scholarly journals Design, simulation and optimisation of lattice structures for remote control aeroplane

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Théo Laporte
Keyword(s):  
Situation Awareness ◽  
Lattice Structure ◽  
Lattice Structures ◽  
Complex Behaviour ◽  
Content Type ◽  
Vibration Absorption ◽  
Brushless Motor ◽  
Aerial Vehicle ◽  
Complex Parts ◽  
Practical Implications

PurposeThus, in this work the goal is to design, simulate and optimise a holder of a brushless motor in lattice structure to get the best performance in terms of mechanical strength, vibration absorption and lightness.Design/methodology/approachNowadays, most manufacturers and designers' goal are to sell efficient products in mass to keep up or outrun competition. Medical, aeronautical, automobile and civil engineering sectors produce complex parts and products that encompasses multiple properties such as lightweight, energy absorbance, vibration reduction and stress resistant. Studies found that lattice structures are more and more useful in these fields since their characteristics satisfy complex behaviour.FindingsThe study's outcome suggests that the use of lattice structure reduces 60% of the actual motor holder mass while keeping the strength of the material, meeting initial specifications.Research limitations/implicationsThe Ram capacity of the PC.Practical implicationsLight materials for aerospace engineering elongate the range of the unmanned aerial vehicle (UAV) to an extra range of flight.Social implicationsSituation awareness of the country border using surveillance drone and minimising the consumption of fuel.Originality/valueThe research allowed reducing 60% the actual holder mass.

Finite element analysis of gradient lattice structure patterns for bone implant design

2020 ◽  
Vol 11 (4) ◽  
pp. 535-545
Author(s):  
Asliah Seharing ◽  
Abdul Hadi Azman ◽  
Shahrum Abdullah
Keyword(s):  
Finite Element Analysis ◽  
Relative Density ◽  
Mechanical Behaviour ◽  
Lattice Structure ◽  
Lattice Structures ◽  
Element Analysis ◽  
Bone Implant ◽  
Content Type ◽  
Octet Truss ◽  
Structure Patterns

PurposeThe objective of this paper is to identify suitable lattice structure patterns for the design of porous bone implants manufactured using additive manufacturing.Design/methodology/approachThe study serves to compare and analyse the mechanical behaviours between cubic and octet-truss gradient lattice structures. The method used was uniaxial compression simulations using finite element analysis to identify the translational displacements.FindingsFrom the simulation results, in comparison to the cubic lattice structure, the octet-truss lattice structure showed a significant difference in mechanical behaviour. In the same design space, the translational displacement for both lattice structures increased as the relative density decreased. Apart from the relative density, the microarchitecture of the lattice structure also influenced the mechanical behaviour of the gradient lattice structure.Research limitations/implicationsGradient lattice structures are suitable for bone implant applications because of the variation of pore sizes that mimic the natural bone structures. The complex geometry that gradient lattice structures possess can be manufactured using additive manufacturing technology.Originality/valueThe results demonstrated that the cubic gradient lattice structure has the best mechanical behaviour for bone implants with appropriate relative density and pore size.

Vision-based pose estimation of a multi-rotor unmanned aerial vehicle

2019 ◽  
Vol 7 (3) ◽  
pp. 120-132
Author(s):  
Kashish Gupta ◽  
Bara Jamal Emran ◽  
Homayoun Najjaran
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Three Dimensional ◽  
Processing System ◽  
Training Procedure ◽  
Autonomous Landing ◽  
Content Type ◽  
Landing Platform ◽  
Aerial Vehicle ◽  
Autopilot Systems ◽  
Practical Implications

Purpose The purpose of this paper is to facilitate autonomous landing of a multi-rotor unmanned aerial vehicle (UAV) on a moving/tilting platform using a robust vision-based approach. Design/methodology/approach Autonomous landing of a multi-rotor UAV on a moving or tilting platform of unknown orientation in a GPS-denied and vision-compromised environment presents a challenge to common autopilot systems. The paper proposes a robust visual data processing system based on targets’ Oriented FAST and Rotated BRIEF features to estimate the UAV’s three-dimensional pose in real time. Findings The system is able to visually locate and identify the unique landing platform based on a cooperative marker with an error rate of 1° or less for all roll, pitch and yaw angles. Practical implications The proposed vision-based system aims at on-board use and increased reliability without a significant change to the computational load of the UAV. Originality/value The simplicity of the training procedure gives the process the flexibility needed to use a marker of any unknown/irregular shape or dimension. The process can be easily tweaked to respond to different cooperative markers. The on-board computationally inexpensive process can be added to off-the-shelf autopilots.

