Search

This Special Issue contains selected papers from works presented at the 10th EASN International Conference on Innovation in Aviation & Space to the Satisfaction of the European Citizens, which was held successfully from the 2nd until the 4th of September, 2020 [...]

Recent developments in emissions regulations are pushing Non-Road Mobile Machineries manufacturers towards the adoption of more efficient solutions to reduce the amount of pollutants per unit of work performed. Electrification can be a reasonable alternative to traditional powertrain to achieve this goal. The higher complexity of working machines architectures requires, now more than ever, better design and testing methodologies to better integrate electric systems into mechanical and hydraulic layouts. In this work, the attention focused on the use of a Hardware in the Loop (HIL) approach to test performance of an energy management strategy (called load observer) developed specifically for an orchard tractor starting from field characterization. The HIL bench was designed to replicate a scaled architecture of a parallel hybrid electric tractor at mechanical and electrical level. The vehicle behavior was simulated with a personal computer connected on the CAN BUS network designed for the HIL system. Several tasks were simulated starting from data gathered during field measurements of a daily use of the machine. Results showed good performance in terms of load split between the two power sources and stability of the speed control although the variability of the applied load.

Structural lightweight is an important development trend in aerospace and automotive fields, and the demand for lightweight metal materials represented by aluminum alloy, magnesium alloy, and titanium alloy is increasing continuously. Predicting the damage and fracture behavior of advanced metal materials is the key to forming process design and service performance evaluation of high - performance aerospace components, and the development of advanced ductile fracture criteria (DFCs) is the main approach. This paper firstly introduces the microscopic mechanism of ductile fracture of metals, including the shear fracture dominated by shear or compression stress, the tensile fracture dominated by tensile stress, and the mixed fracture. Then, the development history, characteristics, and applications of the traditional uncoupled DFCs are reviewed, and several typical uncoupled ductile fracture models established in recent years as well as their main characteristics and advantages are emphatically discussed. The traditional uncoupled DFCs usually only consider the influence of maximum principal stress or average stress on damage/fracture, and ignore the effect of deviatoric stress, it is not suitable for the prediction of fracture behavior of materials under small stress triaxiality or complex stress state. The recently developed DFCs are more suitable for complex strain path and stress state by considering the joint influence of both stress triaxiality and Lode angle parameter on damage evolution. Whereafter, the development status and typical applications of uncoupled DFCs in aeronautic metals such as aluminum alloy, magnesium alloy, and titanium alloy are reviewed. Finally, this work ends with prospecting the development trend and research direction of DFCs. According to the deformation characteristics of advanced structural metals, new uncoupled DFCs should comprehensively consider the effects of stress state, strain rate, temperature and anisotropy on damage fracture, so as to make it have better applicability and prediction accuracy.

Viscosity is the main rheology parameter of thermosetting resin matrix processing, which is an important factor effecting processing performance. The viscosity-temperature curves at dynamic states and viscosity-time curves at stead state were measured by cone-plate rotate viscosimeter, and the rheology property of bio-based resin system based on rosin-sourced anhydride curing agent was studied according to the optimization improved six parameter dual-arrhenius equation. Two kinds of rheology models were established by fitting reaction rate constant K and pre-exponential factor A according to the exponential or logarithm viscosity relative equation, respectively. The rheology model based on logarithm viscosity relative equation simulation was in good agreement with experimental data than exponential viscosity relative equation fitting. The rheology model demonstrated the law of viscosity change at different processing conditions, which provided necessary scientific basis for processing parameter optimization.

Additive manufacturing technology (AM) is a new type of manufacturing technology based on the discrete-stacking principle and processing component with computer model data. Selective laser melting (SLM) is an important technology in the field of additive manufacturing. With its integrated manufacturing characteristics and significant advantages in the field of complex structural parts manufacturing, it has become a key development technology and frontier direction in the field of aerospace manufacturing. This article reviews the material system and application fields of SLM technology, and mainly analyzes the latest process research of SLM technology and typical applications in the aerospace field. It focuses on the research progress and results of SLM iron-based alloys, nickel-based alloys, titanium alloys and aluminum alloys. While SLM technology is widely used in various fields, there are also many problems and shortcomings, such as many internal defects of forming materials, cracks and deformations of high-performance materials, lack of standard systems, and low compatibility of powder materials. Constraints require further in-depth work in these areas.

Spark discharge phenomenon in solution is a typical characteristic in metal microarc oxidation (MAO) surface treatment, and the optical emission spectroscopy (OES) is an effective way of characterizing micro-discharge optical emission spectra and studying the MAO mechanism. In this paper, the research status of OES analyses in MAO process of Al, Mg, Ti and their alloys was reviewed, the calculation principle of electron temperature and density in microarc plasma discharge channels was introduced, and the influence of the plasma discharge behavior on the microstructure of MAO coatings at different metals, electrical parameters and electrolyte solutions was evaluated. Furthermore, the different discharge models on the basis of OES analyses were also discussed. The plasma temperature in microarc discharge zone for different metals calculated from OES was in the range of 3000 - 10000 K, which provided the evidence for the growth mechanism of ceramic coatings enhanced by quick molten-solidification process in discharge channel.

