Thesis (M.S.) -- Mississippi State University. Department of Mechanical Engineering. / Title from title screen. Includes bibliographical references.

The nonlinear elastic behavior of infrastructure materials is a critical factor in the design and performance of various structural systems. This research introduces a novel approach to enhance the flexural rigidity and deflection control of large-spanned beams, aerial personal rapid transit (PRT) structures, and packed parallel wire cables by leveraging configurational forces, such as horizontal constraints and wrapping forces. These forces produce prestress over the structure members, but the prestress changes with the configuration, and therefore, the effective stiffness can be tailored by these configurational forces. In the first part of this research, the governing equation considering the horizontal force is formulated to address the large deflections commonly encountered in beams subjected to transverse loading with horizontal constraints. The study demonstrates that deflection can be significantly reduced, thereby increasing the effective flexural rigidity without necessitating larger cross-sections. Green’s functions for various boundary conditions are derived, and the theory is validated through a series of experimental tests on Building Integrated Photovoltaic (BIPV) panels and PRT guideways. The case studies show that horizontal prestress enhances beam stiffness, reducing deflection by up to 87% within the elastic load range. The research further extends to the mechanical behavior of packed parallel wire cables arranged in hexagonal patterns and wrapped with bands. The wrapping force is shown to modify the effective stiffness of the cables, a phenomenon modeled using the Singum model and Hertz contact theory. This approach simulates the stress transfer between wires under transverse loading, introducing an elastoplastic contact model that accounts for yielding in the contact zones. The study presents a methodology for predicting the development length and critical axial load in cables with broken wires, providing a robust tool for the design and maintenance of suspension bridge cables. In the final part of this research, the focus shifts to the mechanical performance of a fivelayered mullion design for energy-efficient building facades. Comprising three aluminum layers sandwiched between two polyamide cores, the beam is analyzed using linear and nonlinear elastic sandwich beam theory to derive expressions for effective stiffness. These theoretical predictions are compared with finite element method simulations and validated against experimental data from three-point and four-point bending tests. The results confirm the accuracy of the analytical models presented, demonstrating their potential for enhancing the structural performance of modern building facades. A significant contribution of this research is the development of a comprehensive framework for understanding and predicting the nonlinear elastic behavior of infrastructure materials under complex loading conditions, which the superposition principle may not be simply applicable even though the material behavior is elastic. By integrating configurational forces into the design process, this work offers a novel approach to improving the structural integrity and performance of beams, cables, and facade systems, with wide-ranging implications for the fields of structural engineering and material science.

When a mechanical system is subject to constraints its motion is in some way restricted. In accordance with Newton's second law, motion is a direct result of forces acting on a system; hence, constraint is inextricably linked to force. The presence of a constraint implies the application of particular forces needed to compel motion in accordance with the constraint; absence of a constraint implies the absence of such forces. The objective of this thesis is to formulate a comprehensive, consistent, and concise method for identifying a set of forces needed to constrain the behavior of a mechanical system modeled as a set of particles and rigid bodies. The goal is accomplished in large part by expressing constraint equations in vector form rather than entirely in terms of scalars. The method developed here can be applied whenever constraints can be described at the acceleration level by a set of independent equations that are linear in acceleration. Hence, the range of applicability extends to servo-constraints or program constraints described at the velocity level with relationships that are nonlinear in velocity. All configuration constraints, and an important class of classical motion constraints, can be expressed at the velocity level by using equations that are linear in velocity; therefore, the associated constraint equations are linear in acceleration when written at the acceleration level. Two new approaches are presented for deriving equations governing motion of a system subject to constraints expressed at the velocity level with equations that are nonlinear in velocity. By using partial accelerations instead of the partial velocities normally employed with Kane's method, it is possible to form dynamical equations that either do or do not contain evidence of the constraint forces, depending on the analyst's interests.