Aircraft Cable Research Articles

Calculation and Measurement of Transport AC Loss of ReBCO CORC Cables for Electric Aircraft

Calculation and Measurement of Transport AC Loss of <i>Re</i>BCO CORC Cables for Electric Aircraft

Design of High Power Density MVDC Cables for Wide-Body All Electric Aircraft

Aircraft electrification yields the next generation of aircraft such as more electric aircraft (MEA) and all electric aircraft (AEA). These aircraft require high-power-density and low-system-mass electric power systems (EPS). To this end, the voltage of the system must be enhanced to reach medium voltage levels in a few kV ranges. However, using medium voltage (MV) EPS for aircraft exacerbates the challenges of designing aircraft cables such as arc and arc tracking, partial discharges (PD), and thermal management. In this paper, several novel multi-layer based insulation systems for MVDC power cables are proposed to resolve aircraft cables’ challenges while maintaining low weight and size. The proposed cables are thermally and electrically analyzed and compared to cable systems designed based on IEC60502 and AS50881 standards. We use a coupled electrical-thermal-fluid flow dynamic model, for simulations where all possible heat transfer approaches, including conduction, convection, and radiation, to transfer mainly the joule heating generated in the core conductor to ambient with a low pressure of 18.8 kPa which is the air pressure at cruising height of wide-body aircraft (12.2 km) are considered and modeled. To compare the proposed cables to the designs based on IEC 60502 and AS50881, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> is introduced, which is the product of cables’ overall mass in a unit length and diameter. The results show that besides benefiting multi-layer, multi-function insulation systems to resolve aircraft cables’ challenges, the overall diameter and weight of the designed cables are lower than single-layer insulation system designs based on AS50881 and IEC60502.

Defect detection and identification for aircraft cable insulation layer based on deep forest

Due to the special internal environment of aircraft, cable damage is inevitable, which usually starts from insulation layer defects and may cause major economic losses, and even seriously threaten the life of people on board. According to the above issue, a defect detection system for aircraft cable insulation layer based on ultrasonic guided waves (UGWs) is built in this paper. In order to ensure the complete coupling between the sensor and the insulation layer of the aircraft cable, the macro fiber composite (MFC) flexible sensor is employed in the system. Both simulation and experimental results show that this method can simultaneously monitor four different types (abrasion, cut, semi-stripping and full-stripping) of cable insulation layer defects at different locations on the same cable. The reflection signals of different types of defects are extremely similar and difficult to distinguish directly. In this paper, a classification method for four types of defects based on the deep forest method is proposed. This method requires a small sample size, and the classification performance is not affected by network structure and parameters. The recognition accuracy can reach 100%, avoiding the problem of traditional deep learning classification relying on a large number of samples and requiring parameter adjustment. The proposed method in this paper is proven to be able to effectively carry out online monitoring and accurately classify defect types, which has guiding significance for aircraft maintenance personnel to take corresponding measures in time.

Defect Detection for the Insulation Layer of Bent Aircraft Cables Based on Ultrasonic Guided Waves

The damage of aircraft cables is a major issue in the aerospace industry, which usually starts from insulation layer defect and can lead to serious casualties and financial losses. In this article, a method for defect detection for the insulation layer of bent aircraft cables is proposed, which is based on ultrasonic guided waves (UGWs). The propagation characteristics of UGWs in bent cables were studied by simulation and experiments, and wavelet packet decomposition (WPD) was used for feature extraction of the detection signals to distinguish bending and defects in the insulation layer. The experimental results show that the method is able to detect and locate both bending and defects (abrasion and cut) in the insulation layer. The maximum relative error in bending and defect localization does not exceed 0.3%.

Sizing of Superconducting Cables for Turbo-ElectricDistributed Propulsion Aircraft Using a Particle Swarm Optimization Approach

Superconducting electrical power systems are proposed to meet high specific power densities required for turbo-electric distributed propulsion aircraft. Superconducting materials have unique thermal and electrical requirements for maintaining the superconducting state, which is critical to their normal operation. Electrical system faults can lead to this state being lost for all network assets in the electrical fault path. The resulting temperature rise can prevent the superconducting state from being immediately resumed following fault clearance, requiring disconnection of nonfaulted equipment. Undersized cables experience a higher temperature rise under faulted conditions and disconnect from the system more readily. Oversized cables are heavier and more costly. Therefore, there is a need to optimize the cable size, preventing disconnection of equipment due to temperature rise following a fault while minimizing the weight and cost penalty. This article proposes a system parameter-driven methodology, using particle swarm optimization, to identify fault-tolerant cable designs, which deliver minimum through-life costs. This facilitates high-value, quantifiable design trade studies incorporating system parameters. Key observations drawn are that the choice between improving fault ride-through capability of a superconducting cable by increasing the amount of either superconducting material or conventional former material strongly depends on acceptable system operating temperature and voltage.