Autonomous performance maximization of research-based hybrid unmanned aerial vehicle

2020 ◽  
Vol 92 (4) ◽  
pp. 645-651
Author(s):  
Sezer Çoban
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Performance Optimization ◽  
Flight Trajectory ◽  
Content Type ◽  
Lateral Dynamics ◽  
Aerial Vehicle ◽  
Improved Design ◽  
Autopilot Systems ◽  
First Time ◽  
Practical Implications

Purpose This paper aims to investigate the autonomous performance optimization of a research-based hybrid unmanned aerial vehicle (i.e. HUAV) manufactured at Iskenderun Technical University. Design/methodology/approach To maximize the autonomous performance of this HUAV, longitudinal and lateral dynamics were initially obtained. Then, the optimum magnitudes of the autopilot system parameters were estimated by considering the vehicle’s dynamic model and autopilot parameters. Findings After determining the optimum values of the longitudinal and lateral autopilots, an improved design for the autonomously controlled (AC) HUAV was achieved in terms of real-time flight. Practical implications Simultaneous improvement of the longitudinal and lateral can be used for better HUAV operations. Originality/value In this paper, the autopilot systems (i.e. longitudinal and lateral) of an HUAV are for the first time simultaneously designed in the literature. This helps the simultaneous improvement of the longitudinal and lateral flight trajectory tracking performances.

scholarly journals Alternative steel lattice structures for wind energy converters

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Slobodanka Jovasevic ◽  
José Correia ◽  
Marko Pavlovic ◽  
Rita Dantas ◽  
Carlos Rebelo ◽  
...  
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Lattice Structure ◽  
Renewable Energies ◽  
Maximum Diameter ◽  
Lattice Structures ◽  
Cold Forming ◽  
Content Type ◽  
Supporting Structure ◽  
Energy Converters

Purpose In the last decades, the demand and use of renewable energies have been increasing. The increase in renewable energies, particularly wind energy, leads to the development and innovation of powerful wind energy converters as well as increased production requirements. Hence, a higher supporting structure is required to achieve higher wind speed with less turbulence. To date, the onshore wind towers with tubular connections are the most used. The maximum diameter of this type of tower is limited by transportation logistics. The purpose of this paper is to propose an alternative wind turbine lattice structure based on half-pipe steel connections. Design/methodology/approach In this study, a new concept of steel hybrid tower has been proposed. The focus of this work is the development of a lattice structure. Therefore, the geometry of the lattice part of the tower is assessed to decrease the number of joints and bolts. The sections used in the lattice structure are constructed in a polygonal shape. The elements are obtained by cold forming and bolted along the length. The members are connected by gusset plates and preloaded bolts. A numerical investigation of joints is carried out using the finite element (FE) software ABAQUS. Findings Based on the proposed study, the six “legs” solution with K braces under 45° angle and height/spread ratio of 4/1 and 5/1 provides the most suitable balance between the weight of the supporting structure, number of bolts in joints and reaction forces in the foundations, when compared with four “legs” solution. Originality/value In this investigation, the failure modes of elements and joints of an alternative wind turbine lattice structures, as well as the rotation stiffness of the joints, are determined. The FE results show good agreement with the analytical calculation proposed by EC3-1-8 standard.

PIL simulations of an FWUAV under windy conditions

2018 ◽  
Vol 90 (2) ◽  
pp. 461-470
Author(s):  
Hakan Ülker ◽  
Cemal Baykara ◽  
Can Özsoy
Keyword(s):  
Linear Models ◽  
Low Cost ◽  
Wind Gust ◽  
Content Type ◽  
Flying Qualities ◽  
Aerial Vehicle ◽  
Model Predictive Controllers ◽  
Predictive Controllers ◽  
Complex Trajectories ◽  
Practical Implications

Purpose A fixed wing unmanned aerial vehicle (FWUAV) is targeted to perform processor in the loop (PIL) simulations for the flight scenarios such as straight and level, level climb, level turn, climbing turn and level steady heading sideslip under windy conditions such as steady wind (SW) and wind gust (WG) in a desired and controlled manner. Design/methodology/approach The constrained multi-input–multi-output (MIMO) lateral and longitudinal linear models-based model predictive controllers (MPCs) which are proposed in a previous study (Ulker et al., 2017) are tested in the PIL simulations under specified windy conditions. BeagleBone Black Rev C is used as a target hardware or processor in the PIL simulations. Findings The results of the PIL simulations show that the MPCs proposed in the previous study can achieve satisfactory performance and flying qualities for the all flight scenarios handled in this paper under windy conditions. Practical implications The MPCs proposed in the previous study can be easily implemented in the real world to a low-cost and small-sized board like BeagleBone Black Rev C which is used in this paper. Originality/value The proposed MPCs in the previous study which are capable of providing more flexibility in terms of tracking complex trajectories are showed to be able to be implemented to real system by means of PIL simulations under the changeable windy conditions which are difficult for performance tests.

