bluuebunny/crossref_metadata_2025_split huggingface dataset:
Constitutive Modeling of Magnetostrictive Materials
Authors: Gopalakrishnan Srinivasan 
Published: September 2009

Abstract
The constitutive model for a magnetostrictive material is presented in this article. An example of a magnetostrictive material is Terfenol‐D. Like the piezoelectric material, this material has two constitutive laws, one of which is the sensing law and the other the actuation law, both of which are highly coupled and nonlinear. For the purpose of analysis, the constitutive laws can be characterized as coupled or uncoupled and linear or nonlinear. The coupled model is studied without assuming any explicit direct relationship with the magnetic field. In the linear‐coupled model, which is assumed to preserve the magnetic flux line continuity, the elastic modulus, the permeability, and magnetoelastic constant are assumed as constant. In the nonlinear‐coupled model, the nonlinearity is decoupled and solved separately for the magnetic domain and the mechanical domain using two nonlinear curves, namely, the stress versus strain curve and the magnetic flux density versus magnetic field curve. This is performed by two different methods. In the first, the magnetic flux density is computed iteratively, while in the second, the artificial neural network is used, wherein the trained network gives the necessary strain and magnetic flux density for a given magnetic field and stress level. The effect of nonlinearity is demonstrated on a simple magnetostrictive rod.
Modeling Aspects in Finite Elements
Authors: Gopalakrishnan Srinivasan 
Published: September 2009

Abstract
This article presents some of the modeling aspects in finite element (FE) analysis for structural health monitoring (SHM) problems. First, the procedure to select a proper FE mesh size for a given frequency content of a predefined input is given. A relationship between the damage sizes and the frequency content of the predefined input signal is then established. Different methods of modeling flaws in finite element method (FEM) and their utility in SHM studies are explained in detail through numerical examples. Limitations of FEM for SHM and their possible remedies are discussed. The article ends with a summary and some useful modeling suggestions.
Development of Fuzzy Rules for Damage Detection and Location
Authors: Ganguli Ranjan 
Published: September 2009

AbstractWork done in using fuzzy logic for structural damage detection is reviewed. An introduction to fuzzy logic is given and the process of developing rules is illustrated using two examples for damage detection in cantilever beams made of isotropic and composite materials, respectively. It is shown that fuzzy logic provides a practical alternative to neural network and genetic algorithm–based damage detection approaches popular with structural health monitoring researchers. Fuzzy logic–based damage detection algorithms can detect, locate, and identify the size of damage from noisy data. Moreover, the process of rule development in fuzzy systems can be automated via learning algorithms leading to genetic fuzzy systems.
Loads Monitoring in Aerospace Structures
Authors: Reed Steve 
Published: September 2009

Abstract

Loads monitoring can be defined as
a structural usage substantiation activity
. This activity involves the capture, analysis, and reporting of representative, directly measured strain data or derived loads and associated flight parameters from a sample of suitably instrumented in‐service air vehicles within a fleet. The aim of this article is to describe the philosophy behind operational loads monitoring in aerospace structures, within the context of in‐service structural health monitoring.
Loads and Temperature Effects on a Bridge
Authors: Wang Ming L. 
Published: September 2009

AbstractA number of efforts had been made to instrument bridges for the purpose of structural monitoring and assessment. The outcome of these efforts, as gauged by advances in the understanding of the definition of structural damage and their role in sensor selection as well as in the design of cost and data‐effective monitoring systems, has itself been difficult to assess. The authors experience with the design, calibration, and operation of a monitoring system for the Kishwaukee Bridge in Illinois has provided several lessons that bear upon these concerns. The systems have performed well in providing a continuous, low‐cost monitoring platform for bridge engineers with immediate relevant information. Specifically, load and environmental effects are addressed in detail.
Maintenance Principles for Civil Structures
Authors: Frangopol Dan M. , Messervey Thomas B. 
Published: September 2009

Abstract
This chapter explores the rapidly evolving field related to incorporating information obtained through structural health monitoring (SHM) into the design, maintenance, and management of civil structures. Herein, the employment of monitoring technologies is investigated with respect to the following topics: development of a strategic, top‐down monitoring approach; collecting the most critical information, at the right time, with the right instrument; probabilistic formulation of the analysis; conducting structural assessment; updating with monitoring information; life‐cycle costing; and inclusion of risk. Simple examples are utilized to highlight the issues related to the use of monitoring technologies as a natural part of design and management. In this article, the need for performance‐based design, several examples of monitoring‐based structural assessment, and calculating life‐cycle costs are treated in detail. In the end, the reader should gain an appreciation of recent progress in the rapidly developing field of SHM, some of the considerations for its implementation, and needs for further study.
Usage Management of Military Aircraft Structures
Authors: Neunaber Rolf H. 
Published: September 2009

