No description available.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 1990. / Thesis Advisor(s): Salinas, David. "December 1990." Description based on title screen as viewed on April 1, 2010. DTIC Identifier(s): Arches, Stress Analysis, Weight, Finite Element Analysis, Computer Programs, Optimization, Theses, Degrees Of Freedom, FORTRAN, Stiffness, Case Studies. Author(s) subject terms: Finite Element Method, Arches, Weight Optimization. Includes bibliographical references (p. 107). Also available in print.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 1990. / Thesis Advisor: Salinas, D. "December 1990." Description based on title screen as viewed on April 1, 2010. DTIC Identifier(s): Boundary value problems, finite element analysis, differential equations, problem solving, theses, interpolation, iterations, one dimensional, computer programs, approximation/mathematics, linearity. Author(s) subject terms: Galerkin FEM, nonlinear, quasilinearization, linearization, interpolation, iteration, differential equation, convergence. Includes bibliographical references (p. 164). Also available in print.

No description available.

The results of a study to model a circular mine shaft constructed in a time-dependent medium are presented. The construction sequence is considered as well as the time-dependent properties of the media around the shaft. The loads acting on the shaft liner are due to excavation of the shaft material and to the loads relieved from the media onto the liner. The results show the importance of considering the time-dependent behavior of media. The analysis was carried out using the Finite Element Method. Axisymmetric triangular and quadrilateral elements were used to model the medium, and axisymmetric shell elements were used to model the liner. The construction sequence was modeled by analyzing the system under small load increments where each load increment represents a construction step. The time behavior was modeled by using the initial strain method, which assigns a different strain value for each element in the medium. The strains are transferred to stresses and then to forces, and an incremental process is started to cover the time range desired. The results for a 400-foot shaft are shown, and changes in liner stresses were monitored as time passes. Different rock materials were modeled by using different constants in the creep law. Some materials showed significant changes in the results, and others did not. The liner horizontal displacement, and horizontal and vertical stresses increased when material constants for rock salt and anhydrite were used. Stresses in the elements adjacent to the liner decreased as time passed by, and some even went into a tensile stress site. A comparison between two solutions, one representing a multi-step construction sequence and another representing an instantaneous construction of the lined shaft, showed that liner stresses are much higher when the construction sequence is not modeled. This is due to the fact that when the excavation is modeled the forces representing the construction sequence are applied to the medium. In the other case, the forces are directly applied to the liner.

No description available.

No description available.

A computer program based on Maxwell's equations is developed to calculate two-dimensional complex potentials by the Finite Element Method. This study offers a solution to a complex continuum problem by allowing a subdivision into a series of simple interrelated problems. The region of interest is divided into triangular elements. For each node in the grid, the Finite Element Method is used to set up an equation for the potential as a function of those of the surrounding nodes. All these equations are solved by the Gaussian Elimination Method. For increased accuracy this method requires a high degree of division of the region of interest. This could cause a storage problem on the computer. To alleviate this problem a half-banded scheme is used.

No description available.

Call number: LD2668 .T4 1978 L44 / Master of Science