Experimental investigation on lift generation of flapping MAV with insect wings of various species

2019 ◽  
Vol 92 (2) ◽  
pp. 139-144
Author(s):  
Syam Narayanan S. ◽  
Asad Ahmed R. ◽  
Jijo Philip Varghese ◽  
Gopinath S. ◽  
Jedidiah Paulraj ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Design Methodology ◽  
Span Length ◽  
Micro Aerial Vehicle ◽  
Content Type ◽  
Insect Wing ◽  
Insect Wings ◽  
Aerial Vehicle ◽  
The Military ◽  
Practical Implications

Purpose The purpose of this paper is to experimentally analyze the effect of wing shape of various insects of different species in a flapping micro aerial vehicle (MAV). Design/methodology/approach Six different wings are fabricated for the MAV configuration, which is restricted to the size of 15 cm length and width; all wings have different surface area and constant span length of 6 cm. The force is being measured with the help of a force-sensing resistor (FSR), and the coefficients of lift were calculated and compared. Findings This study shows that the wing “Tipula sp” has better value of lift than other insect wings, except for the negative angle of attacks. The wing “Aeshna multicolor” gives the better values of lift in negative angles of attack. Practical implications This paper lays the foundation for the development of flapping MAVs with the insect wings. This type of wing can be used for spying purpose in the military zone and also can be used to survey remote and dangerous places where humans cannot enter. Originality/value This paper covers all basic insect wing configurations of different species with exact mimics of the veins. As the experimental investigation was carried for different angle of attacks, velocities and flapping frequencies, this paper can be used as reference for future flapping wing MAV developers.

Support vector machines for predicting the compressive response of defected 3D printed polymeric sandwich structures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Khameel Mustapha ◽  
Jamal Alhiyafi ◽  
Aamir Shafi ◽  
Sunday Olusanya Olatunji
Keyword(s):  
Nonlinear Response ◽  
Lattice Structure ◽  
Structural Defects ◽  
Periodic Lattice ◽  
Support Vector ◽  
Fused Deposition Modelling ◽  
Lattice Structures ◽  
Compression Tests ◽  
Content Type ◽  
Fused Deposition

Purpose This study aims to investigate the prediction of the nonlinear response of three-dimensional-printed polymeric lattice structures with and without structural defects. Unlike metallic structures, the deformation behavior of polymeric components is difficult to quantify through the classical numerical analysis approach as a result of their nonlinear behavior under mechanical loads. Design/methodology/approach Geometric models of periodic lattice structures were designed via PTC Creo. Imperfections in the form of missing unit cells are introduced in the replica of the lattice structure. The perfect and imperfect lattice structures have the same dimensions – 10 mm × 14 mm × 30 mm (w × h × L). The fused deposition modelling technique is used to fabricate the parts. The fabricated parts were subjected to physical compression tests to provide a measure of their transverse compressibility resistance. The ensuing nonlinear response from the experimental tests is deployed to develop a support vector machine surrogate model. Findings Results from the surrogate model’s performance, in terms of correlation coefficient, rose to as high as 99.91% for the nonlinear compressive stress with a minimum achieved being 98.51% across the four datasets used. In the case of deflection response, the model accuracy rose to as high as 99.74% while the minimum achieved is 98.56% across the four datasets used. Originality/value The developed model facilitates the prediction of the quasi-static response of the structures in the absence and presence of defects without the need for repeated physical experiments. The structure investigated is designed for target applications in hierarchical polymer packaging, and the methodology presents a cost-saving method for data-driven constitutive modelling of polymeric parts.

Geometric modeling of lattice structures for additive manufacturing

2018 ◽  
Vol 24 (2) ◽  
pp. 351-360 ◽  
Author(s):  
Gianpaolo Savio ◽  
Roberto Meneghello ◽  
Gianmaria Concheri
Keyword(s):  
Additive Manufacturing ◽  
Computer Aided Design ◽  
Geometric Modeling ◽  
Lattice Structure ◽  
Subdivision Surfaces ◽  
Lattice Structures ◽  
Content Type ◽  
Critical Issues ◽  
Surface Subdivision ◽  
Manufacturing Technologies

