Browse Topic: Underride guards

Items (2,652)

Unmanned Aerial Vehicles (UAVs) are becoming an effective way to serve humanitarian relief efforts during environmental disasters. The process of designing such UAVs poses challenges in optimizing design variables such as maneuverability, payload capacity and maximizing endurance because the designing of a BWB takes into account the interdependency between the stability and aerodynamic performance. The Blended Wing Body is an unconventional aircraft configuration which offers enhanced performance over conventional UAVs. In this study the designing of a BWB is investigated with an aim to achieve structurally sound and aerodynamically stable configuration. The design has been done by taking into consideration the side and top view airfoil for fuselage, because fuselage is a major lift generating portion in the UAV. For designing the control surfaces, the two major requirements for a controlled and safe flight of a UAV are its stability and maneuverability. The purpose of this study is also to design and validate elevons for a UAV having Blended Wing Body configuration which requires knowledge of various domains applied in a complex combination. Elevons are the unconventional control surfaces for the flying wings which will cause a pitching moment when moved in the same direction and will cause a rolling moment when moved differentially and their preliminary design is affected by the function which is dominant. A MATLAB code was written to decide the position, shape and size of elevons and later on accurately evaluated them using high fidelity X-FOIL aerodynamic analysis. The MATLAB© code calculates the required roll time rate taking into consideration the longitudinal and lateral control requirements. Using this coupled approach of MATLAB© code and XFLR5 analysis significant optimization is achieved in designing the elevons. The Blended wing body has been iteratively optimized in XFLR-5 for its static and dynamic stability. The 3D CAD model was designed on Solidworks and analyzed in Pressure Based Solver. So, in this study a system engineering approach has been used wherein the first phase is to conceptualize the design followed by preliminary design wherein the airfoil selection and constraint analysis is being carried out and finally a detailed design phase was used to validate the design.

Bainsla, Amit, Singari, Ranganath, Pal, Akshit, Kumar, Amit

Improved Energy Management System for Airplane Electrical Power

2021-01-00083/2/2021

As commercial transport aircraft progress toward a future More Electric Airplane (MEA) there are numerous opportunities to improve energy management of the electrical power system. Improved energy management of the airplane electrical power system not only has the potential to decrease the weight and improve the efficiency of the system, but also to improve system stability and reliability. This paper analyzes re-architecting of an MEA airplane electrical power system in order to better manage the current electrical loads. It also considers the use of new sources of power generation and energy storage that would enable improved energy management for a new improved MEA such as fuel cells, batteries and super capacitors. The analysis uses data associated with current methods for calculating electrical loads and evaluates how the energy management of those loads can be improved with a better understanding of their usage in various flight phases, their criticality, and their power quality requirements. It also investigates how the re-architecting of different loads can be used to improve airplane dispatch reliability and improve system stability. Finally, it examines how the efficiency of various systems, in conjunction with improved energy management, can be used to result in a better controlled, more efficient and reliable airplane. The results of these improvements in energy management are included in new MEA power system architecture to summarize the benefits.

Breit, Joseph Sherman

A Novel Approach to Dynamic Contact Analysis in the Course of Aircraft Assembly Simulation

2021-01-00043/2/2021

A new numerical approach is proposed for studying possible vibrations caused by drilling during the assembly of aircraft structures. It is based on modelling of the stress-strain state of assembled structures by solving the corresponding transient contact problem. This approach is intended for fast dynamic analysis of the structure in the drilling area. It includes a time discretization algorithm, a special reduction technique and a reformulation of contact problem in terms of quadratic programming. The high speed of the algorithm allows one to combine the non-stationary calculations with variation analysis in order to check the possible deviations in the shape of assembled parts. The proposed approach is validated by commercial software and it is also applied for analysis of a test problem.

Vasiliev, Alexey, Minevich, Olga, Lapina, Evgeniia, Shinder, Julia, Lupuleac, Sergey, Barboule, Joel

Evaluation of General Motors Event Data Recorder Performance in Semi-Trailer Rear Underride Collisions

2020-01-13284/14/2020

The objective of this study was to analyze the validity of airbag control module data in semi-trailer rear underride collisions. These impacts involve unusual collision dynamics, including long crash pulses and minimal bumper engagement [1]. For this study, publicly available data from 16 semi-trailer underride guard crash tests performed by the Insurance Institute for Highway Safety (IIHS) were used to form conclusions about the accuracy of General Motors airbag control module (ACM) delta-V (ΔV) data in a semi-trailer rear underride scenario. These tests all utilized a 2009 or 2010 Chevrolet Malibu impacting a stationary 48’ or 53’ semi-trailer at a speed of 35 mph. Nine tests were fully overlapped collisions, six were 30% overlapped, and one was 50% overlapped [2]. The IIHS test vehicles were equipped with calibrated 10000 Hz accelerometer units. Event Data Recorder (EDR) data imaged post-accident from the test vehicles were compared to the reference IIHS data. For each test, root mean square error (RMSE), the percent error over time, and the difference between the EDR ΔV and the IIHS ΔV, was quantified, plotted, and related to crash pulse. This analysis revealed a general trend of decreasing EDR ΔV parity with an increasing crash pulse duration, although overall differences remained low for most tests. Eleven tests, all with airbag deployments, converged towards an average of 3.3% error at the end of the crash pulse, which were 150-270 ms. EDR recorded ΔVs were in the range of 29.8-39.9 mph. Five tests, three of which were non-deployments, diverged to higher percentage error averaging 12.7% at an EDR ΔV of 31.8-40.0 mph. All higher error tests were 30% overlapped and had the highest crash pulse durations of 240-300 ms. One fully overlapped test generated highly unusual EDR data due to failure of the rear underride guard mounting bolts and plates.

