Flight Loads Research Articles

Application and Communication Optimization Technology of Unmanned Distribution Car under Deep Learning in Logistics Express of COVID-19.

This work aims to solve the problem that the daily necessities of urban residents cannot be delivered during coronavirus disease 2019 (COVID-19), thereby reducing the possibility of the delivery personnel contracting COVID-19 due to the need to transport medicines to the hospital during the epidemic. Firstly, this work studies the application and communication optimization technology of unmanned delivery cars based on deep learning (DL) under COVID-19. Secondly, a route planning method for unmanned delivery cars based on the DL method is proposed under the influence of factors such as maximum flight time, load, and road conditions. This work analyzes and introduces unmanned delivery cars from four aspects combined with the actual operation of unmanned delivery cars and related literature: the characteristics, delivery mode, economy, and limitations of unmanned delivery cars. The unmanned delivery car is in the promotion stage. A basic AVRPTW model is established that minimizes the total delivery cost without considering the charging behavior under the restriction of some routes, delivery time, load, and other factors. The path optimization problem of unmanned delivery cars in various situations is considered. A multiobjective optimization model of the unmanned delivery car in the charging/swap mode is established with the goal of minimizing the total delivery cost and maximizing customer satisfaction under the premise of meeting the car driving requirements. An improved genetic algorithm is designed to solve the established model. Finally, the model is tested, and its results are analyzed. The effectiveness of this route planning method is proved through case analysis. Customer satisfaction, delivery time, cost input, and other aspects have been greatly improved through the improvement and optimization of the unmanned delivery car line, which has been well applied in practice. In addition, unmanned delivery cars are affected by many factors such as load, and the service time required for delivery is longer. Therefore, this work chooses an unmanned distribution car with strong endurance to improve distribution efficiency. The new hospital contactless distribution mode discussed here will play an important role in promoting future development.

Bubble Templated Flexible Ceramic Nanofiber Aerogels with Cascaded Resonant Cavities for High-Temperature Noise Absorption.

Aviation noise pollution has become a significant public health problem, especially with the endless improvement of flight speed and loading capacity. Existing aviation noise absorbers have fatal defects of large weight, weak high-temperature stability, and difficulty to achieve both good low-frequency (<1000 Hz) and high-frequency (up to 6000 Hz) noise absorption simultaneously. Herein, we report a robust strategy to create flexible ceramic nanofiber aerogels with cascaded resonant cavities by the air bubbles-assisted freeze-casting technology. The stable hinged resonance cavity structures coassembled by flexible ceramic nanofibers, soft montmorillonite nanosheets, and silica sol glue endow the aerogels with temperature-invariant compressibility (from -196 to 1100 °C) and bendability. Moreover, the comprehensive advantages of cascaded resonance cavities and interconnected fibrous networks enable flexible ceramic nanofiber aerogels to have temperature-invariant full-frequency noise absorption performance (noise reduction coefficient up to 0.66 in 63-6300 Hz). The synthesis of this flexible ceramic nanofiber aerogel provides a versatile platform for the design of high-efficiency noise-absorbing material for various fields.

Factors Affecting Demand Consolidation in Urban Air Taxi Operation

Urban air taxi (UAT) is envisioned as a point-to-point, (nearly) on-demand, and per-seat operation of passenger-carrying urban air mobility (UAM) in its mature state. A high flight load factor has been identified as one of the influential components in the successful operation of UAT. However, the uncertainties in demand, aircraft technology, and concept of operations have raised doubts about the viability of UAT. This study examines the impacts of exogenous parameters, such as demand intensity, demand spread, and ground speed, in addition to design parameters, including aerial speed, maximum acceptable delay, and reservations on average load factor and rate of rejected requests. The dynamic and stochastic problem of UAT fleet operation is studied by implementing a dynamic framework that aims to provide a solution to the problem via a discrete-event simulation. The results highlight the significance of demand spread, ground speed, and maximum acceptable delay in demand consolidation. Therefore, to ensure a high aircraft load factor, the UAT operator should specify the maximum acceptable delay and reservation time window given the demand pattern and ground-based transportation in the network.

