Recognition of the positive features of elastic instabilities for use in smart and adaptive materials and structures has increased in recent years. Among many unstable events, buckling is one of the oldest and most well-understood types of response and yet this critical condition has been mainly regarded as a failure limit and the afterward response (postbuckling) as a safeguard. However, research on smart/adaptive devices has identified buckling and postbuckling as a favorable behavior. This dissertation explores the potential of cylindrical shells under axial compression, for which mode transitions during the postbuckling response lead to sudden and high-rate deformations from generally smaller changes in the controlling load or displacement input to the system. Such geometric nonlinear responses allow cylindrical shells to be considered as a viable structural prototype for purposes such as energy harvesting, sensing, actuation, etc.Experimental and numerical studies evaluated three avenues for modifying and controlling the postbuckling response of cylindrical shells: (1) by introducing seeded geometric imperfections (SGI); (2) by introducing non-uniform stiffness distributions (NSD); and (3) by providing lateral constraints and interactions (LCI). An SGI cylinder is obtained by superposing a single mode shape from the eigenvalue analyses on a uniform cylinder to provide a governing role over other initial random imperfections. An NSD cylinder follows a similar concept of introducing artificial imperfections but by strategically placing patterned thickened regions (which alter the stiffness distribution) on the shell surface with the aim of triggering localized buckling events in non-thickened regions. Finally, an LCI cylinder is driven by the desire to gain further control of the postbuckling response through the interaction of multiple cylinders in nested assemblies. The numerical simulations were conducted through extensions on established methods for simulating nonlinear geometric response in slender structures. Prototyped cylinder were fabricated, first by using laminated composite materials and later through 3D printing and tested under cyclic loading. Further extension of these concepts was explored through a design optimization process.Numerical and experimental results suggest that SGI and NSD cylinders can attain a controllable postbuckling response due to the governing role of artificial imperfections. For both cases, the localized buckling events can be triggered in predefined regions; and careful selection of the geometry and stiffness distribution can lead to elastic postbuckling responses with tailorable features, which implies diverse design opportunities. Further, simulations and test results demonstrated that the elastic postbuckling response of SGI and NSD shells was less sensitive to initial (manufacturing) imperfections as well as loading variations compared to that of uniform cylinders. Studies on LCI cylinders showed that this concept allows the attainment of a higher number of mode transitions in the elastic postbuckling regime and the post-buckling stiffening behavior increases to levels that surpass the initial buckling load. Optimization results showcased that postbuckling response can be tailored into three types (softening, sustaining and stiffening) and design guidelines were developed to achieve a targeted behavior. The study has led to knowledge on the possibilities, extent and means to control (and thus design) the elastic far postbuckling response of cylindrical shells with the noted variations in geometry, stiffness and boundary conditions. Full characterization and understanding of these variables in the attainment and control of postbuckling response with desirable features can promote the use of the presented cylindrical shell concepts for a variety of purposes of emerging interest and across scales for various applications.
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