Experimental Measurement of Tearing and Cutting in Highly Deformable Solids Relating to the Mechanical Origin of Crack Blunting-Mediated Toughness

高变形固体撕裂和切割的实验测量与裂纹钝化介导的韧性的机械起源相关

• 批准号: 1562766
• 负责人: Shelby Hutchens
• 金额: $ 30.05万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1562766&HistoricalAwards=false
• 关键词: Experimental; Measurement; Tearing; Cutting; Highly

This award aims to determine the relationship between cutting and tearing failure modes in order to re-examine and provide new insight into the mechanical origin of tearing in highly deformable materials. Failure in these rubber-like materials governs design rules in applications ranging from transportation to biomaterials. Unlike many rigid materials, cracks in rubber-like materials can blunt macroscopically as the material undergoes large deformations. This complicates the stress state at the tip of the crack, which varies depending on the material. Current understanding of the failure mechanism cannot explain the energy differences in two different loading geometries, cutting versus tearing. Potential benefits include design criteria to serve as targets to guide the fabrication of new materials. Results can be generalized to describe puncture and insertion of needles in soft tissue; these failure mechanisms play a key role in diagnostics and guided-needle therapeutics. This project will provide educational opportunities facilitated by the PI as many of the experiments in this project are accessible to undergraduate researchers. The PI will recruit female undergraduate students to participate in data-gathering throughout the project.Highly deformable, crack-blunting solids exhibit fracture energies many times larger than predicted by simple cohesive models. Researchers have postulated more complex models that indicate fracture is governed by the local mechanics of the tip. These local mechanics include the material's large strain response, tip radius, and local fracture energy. To fully characterize each of these important features, the PI will supplement experimental mechanical failure data with in situ and post-mortem imaging, documenting crack tip radius, near-tip strain, and fracture mechanism. The mechanism map resulting from this experimental characterization will guide examination and, if necessary, re-interpretation of existing models describing the mechanical origin of tearing in highly deformable materials. Once established for the standard plane stress geometry, the relationship quantified in this project, between geometrically controlled (cutting) and remote-load (tearing) failure energies, will be applied to relate needle-mediated failure to standard, mode I fracture energy values.

该奖项旨在确定切割和撕裂故障模式之间的关系，以重新检查并提供有关高度变形材料撕裂的机械起源的新见解。这些类似橡胶的材料的故障控制着从运输到生物材料的应用中的设计规则。与许多刚性材料不同，橡胶状材料的裂纹会在材料发生较大变形的情况下钝化宏观。这使裂纹尖端处的应力状态复杂化，这取决于材料。当前对故障机制的理解无法解释两种不同的载荷几何形状的能量差异，切割而不是撕裂。潜在的好处包括设计标准，以作为指导制造新材料的目标。可以将结果推广以描述针中针中针中的穿刺和插入。这些失败机制在诊断和指导性针治疗中起关键作用。该项目将为PI提供促进的教育机会，因为本科研究人员可以访问该项目中的许多实验。 PI将招募女性本科生参加整个项目的数据收集。高变形，裂纹的固体表现出比简单凝聚模型预测的大量骨折能量。研究人员假设更复杂的模型表明断裂受尖端的局部力学支配。这些局部力学包括材料的较大应变响应，尖端半径和局部断裂能。为了充分表征这些重要特征，PI将用原位和验尸成像补充实验机械故障数据，记录裂纹尖端半径，接近尖端应变和断裂机制。该实验表征产生的机制图将指导检查，并在必要时重新解释现有模型，描述了高度变形材料中撕裂的机械起源。一旦建立了标准平面应力几何形状，将在几何控制（切割）和远程载荷（撕裂）故障能量之间进行量化的关系，以将针头介导的失败与标准，模式I骨折能量值相关联。