CAREER: Computational Platform for Recursive Adaptive Multi-level Analysis of Structures under Extreme Events

摘要：本项目拟开发一个计算平台，用于爆炸、爆炸和高速撞击等极端事件下结构响应的分析和全系统模拟。该平台将采用通过研究开发的新方法，以及可用于极端事件模拟的最佳技术来构建。同时在多个空间和时间尺度上获得结构响应，以达到高保真度和计算效率。将考虑三种不同的尺度：（细尺度）在极端事件附近，将使用一种新颖的无网格方法模拟响应。在该区域内，需要考虑极其精细的时空尺度来捕捉材料在高应变速率下的断裂、破碎和相变。（中尺度）对于靠近细尺度区域的结构构件，将采用新颖的有限元方法来捕获裂纹、大变形和非弹性材料行为的破坏。对于结构的其余部分，将使用鲁棒和精确的结构（梁，板）有限元来获得整体响应。这三种类型的区域将通过新颖的方法进行接口，这些方法将能够在每个区域内使用非匹配的时间和空间离散化（即不同的时间步长，有限元和无网格节点）。通过这种方法，将有可能以高精度和计算效率获得局部（构件和材料失效）和全局（结构倒塌）响应。该平台还将能够执行递归和自适应计算，以提高计算效率。所提出的计算平台将能够考虑结构在极端事件中的全局和局部响应。这种方法对于确定直接暴露在极端事件中的构件的破坏和整个结构的渐进破坏机制是必要的。目前还没有这样的模拟工具存在。因此，拟议的平台将帮助法医工程师进行脆弱性评估研究，以及开发抗爆炸/抗冲击设计和改造技术。研究成果将对相关领域产生广泛影响。在整个项目中产生的元素公式、分析方法和算法将适用于地震工程、材料响应建模、断裂力学和结构动力学等领域。通过外联活动，该项目将在学术界、国家研究实验室的研究人员和法医工程师之间产生可行的协同作用。研究生将通过研究、实习和参与外展活动来接受培训。

Abstract : In this project, development of a computational platform is proposed for analyses and whole-system simulations of structural response during extreme events, such as blasts, explosions and high-velocity impact. The platform will be constructed with novel methods developed through research, and with best available technologies for extreme event simulations. The structural response will be obtained at multiple spatial and temporal scales simultaneously, in order to achieve high fidelity and computational efficiency. Three different scales will be considered: (Fine Scale) In the immediate vicinity of the extreme event, response will be simulated using a novel Mesh-free method. Within this zone, the consideration of extremely fine spatial and temporal scales is needed to capture fracture, fragmentation and phase changes of materials under high-strain rates. (Medium Scale) For the structural members adjacent to the fine scale zone, novel Finite Element methods will be utilized to capture failure through cracking, large deformations, and inelastic material behavior. (Coarse Scale) For the rest of the structure, robust and accurate structural (beam, plate) finite elements will be used to obtain the global response. These three types of zones will be interfaced with novel methods that will enable the use of non-matching temporal and spatial discretizations (i.e., different time-step sizes, finite elements and mesh-free nodes) within each zone. Through this methodology, it will be possible to obtain local (member and material failure) and global (structural collapse) responses with a high accuracy and computational efficiency. The proposed platform will also be capable of performing recursive and adaptive computations to enhance computational efficiency. The proposed computational platform will be capable of considering the global and local response of structures during extreme events. This approach is necessary to determine the failure of members that are directly exposed to the extreme events and the progressive collapse mechanisms of the structure as a whole. Currently there is no such simulation tool in existence. As such, the proposed platform will aid forensic engineers in vulnerability assessment studies, and in the development of blast/impact-resistant design and retrofitting techniques. The research outcomes will have a broad impact on related fields. The element formulations, analysis methods and algorithms generated throughout the project will be applicable to earthquake engineering, material response modeling, fracture mechanics, and structural dynamics fields in general. Through the outreach activities, the project will generate a viable synergy between researchers in academia, in national research laboratories, and forensic engineers. The graduate students will be trained through research, internships, and participation in outreach.