Analisis Perpindahan Besar Akibat Gaya Non-Konservatif

Structural applications based on large displacement analysis are widespread in various fields, such as the application of aircraft structures, membranes, cables, pipelines and risers. In this study, the author reviews the structural responses based on large displacement theory and non-conservative load models, assuming linear sections and materials. The parameters reviewed are the variation of the load factor and the variation of the slope angle of the load P at the end of the span. Solving non-linear differential equations with non-conservative force, using numerical integration method. The simulation results with the variation of the load factor with the angle of inclination, vertical and horizontal displacements are obtained, where the final orientation of the acting force corresponds to the deformation of the structure, and the maximum deformation occurs at a load angle of 90o, the deformation decreases for the angle orientation is getting smaller.

Heat Transfer Challenges for MVDC Power Cables Used in Wide Body All Electric Aircraft Under Low Pressures

Power cables are a vital component of the future electric power systems (EPS) envisaged in wide body all electric aircraft (AEA). They are required to be high power delivery and low system mass. Designing proper power cables for AEA faces thermal challenges due to the lower pressure of 18.8 kPa at the cruising height of a wide body aircraft. Due to the limited heat transfer at that pressure, the temperature field distribution across the aircraft cable, mainly a function of pressure, surface emissivity, and ambient surface geometry, is likely to diverge from that at atmospheric pressure. Moreover, temperature field distribution affects the conductivity of the insulation, which in turn alters and may inverse the electric field distribution across the DC cables. Therefore, a coupled multi-physics study should be conducted to calculate the temperature field and electric field across the cable at different ambient temperatures and various possible geometries of the ambient environment. In this paper, the temperature field distribution across a 5 kV DC cable is studied at atmospheric and 18.8 kPa pressures. The voltage level of 5 kV was resulted from our previous studies where we proposed new EPS architectures for a wide-body AEA. The main purpose of this study is to obtain the maximum permissible current flowing the cable at the atmospheric and 18.8 kPa pressures regarding the thermal limits of the cable. It is shown that at 18.8 kPa the maximum permissible current flowing the cable is decreased by 14.75% compared to its value at atmospheric pressure when the size of the ambient surface is 250 mm. Also, the electric conductivity and electric field across the cable insulation are evaluated at different conductor currents and insulator temperature gradients.

Effect of Radiation-Induced Cross-Linking on Thermal Aging Properties of Ethylene-Tetrafluoroethylene for Aircraft Cable Materials.

The effects of electron beam irradiation on ethylene-tetrafluoroethylene copolymer (ETFE) were studied. Samples were irradiated in air at room temperature by a universal electron beam accelerator for various doses. The effect of irradiation on samples and the cross-linked ETFE after aging were investigated with respect to thermal characteristics, crystallinity, mechanical properties, and volume resistivity using thermo-gravimetric analysis (TGA), differential scanning calorimeter (DSC), universal mechanical tester, and high resistance meter. TGA showed that thermal stability of irradiated ETFE is considerably lower than that of unirradiated ETFE. DSC indicates that crystallinity is altered greatly by cross-link. The analysis of mechanical properties, fracture surface morphology, visco-elastic properties and volume resistivity certify radiation-induced cross-linking is vital to aging properties.

Some Comments on Fatigue Life Tests of Aircraft Cable Control Systems

Abstract Cable control systems are widely used in aircraft and gliders. This paper deals with the problem of collecting real loads acting cable control systems and cable tests preparation (load spectrum) and performance. The author proposes a method for defining real loads acting on control systems, preparing and carrying out fatigue tests of cables revealing symptoms of fretting. The fatigue tests results can be used to predict service life, to plan and prepare periodic and details inspections. This method could be used to increase service life of aircraft control cables and could help to replace the commonly used Time-Based Maintenance (TBM) strategy with the Damage Tolerance (DT).