Graphene/Al composites have the characteristics of high strengthening efficiency, synergistic improvement of strong plasticity, and excellent comprehensive performance, which is expected to break through the bottleneck problem of poor strength- plasticity matching of metal matrix composites. However, the dispersion of graphene is an important issue that plagues the preparation of materials. The flaky powder metallurgy technology based on the mechanical ball-milling process can transform the spherical aluminum powder into flakes and realize the uniform dispersion of graphene. In this study, the mechanical ball-milling process was controlled by adding a process control agent (polydimethylsiloxane, PDMS) to prepare flaky Al powder, combined with pressure infiltration technology to prepare 0.6%(mass fraction) GNPs/6061Al composites. The results show that the diameter of flaky aluminum powder increases first and then stabilizes with the prolongation of milling time. As the viscosity of process control agent increases, the diameter of flaky aluminum powder is increased, and the flaky effect of aluminum powder is more obvious. At the same time, the viscosity of graphene defect content decreases first and then increases. Moreover, it is revealed that the graphene defects show a decreasing and increasing change pattern as the viscosity increased. Combined with the structure characterization and mechanical property test, the relationship between properties and structure is discussed, which has provided a reference for the subsequent preparation of graphene/Al composites.

TiAl alloy was electrochemically anodized in ethylene glycol electrolyte containing with NH4F to prepare anodic film. The influence of anodization treatment on the oxidation behavior and mechanical properties of the anodized TiAl alloy were then characterized. Results shown that based on the halogen effect a continuous and dense Al2O3 oxide scale will generate on the anodized TiAl alloy after high temperature oxidation. After oxidation at 1000 ℃ for 100 h, the weight gain of the anodized TiAl alloy was dramatically decreased from 85.86 mg/cm2 to 0.67 mg/cm2. Moreover, it is shown that the surface hardness and elastic modulus of the anodized TiAl alloy decreased first and then increased with the prolonging of oxidation time. Meanwhile, the friction coefficient of the anodized TiAl alloy increased comparing to the bare TiAl alloy. The surface wear resistance of the anodized TiAl alloy exhibited similar phenomena. This is because that during high temperature oxidation process, aluminum fluorides selectively transport to the surface through pores or micro-cracks, and are oxidized to Al2O3 at the surface region. The influence of anodization treatment on the mechanical properties of the anodized TiAl alloy is attributed to the Al2O3 content contained in the oxide scale.

The casting simulation software ProCAST was used to achieve the simulation of the filling and solidification process of the high Nb-TiAl alloy impeller investment casting. The influence of the casting and filling process on the filling and solidification characteristics of alloy melt filling, shrinkage cavity and porosity was studied, and the corresponding process was optimized. The casting test and the non-destructive testing analysis of the casting were carried out, and the anatomical analysis of the casting was performed to verify the distribution of the shrinkage cavity and porosity. The mechanical properties of the impeller at room temperature and high temperature were studied using attached test rods. The results show that ProCAST software is more accurate in predicting shrinkage cavity and porosity of the high Nb-TiAl casting, and the process scheme is optimized by simulation and prediction results to avoid the formation of large shrinkage cavity and porosity in casting, only micro shrinkage cavity less than 22 μm is existed in the final casting. All castings are fully filled, with the tensile strength about 580 MPa at room temperature and about 450 MPa at high temperature of 850 ℃.

SiCf/SiC composites with the polycarbosilane and silicon carbide fiber of different pyrolytic carbon (PyC) interphase thicknesses as the reinforcement phase were fabricated by a polymer impregnation and pyrolysis (PIP) method. And SiC whisker was introduced into the SiCf/SiC composites to further improve its performance. It is found that the mechanical properties of SiCf/SiC composites have outstanding tensile strength, fracture toughness and flexural strength of 192.3 MPa, 446.9 MPa and 11.4 MPa·m1/2,, when the PyC interphase thickness is about 230 nm. After the introduction of SiC whisker, into the SiCf/SiC composite matrix, the toughening mechanisms such as whisker pull-out, whisker bridging and crack deflection increase the energy consumption when the crack is transferred in the matrix, and the fracture toughness and bending strength of the composite are increased by 22.9% and 9.1% respectively.

In this work, numerical simulation was used to investigate the distribution of cooling rate during DC semi-continuous casting of 4032 aluminum alloy billets with the diameters of ϕ120 mm, ϕ300 mm and ϕ500 mm. Further, the effect of cooling rate on the modification of eutectic silicon by Sr addition was investigated. The simulation results indicate that the cooling rate from the surface to the center of the billet generally decreases. As the billet diameter increases, the sump depth becomes deeper, the distance between the isothermal lines of liquidus and solidus becomes larger, and the cooling rate at the billet center decreases sharply. The cooling rate affects the modification results of eutectic silicon by Sr addition. When the cooling rate is higher than 1.8 K/s, Sr addition can achieve excellent modification results. However, as the cooling rate decreases, the modification of eutectic silicon becomes worse, even the Sr contents are the same. At the industrial casting conditions, the cooling rates of inner part of the ϕ500 mm billet are below 1 K/s. At this low cooling rate, the Sr content of 0.033%-0.036% is not enough to modify the eutectic silicon any more. To the billet with the diameter as large as 500 mm, the casting speed is the most important factor that influence the cooling rate distribution. But the influenced area is only limited within the distance of R/2 to the surface, and little influence to the center of the billet.

Bumper and crash boxes are vehicle structural elements that convert the collision (kinetic) energy at the collision into deformation energy. Failure of the bumper system to sufficiently absorb the collision energy in the event of a collision will result in the resulting forces being transferred directly to the driver and passenger area. It will result in deaths or injuries to people in the vehicle and further damage to the vehicle. In this study, the collision performance of an existing aluminum crash bumper system produced by the extrusion method with a 40% offset collision analysis is examined. A magnesium crash bumper with improved collision performance is designed by this reference. In this design process, the design of experiment method is used. With the combinations created with the Taguchi method, the long design and analysis process is completed in a shorter time. Taguchi experiment design process; four different design variables and three-level combinations of these variables are used. With the table's help created at the L9 level, models corresponding to the variables are prepared, crash analyzes are performed with finite element analysis, and crash performances are examined. After revealing the results, optimization is carried out with Minitab software; the optimum design is achieved in crash performance and lightness.

