bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hypersonic Aeroelasticity and Aerothermoelasticity
Authors: McNamara Jack J. , Friedmann Peretz P. 
Published: December 2010

AbstractHypersonic aeroelasticity and aerothermoelasticity involves the study of mutually coupled fluid‐structure interactions that occur as a result of flexible structures operating in hypersonic flow. Starting between Mach 3.0 and Mach 5.0, the effect of flow nonlinearities and aerodynamic heating on the structural response of hypersonic vehicles becomes an important consideration. Aeroelastic phenomena in hypersonic flow is an essential consideration in the hypersonic flow regime due to the potential to lead to structural failures (e.g., flutter, fatigue, buckling, etc.) and increase the complexity of interactions between the aerodynamic, structural, control, and propulsion systems (i.e., aero‐servo‐thermo‐elastic‐propulsive interactions). This article discusses the fundamental aspects of the problem, strategies for solution, modeling approaches, and hypersonic aeroelastic and aerothermoelastic behavior as observed from previous experimental and computational investigations.
Rotary Wing Aeroelasticity
Authors: Friedmann Peretz P. 
Published: December 2010

AbstractThis chapter provides an introduction to rotary wing aeroelasticity (RWA). Basic rotor configurations in use currently are described. Fundamental differences between RWA and fixed wing aeroelasticity are identified. The methodology for formulation and solution of the RWA problem is given, followed by a limited number of illustrative results. These examples illustrate several key problems in RWA such as the coupled flap–lag and coupled flap–lag–torsional isolated blade stability in hover, followed by the coupled rotor–fuselage problem in hover. Comprehensive rotorcraft analysis codes are also discussed, and their application to bearingless rotor stability analysis is illustrated. Modeling of composite blades is also briefly described. The chapter describes noteworthy current activities and concludes by discussing future developments.
Error Estimation and Quality Control
Authors: Díez Pedro , Parés Núria , Huerta Antonio 
Published: December 2010

AbstractThis chapter provides a description of the error assessment tools available for general finite element analysis, in particular those for solid and structural mechanics. The text focuses on goal‐oriented error estimation, in terms of general quantities of interest rather than on energy norm. However, the energy norm estimates are also discussed because they are seen as basic tools that must be used for assessing the error in arbitrary functional outputs of the solution. Attention is paid to the classification of the different methodologies and their main characteristics.
Computational Methods in Buckling and Instability
Authors: de Borst René 
Published: December 2010

Abstract
This chapter gives a succinct overview of computational methods to identify instability and bifurcation phenomena in systems that arise after discretization of solids and structures. Next, path‐following methods are discussed, which allow for tracing the complete load‐displacement behavior of thin‐walled structures, including snap‐through and snap‐back behavior.
Computational Optimization
Authors: Maute Kurt 
Published: December 2010

AbstractAerospace systems are often subject to challenging requirements on performance and reliability. Computational design optimization is an approach assisting design engineers in meeting these requirements. It automates the design procedure, allows for predicting the performance of a system by large, high‐fidelity numerical models, and enables consideration of a large number of design constraints and optimization variables. The formulation and solution of design optimization problems can be organized around three tasks: (i) transforming an engineering design problem into a mathematical optimization problem which is then solved by numerical algorithms, (ii) selecting the features of the systems that can be altered in the optimization process and expressing these modifications as functions of the optimization variables, and (iii) predicting the performance of the system as a function of the optimization variables. Today design optimization methods are used to optimize the material composition and the geometry of aerospace structures, considering for example structural, aerodynamic, and thermodynamic performance criteria. Optimization approaches are used to determine the conceptual layout of the system and to fine‐tune a particular feature. Computational design optimization supports design engineers in efficiently developing products. However, it requires an in‐depth understanding of the numerical models and methods used in the optimization process to obtain reliable optimization results.
Static Fracture Response of Materials
Authors: Zehnder Alan T. 
Published: December 2010

Abstract
Attention to the fracture of aerospace materials is critical to the safety and performance of aerospace structural systems. Basic concepts of linear elastic fracture mechanics, including crack tip stress and displacement fields, stress intensity factor, energy release rate and fracture initiation, and growth criteria are reviewed. Analytical, computational, and experimental methods for calculating and measuring crack tip stress intensity factors are discussed. Several experimental methods for the measurement of fracture initiation toughness and crack propagation resistance are described as well.
Testing of Structural Joints
Authors: Smeltzer Stanley S. 
Published: December 2010

