Collaborative Research: Micromechanics-based Framework for Modeling Fracture of Weldments in Structural Steel

合作研究：基于微观力学的结构钢焊件断裂建模框架

• 批准号: 2129499
• 负责人: Machel Morrison
• 金额: $ 37.03万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-11-01 至 2024-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2129499&HistoricalAwards=false
• 关键词: Collaborative; Research; Micromechanics; based; Framework

Civil infrastructure constructed from steel relies heavily on welding to connect various parts (such as beams and columns) to each other. Welded connections are often the weak points in these structures and are prone to fracture, leading to catastrophic failure or collapse under loads such as during earthquakes. Predicting and simulating such fracture are essential for safety assessment and design of these structures. However, this type of failure is challenging to simulate in computer models, because current methods cannot properly represent the changes in material properties caused by welding processes and how these changes weaken the structure. This award will support fundamental research to understand how welding changes material properties over very small dimensions in these connections, and then will create a method to use these properties within computer simulations to predict the failure of welded connections. The findings and software technology from this research will enhance the safety and resilience of buildings and other infrastructure, benefiting the nation’s society and economy. The involvement of underrepresented groups, education of students with new knowledge, and technology transfer to practitioners will result in broad impacts. This award will contribute to the National Science Foundation role in the National Earthquake Hazards Reduction Program (NEHRP). Welded steel connections often fail under extreme loads due to the complex and multiple microstructures that are formed in weldments, and the steep stress and strain gradients that interact with these microstructures. Current methods for simulating weldments cannot simulate the mechanical properties of these microstructures or their interactions with applied loads. This is especially true when these connections are subjected to large-scale yielding or Ultra Low Cycle Fatigue fracture (which occur commonly under extreme loads such as earthquakes). This research will develop fundamental understanding of weld microstructures and their mechanical properties through laboratory experiments on thermomechanically generated samples. Then, the research will upscale these findings to the structural scale through an innovative framework of multi-scale simulation. This knowledge and framework will be implemented for convenient integration within various numerical platforms (open source as well as commercial) that are popular with researchers and structural engineers. This approach (including its implementation) will be informed and validated by extensive laboratory testing and finite element simulation, and broadly disseminated to target audiences and user groups. Data generated by this research will be archived in the Natural Hazards Engineering Research Infrastructure (NHERI) Data Depot (https://www.DesignSafe-ci.org).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.

由钢建造的民用基础设施严重依赖焊接来将各个部分（如梁和柱）相互连接。焊接连接通常是这些结构中的薄弱点，并且容易断裂，导致在地震等载荷下发生灾难性故障或倒塌。预测和模拟此类断裂对此类结构的安全评估和设计至关重要。然而，这种类型的故障在计算机模型中模拟是具有挑战性的，因为目前的方法不能正确地表示焊接过程引起的材料性能变化以及这些变化如何削弱结构。该奖项将支持基础研究，以了解焊接如何改变这些连接中非常小尺寸的材料特性，然后将创建一种方法，在计算机模拟中使用这些特性来预测焊接连接的故障。这项研究的结果和软件技术将提高建筑物和其他基础设施的安全性和弹性，造福国家的社会和经济。代表性不足的群体的参与、对学生的新知识教育以及向从业人员的技术转让将产生广泛的影响。该奖项将有助于国家科学基金会在国家减少地震灾害计划（NEHRP）中的作用。 由于焊接件中形成的复杂和多种微观结构以及与这些微观结构相互作用的陡峭应力和应变梯度，焊接钢连接件经常在极端载荷下失效。目前用于模拟焊接件的方法不能模拟这些微结构的机械性能或它们与所施加的载荷的相互作用。当这些连接受到大规模屈服或超低周疲劳断裂（通常发生在极端载荷下，如地震）时，尤其如此。这项研究将通过对热机械产生的样品进行实验室实验，对焊缝显微组织及其机械性能有基本的了解。然后，本研究将通过多尺度模拟的创新框架将这些发现升级到结构尺度。这些知识和框架将被实现，以便在研究人员和结构工程师流行的各种数值平台（开源和商业）中进行方便的集成。将通过广泛的实验室测试和有限元模拟来了解和验证这一方法（包括其实施），并将其广泛传播给目标受众和用户群体。这项研究产生的数据将存档在自然灾害工程研究基础设施（NHERI）数据库（www.DesignSafe-ci.org）。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

项目成果

Fracture Mechanics–Based Fragility Assessment of Pre-Northridge Welded Column Splices

基于断裂力学的 Northridge 焊接柱接头脆性评估

• DOI: 10.1061/jsendh.steng-11749
• 发表时间: 2023
• 期刊: Journal of Structural Engineering
• 影响因子: 4.1
• 作者: Jhunjhunwala, Aditya;Kanvinde, Amit
• 通讯作者: Kanvinde, Amit