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Articles 31 - 45 of 45
Full-Text Articles in Aerospace Engineering
Machine Learning Methods For Rapid Inspection Of Automated Fiber Placement Manufactured Composite Structures, Christopher Sacco
Machine Learning Methods For Rapid Inspection Of Automated Fiber Placement Manufactured Composite Structures, Christopher Sacco
Theses and Dissertations
The advanced manufacturing capabilities provided through the automated fiber placement (AFP) system has allowed for faster layup time and more consistent production across a number of different geometries. This contributes to the modern production of large composite structures and the widespread adaptation of composites in industry in general and aerospace in particular. However, the automation introduced in this process increases the difficulty of quality assurance efforts and inspection. The AFP process can induce a number of manufacturing defects including wrinkles, twists, gaps, and overlaps. The manual identification of these defects is often laborious and requires a measure of expert knowledge. …
Experimental Analysis Of The Automated Fiber Placement Manufacturing Parameters For High And Low Tack Prepreg Material, Anis Baz Radwan
Experimental Analysis Of The Automated Fiber Placement Manufacturing Parameters For High And Low Tack Prepreg Material, Anis Baz Radwan
Theses and Dissertations
Automated Fiber Placement (AFP) is a flexible but complex manufacturing technique which is used to layup carbon fiber tows into flat or curved structures. That could be achieved through linear and steered paths of fibers. The quality of AFP layup is highly dependent on the manufacturing process parameters such as layup temperature, tow feedrate, compaction force, and tow tension. Understanding how those parameters affect the process is crucial for achieving the desirable quality and productivity. For this work, an experimental investigation is carried out to determine the processing window that yields optimal quality for two types of material: High tack …
Development Of An Automated Fiber Placement Process For The Fabrication Of Thermoplastic Composite Laminates, Anthony M. Sabido
Development Of An Automated Fiber Placement Process For The Fabrication Of Thermoplastic Composite Laminates, Anthony M. Sabido
Theses and Dissertations
An automated fiber placement process is desired for manufacturing variable-stiffness thermoplastic composite laminates. By developing such a composite laminate, it is possible to take advantage of the tunable performance increases that are achievable by spatially steering individual tows. In addition, using a thermoplastic polymer as the matrix material has many advantages: a high toughness, ability to employ thermoplastic joining processes that do not require adhesives, long storage life, and lacks the need to be refrigerated. This process was experimentally developed, where the effect of various process parameters on the quality of the laminate were evaluated. An experimental AFP head was …
Continuous Tow Path Generation For Constant And Variable Stiffness Composite Laminates On Single And Double Curved Surfaces, Caleb R. Pupo
Continuous Tow Path Generation For Constant And Variable Stiffness Composite Laminates On Single And Double Curved Surfaces, Caleb R. Pupo
Theses and Dissertations
A novel approach for the generation of steered tow paths on curved shell surfaces is presented. The approach is used to translate optimal theoretical analysis expressed from ply to ply as fiber angle distributions for steered laminates into discrete tow paths on planar, single and double curved surfaces. By adapting the multi mesh approach earlier developed by van Tooren and Elham [1–3] to the new tow path generation code. Two meshes are utilized, a coarse mesh which is generated during the optimization and contains the optimal fiber angle distributions, and a denser mesh obtained from tessellating the surface to better …
Investigation Of The Mechanical Behavior Of Non-Conventional Laminates: Anisotropy Of Tensile Strength In Coupons With Quasi-Isotropic Stiffness Characteristics, Israel Oluwatunmise Ayodele
Investigation Of The Mechanical Behavior Of Non-Conventional Laminates: Anisotropy Of Tensile Strength In Coupons With Quasi-Isotropic Stiffness Characteristics, Israel Oluwatunmise Ayodele
Theses and Dissertations
Advanced composites have emerged as viable structural solutions over the years and have therefore become implemented in several applications, notably aerospace structures. In modern aircraft structures, they have been gradually introduced to both secondary and primary components. Laminated composites used in such applications have generally been restricted to those with straight fibers, that are aligned to only a handful of pre-selected fiber orientations; 0˚, 45˚, 90˚ and -45˚. Recent advances in the technology of laminated composites have however indicated the possibility to harness significantly higher structural gains by allowing the use of other fiber orientations, and even implementing curvilinear fibers …
