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

飓风、龙卷风和地震等自然灾害对美国构成持续威胁，可能造成经济损失和生命损失。不可预测的天气模式导致了更严重和更频繁的自然灾害，因此，减轻灾害对建筑结构的影响对于灾后国家福利和繁荣的连续性非常重要。除了能够承受各种极端事件的建筑结构外，现代和未来的建筑已经转向复杂的自由结构，超越了简单的几何形状，以实现美观的结构和有效地利用空间。同时解决上述所有问题的解决办法将需要重新定义建筑材料设计和部署方面的一些传统范例。这项具有早期概念的探索研究基金(EARGER)将研究一种新的建筑材料方法，用于建筑皮肤和立面，这种材料可以塑造各种复杂的几何形状，同时具有操纵传递给建筑物的波浪和消散高速风产生的能量的能力。可成型性将通过浮雕切割具有一定微观结构图案的木材和金属制成的实心面板来实现，这是一种低成本的工艺，因此适用于建筑业。虽然浮雕切割促进了柔性表面，但这种方法通常会降低面板的承载能力，这可能是不可取的。这项研究将提供一种潜在地将切割方法的缺点转化为优势的方法，即利用切割图案来调整动态特性，以更好地抵抗危险载荷。由于建筑的性质，切割表面有望显示出广泛的波浪和振动控制和消能机制。为建筑物配备重定向、定位、捕获和消散能量的能力，而不仅仅是抵抗受影响的力量，可以带来更有效的减灾战略。这项研究可以通过将复杂的自由形状推向将美学论点、建筑性能要求和材料设计考虑相互交织在一起的标准实践来推动结构工程。更大的影响是，自由形状的复杂形状可以为建筑提供默认承载和遮挡功能之外的额外功能。该项目将为本科生和研究生提供跨学科的专业和研究培训机会。项目数据将在国家科学基金会支持的自然灾害工程研究基础设施(NHERI)数据仓库(https://www.DesignSafe-ci.org).)中存档并公开提供本研究旨在提供有关建筑材料中复杂的自由几何形状、微结构形态、组成属性(粘弹性和非弹性变形)以及波的传播和能量耗散机制之间相互作用的基础知识。一种称为浮雕切割(或称削角)的技术将被用来赋予薄板指定的曲面形状和表面图案。这种图案化的目的有两个。首先，它将允许将平板模塑成几乎无穷无尽的复杂自由形状阵列，以满足各种功能和美学建筑需求。其次，它将通过能量吸收和耗散机制，诱导微结构几何和性质调节，有助于操纵广泛的波动和振动事件。在基于模拟的设计阶段探索可通过截口获得的设计空间后，将制造自由形状的部件，将其模制成形状，并进行测试。在实验室试件的设计和测试中，将考虑模拟高速风动载荷的激励，以实现与实际建筑结构中使用的真实自由形状结构中观察到的应力和变形场相似的应力场和变形场。这项研究是高风险和高回报的，因为它将显著背离传统的建筑方法：1)它将导致建筑设计的范式转变，其中自由形状的复杂形状将被证明具有更好的抗动态荷载能力；2)它将为自由形状引入一种新的大胆的模块化制造理念，将产生最少的材料浪费，消除模具铸造的需要，并简化材料运输的物流；3)通过利用复杂形状和微结构图案的内在机械和美学属性，它将和谐地融合动态性能和建筑约束-这两个通常被认为是相互排斥的要求。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.