This work examines the most promising design solutions for the creation of propulsion systems for ultra-light launch vehicles by small private enterprises in the rocket and space industry. Comparison of the metal consumption of the combustion chambers with the energy characteristics at different operating pressures showed that the most optimal operating pressure is 12,16 MPa. Comparison of the relative and absolute values of the masses of various configurations describes the nature of the relationship between the number of combustion chambers and the total mass of the propulsion system. It was found that nine-chamber propulsion systems with cameras made with extensive use of additive technologies best meet the key requirements. The analysis carried out includes an assessment of the design parameters of both various components and assemblies and the propulsion system as a whole. Various layouts of propulsion systems are considered in detail, the required degree of technological complexity of structures of various units and assemblies, their production cost are estimated. The ratio of the obtained mass-energy characteristics was achieved through the implementation of design solutions that became available due to the use of additive technologies. The obtained results of preliminary calculations demonstrate the applicability and efficiency of design solutions considered for use in the propelled propulsion system for a promising launch vehicle.

The dynamic analysis and motion control of a spinning tether system for an interplanetary mission to Mars is considered. The space system consists of two spacecraft connected by a tether with thrusts to control its movement. The movements of the tether system in the sphere of action of the Earth, on the interplanetary trajectory and in the sphere of action of Mars are consistently analyzed. In near-Earth orbit, the transfer of the system into rotation with the help of jet engines installed on the end spacecrafts is considered. The spin of the system is used to create artificial gravity during the interplanetary flight. The tether system spins in the plane perpendicular to the plane of the orbital motion of the center of mass of the system. To describe spatial motion of the system, a mathematical model is used, in which the tether is represented as a set of material points with viscoelastic unilateral mechanical connections. When calculating the movement of the system, an approach based on the method of spheres of action is used. Spacecrafts are considered as material points. The level of gravity and spin of tether system is controlled by thrusters. The structure of the controller for controlling the angular speed of rotation of the tether system is proposed. The simulation results are presented to confirm the effectiveness of the proposed control algorithm, which provides a given level of artificial gravity for th e interplanetary mission under consideration.

The article provides an overview of designs of reflector antennas for spacecraft with solidstate precision dimensionally stable reflectors. The requirements for modern reflector antennas of spacecraft intended for the transmission of high-frequency radio signals are formulated. The features of using composite materials in manufacture of antenna reflectors in the context of their reflective capabilities are considered. The classification of reflector antennas is given. Features of the placement of antennas on a spacecraft are outlined. Multiple designs of reflectors of modern antennas are considered. Various ways of ensuring accuracy of shape and rigidity of reflectors are analyzed. Designs of antennas with a contoured service area and dichroic antennas are described. Antenna assemblies which are placed on a spacecraft and their advantages are considered. An overview of the engineering analyzes carried out during the antenna design phase is provided. The types of tests used to check the performance of spacecraft antennas are considered.

The purpose of this article is to analyze the existing algorithms of autonomous control of the integrity of the navigation field of the GLONASS system. The analysis is based on domestic materials and official foreign applications. At the beginning of the article, the concept of the integrity of the global navigation satellite system is given in the form in which it is used in International Civil Aviation Organization and among the developers of such systems. The differences between the common types of control of the integrity of the navigation field are shown. The modeling of individual operational characteristics, including the average geometric factor, visibility, and accessibility for different angles of the site, is carried out. The main solutions to the problem of reduced tactical and technical characteristics of the system are compared. The existing prerequisites for the improvement of the GLONASS system and for the use of small navigation spacecraft to eliminate the gap between GLONASS and competing global navigation satellite systems are listed. As a result, a variant of improving the circumstances for the application of these algorithms in unfavorable conditions in relation to the GLONASS system is proposed. It is shown that the low-orbit addition to the GLONASS system can significantly improve the tactical and technical characteristics of the complex as a whole and provide higher reliability of the system as a whole due to the operational maintenance of the integrity of the navigation field.

An Attitude control system for a satellite in low earth orbit is designed in this project. As a reference, CARTOSAT-2 is selected to design the AOCS. CARTOSAT-2 is located in LEO so it suits the needs of the projects. It is mainly used for mapping of urban, rural areas and wetlands in India. To design a basic AOCS, a DC motor based model is considered. Transfer functions of DC motor and satellite dynamics model are calculated using Laplace transformation. Stability of the system is checked by plotting poles and zeroes of the systems. PID controller is used to improve the overall stability of the system by decreasing the errors in the output of the system. The systems are subjected to sine and step inputs and responses are plotted in the form of graphs. The plots are studied using SciLab as the tool to design the block diagram and the control system for the AOCS. Scilab along with FlightGear is used to visualize the response of the system.

This paper deals with the dynamic characteristics for bending vibrations of Euler-Bernoulli type nanobeams taking into account the scale effects via the nonlocal motion equations. An integral method, based on the use of Green’s functions, has been used in order to obtain the corresponding eigenvalue problem. The proposed integral approach is an approximate matrix method. Effects of different boundary conditions and of an elastic foundation have been also included. The presented numerical examples show good agreement when compared to results from literature. The proposed method can be used in the case of nanodevices analysis modeled as beams (MEMS, NEMS).