Abstract
The aircraft structure is designed and certified for an allowable number of flight hours in a specific usage environment. Deviation from the certified usage spectrum has effects on the allowable number of flights. This is owing to the fatigue behavior of the metallic structure, which is highly sensitive to variations in load spectra. Such variations are particularly common in the use of military aircraft, because of frequent changes in configurations and role.
Structural health monitoring (SHM) allows the monitoring of structural degradation. This is not only for flight safety but with an increasing tendency for reasons of material conservation, e.g., the planning of structural inspections and modifications.
This article starts with a more general differentiation of load and condition‐acquisition systems. Furthermore, as an example of load‐acquisition systems, the tracking concept for the German Tornado aircraft is explained; this is built on flight parameter recording followed by the evaluation of the gathered data.
The results generated in this way are interpreted, on one hand, for reasons of material conservation like nonperiodic inspection planning and modification planning and, on the other hand, for the fleet management.
Furthermore, the associated tasks, analytical condition monitoring, and fleet leader inspections, are explained.
Finally, the considerable saving in cost, which can be achieved by the use of SHM, is illustrated using an appropriate example.
Monitoring Marine Structures
Authors: Salvino Liming W. , Collette Matthew D. 
Published: September 2009

Abstract
Technologies and methodologies need to be developed to monitor ship hull and structural integrity as US navy and maritime industry designs increasingly rely on lightweight materials such as composites and aluminum for ship structures to meet future high‐speed/high‐performance goals. Wave loadings at high speeds result in pressure fields that challenge local and global structural integrity to a degree not supported by traditional navy or commercial design approaches. There is little generic experience related to maintaining structural performance of lightweight high‐speed ships. This is especially true as they age. There is a fast growing interest in equipping high‐speed vessels with an operational real‐time structural health monitoring system. Currently, there are several US navy research and development programs that contain the development of ship and hull structural health monitoring systems. Examples of such will be given. Previous and current efforts as well as required technologies for health monitoring of ship structures will be reviewed. The importance and the roles of an effective structural health monitoring system throughout the life cycle of a ship are discussed. The continued advancement of pertinent technologies will ultimately enable a comprehensive structural health monitoring system that includes diagnostic methods and prognostic capabilities to proactively manage future ship hull and structures.
History ofSHMfor Commercial Transport Aircraft
Authors: Ikegami Roy , Boller Christian 
Published: September 2009

AbstractFor the commercial transport aircraft industry, structural health monitoring (SHM) is a relatively new technology, and significant effort is required to define, develop, validate, and certify SHM systems for specific structural applications. Additionally, the systems must be demonstrated to be reliable over an aircraft service life of 30 years with low maintenance costs. This article describes some of the past activities on the part of commercial aircraft original equipment manufacturers (OEMs), the aircraft operators, and SHM equipment suppliers to evaluate, develop, and certify SHM technologies for potential application to new commercial aircraft designs and the aging commercial aircraft fleet currently in service.
Fatigue Monitoring in Military Fixed‐Wing Aircraft
Authors: Buderath Matthias 
Published: September 2009

Abstract
This article elaborates on the principles applied in the development of fatigue and usage monitoring systems for military fixed wing aircraft. Various airframe fatigue life monitoring concepts have been applied to the fatigue management of the Tornado aircraft. Experience gained from such aircraft have lead the way for innovative approaches for preceding aircraft such as the Eurofighter and A400M. In these cases the principles of fatigue and usage monitoring are more or less the same but we can see many of improvements in the information fusion, integration, processing, and information management technologies. This is seen as key to manage structural integrity, aircraft/fleet availability, and the reduction of operation and support costs. We have seen that in particular operational availability cannot be dissociated from the related costs going alone with corrective and scheduled maintenance actions. Significant operation and support reductions can only be achieved at aircraft level having a comprehensive view about aircraft, system, and structural performance. The more the information can be integrated into a maintenance information system, the more operational and cost benefit becomes obvious. The next generation of military aircraft will have hopefully a combined usage‐ and damage monitoring system implemented.
Health and Usage Monitoring Systems (
HUM
Systems) for Helicopters: Architecture and Performance
Authors: Pipe Kenneth 
Published: September 2009