Famiglietti, Nicholas, Hoang, Ryan, Fatzinger, Edward, Landerville, Jon

Analysis of Vibroacoustic Behaviors and Torque Ripple of SRMs with Different Phases and Poles

2020-01-04674/14/2020

In this study, the vibroacoustic characteristics and torque fluctuation of switched reluctance motors (SRMs) with different phases and poles have been analyzed in detail. Also, the common four SRMs, i.e., three-phase 6/4 SRM, four-phase 8/6 SRM, five-phase 10/8 SRM, and six-phase 12/10 SRM, have been selected. First, the spatial-temporal distribution characteristics of radial force in SRMs were revealed by virtue of the analytical derivation, which was validated by the 2D Fourier decomposition based on the finite-element results of radial force. Second, a multiphysics model, which was composed of an electromagnetic field, a mechanical field, and an acoustic field, was established to predict the noise behaviors of SRMs with different phases and poles. Third, the relationship between the torque fluctuation and the phases / poles of SRMs, and the relationship between the noise and the radial force / phases / poles are all analyzed. Finally, the results show that the spatial orders of the radial forces in all radial SRMs are kNs/(2Q) and the frequencies are (QN0±k/2)Nrf, where k=0,2,4···, N0=0,1,2···, Q is the phases of SRMs, Ns is the stator poles, Nr is the rotor poles, f is the rotational frequency. Besides, the torque fluctuation gradually decreases as the phases and poles of SRMs increase, so a high-phase and high-pole SRM should be selected to acquire small torque fluctuation. Moreover, the noise peaks in the radial SRMs with any possible phase and pole combinations are mainly caused by the force harmonics with the spatial orders of Ns/Q and the frequencies of (QN0±1)Nrf. In addition, it can be found that the sensitivity of noise to the spatial order of radial force is higher than that to the frequency, and the sensitivity of noise to the frequency is higher than that to the magnitude.

Hu, Shenglong, Zuo, Shuguang, Hu, Xiaorui

Extended Endurance Unmanned Aerial Vehicle via Structural Electrical Power Storage and Energy Generation Devices

2020-01-00413/10/2020

As the application of unmanned aerial vehicles (UAV) have increased in the military, commercial and private sectors, special attention has been focused on improving upon high altitude long endurance (HALE) performance. Therefore, under a multi-year, multi-discipline senior project team comprised of Aerospace Engineering, Electrical Engineering, Computer Engineering, Mechanical engineering, and Chemical Engineering undergraduate teams, investigative and experimental research has begun into the substitution of various aircraft structural components with power storage and power generation devices used also as structure to improve flight endurance and performance capabilities of solar powered UAVs. One viable solution may be found in the reduction of the amount of parasitic weight due to the required power systems on board these types of aircraft. These power systems are usually found in the form of energy storage devices such as lithium polymer batteries and energy generation devices such as solar cells. This path led to the innovation of the ‘Flying Battery’. The ‘Flying Battery’ integrates various free energy generating devices such as structural solar cells, structural energy storage devices, thermo-electric generators, and vibration induced power generators to create a flying structure that will be more efficient overall. By weighting the design factors for the power systems by their structural strengths and stiffnesses, the power-to-weight ratio of the aircraft may be significantly improved in the long run while also enabling a structure that may withstand the various nominal and off-nominal aerodynamic loading conditions experienced during flight. This paper discusses the mission operations, methods of testing and the progress achieved thus far toward achieving potential endurance and efficiency increases in unmanned aerial vehicles. These will be done through laboratory and eventual model flight experiments of novel structural designs for graphene super-capacitors, solar cells, and other power generation devices.

Oetting, Geoffrey Smith

Celebrating Women in Engineering & Science: Jasmin Moghbeli, NASA Astronaut

TBMG-361663/1/2020

Jasmin Moghbeli’s astronaut class graduated in January 2020 — the first class to graduate since the agency announced the Artemis program. She holds a BS degree in aerospace engineering with information technology from the Massachusetts Institute of Technology and a MS in engineering science in aerospace engineering from the Naval Postgraduate School. Moghbeli was commissioned as a Second Lieutenant in the United States Marine Corps in 2005 upon completion of her undergraduate degree. An AH-1W Super Cobra helicopter pilot and Marine Corps test pilot, Moghbeli served in Operation Enduring Freedom in Afghanistan from 2009 to 2010. At the time of her selection as an astronaut candidate, Moghbeli was testing H-1 helicopters. She has accumulated more than 150 combat missions and 2,000 hours of flight time in more than 25 different aircraft. She is eligible for assignment to missions destined for the International Space Station, the Moon, and ultimately, Mars.

