Date of Award

12-2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Committee Chair/Advisor

Dr. Oliver J Myers

Committee Member

Dr. Gang Li

Committee Member

Dr. Zhaoxu Meng

Abstract

Bistable composite laminates gained significant attention due to their distinct feature of maintaining multiple stable equilibrium states. The phenomenon stems from thermal stress during the curing process of systematically laid-up Carbon Fiber Prepreg (CFRP), resulting in snap-through behavior with dual cylindrical shapes characterized by opposite signs and perpendicular axes of curvature. In addition to exploring the fundamental characterization of bistable behavior and equilibrium shapes, investigating the impact of boundary conditions on such laminates poses great potential. In this research, the shape-changing behavior of a cross-ply bistable laminate with varying lengths under the boundary condition of a fixed tab on one edge inherent to its structure has been numerically analyzed. Bistable laminates with such restraint incorporated in their geometry lose the ability to acquire two cylindrical stable shapes, and after a critical length is reached, it also loses bistability. Critical length is defined as the threshold point in two opposite side lengths of a rectangle with the other two sides constant, below which the structure is not bistable anymore. The change in curvature due to the imposed dimensional altercations has been observed. FEA analysis was done on ABAQUS™ Multiphysics software, and results were validated by experimentation on specimens fabricated with carbon-fiber-epoxy unidirectional prepregs with desired geometric structure.

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