Research and Technology

Langley Research Center is engaged in the basic an applied research necessary for the advancement of aeronautics and space flight, generating advanced concepts for the accomplishment of related national goals, and provding research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Highlights of major accomplishments and applications are presented

Temperature-Driven Structural Identification for Bridge Performance Evaluation

Bridges serve as integral components of infrastructure all around the world. Their direct impact to society is substantial, and their reliability is paramount. As such, confidence in the integrity of these structures is important not only for individuals who utilize these structures but also for the bridge owners and engineers who operate and maintain them. In order to develop a comprehensive understanding of the structural behavior, evaluations are conducted to assess the structure’s performance. By utilizing input-output relationships between loads and responses, structural performance evaluations provide an opportunity to assess unique bridge behavior such as complex mechanisms or deterioration. The research presented herein investigates a novel, temperature-driven concept for bridge performance evaluation wherein thermal behavior in response to environmental temperature changes is used to assess the structure. Within this research, two bridges are evaluated using a probabilistic approach of single and multiple model updating within the temperature-driven structural identification process. This technique utilizes Latin Hypercube Sampling as well as Bayesian calibration to identify unknown bridge parameters and evaluate the structural performance. Then, these studies are compiled into a synthesis of temperature-driven evaluations from nineteen bridge studies throughout the world to develop a comprehensive framework and to provide guidance for using thermal behavior for performance evaluations. The intellectual merit from each study illuminates various motivations, methods, successes, and challenges of temperature-driven evaluations. Guidance regarding structure details, monitoring criteria, as well as data and analysis is provided to assist bridge owners, engineers, and researchers who utilize this temperature-driven technique to conduct evaluations. Based on the research presented herein, temperature-driven performance evaluations provide extensive insight, not only to the thermal behavior of the bridge, but the overall structural health

Critical Infrastructures: Enhancing Preparedness & Resilience for the Security of Citizens and Services Supply Continuity: Proceedings of the 52nd ESReDA Seminar Hosted by the Lithuanian Energy Institute & Vytautas Magnus University

Critical Infrastructures Preparedness and Resilience is a major societal security issue in modern society. Critical Infrastructures (CIs) provide vital services to modern societies. Some CIs’ disruptions may endanger the security of the citizen, the safety of the strategic assets and even the governance continuity. The European Safety, Reliability and Data Association (ESReDA) as one of the most active EU networks in the field has initiated a project group on the “Critical Infrastructure/Modelling, Simulation and Analysis – Data”. The main focus of the project group is to report on the state of progress in MS&A of the CIs preparedness & resilience with a specific focus on the corresponding data availability and relevance. In order to report on the most recent developments in the field of the CIs preparedness & resilience MS&A and the availability of the relevant data, ESReDA held its 52nd Seminar on the following thematic: “Critical Infrastructures: Enhancing Preparedness & Resilience for the security of citizens and services supply continuity”. The 52nd ESReDA Seminar was a very successful event, which attracted about 50 participants from industry, authorities, operators, research centres, academia and consultancy companies.JRC.G.10-Knowledge for Nuclear Security and Safet

A state-of-the-art assessment of active structures

A state-of-the-art assessment of active structures with emphasis towards the applications in aeronautics and space is presented. It is felt that since this technology area is growing at such a rapid pace in many different disciplines, it is not feasible to cover all of the current research but only the relevant work as relates to aeronautics and space. Research in smart actuation materials, smart sensors, and control of smart/intelligent structures is covered. In smart actuation materials, piezoelectric, magnetostrictive, shape memory, electrorheological, and electrostrictive materials are covered. For sensory materials, fiber optics, dielectric loss, and piezoelectric sensors are examined. Applications of embedded sensors and smart sensors are discussed

Aeroelastic Stability Assessment Of a CS-25 Category Aircraft Equipped With Multi-Modal Wing Morphing Devices