Purpose This paper aims to propose a consistent approach to geometric modeling of optimized lattice structures for additive manufacturing technologies. Design/methodology/approach The proposed method applies subdivision surfaces schemes to an automatically defined initial mesh model of an arbitrarily complex lattice structure. The approach has been developed for cubic cells. Considering different aspects, five subdivision schemes have been studied: Mid-Edge, an original scheme proposed by the authors, Doo–Sabin, Catmull–Clark and Bi-Quartic. A generalization to other types of cell has also been proposed. Findings The proposed approach allows to obtain consistent and smooth geometric models of optimized lattice structures, overcoming critical issues on complex models highlighted in literature, such as scalability, robustness and automation. Moreover, no sharp edge is obtained, and consequently, stress concentration is reduced, improving static and fatigue resistance of the whole structure. Originality/value An original and robust method for modeling optimized lattice structures was proposed, allowing to obtain mesh models suitable for additive manufacturing technologies. The method opens new perspectives in the development of specific computer-aided design tools for additive manufacturing, based on mesh modeling and surface subdivision. These approaches and slicing tools are suitable for parallel computation, therefore allowing the implementation of algorithms dedicated to graphics cards.

scholarly journals A cyber situational awareness model to predict the implementation of cyber security controls and precautions by SMEs

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Karen Renaud ◽  
Jacques Ophoff
Keyword(s):  
Situation Awareness ◽  
Cyber Security ◽  
Best Practice ◽  
Online Survey ◽  
Situational Awareness ◽  
Security Measures ◽  
Content Type ◽  
Resource Limitations ◽  
Security Controls ◽  
Practical Implications

PurposeThere is widespread concern about the fact that small- and medium-sized enterprises (SMEs) seem to be particularly vulnerable to cyberattacks. This is perhaps because smaller businesses lack sufficient situational awareness to make informed decisions in this space, or because they lack the resources to implement security controls and precautions.Design/methodology/approachIn this paper, Endsley’s theory of situation awareness was extended to propose a model of SMEs’ cyber situational awareness, and the extent to which this awareness triggers the implementation of cyber security measures. Empirical data were collected through an online survey of 361 UK-based SMEs; subsequently, the authors used partial least squares modeling to validate the model.FindingsThe results show that heightened situational awareness, as well as resource availability, significantly affects SMEs’ implementation of cyber precautions and controls.Research limitations/implicationsWhile resource limitations are undoubtedly a problem for SMEs, their lack of cyber situational awareness seems to be the area requiring most attention.Practical implicationsThe findings of this study are reported and recommendations were made that can help to improve situational awareness, which will have the effect of encouraging the implementation of cyber security measures.Originality/valueThis is the first study to apply the situational awareness theory to understand why SMEs do not implement cyber security best practice measures.

Optimisation of process parameters for lattice structures

2015 ◽  
Vol 21 (1) ◽  
pp. 117-127 ◽  
Author(s):  
Eberhard Abele ◽  
Hanns A. Stoffregen ◽  
Klaus Klimkeit ◽  
Holger Hoche ◽  
Matthias Oechsner
Keyword(s):  
Process Parameters ◽  
Lattice Structure ◽  
Research Work ◽  
Dimensional Accuracy ◽  
Superior Performance ◽  
Future Research ◽  
Significant Shift ◽  
Lattice Structures ◽  
Content Type ◽  
Adapted Process

Purpose – This paper aims to develop a set of process parameters tailored for lattice structures and test them against standard process (SP) parameters. Selective laser melting (SLM) is a commonly known and established additive manufacturing technique and is a key technology in generating intricately shaped lattice structures. However, SP parameters used in this technology have building time and accuracy disadvantages for structures with a low area-to-perimeter ratio, such as thin struts. Design/methodology/approach – In this research work, body-centred cubic structure specimens are manufactured using adapted process parameters. Central to the adapted process parameters is the positioning of the laser beam, the scan strategy and the linear energy density. The specimens are analysed with X-ray micro-computed tomography for dimensional accuracy. The final assessment is a comparison between specimens manufactured using adapted process parameters and those using SP parameters. Findings – Standard parameters for lattice structures lead to a significant shift from the nominal geometry. An extensive manufacturing and computation time due to several exposure patterns (e.g. pre-contours, post-contours) was observed. The tailored process parameters developed had good dimensional accuracy, reproducible results and improved manufacturing performance. Research limitations/implications – The results are based on a distinctive geometry of the lattice structure and a specific material. Future research should be extended to other geometries and materials. Practical implications – Optimisation of process parameters for the part geometry is a critical factor in improving dimensional accuracy and performance of SLM processes. Originality/value – This study demonstrates how application-tailored process parameters can lead to superior performance and improved dimensional accuracy. The results can be transferred to other lattice structure designs and materials.

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