EAGER: DREAM-B: Collaborative Research: Moldable and Wave Tunable Materials for Complex Freeform Structures

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Natural disasters, such as hurricanes, tornados, and earthquakes, pose a continuous threat in the United States, which can result in economic losses as well as loss of life. Unpredictable weather patterns have led to more severe and frequent natural disasters and, therefore, mitigating the impact of hazards on building structures is important for continuity in national welfare and prosperity following a disaster. Aside from building structures that can sustain various extreme events, modern and future architecture has shifted towards complex freeform structures, beyond simple geometries, to achieve aesthetically pleasing structures and to make efficient use of space. A solution that simultaneously addresses all the above issues will require redefining some of the conventional paradigms in construction material design and deployment. This EArly-concept Grant for Exploratory Research (EAGER) will investigate a new construction material approach for building skins and facades that are moldable to various complex geometries and, at the same, have the ability to manipulate waves imparted to the buildings and dissipate energy from high velocity winds. The moldability will be achieved by relief cutting solid panels made of wood and metals with certain microstructural patterns, which is a low-cost process and hence suitable for the building industry. While relief cutting promotes flexible surfaces, this approach generally reduces the load carrying ability of the panels, which may not be desirable. This study will provide a means to potentially turn the disadvantage of the cutting method into an advantage, i.e., utilizing the cut patterns for tuning the dynamic properties to better resist hazard loadings. Because of the architected nature, the cut surfaces are expected to display a wide range of wave and vibration control and energy dissipation mechanisms. Equipping buildings with the ability to redirect, localize, trap, and dissipate energy, instead of merely resisting the impacted forces, can lead to a more efficient hazard mitigation strategy. This research can advance structural engineering by pushing complex freeform shapes to a standard practice that intertwines aesthetic arguments, building performance requirements, and material design considerations. To a greater impact, freeform complex shapes can provide buildings with additional functionalities beyond their default load bearing and shelter capabilities. This project will provide undergraduate and graduate students with interdisciplinary professional and research training opportunities. Project data will be archived and made publicly available in the NSF-supported Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (https://www.DesignSafe-ci.org). This research aims to provide fundamental knowledge regarding the interplay between complex freeform geometries, microstructural morphologies, constituent properties (viscoelastic and inelastic deformations), and mechanisms of wave propagation and energy dissipation in architectural materials. A technique known as relief cutting (or kerfing) will be used to endow thin material sheets with prescribed curved shapes and surface patterns. The objective of such patterning is two-fold. First, it will allow molding flat plates into a nearly endless array of complex freeform shapes to fulfill a variety of functional and aesthetic architectural needs. Second, it will induce a microstructural geometry and property modulation that can help manipulate a wide range of wave and vibration events, through energy absorption and dissipation mechanisms. After a simulation-based design stage exploring the design space available via kerfing, freeform components will be fabricated, molded into shape, and tested. In the design and testing of laboratory specimens, excitations that mimic the dynamic loads of high velocity winds will be accounted for to realize stress and deformation fields similar to those observed in realistic freeform structures used in actual architectural structures. This research is high risk and high reward as it will be a significant departure from traditional construction methodologies: 1) it will lead to a paradigm shift in building design, in which freeform complex shapes will be demonstrated to offer better resistance to dynamic loadings; 2) it will introduce a new and bold modular fabrication philosophy for freeform shapes that will generate minimal material waste, eliminate the need for mold casting, and simplify the logistics of material transportation; and 3) it harmoniously will blend dynamic performance and architectural constraints - two requirements that are often perceived to be mutually exclusive - by taking advantage of the intrinsic mechanical and aesthetic attributes of complex shapes and microstructural patterns.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.