High-Performance, Piezoelectric, Hybrid Synthetic Jet Actuators

TBMG-361813/1/2020

NASA Langley Research Center has invented three serial high-performance, piezoelectric, hybrid synthetic jet actuators to provide active flow control for current and future wing-borne vehicles in subsonic, transonic, and supersonic flow. Effective active flow control results in reduced vehicle drag and the prevention of events that can lead to catastrophic loss.

Multi-Objective Flight Control Optimization Framework

TBMG-362013/1/2020

Composite materials are used in aerospace design because of their high strength-to-weight ratio. On modern airplanes, composite wings offer a greater degree of aerodynamic efficiency due to weight savings but at the same time introduce more structural flexibility than their aluminum counterparts. Under off-design flight conditions, changes in the wing shape due to structural flexibility cause the wing aerodynamics to be non-optimal. This effect could offset any weight-saving benefits realized by the composite wings. Structural flexibility could also cause adverse interactions with flight control and structural vibration that can compromise aircraft stability, pilot handling qualities, and passenger ride quality.

Leading Women in Engineering & Science: Dawn F. Massa Stancavish, Chief Innovation Officer & COO

TBMG-362613/1/2020

Evaluation of the Effects of Hydrogen Peroxide on Common Aircraft Electrical Materials

TBMG-360582/1/2020

Among all of the large-scale disinfection and/or decontamination technologies available, vaporized hydrogen peroxide (VHP®) is of particular interest due to its rapid sterilization, easy usage, intrinsic environmental friendliness (i.e. simple by-products composed of only water and oxygen), and compatibility with many materials and systems.

Insect-Inspired Motion Sensing

TBMG-359932/1/2020

Researchers have taken inspiration from flying insects to demonstrate a miniaturized gyroscope, a special sensor used in navigation technologies. Gyroscopes sense rotational motions to provide directional guidance without relying on satellites, so they are immune to signal jamming and other cyber threats, making them ideal for aircraft and submarines.

Implementing an Aerospace Factory of the Future

TBMG-360562/1/2020

Companies across a wide range of segments are introducing Industry 4.0 (i4.0) technology at a rapid pace, turning the next-generation vision of manufacturing — the Factory of the Future — into reality. Many of the advances in this transformation have been in highly automated industries such as vehicle manufacturing. Conversely, the aerospace industry, with its staged approach to assembling aircraft, satellites and other products, has only begun to investigate how i4.0 technologies can improve operations, throughput, quality control and cost challenges.

Underwater Signal Processing System

TBMG-360542/1/2020

DSIT Solutions Ltd. Givat Shmuel, Israel +972-3-531-3333

Shape Sensing Innovations Dramatically Improve Structural Design Tools

TBMG-357931/1/2020

Advances in fiber optic shape sensing developed at NASA's Armstrong Flight Research Center are enabling the development of next-generation flexible aircraft wings that maximize structural efficiency and reduce weight, improving fuel efficiency. These same advances will help engineers design stronger bridges, buildings, ocean vessels, and more.

Design Treatment for Advanced Metals Enables Easier Machining

TBMG-358021/1/2020

Exotic and advanced metals are used in aircraft, orthopedic components, medical instruments, cars, solar panels, military equipment, and other applications. They are referred to as advanced or exotic because they are more difficult to find and more costly to use in manufacturing.

Pinpointing Consumption “Sweet Spot” Makes Formation Flight More Fuel-Efficient

TBMG-358251/1/2020

Formation flying — when one aircraft flies behind another — reduces drag and results in improved fuel consumption in the trailing vehicle; however, no sensor currently exists that directly measures drag. Instead, pilots rely on fuel flow measurements or induced aircraft moments — roll, pitch, and yaw — to estimate the best location within a leading vehicle's wave vortex. Fuel flow alone is a lagging drag estimate, which leads to inaccurate estimates. Aircraft moments alone also do not sufficiently indicate the best location for the trailing aircraft.

Thin Heat Shield for Superfast Aircraft

TBMG-357911/1/2020

The world of aerospace increasingly relies on carbon fiber-reinforced polymer composites to build the structures of satellites, rockets, and jet aircraft. But the life of those materials is limited by how they handle heat. Researchers have developed a heat shield that better protects those extremely fast machines.

Flow Disruption Devices for the Reduction of High Lift System Noise

TBMG-357921/1/2020

During airport approach and landing, airstream noise is a dominant aircraft noise source, and the noise that is generated at the side edges of the deployed flaps, elevons, and slats is an important component of that noise. The noise radiating from these side edges is caused by their interaction with the strong vortex systems that are present along these edges. The purpose of flow disruption devices is to reduce that noise.

Acoustic Interactions Change Materials at the Atomic Level

TBMG-357981/1/2020

When exposed to stress and strain, materials can display a wide range of different properties. Using sound waves, scientists have begun to explore fundamental stress behaviors in a crystalline material that could form the basis for quantum information technologies. These technologies involve materials that can encode information in a number of states simultaneously, allowing for more efficient computation.