An algorithm based on bidirectional searching and geometric constrained sampling for automatic manipulation planning in aircraft cable assembly

Robotic manipulation of deformable linear objects has potential application in aircraft cable assembly. However, it is difficult to be implemented in real tasks due to requiring prediction of the object’s deformation and obstacle-free manipulation planning with high efficiency. Aiming at exploring automatic assembly planning for aircraft cables assembly in narrow cabins with obstacles, this paper proposes a novel planning algorithm named RRT-BwC (Bi-direction with Constrain). Firstly, formulation of the question and the manipulation objects are presented with geometric definitions. Then a bi-RRT-tree searching method is developed to design the planner for overcoming obstacles in the high dimensional planning space. The numerical distance between configurations in the cable shape space are defined to measure the demands for their transition in consideration of the manipulation logics. And the sampling zone constrains to the shape configuration nodes are also discussed. Finally, the algorithm presents a valid manipulation sequence for robotic manipulation. The functionality and performance of the improved RRT approach are demonstrated with a simulated real-world problem of aircraft cable assembly, exhibiting computation efficiency promotion.

A smart assistance system for cable assembly by combining wearable augmented reality with portable visual inspection

BackgroundAssembly guided by paper documents is the most widespread type used in the process of aircraft cable assembly. This process is very complicated and requires assembly workers with high-level skills. The technologies of wearable Augmented Reality (AR) and portable visual inspection can be exploited to improve the efficiency and the quality of cable assembly. MethodsIn this study, we propose a smart assistance system for cable assembly that combines wearable AR with portable visual inspection. Specifically, a portable visual device based on binocular vision and deep learning is developed to realize fast detection and recognition of cable brackets that are installed on aircraft airframes. A Convolutional Neural Network (CNN) is then developed to read the texts on cables after images are acquired from the camera of the wearable AR device. An authoring tool that was developed to create and manage the assembly process is proposed to realize visual guidance of the cable assembly process based on a wearable AR device. The system is applied to cable assembly on an aircraft bulkhead prototype. ResultsThe results show that this system can recognize the number, types, and locations of brackets, and can correctly read the text of aircraft cables. The authoring tool can assist users who lack professional programming experience in establishing a process plan, i. e., assembly outline based on AR for cable assembly. ConclusionsThe system can provide quick assembly guidance for aircraft cable with texts, images, and a 3D model. It is beneficial for reducing the dependency on paper documents, labor intensity, and the error rate.

Aircraft Cable Fault Detection and Location Based on SSTDR

In the detection and positioning of aircraft cable faults based on Time Domain Reflectometry (TDR), due to the multiple cable connectors of the aircraft and in a severely noisy environment, the reflected signals are severely attenuated and waveform distortion exists, making it impossible to achieve accurate cable fault detection. In order to solve these problems, this paper designs the spread spectrum time domain reflectometry (SSTDR) for the characteristics of the aircraft cable, selects the m-code as the original signal, outputs the BPSK modulation with a modulation ratio of 0.5, and finally uses the correlation algorithm to obtain the fault type and distance. Using a signal source, an aircraft cable and an oscilloscope, an actual measurement system is used to test aircraft cables of different lengths. The test results show that SSTDR has high noise immunity and detection accuracy in actual tests.

Reading Aviation Wire Text in Natural Images under Assembly Workshop via Deeplearning

Reading aviation wire text is an important step for aircraft wire assembly and also a challenging problem. Aviation wire text reading means to detect and recognize the serial number printed on the surface of aviation wires or aircraft cables. The main challenges of this task lie on small sizes, low contrast and background noise in images. In this paper, we propose a new method for aviation wire text detection and recognition via deep neural networks. The detection network utilizes text border features to roughly locate text regions in images. Then the coordinates of bounding boxes of texts are regressed by pixel-level predicted offsets in adjacent regions. The recognition network is capable to recognize the text regions with diverse lengths after padding strategies. In addition, a dataset of aviation wires captured by machine vision camera in the assembly workshop is developed. A flexible method to generate synthetic images of text whose characters are arranged in styles of both head-to-tail and left-to-right is presented. On aviation wire datasets, the proposed method for text detection and recognition achieves comparable performance and significantly outperforms previous approaches.

Influence of Microalloying (Including Rare-Earth Metals) on the Phase Composition and Properties of Aluminum Alloys

In connection with the search for new materials and the more extensive use of metals and alloys with special physical and chemical properties, rare-earth metals (REMs) are attracting increasing interest not only as alloying additives but also as the main components of structural materials. The Al-Fe alloys are of great practical interest, and the purpose of this work was to study the influence of microalloying by REMs on the mechanical and acoustic damping properties of Al-Fe alloys. REMs were selected as alloying components because of their properties and their widespread use in improving the structure and properties of structural alloys, including mechanical and acoustic damping properties. The results of these investigations are expected to enable the use of secondary Al (i.e., waste Al manufacture with a high Fe impurity concentration) as a base material for the development of structural alloys with improved mechanical properties for use in mechanical and electrical engineering applications. The use of secondary Al will provide economic advantages and will contribute to the conservation of resources.This work is actual because Al alloyed with Fe and REMs can be used as corrosion-resistant materials and conductive materials in electronics and for automotive and aircraft engines, wires, cables, rods, tires and other products of the electrical engineering industry, thus expanding the scope of applications of these alloys [1-4].