Developmental temperature predicts body size, flight, and pollen load in a widespread butterfly

Abstract Most of our understanding of the effects of climate warming on insect body size comes from laboratory experiments. Whether these studies predict patterns in nature is largely unknown. Here we examine the relevance of laboratory warming experiments for wild populations of the butterfly Pieris rapae. We tested two predictions: (i) butterflies reared at warmer temperatures in the laboratory should attain smaller adult sizes and have reduced flight ability, and (ii) in nature, this trait combination should lead to smaller butterflies visiting fewer flowers and accumulating less pollen. Overall, we found that warm‐reared butterflies were indeed smaller and flew more slowly compared to colder‐reared conspecifics. Additionally, wild‐caught small butterflies carried fewer, and a lower diversity of pollen grains compared to larger butterflies. Our warming experiments thus largely predicted pollen collection patterns in wild P. rapae. This study demonstrates that increased temperatures will likely have important consequences for butterfly‐plant interactions in nature.

An analysis of optimal segmented flight design in a rotary dryer

In this paper, an analysis of the optimal design for two-segmented flight is performed with the aim to obtain some practical recommendations for the design of a rotary dryer. Using a geometrical model, validated with experimental results, flight loading and unloading are studied over the range of every possible angle between the flight segments. Maximum volume carried out by the flight, the maximum discharging angle and the mean falling height of material are computed for all configurations. Influence of size ratio between segments and drum radius are also investigated. By determining the curtain filling degree and the cumulative transfer area of material over one drum revolution, we estimate what the best flight design is, in order to maximise the contact surface between material and air flow necessary to increase the dryer performance.

Aeroelastic Topology Optimization of Wing Structure Based on Moving Boundary Meshfree Method

The increasing structural flexibility of large aircraft leads to significant aeroelastic effects. More efficient topology optimization techniques are required for the design to further take advantage of aeroelasticity and obtain lightweight structures. This paper proposes a moving boundary meshfree topology optimization that combines the Galerkin method of weighted residuals and non-uniform rational B-splines (NURBS). The solution domain is described by the control points of NURBS and its property is calculated adaptively with an integration subtraction technique. The minimal compliance is searched for using the globally convergent method of moving asymptotes (GCMMA) by designing the locations of control points as subject to volume and flux constraints. The method is first applied to a typical two-dimensional design example with symmetric boundary conditions. The results show that the shape constraints can be conveniently applied, and smoother boundaries are obtained with fewer parameters. Then, a three-dimensional wing structure with asymmetric boundary conditions is optimized. A three-dimensional flight load that combines the high-order-panel and meshfree methods is employed to calculate the elastic loads and update asymmetric external loads during the optimization process. The designed wing satisfies engineering requirements and the presented method can solve the practical topology optimization problems of three-dimensional structures.

Разработка новой концепции оценки напряженности труда пилотов гражданской авиации

The article describes a concept for assessing labor intensity (LI) developed by the authors. This concept is based on the results produced by comprehensive assessment of the current working conditions, by analyzing the psychophysiological state of civil aviation (CI) pilots in flight, as well as by assessing a contribution made by flight loads and signs of fatigue to an increase in a risk of aviation accidents (AA). It has been established that, according to sanitary and hygienic profiles, LI levels at all workplaces of civil aviation pilots correspond to harmful working conditions, which are aggravated by exposure to four other harmful factors (noise, microclimate, vibration, and working posture) in 48 % of cases. The research results have shown that the risks of fatigue increase significantly after 5 hours of flight. This fatigue manifests itself in the growing number of gaze fixations by 11 %; an increase in an average latency period of a complex visual-motor reaction, by 12 %; the growing number of significant errors for flight safety, by 50 %. All these processes occur in the absence of physiological recovery of the cardiovascular system, p &lt; 0.05. Pilots who are in a state of fatigue and stress due to violated work and rest regimes tend to have more AA. This accounts for at least 8.4 % of cases from all others causes. It is proposed to introduce the 3rd degree of harmfulness for strenuous work, as well as new LI indicators for sensory, informational and intellectual loads, such as an increase in a time required to fix the gaze on a device (in %), the frequency of image / value change on a screen (times/min), the volume of information flows per unit of time (bps), and the number of multifunctional devices (more than 10 bits per second). It has been established that the assessment of LI should be supplemented with specific indicators of the flight load and work regimes. These indicators include the number of takeoffs and landings, the number of crossed time zones, the number of stress factors during a flight, and the number of night flight shifts per week. They are directly related to developing fatigue among pilots and an increased risk of AA occurrence.

