The Bell Helicopter M407 main rotor yoke is a structural helicopter part made of laminated glass-epoxy composite material. Delamination failure of the main rotor yoke under static and fatigue loading conditions is investigated, both analytically and experimentally. A finite element model of the yoke is developed with a commercial finite element code, using the 'dummy plies' technique to allow modeling of a tapered laminate. The model is validated against the available experimental data. A set of static and fatigue experiments---limited to beamwise bending loads---are performed on representative test specimens cut out of actual yokes. The model is able to accurately predict the location of initial static failure, which corresponds to the interlaminar shear stress concentration predicted by the stress analysis. Results of the specimen fatigue tests are successfully correlated with the glass-epoxy material fatigue properties, using the Normalized Fatigue Life Model and the finite element model of the specimen.

Issues associated with dynamical modelling and control of a spacecraft-mounted robotic manipulator capturing a spinning satellite are investigated in this research. The formulation of the post-capture dynamical equations of the system was carried out by writing the individual Lagrange's equation for the mother spacecraft, the two-link robotic manipulator, and the captured payload. These equations were then assembled to obtain the constrained dynamical equations of the system as a whole. This method, however, introduces the non-working constraint forces and moments which substantially complicate the dynamical analysis and therefore have to be eliminated. A novel technique that involves the use of the natural orthogonal complement of the velocity-constraint matrix was used in order to obtain a set of unconstrained independent equations. A computer code was written using FORTRAN and the IMSL subroutine DIVPAG was used to integrate the equations of motion. The pitch angle of the mother spacecraft, the joint angles of the manipulator, and their rates just after capture were calculated by solving the inverse kinematics problem and using impact dynamics principles. These were then used as initial conditions for the post-capture dynamics. A dynamical simulation of the system for the uncontrolled case was carried out to study the effect of the disturbance, resulting from the capture of the satellite, on the spacecraft/manipulator system. In light of the results corresponding to the uncontrolled system, a control algorithm, whose objective is to produce a set of feedback-linearized, homogeneous, and uncoupled equations, was designed and implemented. The effect of structural flexibility in the robot links on the response of the system was also investigated for both the uncontrolled and controlled cases.

The Multidisciplinary Design Optimization (MDO) can be defined as a methodology for the design of complex engineering systems where collaboration and abilities to mutually interacting between different disciplines are fundamental. In this thesis, Virtual Aircraft Design and Optimization fRamework (VADOR), a distributed, object-oriented, component-based framework enabling MDO practice at Bombardier Aerospace is introduced. The purpose of the VADOR framework is to enable the seamless integration of commercial and in-house analysis applications in a heterogeneous, distributed computing environment, and allow the management and sharing of the data. The VADOR distributed environment offers visibility to the process, permitting the teams to monitor progress or track changes in design projects and problems. Documentation of the MDO process is vital to ensure clear communication of the process within the team defining it and in the broader design team interacting with it. VADOR is implemented in Java, providing an object-oriented, platform-independent framework. The concepts of design pattern and component-based approach are used along with multi-tiered distributed design to deliver highly modular and flexible architecture. (Abstract shortened by UMI.)

Containment structures for aircraft engines must withstand impacts of failed engine components, which may be traveling at extremely high velocities. Therefore, the design of such structures requires a thorough knowledge of material behaviour at high rates of deformation. It is well known that at strain rates above 102 s-1, the yield stress of metals may be significantly different than at quasi-static rates. In addition, material fracture under dynamic loading can also differ from that at slower rates due to manifestation of different failure mechanisms. The purpose of this study was to gain an understanding and determine the constitutive behaviour and failure criteria for several metals used in the aerospace industry; specifically Aluminium (6061-T6), Titanium (Ti-6Al-4V) and Stainless Steel (Nitronic 33). An extensive procedure for determining the constitutive response and ductility limits of those materials, at quasi-static and dynamic strain rates, was developed relying on laboratory experiments and computational simulations. The Johnson-Cook constitutive model coupled with a critical equivalent plastic strain failure criterion was used in simulating the material. Results of the different tests and simulations indicated the success of the modeling process for the 6061-T6 and Ti-6Al-4V, however considerable discrepancies were observed when simulating the behaviour of Nitronic 33 using the Johnson-Cook model. The multiplicative nature of the model, and the high strain hardening of this material were among the reasons the Johnson-Cook is unable to represent the material when simulating events with high strain and high strain rates such as punching.

The flow produced by a rotating propeller is inherently unsteady and three-dimensional. Conventional design of propellers uses blade-element theory but becomes inaccurate in capturing three-dimensional vortical and compressible effects at the tips, as well as the effect on downstream bodies. A propeller is always attached to a fixed component that affects its performance, thus the need arises to couple a fixed domain to a rotating domain in an unsteady aerodynamic simulation. A finite element formulation for the simulation of propellers is presented in terms of the Reynolds-averaged Navier-Stokes equations for unsteady, three-dimensional, viscous, compressible flows. The first step consists of preparing a mesh containing two separate domains interfacing at a virtual surface. Then, simulation is run to obtain an initial solution. This step highlights the live/dead interfacing scheme between the fixed and rotating domains without mesh movement. Finally the unsteady simulation performs interpolations at each time step with node movement until a periodic steady state is reached. Mesh movement can be treated by either an ALE formulation or a rotating frame of reference correction. Two test cases are used to validate the code: a two-dimensional pitching airfoil in transonic flow and a 3-bladed 5868-9 propeller with a liquid cooled nacelle.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-06, Section: B, page: 3923. Adviser: Philippe H. Geubelle. Includes bibliographical references (leaves 169-175) Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--Lehigh University, 2008. / Adviser: Donald O. Rockwell.

Thèse (M.Sc.A.)--Université de Sherbrooke (Canada), 2008. / Titre de l'écran-titre (visionné le 1 février 2007). In ProQuest dissertations and theses. Publié aussi en version papier.

Thesis (PH.D.)--Syracuse University, 2003. / "Publication number AAT 3118426."

<p> This thesis implements a state-of-the-art solution separation advanced RAIM (ARAIM) algorithm as it is written as reported in the literature. Specifically, a GNSS fault detection and exclusion algorithm for a multi-constellation GNSS was implemented in software and tested against simulated data. RAIM algorithms have been created in many forms over the last couple of decades and are still in development today. The position solution results produced by this ARAIM algorithm were compared to that of a snapshot weighted least squares (WLS) solution in which failed satellites are removed before processing and an WLS solution with no corrections applied. In addition, the difference in position solution between ARAIM and the simulation truth was compared to the ARAIM reported horizontal and vertical protection limits, as well as, the position performance criteria. This thesis also investigates the performance of the exclusion method and how it affects the performance of the overall ARAIM algorithm. The algorithm implemented and tested in this thesis will be used as a basis of comparison for on-going research into robust GNSS processing techniques. </p><p>