Distributed data acquisition systems are the norm in the great majority of industry branches where the process to be controlled covers a physically large and often fragmented area. Many local smaller data acquisition modules are interfaced and pass raw or pre-processed data along with the timing signals. These timing signals are a vital part of data acquisition as oftentimes raw data is processed as time series and correlations are made based on timestamps. This paper presents a study for implementation of a cost-effective high precision time base (reference clock) using a GPS receiver as a primary time source and a local high precision real time clock as a secondary oscillator.

This paper deals with airlines business models, mostly full service network carriers (FSNC) and low-cost carriers (LCC) and their position on the airline market. Covid-19 crisis causes many negative impacts on all airline industry. Hybridisation process in aviation industry is described many times in the past; now it has a stronger impact on airline business model development and it is oriented on different aspects than before. The paper emphasises the fact that low-cost carrier’s business model is much closer to the features of the FSNC carriers from the price point of view and vice versa. Furthermore, the authors introduce some other diversifications of airlines business models and the paper offers the new stimulus to move forward in this tough time for airlines business, paradoxically, thanks to Covid-19. Finally, yet importantly, the authors emphasise the important role of the state in the further direction of the airlines during and after the Covid-19 crisis

The gravity or reactive bundle energy is the outlet of the morphogenetic impact, known as “BIG BANG”, creating a bounded ordered/structured universe along with the solar system, including the EARTH-world with its human race. Post-impact, the huge kinetic energy is spread into stellar bodies associated with the light flux under strong mutual connections or gravitational bundle. Einstein’s general relativity theory including the gravitational field can be expressed under a condensed tensor formulation as E  R − Rg =  T where E defines the geometry via a curved space-time structure (R) over the gravity field (1/2Rg), embedded in a matter distribution T The fundamental (ten non-linear partial differential) equations of the gravitational field are a kind of the space-time machine using the curvature of a four-dimensional space-time to engender the gravity field carrying away material structures. Gravity according to the curved space-time theory is not seen as a gravitational force, but it manifests itself in the relativistic form of the space-time curvature needing the constancy of the light speed. But the constant light velocity makes the tidal wave/pulsating energy, a characteristic of solar energy, impossible. The Einstein’s field equation, expressed in terms of tensor formulation along with the constant light speed postulate, needs two special space-time tensors (curvature and torsion) in 4 dimensions, where for the simplicity the torsion/twist tensor is less well approximated (Bianchi identity) leading to a constant/frozen gravity (twist-free gravity).The non-zero torsion tensor plays a significant physical role in the planetary dynamics as a finest gear of a planet, where its spinning rotation is directly connected to the own work and space-time structure (or clock), controlled by light fluctuations (or tidal effect of gravity). The spin correction of Einstein’s gravitational field refers to the curvature-torsion effect coupled with fluctuating light speed. The mutual curvature-torsion bundle self-sustained by the quantum fluctuations of light speed engenders helical gravitational wave fields of a quantum nature where bodies orbit freely in the light speed field (cosmic wind). In contrast to the Einstein’s field equation describing a gravitational frozen field, a quantum tidal gravity model is proposed in the paper.

The new challenges in the aerospace field lead to the need to develop new materials with complex shapes, without major intervention in their definition. Thus, laser 3D printing technologies have been developed for both composite and metallic materials. This paper presents a study of characterization and testing of a 3D printed metal material (Maraging steel 1.2709) in three different directions (x, y and z) to observe, from a mechanical point of view, the behavior depending on the printing direction and the structural changes that intervene following the tensile stress. Mechanical tests consisted of tensile testing in accordance with current international standards, and morphostructural analyzes consisted of investigation of the failure area using optical microscopy and scanning electron microscopy (SEM), respectively.

The stick-slip phenomenon is a dynamic instability that appears at the contact interface of two sliding surfaces. Its occurrence is influenced by the relative sliding speed, the contact pressure, and the system rigidity, but also by the state of contact between the two sliding surfaces. The present paper aims to study the influence of the anisotropy of an aluminium AA2021-T351 plate on the stick-slip phenomenon. For this, using the CETR UMT II tribometer, linear sliding tests have been performed on the aluminium alloy thick plate surface using a cylindrical pin made of ultra-high-molecular-weight polyethylene (UHMWPE) along three directions: a longitudinal one, corresponding to the rolling direction of the sample (0°), a transverse one, perpendicular to the rolling direction (90°), and a median direction (45°). Varying the sliding speed, the contact pressure, and the system rigidity, it was possible to observe the influence of the material anisotropy on the specific parameters of the stick-slip phenomenon.

Research in biomechanics has numerous applications including rehabilitation which helps in the fabrication of assistive devices. The Assistive devices or exoskeletons are used to serve the patients affected by stroke and spinal cord malfunctioning. These devices are programmed to follow a fixed redundant gait cycle and are lacking in producing natural movement of the gait. To overcome this limitation and make the device more user comfortable during usage of their daily life activities, a thorough study was done using an open source software that contributed to the design of exoskeleton device for the subject. In the current study, a simulation of various daily life activities are thoroughly studied using a musculoskeletal simulator package like OpenSim. The paper presents the observations of muscle responses from ground reaction forces with minimized metabolic cost function in various activities of daily living such as sitting to standing, standing to sitting, jumping, twisting suddenly while walking and turning suddenly. The study deliberates the inputs for developing more comfortable exoskeletons in performing tasks in a more sophisticated manner.