AbstractStructural joints are tested primarily to determine the maximum single‐use load or continuous, time varying load spectrum a specific joint architecture can sustain prior to failure. The behavior of bolted and bonded joints is the focus of the testing described in this section. The test conditions and resulting failure mechanisms identified for each joint type are important parameters documented from the test, which help identify trends within certain joint architectures for classification purposes. Ultimately, joint test results are used to develop empirical prediction methods to predict the performance of related joints when subjected to similar applied loads.
Dynamic Response of Materials
Authors: Lambros John 
Published: December 2010

AbstractThe dynamic response of materials necessitates a separate study than that at quasi‐static loading rates primarily for two reasons:the mechanics of a dynamic problem in which material inertia has to be accounted for are different than the static case because they allow for traveling discontinuities, stress waves, in the material, andthe constitutive response of many materials exhibits rate sensitivity.This rate dependent response can manifest itself as an increase in elastic modulus with increasing strain rate (or decreasing temperature), and/or a change in yield properties such as yield strength and hardening rate. Unlike polymers, it is rare that metals exhibit a strain rate dependence of elastic modulus, but they can have a strong viscoplastic response. Various techniques have been employed to accurately measure rate dependent material response. The main challenge in these techniques is to separate the inertial (i.e., wave propagation) effects from the actual material response. The two most common high rate constitutive measurement techniques are the split‐Hopkinson, or Kolsky, bar, and the pressure shear plate impact experiment. Following a short introduction, which describes some fundamental aspects of the mechanics of wave motion in solids, these two experimental techniques are discussed in some detail, and sample results from each are presented.
Nondestructive Evaluation of Structures
Authors: Regez Brad , Krishnaswamy Sridhar 
Published: December 2010

AbstractThis chapter summarizes why nondestructive evaluation (NDE) is important in the aerospace industry, and then reviews both classical and emerging NDE techniques. Classical techniques presented include visual, penetrant testing, magnetic particle, eddy current, ultrasonic, and x‐ray. The emerging techniques discussed include thermal imaging, laser based optical, terahertz, microwave, millimeter‐wave, and real‐time ultrasonic imaging. The strengths, limitations, flaw detectability, and typical aerospace applications of the techniques are discussed.
Nondestructive Evaluation of Structures
Authors: Farrar Charles R. , Worden Keith , Lieven Nicholas A. J. , Park Gyuhae 
Published: December 2010

AbstractThe process of implementing a damage identification strategy for aerospace systems is referred to as structural health monitoring (SHM). Here, damage is defined as changes to the material and/or geometric properties of these systems, including changes to the boundary conditions and system connectivity, which adversely affect the system's current or future performance. A wide variety of highly effective local non‐destructive evaluation tools are available for such monitoring. However, the majority of SHM research conducted over the last 30 years has attempted to identify damage in structures on a more global basis and in a more autonomous manner. Recent research has begun to recognize that the SHM problem is fundamentally one of statistical pattern recognition, and a strategy to address this problem as it applies to aerospace structures is described herein. To conclude this discussion, technical challenges that must be addressed if SHM is to gain wider application in the aerospace industry are summarized.
Guided Wave Methods for Structural Health Monitoring
Authors: Giurgiutiu Victor , Soutis Constantinos 
Published: December 2010

Abstract

This article reviews the state of the art in guided wave (GW) methods for structural health monitoring (SHM). The GW methods permit
on‐demand
interrogation of the structure to determine its current state of structural health (“active SHM”). The enabling element for active SHM is the piezoelectric wafer active sensor (PWAS), which allows both transmission and reception of GW into the structure. The mechanisms of Lamb wave excitation and detection with PWAS transducers are first presented. It is shown that Lamb wave mode tuning can be achieved by the combination of PWAS dimensions, frequency values, and mode characteristics. The isotropic GW theory is subsequently extended to GW propagation in composites. The pitch‐catch, pulse‐echo, and phased array ultrasonic methods for damage detection are also addressed. Detection of cracks, disbonds, delaminations, and diffuse damage in metallic and composite structures are exemplified. Finally, suggestions for further work are made.
Signal Processing for Structural Health Monitoring
Authors: Staszewski Wieslaw J. , Sohn Hoon 
Published: December 2010

Abstract

Recent years have shown a number of new structural health monitoring (SHM) technologies that have the potential for online damage detection in aircraft structures. Signal processing will become more critical in the implementation of these technologies because automated signal processing and data interpretation are the key for the success of online SHM. Signal processing can mainly address seven different problems related to SHM:

measurements and data acquisition,

data pre‐processing,

signal feature analysis,

pattern recognition and machine learning,

reliability analysis,

uncertainties, and

data fusion.