Efficient Design Optimization Methodology For Nonconventional Laminated Thin-Walled Composite Structures, Mazen Albazzan
Efficient Design Optimization Methodology For Nonconventional Laminated Thin-Walled Composite Structures, Mazen Albazzan
Theses and Dissertations
Structural designers seek the best possible design of a structure that optimally meets the requirements of a specific application. The measure of the quality of the final design can often be related to specific stiffness and strength of the structure. Because of their superior mechanical and environmental properties compared to traditional metals, fiberreinforced composite materials have earned a widespread acceptance for different structural applications. The tailoring potential of composites to achieve high specific stiffness and strength has promoted them as promising candidates for constructing lightweight structures. From that aspect, designers have tackled the problem of designing composite laminates, which is …
Development Of A Supplier’S Delivery Time And Delivered Quality Performance Index And Assessment Of Alternative Decisions Regarding Underperforming Suppliers For The Aerospace Industry, Clint Saidy
Theses and Dissertations
This study investigates current practices of supplier’s delivery assessment so that a comprehensive index and a cost function model could be properly developed. Following a thorough literature review, a framework was created based on a penalty cost function that integrates both suppliers’ ability to deliver on time, as well as suppliers’ capability to deliver good quality. Afterward, suppliers could then be ranked and placed either in good standing, or transversely on probation. Underperforming suppliers face three potential outcomes based on current literature: (1) switching supplier, (2) increase collaboration, (3) maintaining the status quo. The decision vis-à-vis failing suppliers is based …
Multidisciplinary Shape Optimization Of A Composite Blended Wing Body Aircraft, Charles Maxwell Boozer
Multidisciplinary Shape Optimization Of A Composite Blended Wing Body Aircraft, Charles Maxwell Boozer
Theses and Dissertations
A multidisciplinary shape optimization tool coupling aerodynamics, structure, and performance was developed for battery powered aircraft. Utilizing high-fidelity computational fluid dynamics analysis tools and a structural wing weight tool, coupled based on the multidisciplinary feasible optimization architecture; aircraft geometry is modified in the optimization of the aircraft’s range or endurance. The developed tool is applied to three geometries: a hybrid blended wing body, delta wing UAS, the ONERA M6 wing, and a modified ONERA M6 wing. First, the optimization problem is presented with the objective function, constraints, and design vector. Next, the tool’s architecture and the analysis tools that are …
Modeling Of Tow Wrinkling In Automated Fiber Placement Based On Geometrical Considerations, Roudy Wehbe
Modeling Of Tow Wrinkling In Automated Fiber Placement Based On Geometrical Considerations, Roudy Wehbe
Theses and Dissertations
Automated manufacturing of fiber reinforced composite structures via numerically controlled hardware yields parts with increased accuracy and repeatability as compared to hand-layup parts. Automated fiber placement (AFP) is one such process in which structures or parts are built by adding bands of prescribed number of tows or slit-tape with prescribed width using robotic machine heads over 3D surfaces following prescribed paths. Despite the improved accuracy, different types of defects or manufacturing features arise during fabrication. These defects can be due to geometrical features, materials, and process planning parameters and are detected in the form of wrinkling, tow twist, tow folding, …
Ultra-High Temperature Full Field Deformation Measurements Of Materials Subjected To Thermo-Mechanical Loading: A Dic Based Study, Guillemo A. Valeri Paoli
Ultra-High Temperature Full Field Deformation Measurements Of Materials Subjected To Thermo-Mechanical Loading: A Dic Based Study, Guillemo A. Valeri Paoli
Theses and Dissertations