An aircraft is an advanced mechanical structure made by man which has been dominating the skies from the early 19th centuries. It has been used for transportation of cargo/ passengers from one place to another in a shorter period of time. Advances in aeronautics lead to the development of fighter aircrafts with exciting and dominating characteristics. A fighter aircraft is to be designed in such a way that it can withstand heavy loadings on the wing due to its high manoeuvrability. A fighter aircraft is designed to be marginally unstable, which makes control easier and better during manoeuvrability at high speeds, but in this state there is a heavy fluctuating load acting on the wing. The wing is connected to the fuselage using wing fuselage lug attachment bracket. Since the wing is a cantilever structure, the load acting on the wing is concentrated on the hinge (lug bracket assembly). In this paper, a lug bracket is designed according to the standard design procedure and is validated using Finite Element Methods to ensure the static loading capability and stress concentrations in lug bracket. The validated model has been optimized using Altair Optistruct. The optimized model has been validated under static loading condition for the stress concentration and displacement and is compared with initial model in order to study and understand its behaviour under various conditions.

Cerium oxide rice grain like nanoparticles have been synthesized using wet chemical hydrothermal synthesis method. Hydrothermal synthesis method provides nanoparticles with unique dimension and shape due to supercritical synthesis conditions than conventional precipitation techniques. The hydrothermal synthesis of Cerium salt in the presence of urea produces Cerium carbonate hydroxide nanoparticles with rice-grain morphology, which are reduced into Cerium oxide by heat-treating at 600°C, for 4 hours, without changing its morphology. The formation of Cerium carbonate hydroxide with orthorhombic crystal structure and Cerium oxide with cubic crystal structure were confirmed by X-Ray Diffraction [XRD] spectroscopy studies. Thermo-gravimetric analysis [TGA] in inert nitrogen atmosphere and ambient air provides the reduction temperature of hydroxide and carbonate is about 600°C. Scanning electron microscope [SEM] studies show the uniform rice grain like morphology of as-prepared Cerium carbonate hydroxide and Cerium oxide, due to the reduction at elevated temperature and crystalline structural deformation Cerium oxide shows cracks and porous on its surfaces.

In our days, there is a priority to diversify the sources of energy, in order to prevent the negative effects of human activity on the environment. One of the interestings solutions is to use the animal waste from the food industry. Turning animal fat into combustible would allow substituting it to oil in systems like boilers. But for using animal fat as energy in these systems, we should characterize it before by studying its rheological properties and especially the viscosity, in order to design the systems as well as possible. The purpose of the following study is to establish the main rheological properties of the pork fat, which is one of the most important waste source of animal fat from the food industry

Aerospace actuators can be found throughout modern commercial and experimental aircraft, as well as in military and space exploration. The aerospace industry is not only growing, but also rapidly changing and the demand for aerospace actuators is permanently increasing. Linear actuator is able to push, pull, and hold objects in a way that our bodies cannot. Additionally, electrically powered technology provides more sophisticated control options. Linear actuator drive many different functions that are essential to safe and efficient aircraft operation. Manufacturers and hobbyists alike are always on the hunt for new ways to automate functions while keeping development costs low. Providing cost-effective linear solutions for aerospace application is one of the biggest challenge. This research will provide a cost-effective actuator conceptual design for variable span morphing wing UAV. The cost-effective design will be presented along with the application-based selection of linear actuators for morphing wing UAV.

In the aerospace industry, Liquid Resin Infusion (LRI) is gaining more and more importance as an out-of-autoclave alternative manufacturing technique to traditional pre-impregnated (prepreg) fabrics. The research in this field has been focused on understanding the cure and the process parameters of these materials, aiming to optimize the manufacturing process and reduce costs. A major problem derived from these technologies is the distortions induced by LRI process, affecting to composite parts due to non-uniform distribution of residual stresses. Such distortions can lead to non-uniform parts with shape distortions, which is a critical issue when trying to assembly with other parts due to mismatches in shape, leading to the rejection of such components. In this context, ELADINE project aims to understand and quantify the key manufacturing parameters that cause shape distortions on composite coupons (such as spring-in of curved parts) using an integrated numerical-experimental approach. The manufacturing process will be accurately monitored through Fiber Optic Sensors (FOS) and Dielectric sensors (DC) to understand how the process variables affect the distortion phenomena. The monitored data will feed a simulation tool for spring-in prediction for large integral composite wing structures. This article covers the preliminary results of cure monitoring and process parameters of thermoset composites implementing monitoring strategies for manufactured coupons by LRI.

In this study, the performance and exhaust emission values in a four-stroke, four-cylinder turbocharged Diesel engine fueled with ethanol-diesel fuel blends (10% and 15% involume) were investigated by using Artificial Neural Network (ANN) modeling. The actual data derived from engine test measurements was applied in model training, crossvalidation, and testing. To train the network, fuel injection pressures, throttle positions,engine speed, and ethanol fuel blend ratios were used as input layer in the network. Theoutputs are the engine performance values (engine torque, power, brake mean effectivepressure, and specific fuel consumption) and exhaust emissions (SO2, CO2, NOx, andsmoke level (N%)) which were measured in the experiments.The back-propagation learning algorithm with three different variants, a single layer,and logistic sigmoid transfer function (log-sig) was used in the network. By using theweights of the network, formulations were given for each output. The network for test datayielded the R2 values of 0.999 and the mean % errors for test data are smaller than 3.5%for the performance and 8% for the emissions.Ankara Yıldırım Beyazıt Üniversitesi, Mühendislik ve Doğa Bilimleri Fakültesi, Makine Mühendşiilği Ankara, 06010, Türkiye