This chapter briefly discusses all seven problems. Finally, this chapter illustrates some signal‐processing examples relevant to damage detection in aircraft structure. Four different examples related to fatigue crack in aluminum specimens and impact damage detection in a composite specimen are presented.
Structural Materials: Aluminum and Its Alloys – Properties
Authors: Dashwood Richard J. , Grimes Roger 
Published: December 2010

Abstract
The intention of this chapter is to introduce the reader to the range of aluminum alloys used in the aerospace industry, their key properties, and the reasons for their selection. A brief review of the history of the aluminum industry, its role within the aerospace sector, and the current and future trends for its use is presented. Aluminum alloy metallurgy and the main methods for strengthening aluminum alloys are explained paying particular attention to age hardening. The Aluminum Association alloy designation and temper system is introduced, along with the key characteristics (typical mechanical properties and aerospace applications) of the seven main wrought alloy series. Recent alloy developments, in particular aluminum lithium alloys are highlighted.
Titanium and its Alloys: Processing, Fabrication and Mechanical Performance
Authors: Jackson Martin , Boyer Rodney R. 
Published: December 2010

AbstractTitanium alloys have excellent mechanical properties and corrosion resistance. However, annual global titanium is dwarfed by commodity metals. This is in part due to the current primary production method which requires a complex discontinuous reduction route in addition to several costly downstream processing steps to convert titanium sponge into usable product for aerospace and aircraft components. The processing routes from vacuum arc remelting to downstream forging and extrusion are discussed in detail for titanium alloys. Casting and powder metallurgy (PM) routes are also described for near net shape products and cost savings. A wide range of post processing fabrication routes are presented, including welding, superplastic forming/diffusion bonding, and the most costly fabrication step, machining. Emerging additive manufacturing techniques are also included in this chapter. Finally, the effects of prior processing and resultant alpha and beta morphology on the mechanical performance, including tensile strength, ductility, fatigue, fracture toughness, and creep are covered in detail.
Textile Composite Materials: Polymer Matrix Composites
Authors: Lomov Stepan V. , Verpoest Ignaas 
Published: December 2010

Abstract
The chapter presents an overview of composites reinforced with woven, braided, non‐crimp fabrics (NCFs). Starting with classification of the reinforcements, it discusses their behavior during composite manufacturing (formability and permeability) and internal architecture of the reinforcement. The latter determines mechanical behavior of textile composites. Formulae for calculation of composite stiffness are presented, followed by discussion of strength and damage development in textile composites. Finally, the modeling tools for textile composites are reviewed.
Textile Composite Materials: Ceramic Matrix Composites
Authors: Marshall David , Cox Brian 
Published: December 2010

AbstractThe last decade has seen the maturation of textile methods for making ceramic matrix composites with three‐dimensional (3D) fiber‐reinforcement. Such composites are much less vulnerable than traditional two‐dimensional (2D) ceramic composites to premature brittle failure, especially via delamination. Innovative textile methods also enable the creation of complex features that are formed integrally in a component as local rearrangements of the reinforcement. They also allow design of optimal fiber architectures for individual components to match the thermal and mechanical loads expected in use. This chapter begins with an introduction to conventional 2D laminate ceramic composites, including discussion of approaches that have been taken to achieve damage tolerance, the materials available for fibers, matrices, and coatings, and the rationale for selection of different materials for specific aerospace components. Several examples are then discussed of textile‐based composite components with 3D reinforcement architectures that have been developed for turbine, rocket, and scramjet applications. Some of the complexities of dealing with modeling/life prediction in these materials are discussed, along with some of the approaches for dealing with them.
3D Translaminar and Textile Reinforcements for Composites
Authors: Bogdanovich Alexander E. 
Published: December 2010

AbstractThe group of translaminar‐reinforced composites, which includes stitched and Z‐pinned materials, requires additional manufacturing step (insertion of a stitch thread or Z‐pin) after the in‐plane fiber architecture has been already formed. This is why this group suffers from in‐plane fiber damage, distortions of the fiber architecture and the formation of resin‐rich zones in the vicinity of each stitch or Z‐pin. These negative effects may considerably reduce in‐plane elastic moduli but most significantly reduce in‐plane tension and compression strengths and fatigue resistance. The group of unitary (single‐ply) 3D textile reinforcements includes 3D weaves, 3D braids and 3D warp knits. The principal common feature of all preforms from this group is, that each of them is produced in a single manufacturing step, using either traditional or specialty textile machines. Owed to this feature, unitary 3D textile preforms can be used in a composite fabrication process as‐manufactured, thus greatly simplifying preform handling and resin infusion steps. Comparative analysis of various methods of 3D reinforcement for composites shows that the differences in the processes and machines strongly influence the differences in the reinforcement architectures and, consequently, strongly reflect on mechanical properties of the resulting composites. This is illustrated by experimental data on the in‐plane and out‐of‐plane mechanical properties of 2D weave laminates and composites reinforced with a single‐ply of 3D interlock weave or 3D orthogonal non‐crimp weave.
Lasers in Aerospace Industry Manufacturing
Authors: Mazumder Jyoti 
Published: December 2010