Development of a new concept for assessing labor intensity of civil aviation pilots

The article describes a concept for assessing labor intensity (LI) developed by the authors. This concept is based on the results produced by comprehensive assessment of the current working conditions, by analyzing the psychophysiological state of civil aviation (CI) pilots in flight, as well as by assessing a contribution made by flight loads and signs of fatigue to an increase in a risk of aviation accidents (AA). It has been established that, according to sanitary and hygienic profiles, LI levels at all workplaces of civil aviation pilots correspond to harmful working conditions, which are aggravated by exposure to four other harmful factors (noise, microclimate, vibration, and working posture) in 48 % of cases. The research results have shown that the risks of fatigue increase significantly after 5 hours of flight. This fatigue manifests itself in the growing number of gaze fixations by 11 %; an increase in an average latency period of a complex visual-motor reaction, by 12 %; the growing number of significant errors for flight safety, by 50 %. All these processes occur in the absence of physiological recovery of the cardiovascular system, p &lt; 0.05. Pilots who are in a state of fatigue and stress due to violated work and rest regimes tend to have more AA. This accounts for at least 8.4 % of cases from all others causes. It is proposed to introduce the 3rd degree of harmfulness for strenuous work, as well as new LI indicators for sensory, informational and intellectual loads, such as an increase in a time required to fix the gaze on a device (in %), the frequency of image / value change on a screen (times/min), the volume of information flows per unit of time (bps), and the number of multifunctional devices (more than 10 bits per second). It has been established that the assessment of LI should be supplemented with specific indicators of the flight load and work regimes. These indicators include the number of takeoffs and landings, the number of crossed time zones, the number of stress factors during a flight, and the number of night flight shifts per week. They are directly related to developing fatigue among pilots and an increased risk of AA occurrence.

An Induction Generator based AC/DC Hybrid Electric Power Generation System for Additional Electrically Powered Airliner

For an additional aircraft power system, both AC and DC power having high voltage levels are required. with various flight loads. This paper introduces an induction generator based on AC / DC hybrid MEA power generation system. In the proposed system structure, a high-speed generator/generator and a low-speed generator are fitted with high pressure (HP) and low pressure (LP) of the spools of the engine, respectively. In production mode, all alternating AC power is generated by the HP generator while the DC power supply is supplied by both HP and LP generators. The control system is designed to control the AC power supply and direct the DC power supply between the two generators. The proposed AC / DC-based induction generator system results in reduced demand for computer hardware compared to the AC and DC production systems.

Crack growth regularities and stress equivalent for in-service fatigued fan disk of titanium alloy Ti–6Al–3Mo–2Cr

The in-service fatigue fracture of the fan disk made of titanium alloy is analyzed by complex metallophysical research. The crack path consists of the formation of facetted pattern relief and striations on the fracture surface. From the results of striation spacing measurements, the equivalent stress for various crack sizes is estimated. The number of damaging-loading cycles per one flight is discussed and established by the analysis of the schematized flight loading cycle of the aero-engine. The inspection interval for reliable crack detection in the disk is evaluated. It is demonstrated that, without fan disk damage, its in-service durability can exceed 15,000 flights.