Technology Impact Forecasting for Multi-Functional Composites

TBMG-3567912/1/2019

To survive within today's stringent economic environment, aircraft design, particularly military aircraft design, has been experiencing a paradigm shift from an emphasis on design for optimum performance to design for system effectiveness. As a consequence, designers and manufacturers are increasingly considering the addition of new technologies to aircraft design to reduce their cost, increase their operating capacities, and optimize new capabilities.

Employing the Electrical Digital Twin to Mitigate Compliance Risk in Aerospace

TBMG-3568812/1/2019

Delivering aircraft and various avionics compliant with the latest standards and regulations is increasingly difficult. Today, it’s not uncommon for a single commercial aircraft to comprise hundreds of line-replaceable units, hundreds of miles of wire, and unique configurations throughout all parts of a platform that must meet numerous certification requirements. With increasing electrical system content and complexity, a single change during the design, verification, or compliance process can put the entire program in jeopardy. With the rise in electrification and design complexity, aerospace original equipment manufacturers (OEMs) need to look for new methodologies to mitigate compliance risk.

Aerogel-Fiber Layered Laminate System

TBMG-3571012/1/2019

Scientists at Kennedy Space Center have developed a multifunctional composite laminate material for structural and thermal applications for use in residential and commercial construction. The innovation is a lightweight aerogel-fiber laminate composite system that has good compressive strength, tailorable impact and acoustic energy absorption, reduced heat transfer (compared to a fiber-only system), and fire barrier properties.

5 Ws of EarEcho

TBMG-3569312/1/2019

Anyone who uses a smartphone with in-ear earphones.

Technology Impact Forecasting for Multi-Functional Composites

19AERP12_0912/1/2019

Multi-functional composites offer a possible solution to the conflicting design goals of making new aircraft lighter, stronger, faster, and more environmentally sustainable. Air Force Research Laboratory, Arlington, Virginia To survive within today's stringent economic environment, aircraft design, particularly military aircraft design, has been experiencing a paradigm shift from an emphasis on design for optimum performance to design for system effectiveness. As a consequence, designers and manufacturers are increasingly considering the addition of new technologies to aircraft design to reduce their cost, increase their operating capacities, and optimize new capabilities. For next generation aircraft design, there are many innovative technologies to be developed that are financially constrained. However, infusion of a new technology (or technologies) are leading to another challenge: how does this new technology affect the aircraft system both in capability and economically?

Wind Event Warning System

TBMG-3545411/1/2019

NASA Langley Research Center developed a wind event warning technology that provides a practical early warning system (5-10 minutes) for a severe change in the wind vector. Events such as gusts, shear, microbursts, or thunderstorm outflows can be detected in time to prevent damage to wind turbines or help airports prevent damage to aircraft. Further, an alternative power source could be ramped up or down as needed to accommodate the power draw in the electrical grid.

Aeroacoustic Prediction for Effectiveness of Vortex Suppression Methods for Bluff Bodies at Various Reynolds Numbers

2019-28-011810/11/2019

Noise of almost every form is considered undesirable and hence its reduction is an important area of study. Aerodynamically generated noise due to vortex shedding in the wake of bluff bodies is a major source of such undesirable noise in applications involving overhead wires, poles, automotive components and aircraft landing gears. Vortex suppression methods are employed in these cases to reduce the noise generated by suppressing the pressure fluctuations arising near the bluff body surface. For the present study, flow past different bluff bodies is simulated using commercial CFD software, ANSYS FLUENT, with and without involving suppression methods. The calculations for flow field are performed by solving the two-dimensional governing equations for unsteady isothermal incompressible viscous flow. Turbulence modelling is performed using Large Eddy Simulation (LES) with Smagorinsky-Lilly subgrid model. Simulations for far-field noise are carried out using Ffowcs-Williams and Hawkings model and different aeroacoustic parameters like overall sound pressure level and sound pressure level are computed for different receiver locations. The effectiveness of different suppression methods is tested at different Reynolds numbers and their performance is compared. The obtained results are found to be in good agreement with available experimental data.

Padia, Sanhita, Deep, Dewanshu, Sundararaj, Senthilkumar

Schlieren System Captures Brilliant Shockwave Images

TBMG-3525410/1/2019

Supersonic flight over land is generally prohibited because sonic booms created by shockwaves disturb people on the ground and can damage property. Armstrong innovators are working to solve this problem with a novel system for capturing images of shockwaves created by supersonic aircraft. The Background Oriented Schlieren Using Celestial Objects (BOSCO) technology uses a celestial object, such as the Sun, as a background to secure unique, measurable shockwave images of full-scale aircraft. The patented image-processing technology captures hundreds of observations with each shockwave, benefitting NASA engineers in their efforts to develop a supersonic aircraft that will produce a soft “thump” in place of a disruptive sonic boom.