Morphing wing structures have the greatest ambition to dramatically im-prove aircraft aerodynamic performance (less fuel consumption) and reduce aerodynamic noise. Several studies in the literature have shown their potential for increased aerodynamic efficiency across nearly all flight conditions, en-hanced aircraft maneuverability and control effectiveness, decreased take-off/landing length, reduced airframe noise, etc. However, despite a long herit-age of research, morphing wing technology has yet to be approved by the Euro-pean Aviation Safety Authority (EASA) for use in commercial aviation. Models and approaches capable to predict the aeroelastic impact of a morphing wing still need to be matured to safely alter design and operation of future genera-tions of aircraft. Additionally, a number of practical challenges remain to be addressed in the suitable materials, systems reliability, safety and maintenance. Due to the reduced stiffness, increased mass and increased Degree Of Freedom (DOF) with respect to conventional wings, these mechanical systems can cause significant reduction of aircraft flutter margins. This aspect requires dedicated aeroelastic assessments since the early stages of the design process of such an innovative wing. Flutter boundaries predictions need sensitivity anal-yses to evaluate bending/torsional stiffness and inertial distribution variability ranges of the aircraft wing equipped with the morphing wing devices. In such a way, aeroelastic assessments become fundamental to drive a balance between weight and stiffness of the investigated adaptive systems. Furthermore, in pseu-do rigid-body mechanisms-based morphing structures, the inner kinematics is so important that its faults may compromise the general aircraft-level functions. Similarly to the demonstration means of safety compliance, commonly applied to aircraft control surfaces, the novel functions resulting from the integration of adaptive devices into flying aircraft thus impose a detailed examination of the associated risks. In the framework of Clean Sky 2 Airgreen 2 project, the author provides advanced aeroelastic assessments of two adaptive devices enabling the camber morphing of winglets and flaps, conceived for regional aircraft integration (EASA CS-25 category). Segmented ribs architectures ensure the transition from the baseline (or un-morphed) shape to the morphed ones, driven by em-bedded electromechanical actuators. Some of the advantages resulting from the combination of the two aforementioned morphing systems are wing load con-trol, lift-over-drag ratio increase and root bending moment alleviation. The aircraft aeroelastic model was generated by means of the proprietary code SANDY 3.0. Then, the same code was adopted to solve the aeroelastic stability equa-tions through theoretical modes association in frequency domain. To carry out multi-parametric flutter analyses (P-K continuation method), the actuation lines stiffness and winglet/flap tabs inertial parameters were considered in combina-tion each other. Nominal operative conditions as well as systems malfunction-ing or failures were examined as analyses cases of the investigated morphing devices, together with actuators free-play conditions. Proper design solutions were suggested to guarantee flutter clearance in accordance with aircraft stabil-ity robustness with respect to morphing systems integration, evaluated through a combination of “worst cases” simulating the mutual interaction among the adaptive systems. The safety-driven design of the morphing wing devices required also a thorough examination of the potential hazards resulting from operational faults involving either the actuation chain, such as jamming, or the external interfaces, such as loss of power supplies and control lanes, and both. The main goal was to verify whether the morphing flap and winglet systems could comply with the standard civil flight safety regulations and airworthiness requirements (EASA CS25). More in detail, a comprehensive study of systems functions was firstly qualitatively performed at both subsystem and aircraft levels to identify poten-tial design faults, maintenance and crew faults, as well as external environment risks. The severity of the hazard effects was thus determined and then ranked in specific classes, indicative of the maximum tolerable probability of occurrence for a specific event, resulting in safety design objectives. Fault trees were final-ly produced to assess the compliance of the system architectures to the quanti-tative safety requirements resulting from the FHAs

Aeronautical engineering: A continuing bibliography with indexes (supplement 260)

This bibliography lists 405 reports, articles, and other documents introduced into the NASA scientific and technical information system in December, 1990. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

A Data-Driven Predictive Model of Reliability Estimation Using State-Space Stochastic Degradation Model

The concept of the Industrial Internet of Things (IIoT) provides the foundation to apply data-driven methodologies. The data-driven predictive models of reliability estimation can become a major tool in increasing the life of assets, lowering capital cost, and reducing operating and maintenance costs. Classical models of reliability assessment mainly rely on lifetime data. Failure data may not be easily obtainable for highly reliable assets. Furthermore, the collected historical lifetime data may not be able to accurately describe the behavior of the asset in a unique application or environment. Therefore, it is not an optimal approach anymore to conduct a reliability estimation based on classical models. Fortunately, most of the industrial assets have performance characteristics whose degradation or decay over the operating time can be related to their reliability estimates. The application of the degradation methods has been recently increasing due to their ability to keep track of the dynamic conditions of the system over time. The main purpose of this study is to develop a data-driven predictive model of reliability assessment based on real-time data using a state-space stochastic degradation model to predict the critical time for initiating maintenance actions in order to enhance the value and prolonging the life of assets. The new degradation model developed in this thesis is introducing a new mapping function for the General Path Model based on series of Gamma Processes degradation models in the state-space environment by considering Poisson distributed weights for each of the Gamma processes. The application of the developed algorithm is illustrated for the distributed electrical systems as a generic use case. A data-driven algorithm is developed in order to estimate the parameters of the new degradation model. Once the estimates of the parameters are available, distribution of the failure time, time-dependent distribution of the degradation, and reliability based on the current estimate of the degradation can be obtained

Use, Operation and Maintenance of Renewable Energy Systems:Experiences and Future Approaches

The aim of this book is to put the reader in contact with real experiences, current and future trends in the context of the use, exploitation and maintenance of renewable energy systems around the world. Today the constant increase of production plants of renewable energy is guided by important social, economical, environmental and technical considerations. The substitution of traditional methods of energy production is a challenge in the current context. New strategies of exploitation, new uses of energy and new maintenance procedures are emerging naturally as isolated actions for solving the integration of these new aspects in the current systems of energy production. This book puts together different experiences in order to be a valuable instrument of reference to take into account when a system of renewable energy production is in operation

Langley test highlights, 1982

A 20 ft vertical spin tunnel, a 30 by 60 ft tunnel, a 7 by 10 ft high speed tunnel, a 4 by 7 meter tunnel, an 8 ft transonic pressure tunnel, a transonic dynamics tunnel, a 16 ft transonic tunnel, a national transonic facility, a 0.3 meter transonic cryogenic tunnel, a unitary plan wind tunnel, a hypersonic facilities complex, an 8 ft high temperature tunnel, an aircraft noise reduction lab, an avionics integration research lab, a DC9 full workload simulator, a transport simulator, a general aviation simulator, an advanced concepts simulator, a mission oriented terminal area simulation (MOTAS), a differential maneuvering simulator, a visual/motion simulator, a vehicle antenna test facility, an impact dynamics research facility, and a flight research facility are all reviewed

Aeronautical Engineering: A continuing bibliography with indexes (supplement 207)

This bibliography lists 484 reports, articles and other documents introduced into the NASA scientific and technical information system in November 1986