Approach for Cost Functions for the Use in Trade-Off Investigations Assessing the Environmental Impact of a Future Energy Efficient European Aviation

Aircraft emissions represent a relevant amount of human induced CO2. Globally, up to 2.5 per cent of such emissions stem from the aviation industry. In order to investigate the effects within the atmosphere, realistic flight profiles are necessary to provide quantitatively tangible values of emissions. The flight profiles and the according fuel consumption can be calculated by using waypoints from flight plans and Base of Aircraft Data (BADA). This paper presents an approach to refine the fuel consumption by integrating the passenger load into the calculation. Since effects of emissions have to be assessed on a greater scale, such as on the European air traffic network, the presented approach provides cost functions for CO2 emissions for different aircraft types and load factors. The cost functions were derived by means of regression analyses of BADA based calculated flight profiles with a step size of one second. The calculations are based on real historic traffic scenarios over several days. The derived aircraft specific fuel burn coefficients enable a simple and efficient integration of CO2 estimations depending on the flight distance, load factor and aircraft type. This can be applied to large traffic scenarios to also study different set-ups such as travel restrictions, other disruptions or an alteration in the traffic system as a whole. In order to enable the assessment of further aspects of such changes to the European air traffic system at large and to foster reproducibility and comparability of related studies, we provide further general-purpose cost estimation functions for several important key characteristics. Besides fuel consumption, we develop cost estimations for air navigation fees and maintenance for conventional aircraft. Those functions are also provided for the design concept of a short-range all-electric aircraft. This propeller aircraft features game-changing technologies such as active laminar flow control, active load alleviation and advanced materials and structure concepts. The approaches discussed in this paper will focus on the generic aspects of aircraft related costs, which can be derived from general available data. For the sake of reproducibility, the results will be made publicly available.

Конструкційні алюмінієві сплави систем Al−Cu−Mg і Al−Zn−Mg−Cu в літакобудуванні. Огляд

A review of scientific and technical information on structural deformable aluminum alloys, Al-Cu-Mg (series 2xxx) and Al-Zn-Mg-Cu (series 7xxx) systems was conducted. Their chemical and phase composition, alloying methods, mechanical and operational properties, influence of technological factors were analyzed. Examples of the use of these alloys in aircraft construction are given. It is shown that among the alloys of the Al-Cu-Mg system (D1, B65, D16, D16ч, 1163, D19, etc.), the strongest is D16 and its improved modifications D16ч and 1163, the mechanical properties of which in the heat-hardened state are equal to low-carbon steels. Alloys D16, D16оч, 1163 have high strength characteristics at 20 0С and elevated temperatures, especially in the form of sheets and pressed parts. Therefore, it is a common material for the manufacture of aircraft skins in the engine area, which is subject to heating. However, an increase in strength leads to a decrease in plasticity. Alloys based on the Al-Zn-Cu-Mg system (В95, В95пч, В95оч, В96, В96Ц, В96Ц1, В96Ц3, В94, В93, В92, etc.) are the most high-strength among deformable aluminum alloys, so they are widely used in responsible power elements of aircraft and rocket engineering in the form of pressed and forged products. The strongest of them is B96Ц, especially its modification B96Ц1, in which, unlike the B95 alloy, manganese and chromium are partially or completely replaced by zirconium. The B95 alloy has high compressive strength and is used to cover the upper surface of aircraft wings, which is in a compressed state during flight. The inner surface of the wing is made of D16, D16ч, 1163 alloys that withstand tensile loads in flight. In terms of strength, the B95 alloy exceeds the similar characteristics of the D16 alloy by 20-25%, and in terms of yield strength by 40%. Replacing the D16 alloy with B95 makes it possible to reduce the weight of the aircraft to 5 tons. Almost all the large-sized stamped parts for the world’s largest turboprop An-22 “Antey” transport aircraft are made from the B93 forging alloy, which is alloyed with iron and heat-treated according to the T1 regime.The main disadvantage of high-strength alloys of the Al-Cu-Mg and Al-Zn-Mg-Cu systems is their tendency to degrade, which is caused by the action of various types of loads and corrosive environments during aircraft and flight basing and is accompanied by the development of fatigue or corrosion-fatigue cracks. Alternative points of view regarding the causes of these phenomena and ways of improving the properties of products made of these alloys by alloying, thermal and deformation treatments are considered. Keywords: deformable structural aluminum alloys; aircraft construction, chemical and phase composition, alloying, mechanical properties, corrosion resistance, heat treatment.