New Airplane Wing Assembled from Tiny Identical Pieces

TBMG-3527710/1/2019

A radically new kind of airplane wing, assembled from hundreds of tiny identical pieces, can change shape to control the plane’s flight, and could provide a significant boost in aircraft production, flight, and maintenance efficiency. The new approach to wing construction could afford greater flexibility in the design and manufacturing of future aircraft.

Aircraft Vertical Takeoff and Landing

TBMG-3528410/1/2019

NASA’s Langley Research Center developed an inexpensive, long-endurance, vertical takeoff and landing (VTOL) unmanned aerial vehicle (UAV). It is capable of flying for 24 hours, landing in a 50 × 50 zone, and can be loaded into the back of a cargo van for easy transport. In addition, it can land in either a horizontal or vertical flight configuration.

Structure Deformation Calculation Program for Structural Shape Monitoring

TBMG-3528910/1/2019

Researchers at NASA’s Armstrong Flight Research Center are pioneering shape-sensing technologies that seek to maximize structural integrity and efficiency. A new and versatile computer program offers critical shape-monitoring capabilities and has applications for a wide variety of structures.

Green’s Function Extraction from Atmospheric Acoustic Propagation

TBMG-3536310/1/2019

Acoustic waves propagating in the atmosphere may undergo many effects including refraction by temperature and wind velocity gradients, scattering by atmospheric turbulence, absorption by the atmosphere (fluid), diffraction by terrain features, and absorption and reflection by a porous ground. As a result, there may be insonification in acoustic shadow zones, amplitude and phase fluctuations of the propagating sound signals, loss of signal coherence, changes in the interference maxima and minima of the direct ground reflected waves, and multipath effects. Understanding these effects is important for a variety of military applications, such as acoustic source localization and classification, noise propagation in the atmosphere, and the development of new remote sensing techniques of the atmosphere.

Green's Function Extraction from Atmospheric Acoustic Propagation

19AERP10_0810/1/2019

Understanding what affects acoustic waves propagating in the atmosphere is important for a variety of military applications including the development of new remote sensing techniques. Army Research Laboratory, Adelphi, Maryland Acoustic waves propagating in the atmosphere may undergo many effects including refraction by temperature and wind velocity gradients, scattering by atmospheric turbulence, absorption by the atmosphere (fluid), diffraction by terrain features, and absorption and reflection by a porous ground. As a result, there may be insonification in acoustic shadow zones, amplitude and phase fluctuations of the propagating sound signals, loss of signal coherence, changes in the interference maxima and minima of the direct ground reflected waves, and multipath effects. Understanding these effects is important for a variety of military applications, such as acoustic source localization and classification, noise propagation in the atmosphere, and the development of new remote sensing techniques of the atmosphere. By extracting the medium impulse response, or Green's function, one may obtain information about the medium channel in order to overcome the medium effects or deduce information about the medium. For example, in acoustic communications, information is sent through a medium from a host station to client stations. The transmitted information is subjected to a variety of signal distortions and noise caused by the medium. Using time-reversal processing, it is possible to extract the channel medium impulse response from the transmission of a known pilot signal through the channel medium. This Green's function was then used to modify the subsequent signals to overcome distortion in the channel.

Influence of Leading-Edge Oscillatory Blowing on Time-Accurate Dynamic Store Separation

19AERP10_0710/1/2019

Developing an understanding of, and potentially controlling, pitch bifurcation of a store release from an aircraft during flight could improve weapons delivery. Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio Increasing the operational efficiency of weapons employed in hostile environments is a high priority of the United States Air Force (USAF). In recent history, the USAF has made a move to smaller and internally stored weapons, especially for fighter aircraft. Maintaining a low radar cross section signature, and thus a low observable air vehicle, is desirable so the aircraft is less detectable by the enemy. An internal weapons bay has a reduced load out but yields a low observable profile (reduced radar cross section). Also, aircraft can carry a greater number of weapons if the weapons are smaller, increasing the quantity of targets that can be engaged per sortie. The newer attack aircraft in the United States, such as the P-8A, F-22 and, most recently, the F-35, employ weapons delivery from bomb bays. The effects of this design element have not been fully explored and the impact on weapon release can sometimes be challenging to predict. Thus, it is important to understand the sensitivity of the flow field effects on the internally loaded weapon within a few feet from the carriage.

C919 Trailing Edge Assembly Interchangeable Tooling

2019-01-18809/16/2019

Traditional Trailing Edge (TE) assembly that utilise fixtures for accurate positioning of aircraft (a/c) parts do not allow for removal of specific tooling from the fixtures to travel with the TE, post assembly. Instead, the tooling that positions all the primary a/c assembly datums generally utilise precision pins of various sizes that index and clamp the a/c ribs. Often it is difficult to remove the pins post assembly before the spar can be taken out of the fixture. Use of hammers is common place to hit pins out of holes which is less than ideal considering the a/c parts can be fragile and the tooling is precision set. Also, the Main Assembly Fixture (MAJ) that will receive the TE will inevitably need to relocate some if not all the primary a/c ribs and therefore will most likely be subject to some amount of persuasion. Electroimpact have for many years used cup cone locators that allows static tooling to be temporarily ‘loosened’ and therefore made more compliant for pin insertion/removal, this has been successful to reduce the need for hammering, but doesn’t remove the necessity for extensive manual work to reclaim all the datums. The intent of this paper is to highlight how we, on the C919 project, have successfully designed and implemented the use of removable tooling that travels with the TE sub-assemblies into the main TE assembly fixture and similarly the same interchangeable and removable tooling travels with the completed TE and re-engages with identical tooling receivers in the MAJ. Providing a fast, efficient, reduced man-power and accurate means for building a TE and transfer into the MAJ.