This paper presents the effects of torque preload on the damage initiation and growth in the CFRP (Carbon Fiber Reinforced Polymer) composite laminated adherent of the single-lap, single-bolt, hybrid metal-composite joints. A detailed 3D finite element model incorporating geometric, material and friction-based contact full nonlinearities is developed to numerically investigate the preload effects on the progressive damage analysis (PDA) of the orthotropic material model. The PDA material model integrates the nonlinear shear response, Hashin-tape failure criteria and strain-based continuum elastic properties degradation laws being developed using the UMAT user subroutine in Nastran commercial software. In order to validate the preload effects on the failure modes of the joints with hexagonal head bolts, experiments were conducted using the SHM (Structural Health Monitoring) technique. The results showed that the adherent torque level is an important parameter in the design process of an adequate bolted joint and its effects on damage initiation and failure modes were quite accurately predicted by the PDA material model, which proved to be computational efficient and can predict failure propagation and damage mechanism in hybrid metal-composite bolted joints.

In order to obtain accurate results in wind tunnel testing it is necessary to determine the effect of interaction between the flow around the model and the test section walls. In this paper, the classical theory for wind tunnel wall corrections assessment is used to evaluate the wall induced change in the circulation caused by the presence of the test article in the wind tunnel. This primary correction, also known as lift interference is based on the test section geometry and it is applied to the test article angle of attack. The computations performed in this paper employ the assumption of the potential linearized flow between the test section walls and the model. As well, the principle of superposition is a key element in this analysis.

In this study, the effect of tire inflation pressure on the vehicle during braking was investigated experimentally. The experimental study was carried out in the Brake-Suspension Test Device designed as a half-vehicle model, which enables vehicle brake tests to be performed in the laboratory. During the tests, a total of nine different tire inflation pressures from 26 psi to 40 psi standard value were taken into consideration. As a result of the experiments carried out separately for each tire inflation pressure, a curve characterizing the effect of different pressure values on the pitching force was obtained. Based on the experimental results, dif-ferent mathematical models suitable for the curve obtained are derived by non-linear curve fitting. For the nonlinear curve fitting process, a hybrid iterative re-gression algorithm obtained by combining classical curve fitting algorithm with Newton-Raphson iteration method was used. It was observed that the correlation coefficients (R2) of the mathematical models obtained provided sufficient sensi-tivity to express the problem under consideration.

The objective of the research work to focus on a path planning aims to plan the route of an Unmanned Vehicle (UV) using Global Positioning System (GPS), and the most suitable path is selected avoiding the obstacles along the desired path. The coordinates of the starting point and destination are fed through programming. In addition, an obstacle avoidance algorithm is used and waypoints are given using the AVR Programming. Waypoint Navigation System for the Unmanned Ground Vehicle is use with GPS avoiding the obstacles in its path. The Waypoint Navigation System is the planning of the path of an object so that the path goes through some specified coordinates or benchmarks to the final destination thus avoiding any obstacles. The technology used to accomplish the aim includes Global Positioning System (GPS), Ultrasonic Sonic sensors and Micro-controller for programming. GPS will be the guiding medium from source to destination and two Ultrasonic Sensors will be used. These types of vehicles are used for many purposes and have been used by United States of America for Military and Defense purposes. In advanced cases, an Unmanned Aerial Vehicle may also be developed using these algorithms.

In the present work by employing the Technique for order of preference by similarity to ideal solution (TOPSIS) machining parameters optimization is performed with polycrystalline cubic boron nitride (PCBN) tools while AISI 52100 steel hard turning (HT). Based on the CCD of RSM, 32 experimental runs were performed by varying cutting speed, feed, depth of cut, nose radius, and negative rake angle to identify the optimal level of the process parameters. In this study, the multiple performance characteristics measured are machining force, surface roughness, and workpiece surface temperature. To ascertain the impact of cutting parameters on responses, Analysis of Variance (ANOVA) was deployed. An optimum combination of input process parameters for the multiple performance characteristics should be as follows: speed 200 rpm, feed 0.1 mm/rev, depth of cut 0.8 mm, nose radius 1.2 mm, and negative rake angle 45º leading to the value of optimum response variables machining force 561.163 N, Surface roughness 0.507μm and workpiece surface temperature 84.38°C.

In real crash cases, simple bending behavior is not common. In this case, using the three-point bending test to examine the bending behavior provides a closer simulation in terms of the representation of the structure under loading. It is seen in the literature that products with tube sections are generally used as door im-pact beams. On the other hand, when examining the three-point bending behavior of developed high strength steels, it is seen that the studies on tube profiles are only evaluated in terms of hydroforming. In this study, dual-phase steel tubes used as door impact beams are investigated by means of bending loading with experimental and numerical studies. For this purpose, DP500 and DP600 steel grades are used as materials. Three-point bending tests are performed for both materials then force-stroke curves, and springback values are obtained experi-mentally. In the second stage of the study, finite element analyses are performed using Hill-48 plasticity model. Force-stroke curves, the amount of springback, and the product forms are compared with the experimental results. It is seen that force-stroke curves and product forms are obtained highly compatible with the experimental results however the amount of springback values in finite element analyses are determined higher than the experimental results.

At present, the control capability of dielectric barrier discharge (DBD) plasma actuation covers the flow velocity range of helicopter’s retreating blades, so it is necessary to extend it to the dynamic stall control of rotor airfoils. A DBD plasma actuator was adopted to control the dynamic stall of an oscillating CRA309 airfoil in this paper. The effectiveness of alternating current (AC) DBD plasma actuation on reducing the area of lift hysteresis loop of the oscillating airfoil was verified through pressure measurements at a Reynolds number of 5.2×105. The influence of actuation parameters on the airfoil’s lift and moment coefficients was studied. Both steady and unsteady actuation could effectively reduce the hysteresis loop area of the lift coefficients. The flow control effect of dynamic stall was strongly dependent on the history of angle of attack. Compared with the steady actuation, unsteady actuation had more obvious advantages in dynamic stall control, with reducing the area of lift hysteresis loop by more than 30%. The effects of plasma actuation on the airfoil’s flow field at both upward and downward stages were discussed at last.