Design and testing of a crop growth sensor aboard a fixed-wing unmanned aerial vehicle

• A set of crop growth sensors mounted on a fixed-wing UAV were developed. The system can obtain crop canopies and growth indices, such as LNC and LAI, on-line and in a convenient, high-throughput manner while ensuring that theUAV's airflow does not disturb the crop canopies below. • Flight dynamics computer simulation analysis of the fixed-wing UAV was conducted by the ADAMS software to obtain the deflection angle of the UAV during flight. A ball rolling-type sensor support was designed to ensure that the crop growth sensor is always aimed vertically downwards in-flight. • Due to the adjustment of the sensor support, the system has good dynamic stability and measurement accuracy within the working height range of the sensor. The aim of this study is to overcome disturbance of downwash flow field caused by the low-altitude operation of a multirotor unmanned aerial vehicle (UAV) on crop canopies and interference in spectral reflection information of canopies. For this purpose, a crop growth sensor aboard a fixed-wing UAV was developed through flight dynamics simulation analysis of a fixed-wing UAV. This sensor can collect index data on-line and in real-time including: the ratio vegetation index (RVI) of crop leaves, leaf area index (LAI), leaf dry weight (LDW), and leaf nitrogen content (LNC). Flight dynamics simulation analysis of the fixed-wing UAV was conducted by the automatics dynamic analysis of mechanical system (ADAMS) software to obtain the deflection angle of the UAV during flight. According to the flight characteristics and load on the UAV, a ball rolling-type sensor support was designed to ensure that the crop growth sensor is always aimed vertically downwards in-flight. The field test results show that the crop growth sensor aboard the fixed-wing UAV has good dynamic stability and high measurement accuracy. The RVIs measured by the onboard crop growth sensor in the plots and field were fitted with the results measured by a FieldSpec HandHeld 2 spectroradiometer (ASD, Analytical Spectral Device Co., USA). By analysing the fitted results, the coefficients of determination ( R 2 ) are 0.763 and 0.833 and the root mean square errors (RMSEs) are 0.16 and 0.17, respectively. By linearly fitting RVIs measured by the UAV with rice growth indices including LAI, LDW, and LNC, the coefficients of determination ( R 2 ) are 0.633, 0.581, and 0.528 and RMSEs are 0.18, 0.18, and 0.21, respectively.

Structural static test for validation of the structural integrity of an aircraft pylon

Aircraft components can only be mounted on an aircraft if the structural integrity has been validated under flight load conditions. Among the major components of an aircraft, a pylon is a structure that connects external equipment such as an engine and external attachments (e.g., instruments or weapons) to the main wing of an aircraft. The loads acting on the pylon are transmitted to the main structure of the aircraft. Pylons play a key role in the requirements of aircraft structure, aerodynamics, hydraulics, and electrical systems. In civilian aircraft, pylons also play a role in preventing fire from spreading to the wings in the case of a fire near an engine. This study presents the results of structural static tests performed to validate the structural integrity of a pylon used to mount external fuel tanks and weapons in military aircraft under all loading conditions. Test requirements consisting of flight-load and drop-load conditions are explained in the main text. A test set-up diagram consisting of test fixtures, hydraulic pressure unit, load control equipment, and data acquisition equipment is presented. Moreover, the software needed to control the actuator loads is introduced and the test load profiles for each test load condition are provided. As a result of the structural static test, it is shown that the actuator loads were properly controlled within the allowable error range in each test. It was also confirmed that the behavior of the pylon was well predicted through numerical analysis by comparing the results of the numerical analysis and the structural tests of the main parts of the test specimen. Moreover, it was found that the test specimen did not cause damage or buckling, which would cause serious structural defects for the required load. In conclusion, by performing structural static tests on the design limit load and the design ultimate load, it was proved that the newly developed pylon had sufficient static strength under all load conditions during flight.