Abstract
To enable the helicopter operator to discriminate between wide price/performance variations in the range of systems marketed as HUM system (health and usage monitoring system) requires that the systems' performance can be measured against recognized standards that relate to the HUM system's primary function of enhancing helicopter airworthiness. This article explores the criteria for measuring the performance of a HUM system, the features of the system that are important, and the standards that can be applied.
Ultimately, the performance of a HUM system is measured in actuarial terms, i.e., the impact of the technology in reducing the number of catastrophic and hazardous events on helicopters. The Regulatory Authorities and the manufacturers maintain appropriate statistical records on helicopter safety, but there is no consensus on how to factor in the contribution of HUM systems to the overall safety improvements achieved since the introduction of the technology. Given this difficulty, the article discusses the other performance criteria that are meaningful in establishing a system's efficacy.
The components of a HUM system form a hierarchy, from the sensors, through processing, alarm generation, and finally the operation of the system. The article discusses how the components of a HUM system contribute to its overall performance and the practical performance criteria that can be applied. Health as well as usage functions are covered, as well as functions that relate to maintenance benefits.
HUM systems are unusual in terms of the close interaction between the airborne and ground‐based components of the system. Because of this design feature of maintaining the system's integrity when operating in the helicopter environment is a major issue, the article outlines where standards need to be established.
Finally, the airborne components of a HUM system have to perform as any other item of avionics equipment and the standards that are peculiar to the HUM system are discussed.
Monitoring of Solid Rocket Motors
Authors: Ruderman Gregory A. 
Published: September 2009

AbstractAs so‐called wooden rounds, which are intended to sit stably in storage for extended periods and then function precisely as desired at a moment's notice, missiles would appear to be an ideal application for health monitoring. However, the solid rocket motors that serve as the propulsion system for these missiles present a number of unique challenges for the development of integrated vehicle health monitoring systems. Mechanical and chemical complexity, long service lives, aging materials, and designs with small margins are typical for solid motors, but the payoff for health monitoring is extreme as well. Maintaining a healthy and capable fleet—ensuring the viability of the missiles in the fleet, while not retiring or destroying good assets before it is necessary—could save as much as 50% in costs over a 50‐year life cycle. In this article, a number of unique aspects of solid rocket motors are explored, the difficulties and successes in the development of sensors and diagnostic systems are discussed, and a path to further continue the development of these systems is proposed.
Development of an Active Smart Patch for Aircraft Repair
Authors: Rajic Nik 
Published: September 2009

AbstractThis article describes an application of acousto‐ultrasonics to the development of an “active smart patch” (ASP) repair for the F‐111C, a high‐performance strike reconnaissance aircraft flown by the Royal Australian Air Force. Fatigue cracking caused by poor design of a stiffener depression in the lower wing skin inspired the development of a boron‐composite bonded repair as a cost‐efficient means of restoring wing strength. Although successful, the repair technology is hampered by burdensome structural certification requirements. Embedment in the repair of an acousto‐ultrasonic structural health monitoring system was conceived as an inexpensive approach to satisfying certification concerns. Descriptions are given of the transducer packaging technology and system control hardware developed for the application, and of a laboratory trial of a prototype ASP demonstrating the efficacy of the approach.
Fiber‐optic Sensors
Authors: Foote Peter 
Published: September 2009

AbstractFiber‐optic sensors for use in aerospace structural monitoring applications are described. The principles of operation of some commonly used sensors are described with examples of how they are used in aerospace‐related structural monitoring applications. The rationale for the use of fiber optics rather than electrical sensors is included. Airframe load monitoring and structural damage detection are discussed and the relative merits for fiber sensing techniques are explained. Some published trials over the last two decades of fiber‐optic sensors in aerospace applications are identified with brief descriptions of the outcomes. Finally, some opinions on the future prospects of fiber‐optic sensing in aerospace are offered.
Agile Military Aircraft
Authors: Molent Loris , Agius Jason 
Published: September 2009

AbstractStructural health monitoring (SHM) of airframes has developed over the decades to the stage where it is now incumbent for all fighter‐type aircraft to be fitted with an airborne fatigue monitoring system. These systems typically collect operational data primarily for the calculation of the safe‐life or the inspection interval of the airframe, thus helping to ensure that the structural certification limits for the aircraft are not exceeded. The requirement for SHM systems is explicitly stated in current military structural design standards. This article presents the reasons for requiring such systems and some general requirements for their implementation. The article draws upon the extensive experiences from Australian fatigue monitoring programs, and highlights some of the potential pitfalls in the systems and techniques.
Landing Gear
Authors: Schmidt R. Kyle , Sartor Pia 
Published: September 2009

AbstractLanding gear systems involve several unique issues that differentiate them from other aircraft systems and the airframe itself. These differences mean that often an alternative approach has to be taken with landing gear structural health monitoring solutions. This article discusses past and present approaches for monitoring the movable aspects of the landing gear, methods for detecting landing gear transient overloads, techniques for measuring the forces seen by the landing gear structure, and methods for determining the fatigue state of landing gear structure.
Thermal Protection System Monitoring of Space Structures
Authors: Prosser William H. , Madaras Eric I. , Studor George F. , Gorman Michael R. 
Published: September 2009