The paper presents a method for minimizing the torque value of the multi-time deploymentfolding hinges. The objects of research were the hinges assembly of multi-time deployment-folding mechanical devices of solar array, which are used as part of the platforms of spacecraft. A computational analysis of the forces and moments that act in the hinges in the process of their opening and folding is carried out. The minimization of the excessive torque value without changing the design and layout of the hinge is possible by changing the shape of the dependence of the spring drive force on the angle of rotation of the hinge. The possibility of using constant force springs as part of the hinge is considered, the existing design algorithms are improved and a program for calculating the geometric and mechanical characteristics of constant force springs is developed. Experimental data were obtained for measuring the forces of springs of various configurations, showing the dependence of the magnitude of the force on the magnitude of the spring deformation and confirming the efficiency of the proposed calculation algorithm. A prototype of a hinge assembly with a constant force spring drive was developed and manufactured. The possibility of minimizing the excess torque without the need to change the design of the hinge while maintaining its technical characteristics was experimentally confirmed.

The aim of this paper is to analyze different aspects of microphysical properties of mixed phase clouds, considering also the processes that are contributing to their formation. ATMOSLAB airborne laboratory, equipped with CAPS – Cloud, Aerosol and Precipitation Spectrometer sensors system was exploited to perform three flight research missions focused on cloud microphysics. For this purpose, there was analyzed the variation of 4 major parameters with high influence the cold clouds lifecycle (temperature, pressure, number concentration, effective diameter and 2D images of droplets and ice crystals) and was highlighted the occurrence of nucleation, accretion and droplet coalescence in cirrus and cirrostratus clouds.

This paper presents an experimental study of the influence of nano metric silicon carbide in the composition of phenolic composites on the coefficient of friction. The paper is divided into three distinct parts investigating from a tribological point of view three different types of composite materials based on phenolic resin with three concentrations of nSiC (0.5; 1 and 2% by mass). In the first part, a comparative study of the behavior of phenolic resin was performed, representing the basis for the development of composite materials. In the second part, a study was performed on laminated materials reinforced with two-dimensional fabrics (glass fiber and carbon fiber, respectively). The last part studied two types of ablative phenolic materials based on micronic cork, on one hand, and on carbon felt on the other hand.

The complexity of sandwich structures is a challenge for aeronautics designers. Sandwich construction is widely used in both the aerospace and commercial industries because it is an extremely lightweight structural approach with high rigidity and strength/weight ratios. Although today's technology offers the possibility to combine a variety of materials for these structure solutions, in aviation only a few materials are accepted. This paper presents the technological process of making these sandwich structures, as well as a study of the characterization and testing of a sandwich structure to analyze the behavior from a mechanical point of view. The conclusions of the paper represent an experimental basis on which further research will be built.

In this study the procedures of structural analysis of a typical transport aircraft wing has been followed. The wing model has been drawn using CATIA® V5; this model consists of several structural components such as spars, ribs and skin. The model has been exported into structural analysis software ANSYS® 2016. Stresses, strains, deformations and safety factors were obtained for the model. It is found that the obtained stresses caused by the aerodynamic loads on the wing are within the design structural limits where the failure by yield or buckling has not been occurred

This paper concerns the benefits of the active boundary layer control methods. The main focus was studying the effectiveness of suction control for a laminar flow over an airfoil. However, injection normal to or along the wall was also approached using two numerical methods. For different values and distributions of the velocity control magnitude, a systematic comparison was done. Having the results of the laminar flow, a linear stability analysis based on the small disturbance theory was carried out obtaining both the neutral stability curves and the transition point. In the end, for each case, results were presented with the corresponding observations. Additionally, a study on the dependency of the separation point with respect to the injection velocity magnitude was done.

Logistics can be seen as the compound of all the considerations needed to ensure the efficient and economical support of a system throughout its life cycle. The unscheduled actions, performed as a result of a failure or a perceived failure, that are necessary to restore a system to its required level of performance is corrective maintenance. Such activities may include troubleshooting, disassembly to gain access to the faulty item, repair, remove and replace, reassembly, alignment and adjustment and checkout. The frequency of maintenance for a given item is highly dependent on the reliability of that item. In general, as the reliability of a system increases, the frequency of maintenance will decrease and, conversely, the frequency of maintenance will increase as system reliability is degraded.

Decision-making processes within aeronautical organizations are becoming increasingly challenging not only because of social, economic or flight planning threats, but also because of the need to properly implement new technologies that may require different approaches to allow a high performance operational state in air transport. The paper outlines the organizational management improvements in the complex and dynamic operational environment and analyzes the decision-making processes related to different risk levels which require a strong commitment from organizational management in the context of operational objectives. The authors also analyze the implementation of new technologies that affect the processes carried out within the organization and propose ways to adapt organizational management in order to control safety processes. The authors also analyze the implementation of new technologies that the processes carried out within the organization and propose ways organizational management security processes.

