Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 34 for “"aircraft structures"”.
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Implementation of assembly automation in aircraft structures
… implemented in the assembly of a small number of aircraft structures. These systems have demonstrated the capability to reduce the risk of repetitive use injuries, improve quality, and reduce labor costs. Despite these successes, disruptive delays to production resulted when similar technology was …
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Performance envelopes for preliminary sizing of aircraft structures
… the development of all the load cases that an aircraft may encounter in service, whereas the latter is responsible for the design of the structural components required to carry the predicted loads.<br/><br/>A significant milestone within the airframe development is the preliminary …
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Acoustic emission source location in composite aircraft structures using modal analysis
… Structural Health Monitoring (SHM) of composite aircraft structures. Therefore useful key signal features and sensor configurations were identified and the proposed method was validated using both artificially generated AE as well as actual AE resulting from damage. Acoustic Emission is a …
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Finite element modeling of crack detection in aircraft structures using electrical current
… for the detection of cracks in metallic structures. Electromagnetic non-destructive testing (NDT) is one of the widely used non-destructive methods used for the detection and characterization of cracks. Utilizing the principle of electromagnetic induction, this technique is used in the …
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Design and manufacture of advanced composite aircraft structures using automated tow placement
Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management; and, Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1996.
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Effective and Efficient Non-Destructive Testing of Large and Complex Shaped Aircraft Structures
… of nondestructive testing (NDT) for the aircraft industry. Modem aircraft non-destructive testing requires the detection of small defects in large complex shaped components. Research has therefore focused on the limitations of ultrasonic, radioscopic and shearographic methods and the …
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Investigation of Polymer-Filled Honeycomb Composites with Applications as Variable Stiffness Morphing Aircraft Structures
Shape morphing in aerospace structures has the potential to reduce noise, improve efficiency, and increase the adaptability of aircraft. Among the many challenges in developing morphing technologies is finding suitable wing skin materials that can be both stiff to support the structural loads, …
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Classification of In-Flight Fatigue Cracks in Aircraft Structures using Acoustic Emission and Neural Networks
… analysis and classification of fatigue cracks in aircraft structures. The particular structure that was examined was the vertical tail section of a Cessna T-303 Crusader aircraft. The analysis was performed using the nondestructive evaluation technique known as acoustic emission (AE), as well as …
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Combined Compression and Shear Structural Evaluation of Stiffened Panels Fabricated Using Electron Beam Freeform Fabrication
Unitized aircraft structures have the potential to be more efficient than current aircraft structures. The Electron Beam Freeform Fabrication (EBF3) process can be used to manufacture unitized aircraft structures. The structural efficiency of blade stiffened panels made with EBF3 was compared to …
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Comparative study of non-destructive testing methods of defect detection on aircraft
… materials both in civilian and military aircraft because of their mechanical resistance, high toughness, reduced weight and immunity to corrosion. Any damage in the fibers of these composites requires an evaluation in order to ensure the integrity of aircraft structures. Composite …
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Material Coefficient of Thermal Expansion Investigation for Use in Additive Manufacturing Fused Deposition Modeling for Composite Tooling
… used to manufacture light weight, high stiffness aircraft structures. These structures are often manufactured from carbon fiber reinforced epoxy. When these structures are damaged, they must be repaired to restore strength to the component to avoid the cost and logistics of having replacements …
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Diamond-coated carbon fibres, the new generation of composites (CFRP)?
Carbon-based composites used in aircraft structural applications (wings, fuselage, etc.) consist of sheets of carbon fibre tapes bonded together by a polymer matrix, usually an epoxy resin. This composite material is called Carbon Fibre Reinforced Polymer (CFRP). In recent decades, the proportion …
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Integrated aerodynamic-structural design optimization
The introduction of composite materials in aircraft structures is having a profound effect on the design process. These materials permit the designer to tailor material properties to improve structural and aerodynamic performance. In order to obtain maximum benefits, a more integrated …
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The Development and Application of a Trapezoidal Shear Panel for Use in Finite Element Codes
… panel used in structural analysis codes to model aircraft structures. An equilibrium stress-based element with pure shear resultants on its sides was developed using the principle of complementary virtual work. The internal stress field was derived from a complete polynomial Airy stress function. …
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Water vapor diffusion through glass fiber reinforced polymer nanocomposites
Fiber reinforced plastics (FRPs) are used to make aircraft structures, highway bridges, automobile components, storage tanks, boat hulls, truck beds, and so on. When these FRPs are exposed to the atmosphere, environmental humidity can weaken the structural integrity and cause fiber delamination. …
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Qualitative health monitoring and incipient damage inspection/evaluation
… for real-time damage evaluation of complex structures, is investigated. The basic principle of the technique is to monitor the structure's mechanical impedance which will be changed with the presence of damage. The mechanical impedance variations are monitored by measuring the electrical …
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The Influence of Extended Cure on Mechanical Performance of Aerospace-Grade Film Adhesives
… adhesive joints have seen increased usage in aircraft structures as weight and cost reductions drive manufacturers to composite designs. As the use of epoxy film adhesives become more prevalent, it is important to characterize the thermal and mechanical properties of the adhesive after …
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An Ameliorated Prediction of the Empennage In-Flight Gust Loads for a General Aviation Aircraft
… throughout its life. Nevertheless, the aircraft structures are required to be designed to failsafe or safe-life criteria to be certified by the FAA. AFS-120 provides a database of normal accelerations that can be used to derive airplane wing loads. ACE-100 describes an acceptable method …
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Active control of interior noise using piezoelectric actuators in a large-scale composite fuselage model
… interior noise in a realistic composite aircraft fuselage is experimentally studied. The control inputs are due to piezoelectric actuators bonded to the cylinder wall while error information from the interior acoustic field is sensed by microphones. A preliminary analytical development …
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Utility of Quasi-Static Gust Loads Certification Methods for Novel Configurations
… maneuver loads have driven the sizing of primary aircraft structures since the beginning of aviation. Methodologies for determining the gust loads on aircraft have evolved over the last 100 years. There are three general approaches to gust loads analysis: quasi-static, transient, and continuous …
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