Dineley, James

Improving Competitiveness of Additive Manufacturing Aerospace Serial Parts

2019-01-19009/16/2019

The Powder Bed Fusion technology is exploding in aerospace industry, with various parts adapted to this process. But one of the main limiting factor to use it in the aircraft industry is quantity of parts that can be manufactured per machine within a year. As a major leader in the aerospace fastener industry, LISI AEROSPACE has a long experience in reducing wasted time. Two activities are developed in this article: Decreasing production time thanks to a support structure reduction and simulation Minimizing unproductive time between two consecutive batches, thanks to manufacturing change improvement (LEAN) We took the example of a serial aircraft part, produced on the CONCEPT LASER M1 machine. With these two activities, we save 253 minutes per production. Originally, we had 4 batches per week; after these activities, we can produce 5 batches per week.

Gas, Maxime, Rene-Corail, Alexis, Eyrignoux, Sebastien, Iker, Guillaume, Sudre, Stephane

Low Cost Reconfigurable Jig Tooling and In-Process Metrology for High Accuracy Prototype Rotorcraft Wing Assembly

2019-01-18779/16/2019

Reconfigurable tooling frames consisting of steel box sections and bolted friction clamps offer an opportunity to replace traditional expensive welded steel tooling. This well publicized reconfigurable reusable jig tooling has been investigated for use in the assembly of a prototype compound helicopter wing. Due to the aircraft configuration, the wing design is pinned at both ends and therefore requires a higher degree of end to end accuracy, over the 4m length, than conventional wings. During the investigation some fundamental issues are approached, including: Potential cost savings and variables which effect the business case. Achievable Jig accuracy. Potential sources of instability that may affect accuracy over time. Repeatability of measurements with various features and methods. Typical jig stability over 24hrs including effects of small temperature fluctuations. Deflections that occur due to loading. The cost benefit of reusable tooling in a low volume prototype scenario is examined followed by the design of the jig and location features to enable the accurate build and certification documentation to be completed. A prototype 4m test jig comprising of commercially available components and bespoke machined ‘pick-ups’ is presented. Hardware and measurement process cost modelling is documented along with results for the positional and center-line concentricity setting accuracy that was achieved using a Leica AT901 laser tracking system. Subsequent measurements over a 24hr period are also discussed along with potential sources of deviation in jig accuracy over time and with an applied load.

Crossley, Richard J., Ratchev, Svetan

New Technologies for Airframe Structural Assemblies

2019-01-19159/16/2019

With air traffic demand constantly increasing and several years of aircraft production in their backlog, major aircraft manufacturers are now shifting their focus toward improving assembly process efficiency. One of the most promising solutions, known as “One Side Assembly”, aims to perform the whole assembly sequence from one side of the structure (drilling, temporary fastener installation and removal, blind fastener installation, assembly control) and with a high level of integrated automation. Investments in robotic equipment, automation engineering and innovation are very active and automation capabilities have already increased a lot in the aerospace industry. As an example, drilling operations for large dimensions airframe are clearly moving from manual to automated. However, despite more and more clever and sophisticated robotics, the use of historical fasteners with two side installation method remains a strong limitation to innovative automated assembly sequences. A blind fastener which can provide the same mechanical characteristics than current structural fasteners, while providing automation friendly features and meeting cost objectives is a real “must have” for assembly process efficiency improvements. It is also full of challenges for aerospace fasteners industry. Many research and development activities are on-going to remove fasteners from the equation of aerospace structure assemblies, but we will consider in this article that fasteners will remain a good solution for many years from now, which is shared by a lot of professionals and which doesn’t mean that nothing will change.

Dahane, Mehdi

Self-Affinity of an Aircraft Pilot’s Gaze Direction as a Marker of Visual Tunneling

2019-01-18529/16/2019

For the last few years, a great deal of interest has been paid to crew monitoring systems in order to address potential safety problems during a flight. They aim at detecting any degraded physiological and/or cognitive state of an aircraft pilot or crew, such as visual tunneling, also called inattentional blindness. Indeed, they might have a negative impact on the performance to pursue the mission with adequate flight safety levels. One of the usual approaches consists in using sensors to collect physiological signals which are then analyzed. Two main families exist to process the signals. The first one combines feature extraction and machine learning whereas the second is based on deep-learning approaches which may require a large amount of labeled data. In this work, we focused on the first family. In this case, various features can be deduced from the data by different approaches: spectrum analysis, a priori modeling and nonlinear dynamical system analysis techniques including the estimation of the self-affinity of the signals. In this paper, our purpose was to uncover whether the self-affinity of the pilot gaze direction can be related to his cognitive state. To this end, an experiment was carried out on thirteen subjects in a pilot activity representative environment based on a modified version of the software MATB-II. The scenarios were designed to elicit different levels of mental workload eventually associated to attentional tunneling. A database to train the machine learning step was first created by recording the gaze directions of the subjects with an eye-tracker. The self-affinities of these signals were extracted with the Detrended Fluctuation Analysis method. They constituted the inputs of the classifier. Then, other signals were analyzed and classified. Preliminary results showed promising abilities to detect visual tunneling episodes for different levels of mental workload.

