis Templalexis ◽  
Theodore Lekas ◽  
Agelos Koutsomichalis ◽  
Anestis Kalfas
Keyword(s):  
Aircraft Design ◽  
Communication Link ◽  
Design Project ◽  
Unmanned Air Vehicle ◽  
Interdisciplinary Design ◽  
Operational Profile ◽  
Diverse Field ◽  
Air Vehicle ◽  
One Year ◽  
Design Proposal

Mechanical Engineers graduating from the Hellenic Air Force Academy (HAFA), are initially appointed in a military squadron, to support and manage the aircraft maintenance workload. Throughout their career, they will at some point, be appointed in a procurement or in a research department, where they will need to have an integral understanding of how a certain aircraft in conjunction with its propulsion system, can meet prescribed operational needs. The syllabus of the Mechanical Engineering degree offered at the HAFA, encompasses several modules related to Aircraft Design, Material Science and Propulsion Systems. The Aircraft Design Project (ADP) presented herein, aims to stimulate the cadets in applying a diverse field of knowledge on a single application, building thus soon enough the missing communication link between those who deal with the power plant and those who deal with the aircraft design. The assignment input is only confined in a short description of the operational profile of an Unmanned Air Vehicle (UAV) to be designed. A number of teams are formed which act competitively and develop a design proposal, each one for its own sake. As part of the project, they also have to print a 3D mock-up and do a testing in the wind tunnel operated within the HAFA. Finally, each team has the obligation to defend its design in front of an audience consisting of HAF military officers, HAFA academics and delegates from industries. The proposed exercise constitutes a novel conception of coursework type, extending over one year, engaging three Academic Sectors and aiming to achieve the following educational targets: a) Learn to work in a team within a competitive environment. Each cadet has to collaborate with his teammates and compete with the members of the other team(s). b) Combine and apply knowledge acquired from various scientific fields. c) Learn how to “sell” a product to a diverse audience being interested in engineering excellence (academia) cost effectiveness (industry) and degree of compliance with operational needs (military).

Safety factors in structural integrity assessment of components with defects

2013 ◽  
Vol 4 (4) ◽  
pp. 457-476 ◽  
Author(s):  
Yury Matvienko
Keyword(s):  
Fracture Mechanics ◽  
Safety Factor ◽  
Structural Integrity ◽  
Plastic Collapse ◽  
Safety Factors ◽  
Content Type ◽  
Nonlinear Fracture Mechanics ◽  
Integrity Assessment ◽  
Nonlinear Fracture ◽  
Linear And Nonlinear

Purpose – The purpose of this paper is to develop basic principles of deterministic structural integrity assessment of a component with a crack- or notch-like defect by including safety factors against fracture and plastic collapse in criteria equations of linear and nonlinear fracture mechanics. Design/methodology/approach – The safety factors against fracture are calculated by demanding that the applied critical stress should not be less than the yield stress of the material for a component with a crack or a notch of the acceptable size. Structural integrity assessment of the engineering components damaged by crack- or notch-like defects is discussed from view point of the failure assessment diagram (FAD). The methodology of the FAD has been employed for the structural integrity analysis and assessment of acceptable sizes of throw-thickness notch in a plate under tension and surface longitudinal notch-like defects in a pressure vessel. Findings – Basic equations have been presented to calculate the safety factor against fracture for critical values of the stress intensity factor, crack tip opening displacement (CTOD), the J-integral and the FAD as well as to estimate an acceptable (safe) region for an engineering component with a crack- or notch-like defect of the acceptable size. It was shown that safety factors against fracture depend on both the safety factor against plastic collapse and employed fracture mechanics criterion. The effect of crack/notch tip constraint is incorporated into criteria equations for the calculation of safety factors against fracture. Originality/value – The deterministic method of fracture mechanics is recommended for structural integrity assessment of a component with a crack- or notch-like defect by including safety factors against fracture and plastic collapse in criteria equations of linear and nonlinear fracture mechanics.

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