Abstract

The Aerospace Industry has adopted laser technology from its early days and several laser‐aided manufacturing processes have become routine. Lasers can deliver energy from zero to a trillion watts in a small spot in an instant. That generated a wide portfolio. For example, laser peening needs more than 10
9
W cm
−2
, whereas laser welding can be accomplished with 10
6
W cm
−2
; laser drilling requires 10
8
W cm
−2
compared to 10
5
W cm
−2
or more for laser cladding and solid free form formation. The mechanism for different processes is different although the energy source is common. Interaction time for each process is different, too. Laser shock peening utilizes nanosecond pulses compared to millisecond pulses for drilling. Welding and cladding are generally carried out with continuous wave. The role they play is also varied. Drilling generates cooling holes for turbine blades to enhance the operating temperature whereas shot peening produces residual compressive stress on the blades to improve fatigue properties and reduce crack propagation. Welding is mostly used to join structural components whereas cladding repair of reconfigured aerospace components is used to increase their service life. This chapter will discuss the four most common uses of lasers in Aerospace Industry Manufacturing.
Near Net Shape Forming of Aeroengine Components
Authors: Wu Xinhua 
Published: December 2010

AbstractThis chapter is aimed at providing a brief overview of near net shape forming of aeroengine components. Among many near net shape‐forming processes, this chapter will focus on direct laser deposition (DLD) and net shape HIPping (NSHIPping). DLD has applications in the area of building small components or for precision repair, and NSHIPping is mainly used for manufacturing large components, especially from Ti or Ni alloys. The chapter will cover an introduction to these technologies, their pros and cons, the mechanical properties of the components manufactured using these processes, and the issues for their application in the aerospace industry.
Piezoceramic Actuators and Sensors
Authors: Sirohi Jayant , Chopra Inderjit 
Published: December 2010

Abstract
Piezoceramic actuators and sensors have found wide application in a variety of fields such as aerospace, automotive and biomedical. The coupled electro‐mechanical behavior exhibited by these materials enables them to be used either as actuators or as sensors. The material has a high bandwidth, can be manufactured in a number of different shapes, and can be easily integrated into structures. This chapter focuses on the behavior of piezoceramic actuators and sensors. The electro‐mechanical constitutive equations are discussed, and the static as well as dynamic response of the material to applied electric fields is described. Nonlinear phenomena are also described, and the power consumption of piezoceramic actuators is explained. The use of the material as a strain sensor is also described in detail, along with the required signal conditioning electronics and calibration factors. This information is intended to serve as a reference for the design of a structure incorporating piezoceramic materials.
Polymers in Space
Authors: Skurat Vladimir E. 
Published: December 2010

Abstract
Polymeric materials are widely used in space engineering because of the beneficial combination of their working properties. Being in harsh space environment conditions, mainly in the form of thin films, they are subjected to the action of numerous destructive factors that are absent during their exploitation on Earth. Most serious problems are connected with changes of thermo optical properties, deterioration of mechanical properties, production of components of the intrinsic outer atmosphere of spacecraft that respond to contamination of its surface, and last but not least, mass losses. Here, the main focus is on polymers of two types that are generally used in multilayer insulation (MLI) of spacecraft as thin films – polyimide Kapton H and perfluorocarbon polymers – polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP). Both types of polymers show mass losses, but they are caused by different factors. For Kapton H, it is fast atomic oxygen (FAO) on low Earth orbits (LEO) (altitudes 200–1000 km). For PTFE and FEP, it is mainly the vacuum ultraviolet (VUV) component of solar radiation (wavelengths 1–200 nm) (all altitudes for space flights). Possible mechanisms of mass losses are considered.
Micrometeoroid and Orbital Debris Impact Damage on Materials and Structures in Space
Authors: Tennyson Roderick C. 
Published: December 2010

AbstractThe effect of hypervelocity impacts from micrometeoroids and orbital debris (MOD) on spacecraft materials and structures is discussed in terms of observed flight damage and laboratory simulation tests. Methods of estimating the probability of impact as a function of particle size are presented based on particle distributions and orbital altitude. Two types of damage mechanisms are described: initial impact cratering, and debris plumes emanating from the impact site. Shielding systems currently employed are also described. With the return of human exploration of the moon, the effect of meteoroid impacts on lunar structures and equipment is also examined.