Abstract
The loss of the space shuttle Columbia, as a result of impact damage from foam debris during ascent, led NASA to develop and implement onboard impact‐detection technologies. Acoustic emission sensing, both with accelerometers and ultrasonic sensors, was used to monitor a wide variety of impact conditions on space shuttle components ranging from insulating foam and ablator materials, and ice at ascent velocities to simulated hypervelocity micrometeoroid and orbital debris impacts. Impact testing was performed on both reinforced carbon composite wing leading‐edge materials and shuttle tile materials on representative aluminum wing structures. Results of these impact tests are presented with a focus on the acoustic emission sensor responses to these impact conditions. These tests demonstrated the potential for onboard shuttle impact detection and led to the development and implementation of the shuttle wing leading‐edge impact‐detection system (WLEIDS). The WLEIDS has been installed on all space shuttles and has been monitored on all flights since the Columbia. Results from the WLEIDS are discussed.
Flight Demonstration of a
SHM
System on a
USAF
Fighter Airplane
Authors: Malkin Matthew C. 
Published: September 2009

Abstract
A flight demonstration of a structural health monitoring (SHM) system for a bonded structural repair is described. Motivations for health monitoring of bonded repairs are presented, and the flight test of a health monitoring system for a bonded repair on a fighter airplane is described. Experience gained by fielding a laboratory‐level system is discussed.
The Character of
SHM
in Civil Engineering
Authors: Wenzel Helmut 
Published: September 2009

Abstract
Health monitoring for civil engineering structures is a challenge. Our structures are each a protype and have small safety margins when used by the public. Bridges, for example, were the backbone of powerful empires from China to Rome and the Incas in America. Currently, the transportation infrastructure is directly related to the economic success of a nation. All these facts make structural health monitoring (SHM) of civil engineering structures more difficult than any monitoring of a well‐defined mechanical structure. The major number of uncertainties in geometry, material properties, and the influence of the environment might have a higher impact on monitoring results than any minor damage. Therefore, only complex approaches under consideration and compensation of the already known phenomena will be successful.
The Influence of Environmental Factors
Authors: Wenzel Helmut 
Published: September 2009

Abstract
Recent publications have raised doubts as to whether damage in structures can be detected by the application of frequency analyses. In fact, temperature changes very often show larger reactions in spectra than any smaller damage. Besides temperature, other environmental influences, such as radiation from sunshine, create changes in the structural systems that have to be considered.
When environmental conditions are monitored together with the structural response, a proper reaction can be predicted. The described compensation process, in general, deals with the following sources of input: temperature (daily and annual cycles), compensation of live load (moving vehicles, etc.), influence of wind loads, bearing friction, restoring forces, change of boundary conditions, impact energy, and instrumentation. Separate approaches are necessary, considering that each civil engineering structure is a prototype.
Monitoring of Bridges inKorea
Authors: Koh Hyun‐Moo , Lee Hae‐Sung , Kim Sungkon , Choo Jinkyo F. 
Published: September 2009

AbstractKorea has adopted bridge monitoring systems since early 1990s. Existing bridges were at first instrumented to collect field data for design check and long‐term monitoring. Along with the rapid and massive progresses made in the domain of IT technologies for infrastructures, complete and integrated monitoring systems were systematically installed in all major bridges since 2000 in Korea, which can be seen today as one of the leading countries in bridge monitoring. The so‐collected database is currently exploited for diverse purposes, such as maintenance, evaluation of structural behavior, system identification, and feedback for future constructions. Continuous efforts have been and are being deployed to enhance structural health monitoring (SHM) of bridge structures, and numerous researches are being conducted on emerging smart technologies. Such ongoing efforts are dedicated to realize full integration of monitoring systems, in the future, to produce bridges providing real‐time continuous sensing, remote sensing, and self‐diagnostic and decision‐making functions with a lifetime perspective. Accordingly, bridge monitoring in Korea evolved to reach its third generation now in terms of development stage and functionality. This article reviews the development and applications of SHM for existing and newly built bridges in Korea with their objectives and characteristics.
Suspended Roof of
B
raga Sports Stadium,
P
ortugal
Authors: Cunha Álvaro , Magalhães Filipe , Caetano Elsa 
Published: September 2009

Abstract
Temporary ambient vibration monitoring of the suspended roof of the new Braga Sports Stadium was developed with the purpose of identifying modal properties through operational modal analysis. This experimental work allowed the validation of a numerical modeling that takes into account the geometric nonlinear structural behavior and the progressive application of loads during the construction phase. Special attention was given for the identification of modal damping ratios, owing to the necessity of analyzing the susceptibility of the suspended roof to buffeting effects. Modal damping ratios were estimated from data provided by free, forced, and ambient vibration tests, using an improved implementation of the enhanced frequency domain method and the covariance‐driven stochastic subspace identification (SSI‐COV) method.