Berthelot, Bastien, Mazoyer, Patrick, Egea, Sarah, André, Jean-Marc, Grivel, Éric, Legrand, Pierrick

Development of Multi-Material Overhead Stowage Systems for Commercial Aircrafts by Using New Design and Production Methods

2019-01-18589/16/2019

Innovative, lightweight and cost-efficient aircraft components require the use of modern lightweight materials and efficient production technologies. A promising technology is the combination of chopped fiber Sheet Molding Compounds (SMC) and pre-impregnated, continuous fiber fabrics processed by single-stage compression molding. The so-called Hybrid SMC Technology obtains cost-efficiency as well as time-saving production of loaded and functional aircraft components. However, reliable design principles for components and computing methods for predicting the material behavior have to be developed for a use in aviation industry. Hence, this paper deals with the development of materials, fabrics, manufacturing processes and computing methods related to the Hybrid SMC Technology. Those developments are demonstrated and validated by the implementation of a lightweight multi-material overhead stowage compartment (OHSC) using new design approaches as well as assembly principles.

Fette, Marc, Büttemeyer, Holger, Krause, Daniel, Fick, Gunnar

Step & Repeat: Reduce Derivative Aircraft Development Risk with Design Reuse

2019-01-18719/16/2019

The complex and risky process of designing derivative aircraft, especially when it comes to electrical systems, can be a daunting task at best. There are a number of design strategies that can be employed to mitigate risk and increase the overall efficiency. Quite simply, the current methods of manual processes, design and integration approaches that were optimized from mechanical approaches, are no match for today’s complexities. One method gaining significant traction is to employ a central database serving global interface definitions for the entire design process. Automation through generative design minimizes manual intervention and repetitive work. Furthermore, detecting changes through design rule checks allows system engineers to verify their designs, capturing both inadvertent and planned changes. The ability to instantly update the design content from the new definition streamlines the change management process. Employing these technologies in a digital, connected thread, ensures that intelligent information is leveraged at every step along the way from aircraft conception, realization, and finally to utilization - thereby minimizing risk and maximizing efficiency.

Askar, Muhammad

Understanding Fiber Optic Transceiver Design and Test Rules

TBMG-351199/1/2019

The design of avionics systems must balance several factors. First, engineers want to increase the performance of the systems installed in aircraft or spacecraft. Second, they want to reduce the size and weight of the equipment that must be carried. Third, they want to maximize the safety of the in-flight systems and maintain communication between the aircraft or spacecraft and other flight vessels and the command center, regardless of the circumstances.

Understanding Fiber Optic Transceiver Design and Test Rules

19AERP09_039/1/2019

How Miniaturized Distributed Modular Architecture Advances Avionics Design

TBMG-348658/1/2019

Most of today’s collision-avoidance, in-flight-entertainment (IFE), air-to-ground-communications, and other avionics systems employ electronics packaging based on the Aeronautics Radio INC (ARINC) 600 standard. Compared to the older ARINC 404 standard dating from the 1970s that defined “black box” enclosures and racks within aircraft, ARINC 600 specified a Modular Concept Unit (MCU) – the basic building block module for avionics. An ARINC 600 metal enclosure can hold up to 12 MCUs, allowing a lot of computing power to be placed in a centralized “box.” By making it possible to run numerous applications over a real-time network, ARINC 600 enabled “next generation” integrated modular avionics (IMA).

Sensor Network for Air Vehicles

TBMG-347427/1/2019

Aircraft currently fly based on coarse estimations of environment and aircraft state. Real-time measurements are traditionally restricted to laboratory environments (e.g. wind tunnel) due to the size and weight of instrumentation. NASA Ames has developed a distributed system for sensing the environmental and structural conditions of an air vehicle. It consists of many identical lightweight and low-power network modules that can connect to each other as well as to a number of different sensors of any type. The resulting network produces a robust, responsive system that can transfer structural and environmental information into actionable control objectives in real time.

Developing a Custom Data Acquisition Software Package for a Self-contained Acoustic Test Facility

2019-01-15016/5/2019

This paper provides an overview of a custom software developed to obtain measurement data in a self-contained acoustic test facility system used for conducting random incidence sound absorption tests and sound transmission loss tests on small samples in accordance with SAE J2883 and J1400 standards, respectively. Special features have been incorporated in the software for the user to identify anomalies due to extraneous noise intrusion and thereby to obtain good data. The paper discusses the thoughts behind developing user-friendly algorithms and graphical user interfaces (GUI) for the sound generation, control, data acquisition, signal processing, and identifying anomalies.