Efficient aeroelastic wing optimization through a compact aerofoil decomposition approach

Efficient optimization of an aeroelastic wing is presented through multi-disciplinary analysis using low-dimensional modal design variables. Much work in wing optimization has concentrated on high-fidelity surface control, therefore utilising often hundreds of design variables. However, whilst fine surface control can be useful, problems can arise such as large disparities in design variable values when planform variables are introduced, slow convergence speeds, and lack of compatibility with global algorithms. Therefore, the focus of this paper is to filter the design space of this problem to reduce the dimensionality and complexity of the problem. Orthogonal geometric design variables are derived in the geometric space via singular value decomposition. Orthogonality of design variables leads to a well-conditioned design space and ensures effective optimizer convergence. These variables are applied in a sectional fashion for fixed planform drag minimization of a flexible transonic wing, using a gradient-based optimizer. Shock-free solutions are demonstrated when optimizing a rigid wing, indicating suitability of the aerofoil modes for sectional-based wing optimization. However, it is shown that these wings have poor performance when subsequently deformed under flight loads, hence optimisation including full aeroelastic performance is performed. Encouragingly, shock-free solutions are again computed. Loading is shifted outboard, leading to increased tip deflection. Monotonic improvement in the objective function (drag) with increase in dimensionality is also proven. Furthermore, applying these sectional deformation modes globally across the wing with only 10 design variable leads to a 28% drag reduction, which is within 7 drag counts of when the modes are applied locally through 82 design variables. This therefore opens the possibility of introducing global optimization algorithms to high-fidelity aeroelastic wing optimization.

Structure health monitoring of a composite wing based on flight load and strain data using deep learning method

An investigation was made into a method for Structural Health Monitoring (SHM) of a composite wing using Convolutional Neural Network (CNN) model. In this method, various aerodynamic loads of an aircraft during flight and corresponding strain data were used for CNN model training. The proposed method was demonstrated by numerical simulation using vortex lattice method for aerodynamic loads of an A350-type aircraft in over a thousand flight conditions and a Finite Element (FE) model as a digital twin of the full-scale composite wing. To represent the measurement of 324 sensors mounted in the 18 skin-rib joints of the inboard wing, strain data from the 18 × 18 elements of the FE model in the sensor locations were calculated corresponding to the flight loadings. The strain data from the original structure FE model were employed to train a CNN model that was classified as healthy samples. Damaged elements were then introduced in random locations to produce data samples corresponding to the same set of flight loads for the CNN model training. In the subsequent damage detection process using the trained CNN model, confusion matrix, uncertainty and sensitivity analysis were evaluated. The study results show that robust damage detection results can be obtained with 99% accuracy without noise and 97% accuracy with 2% Gaussian noise. In the damage localization process, threshold value was set at 1.5, 2 or 2.5, and 83% overall accuracy was achieved using the CNN model when the threshold value was 1.5. The study demonstrated that the proposed method is efficient, accurate and robust.