Determining the mechanical response of materials at elevated temperatures is a subject of great interest in metal forming, aerospace and aero-engine industries. For example, measurement of the deformation response under tensile loading at high temperatures is crucial for establishing thermomechanical and thermo-physical properties of materials, consequently, determining the reliability of a component or structure exposed to elevated temperatures. In order to predict the behavior of materials at ultra-high temperatures, a novel experimental approach based on Digital Image Correlation (DIC) is proposed and successfully applied to different materials at temperatures ranging from room temperature to 1100˚C. In these studies, a portable …
Investigation And Development Of Friction Stir Welding Process For Unreinforced Polyphenylene Sulfide And Reinforced Polyetheretherketone, Hossain Ahmed
Theses and Dissertations
The joining of thermoplastics through welding, a specific form of fusion bonding, offers numerous advantages over mechanical joining. It eliminates the use of costly fasteners and has only a limited effect on the strength of the parts being joined since it does not require the introduction of holes and loading pins, and it does not create significant stress concentrations. A specific form of welding, Friction Stir Welding, was investigated for the creation of butt joints of unreinforced polyphenylene sulfide (PPS) and short carbon fiber reinforced polyetheretherketone (PEEK) plates. Friction stir welding requires a rotating pin, a shoulder arrangement, relative movement …
Guided Wave Inspection Of Cracks In The Rivet Hole Of An Aerospace Lap Joint Using Analytical-Fem Approach, Md Yeasin Bhuiyan
Guided Wave Inspection Of Cracks In The Rivet Hole Of An Aerospace Lap Joint Using Analytical-Fem Approach, Md Yeasin Bhuiyan
Theses and Dissertations
Ultrasonic guided waves are very attractive for the inspection of large structures using nondestructive evaluation (NDE) and structural health monitoring (SHM) technique. Combined analytical and finite element analysis (CAFA) has been introduced for the detection of butterfly cracks in the rivet hole of the aerospace lap joint. Finite element analyses have been performed on the local damage area in spite of the whole large structure. Fundamental Lamb wave modes (S0 and A0) have been strike on the local damage from multiple directions to analyze the cracks of multiple-rivet-hole lap joint. The rivet hole cracks (damage) in the plate structure gives …
Momentum Of Particles From Time-Of-Flight Measurements, Joseph Best
Momentum Of Particles From Time-Of-Flight Measurements, Joseph Best
Senior Theses
In order to find the momentum of particles from time of flight measurements, I used a program called Geant4 to simulate experiments. I made a simple two detector setup, and I recreated a real world experiment. I spent a lot of time learning to code in C++ so I could use Geant4 correctly. I simulated these experiments shooting electrons, muons, and pions through the geometry and measured the time at two points in their flight. Subtracting the second time from the first gave me the time of flight distribution for each particle. I used ROOT to draw histograms of the …
Tool Material Degradation Due To Friction Stir Welding Of Aluminum Alloys, Corbin T. Collier
Tool Material Degradation Due To Friction Stir Welding Of Aluminum Alloys, Corbin T. Collier
Theses and Dissertations
The purpose of this study is to investigate the friction stir welding (FSW) tool material degradation factors due variation in tool material properties and the effect of an aluminum diffusion wear mechanism on three different FSW tool material when exposed to various welding temperatures and times. The degradation factors are essential to FSW tool design due to the effect of the tool pin and shoulders on the heat generation and material flow which directly correlated to the weld quality created during the FSW process. For this investigation the three materials used are H13, TSP1, and MP159. To determine degradation factors …
Dielectric Characteristics Of Microstructural Changes And Property Evolution In Engineered Materials, Jallisa Janet Clifford
Dielectric Characteristics Of Microstructural Changes And Property Evolution In Engineered Materials, Jallisa Janet Clifford
Theses and Dissertations
Heterogeneous materials are increasingly used in a wide range of applications such as aerospace, civil infrastructure, fuel cells and many others. The ability to take properties from two or more materials to create a material with properties engineered to specific needs is always very attractive. Hence engineered materials are evolving into more complex formulations or heterogeneities in multiple disciplines. Design of microstructure at multiple scales controls the global functional properties of these materials and their structures. However, local microstructural changes do not directly cause a proportional change to the global properties (such as strength and stiffness). Instead, local changes follow …