Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / M.S.

xii, 205 leaves : photos., diags., tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 1978

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: John C. Wilson. Includes bibliographical references (leaves 299-310).

An experimental study of a passive energy dissipation tension-compression yielding brace or buckling restrained brace has been conducted. The Confined Yielding Damper (CYD) consists of a steel yielding core confined within a tube filled with non-cohesive media. The external tube and confined non-cohesive media provide lateral stability to the core enabling the device to yield in compression as well as tension. This device is similar to the Unbonded Brace developed by Nippon Steel of Japan. Fourteen full-scale CYDs were tested to determine the effect of varied confining media, perforation blocking configuration, and a random displacement history. Based on the Confined Yielding Dampers tested relatively stable and symmetric hysteretic damping can be achieved with the CYD device. / Graduation date: 2003

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Input¬output approximation of spacecraft motion is convenient and necessary in many situations. For a rigid¬body spacecraft, this process is simple because the system is governed by a set of equations that is linear in the system parameters. However, the combination of a flexible appendage and a rigid hub adds complexity by increasing the degrees of freedom and by introducing nonlinear coupling between the hub and appendage. Assumed Modes is one technique for modeling flexible body motion. Traditional Assumed Modes uses a set of linear assumed modes, but when dealing with rotating flexible systems, a modification of this method allows for the use of quadratic assumed modes. The quadratic assumed model provides an increased level of sophistication, but the derivation still neglects a set of higher¬order terms. This work develops the nonlinear equations of motion that arise from retaining these nonlinear, higher¬order terms. Simulation results reveal that the inclusion of these terms noticeably changes the motion of the system. Once the equations of motion have been developed, focus turns to the input¬output mapping of a system that is simulated using this set of equations. Approxi¬mating linear systems is straightforward, and many methods exist that can success¬fully perform this function. On the other hand, few approximation methods exist for nonlinear systems. Researchers at Texas A&M University recently developed one such method that obtains a linear estimation and then uses an adaptive polynomial estimation method to compensate for the disparity between that estimate and the true measurements. This research includes an in¬depth investigation of this nonlinear approximation technique. Finally, these two major research thrusts are combined, and input¬output approx¬imation is performed on the nonlinear rotational spacecraft model developed herein. The results of this simulation show that the nonlinear method holds a significant advantage over a traditional linear method in certain situations. Specifically, the nonlinear algorithm provides superior approximation for systems with nonzero natu¬ral frequencies. For the algorithm to be successful when rigid¬body modes are present, the system motion must be persistently exciting. This research is an important first step toward developing a nonlinear parameter identification algorithm.

Includes bibliographical references (p. 207-216).

Thesis--Ph. D., University of Hong Kong. / Errata slip inserted. Mimeographed.

Thesis--Ph. D., University of Hong Kong. / Mimeographed. Also available on microfilm.

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