Study on the test load for the structural test of the flight-load condition of the external fuel tank for fixed-wing aircraft

In this study, for the purpose of conducting the structural tests for the verification of structural soundness of the flight-load conditions of the external fuel tank for the fixed-wing aircraft, the flight load acting on the external fuel tank was converted to test load and the suitability of the converted loads was verified. The loads imposed on the external fuel tank were expressed as the combination of the inertial load (based on the acceleration in the translational direction) and the tangential direction inertial load (based on the angular acceleration of the moment). To calculate the test load, the transfer function table was generated by calculating the shear load and moment based on the unit load. For this purpose, a transfer function table was established by dividing the external fuel tank into a few sections and calculating the shear load and moment generated by the unit shear load and unit moment in each section. In addition, the test load for each section was calculated by computing the established transfer function table and flight-load conditions. However, in actual structural tests, it is often not possible to impose a load in the same position as the point at which the shear load and moment are calculated. For this reason, the actual test-load positions had to be determined and the calculated test loads were redistributed to those positions. Then, the final test load plan was established by applying a whiffle tree to increase the efficiency of the test while also making it easier to apply the actuators. Finally, the suitability of the established test load plan was confirmed by comparison with the flight-load conditions.

Artificial neural network–based constitutive relation modelling for the laminated fabric used in stratospheric airship

There have been gradually increasing interests in the stratospheric airship (SSA) as a cost-effective alternative to earth orbit satellites for telecommunication and high-resolution earth observation. Lightweight and high strength envelopes are the keys to the design of SSAs as it directly determines the endurance flight performance and loading deformation characteristics of the airship. Typical SSA envelope material is a laminated fabric, which is composed of fabric layer and other functional layers. Compared with conventional composite structures, the laminated fabric has complex nonlinear mechanical characteristics. Artificial neural network (ANN) has good processing ability to nonlinear information so that it is suitable to model the constitutive relation of laminated fabrics. In this work, an ANN based on the Scaled Conjugate Gradient (SCG) algorithm is proposed firstly to model the constitutive relation of fabric Uretek3216LV. Considering significant errors of the SCG ANN results, the network model is optimized through methods of selecting the number of hidden-layer nodes and training algorithms. Results show that the improved network model based on Bayesian Regularization (BR) algorithm and eight nodes of single hidden layer can better describe the constitutive relation of the laminated fabric than other conventional training algorithms. The proposed constitutive modelling method with ANN is expected to gain a deeper understanding of the mechanical mechanism and guide structural design of envelope material in further work.

Calculation of fatigue fracture in structural elements using a multimode damage model

The problem of nucleation and development for the fatigue fracture process in element of aircraft structure is solved using previously developed cyclic damage model. The model contains the evolution equation for the damage function depending on stress state and amplitudes of the cyclic loads. On this basis, calculations of the initiation and development of crack-like fracture zones are carried out for an aircraft structure element of a disk with a blade in a flight loading cycle (HCF mode). The damage function was calculated based on the elastic solution for the element of structure loaded by centrifugal forces in disk and blade and aerodynamical pressure on blade. An alternative cyclic loading regime associated with high-frequency vibrations of the blades was investigated. Fatigue fracture in this process corresponds to the VHCF mode. Simulation of the combined cyclic loading mode was also carried out. In all these modes, the real time of the nucleation and development of quasi-cracks was estimated up to reaching the observed disk surface.

Real-time evaluation method of flight mission load based on sensitivity analysis of physiological factors

As the complexity of flight missions continues to increase, sending a timely warning or providing assistance to pilots helps to reduce the probability of operational errors and flight accidents. Monitoring pilots’ physiological data, real-time evaluation of mission load is a feasible technical way to achieve this. In this paper, a set of flight tasks including aircraft control, human-computer interaction and mental arithmetic tests are designed to simulate five mission loads at different flight difficulty levels. A sensitivity analysis method based on a comprehensive test is proposed to select a set of sensitive physiological factors. Then, based on the SVM hierarchical combination classification method, the pilot mission load real-time evaluation model is established. The test results show significant differences in EMG, respiration rate (abdomen), heart rate, blood oxygen saturation, pupil area, fixation duration, number of fixations, and saccades. The high accuracy obtained from experiments proved that the proposed real-time evaluation model is applicable to meet the requirements of real working environments. The findings can provide methodological references for mission load evaluation research in other fields.