The COVID-19 pandemic has the potential to trigger a global economic crisis of significant dimensions, affecting all industries and activity sectors. One of the industry sectors in the eye of the coronavirus storm is aerospace. As governments all over the world have closed the boarders and imposed quarantine to their citizens, global air traffic has been brought to an almost complete standstill by the COVID-19 outbreak. Aviation leaders all over the world think that “this is still the worst crisis that this industry has ever been faced with. There’s a huge amount of uncertainty going forward.” In Europe and all over the world, governments are taking action adopting measures in support of their national airlines, but besides the grounded planes and canceled flights, a whole aviation and aeronautics industry is suffering from this crises. The big manufacturing companies are suffering and have to let go thousands of employees. There is an enormous pressure also on the aviation research to cope with the new situation. The immediate impact of the crisis is a severe economic downturn of the whole industry, starting with airlines postponing or stopping orders and deliveries, creating a snowball effect on the complete value chain, with a drastic lack of cash to finance research projects. In this challenging times of unprecedented uncertainties, aeronautics research community is trying to answer to two pressing questions: (1) How does this crisis affect research in the European aviation sector? and (2) What needs to be done to face the consequences caused by COVID-19 and boost aviation research in Europe?

Cold spray technology is an advanced spray technology, and its technical principle is the same as that of additive manufacturing technology. Cold spraying technology combines multiple advantages in the spraying field: not only can the deposition of thick coatings be achieved, but the coatings prepared by this technology have the characteristics of high density, low oxygen content, good mechanical properties of the coating surface, and high deposition efficiency. Cold spraying technology can prepare corrosion-resistant coatings, high-temperature resistant coatings, wear-resistant coatings, conductive coatings, anti-oxidation coatings, and other functional coatings. After decades of development and exploration, cold spraying technology is preparing metal coatings. The application is very wide and the process is mature; the same cold spray technology can also prepare non-metallic coatings. Mainly to immerse repair and protect the surface of metal alloy parts and a small part of non-metal parts, so that these parts have better mechanical properties and mechanical behavior. This article mainly reviews the application of cold spray technology in the field of spray materials and summarizes the existing conventional metal series, rare metal series and non-metal material, conventional non-ferrous metals: copper, titanium, aluminum and nickel. Metal materials are currently widely used in the field of cold spraying. Among them, titanium-based metals restrict their applications due to their own properties; rare metals: tungsten, tantalum, and niobium-based metal materials. The application of rare metals in cold spraying is still in its infancy stage; non-metallic materials: polymer materials and ceramic powder materials, non-metallic materials have the characteristics of surface modification and strengthening technology, but also have low oxygen content, low thermal stress, high density, good bonding strength, in the deposition process and the substrate will not change the advantages of physical organization structure. Finally, the existing problems of rare metal materials and non-metal materials are raised.

Direct Yaw Moment Control (DYC) is an effective way to alter the behaviour of electric cars with independent drives. Controlling the torque applied to each wheel can improve the handling performance of a vehicle making it safer and faster on a race track. The state-of-the-art literature covers the comparison of various controllers (PID, LPV, LQR, SMC, etc.) using ISO manoeuvres. However, a more advanced comparison of the important characteristics of the controllers’ performance is lacking, such as the robustness of the controllers under changes in the vehicle model, steering behaviour, use of the friction circle, and, ultimately, lap time on a track. In this study, we have compared the controllers according to some of the aforementioned parameters on a modelled race car. Interestingly, best lap times are not provided by perfect neutral or close-to-neutral behaviour of the vehicle, but rather by allowing certain deviations from the target yaw rate. In addition, a modified Proportional Integral Derivative (PID) controller showed that its performance is comparable to other more complex control techniques such as Model Predictive Control (MPC).

Carbon fiber reinforced silicon carbide ceramic based (C/SiC) composites are widely used in industrial, aerospace and other fields due to their high strength, hardness and wear resistance. However, C/SiC composites are difficult to be removed and processed. In this paper the common preparation methods of C/SiC composites and the performance characteristics of their materials are reviewed. The traditional machining methods, ultrasonic assisted machining, laser processing and other processing methods of C/SiC composites are summarized. The material removal mechanism, processing precision, common defects and problems in the processing are analyzed. Traditional machining needs further optimization cutting tool materials. Ultrasonic assisted machining needs to explore the coupling mechanism of ultrasonic vibration between the tool and the material, and the mechanism of material removal under vibration. The removal mechanism of 2.5-dimensional and 3-dimensional C/SiC composites by laser processing also needs to be studied. On the basis of these studies, the possibility of high efficiency, precision, stability and non-destructive processing of C/SiC composite materials is explored by further adopting the composite machining method.

In order to study the ablation damage law of composite laminates with fasteners under the action of lightning current, the lightning finite element analysis model of fastener-containing laminates was established based on thermoelectric coupling, and the results of lightning ablation damage were analyzed and tested. The results were compared with the validity of the model. The ablation damages of fastener-containing laminates under different peak currents, fastener sizes and laminate width ratios were analyzed, and the variations of ablation damage area under different factors were summarized. The results show that the peak current of the lightning strike, the size of the fastener, and the width of the laminate have great influences on the ablation damage areas of the fastener-containing laminates. The same lightning strike current waveform, the ablation damage area caused by lightning current with a peak value of 150 kA is 15.39 times that of 50 kA The smaller the fastener is, the larger the area of ablation damage is, and the larger the area of delamination damage is. Among them, when the diameter of the fastener is reduced by 2 times, the ablation damage area can be increased by 4.97 times, and the delamination damage area can be increased by 1.91 times. The damage area increases first and then decreases with the increase of the width, and finally tends to be stable. The ratio of the largest damage area to the minimum damage area can reach 1.81 times, and the ratio increases with the increase of the fastener diameter.