Kolano, Richard, Patil, Sagar, Saha, Pranab

Subband Adaptive Filtering Algorithms for Active Broadband Noise Control in Impulsive Vehicle Noise Environment

2019-01-15286/5/2019

Subband adaptive filtering (SAF) techniques have been increasingly used in active noise control (ANC), especially for acoustic broadband noise signal and system models with long impulse responses. In ANC, the closed-loop delayless SAF schemes improve the convergence rate of the widely adopted conventional filtered-x LMS (FxLMS) algorithm in a more computationally efficient manner under wideband noises like colored signals or even nonstationary signals. In most real-world environment like vehicle interior cabin, however, the performance of ANC can be degraded by various outliers, including non-Gaussian impulsive signal such as transient impact acoustic response for road noise. Although several robust objective error criteria as well as threshold based LMS-type adaptive filtering algorithms have been investigated for active impulsive noise control, the computational burden would be challenging for implementation and the requirement of a priori knowledge of noises cannot be fulfilled in many cases. In this paper, various state-of-the-art SAF algorithms with decorrelating property are studied in terms of the convergence property for broadband noise control in impulsive environment since the subband decomposition might alleviate the sudden change of adaptive systems by spreading energy to multiple channels. The SAF algorithms with low-order norm of error evaluation and variable step sizes are further evaluated via simulations for the input of symmetric α-stable (SαS) impulsive noise and colored noise in the impulsive environment, respectively. Results show that the delayless SAF algorithms appear more robust than the conventional LMS-type algorithms for impulsive noises. Moreover, the utilization of band-dependent variable step sizes for the delayless SAF algorithms significantly improves the convergence rate.

Long, Guo, Wang, Kan, Lim, Teik

Design of Lightweight Fibrous Vibration Damping Treatments to Achieve Optimal Performance in Realistic Applications

2019-01-15246/5/2019

In recent work, it has been shown that conventional sound absorbing materials (e.g., lightweight fibrous media) can provide structural damping when placed adjacent to vibrating structures, including infinite panels, partially-constrained panels and periodically-supported panels typical of aircraft structures. Thus, a fibrous layer may serve two functions at once: absorption of airborne sound and the reduction of structure-borne vibration. It has also been found that the damping is primarily effective below the critical frequency of the structure, and that the damping results from viscous interaction between the fibrous layer and the evanescent near-field of the panel, in the region where incompressible flow caused by the panel vibration oscillates primarily parallel with the panel surface. By using a near-field damping (NFD) model based on the Biot model for acoustical porous media, it has been shown that a properly-optimized fibrous layer can provide levels of damping comparable with those provided by conventional, constrained-layer, visco-elastic, damping treatments. Based on the idea that vibrating structures exhibit a certain wavenumber/frequency response spectrum, the focus of the current study has been on evaluating the power dissipated by a fibrous treatment as a function of wavenumber and frequency, and on identifying the material microstructure (i.e., fiber size) required to maximize the power dissipation, and hence damping, in a specific wavenumber/frequency range. To demonstrate the wavenumber/frequency-matching procedure, an example involving a simplified model of a vehicle component will be considered here, and it will be shown how a fibrous layer can be designed to maximize its damping effectiveness when applied to a realistic base structure, such as an automotive floor pan.

Xue, Yutong, Bolton, J Stuart, Herdtle, Thomas

Determining Vibro-Acoustic Characteristics and Structural Damping of an Elastic Monolithic Panel

2019-01-15386/5/2019

Evaluations of the dynamic and acoustic responses of panels, partitions, and walls are of concern across many industries, from building home appliances, planning meeting rooms, to designing airplanes and passenger cars. Over the past few decades, search efforts for developing new methodologies and technologies to enable NVH engineers to acquire and correlate dynamically the relationship between input excitations and vibro-acoustic responses of arbitrary-shaped panels has grown exponentially. The application of a particular methodology or technology to the evaluation of a specific structure depends intimately on the goals and objectives of the NVH engineers and industries. In this work, we present the comparisons between the traditional modal analyses for structural vibrations together with sound intensity measurements of sound radiation and a laser-assisted Helmholtz equation least squares (HELS) method [1, 2, 3, 4] to characterize the dynamic and acoustic responses of an arbitrarily shaped structure subject to non-contact acoustic excitations. Input data for the latter include the normal surface velocities measured at a finite number of points on the surface of the structure that are accessible to a laser beam, and the acoustic pressures measured at a few points in the near field. With these input data, we will be able to reconstruct the normal surface velocity, the surface acoustic pressure, the normal surface acoustic intensity distributions over the entire structure, dimensionless structural damping ratio spectrum, sound transmission losses (STL), and sound transmission paths, etc. These data enable engineers to acquire a comprehensive understanding of the vibro-acoustic characteristics of any arbitrarily shaped vibrating structure, which can lead to the most cost-effective NVH reduction.

Figueroa, Antonio, Wu, Sean, Chen, Lingguang

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