Study on Impedance Characteristics of Aircraft Cables

Voltage decrease and power loss in distribution lines of aircraft electric power system are harmful to the normal operation of electrical equipment and may even threaten the safety of aircraft. This study investigates how the gap distance (the distance between aircraft cables and aircraft skin) and voltage frequency (variable frequency power supply will be adopted for next generation aircraft) will affect the impedance of aircraft cables. To be more precise, the forming mechanism of cable resistance and inductance is illustrated in detail and their changing trends with frequency and gap distance are analyzed with the help of electromagnetic theoretical analysis. An aircraft cable simulation model is built with Maxwell 2D and the simulation results are consistent with the conclusions drawn from the theoretical analysis. The changing trends of the four core parameters of interest are analyzed: resistance, inductance, reactance, and impedance. The research results can be used as reference for the applications in Variable Speed Variable Frequency (VSVF) aircraft electric power system.

Modelling of aircraft harness tests via Petri network

In aircraft factories, automated cable test equipments are used at the final stage of harness manufacturing before hooking up process. They try to find whether there is a broken wire or a leakage on cable. This paper examines the continuity (open-circuit) and insulation (short circuit) test operations of an aircraft cable by using Petri net model and also explains operation principle of test equipment theoretically. The proposed model basically identifies aircraft wiring test operations that are applied by automated test equipments and presents all real test conditions in a realistic way. Different from other literature studies, a general model of automated test equipment is tried to model for detecting both open circuit and short circuit faults. Furthermore, this work shows that basic training test equipment can be constructed easily combining adjustable voltage sources, analog to digital converter (ADC), switches and so on.

Modelling of aircraft harness tests via Petri network

In aircraft factories, automated cable test equipments are used at the final stage of harness manufacturing before hooking up process. They try to find whether there is a broken wire or a leakage on cable. This paper examines the continuity (open-circuit) and insulation (short circuit) test operations of an aircraft cable by using Petri net model and also explains operation principle of test equipment theoretically. The proposed model basically identifies aircraft wiring test operations that are applied by automated test equipments and presents all real test conditions in a realistic way. Different from other literature studies, a general model of automated test equipment is tried to model for detecting both open circuit and short circuit faults. Furthermore, this work shows that basic training test equipment can be constructed easily combining adjustable voltage sources, analog to digital converter (ADC), switches and so on.

Impedance characteristics study of three-phase aircraft power wires

This paper proposes an accurate measurement circuit for three phase aircraft power wires. The impedance characteristics of the three-phase aircraft power wires are related with the following three factors: frequency, wire laying forms, and the distance from the wire to aircraft skin. Three-phase power wires were modeled in this paper using Ansoft’s large finite element analysis software Maxwell. While the circuit to measure the positive sequence impedance and zero sequence impedance were separately built with Ansoft Simplorer. Then the voltage and current data of the three-phase wires under test can be obtained by co-simulating with Maxwell and Simplorer. Sequence impedance can be calculated according to symmetrical component method. The impacts of frequency changing, wire laying forms, as well as the distance between the wire and aircraft skin on phase sequence impedance were thoroughly analyzed. Finally, the simulation results were verified by experimental study. The results can be used as reference for future design and implementation of aircraft cables.

Aircraft Cable with Connector Fault Modeling and Diagnosis

Aircraft Cable with Connector Fault Modeling and Diagnosis

Evaluation of the Modeling of an EM Illumination on an Aircraft Cable Harness

This paper describes the approach developed in order to model the electromagnetic response of a cable bundle, part of the electrical wiring interconnection system of a real aircraft, submitted to an external electromagnetic excitation. The aim of this study is to highlight the main challenges in the synthetic modeling and validation of a fully real setup, from the electromagnetic compatibility point of view. Both conducted and radiated excitations have been considered in the electromagnetic global model. The solution is obtained through a cooperative simulation approach involving one 3-D full-wave solver and a multiconductor transmission line solver. The results are compared with measurements and specific tools, such as feature selective validation and integrated error against log frequency, are used to assess the adequacy of the results.