IMR: Development/Acquisition of a Mixed-Mode Fracture Testing Instrument for Research and Education in Adhesion Science

IMR：开发/采购用于粘附科学研究和教育的混合模式断裂测试仪器

• 批准号: 0415840
• 负责人: David Dillard
• 金额: --
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2008-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0415840&HistoricalAwards=false
• 关键词: IMR; Development; Acquisition; Mixed; Mode

Adhesive bonding has become an essential means for joining components in a wide range of applications, including automotive, aerospace, civil infrastructure, biomedical, and microelectronic fields. Satisfactory performance of these bonds requires retaining structural integrity over the service life where they are often subjected to dead loads, impact, and/or fatigue, while exposed to environmental challenges such as temperature and humidity. A significant need exists for improved understanding of the fracture resistance of bonded joints, and how these properties can be incorporated into meaningful and robust design procedures for bonded structures. Joints often fail by fracture propagating under some combination of mode I (opening), mode II (forward shear), and mode III (tearing) loading. Because fracture energies depend on mode mixity, comprehensive failure envelopes for a range of mode mixities are generated by conducting pure and mixed mode tests. This proposal seeks funding to develop a unique instrument capable of easily varying the mode mix for fracture testing of adhesively bonded beam specimens. Currently, different mode mixities are achieved by using different test configurations, increasing complexity and obscuring meaningful comparisons. Several fixtures have been developed to vary the mode mixity over a limited range for a given specimen geometry, but these techniques are cumbersome to use and limited in their applicability. These complications are a major hindrance to developing an improved understanding of the effects of mode mixity on fracture properties and locus of failure. These limitations will be largely overcome by the unit proposed herein, which offers significant potential for new scientific insights gained through use of a convenient and efficient test method relevant to many fields. The proposed instrument will be built around a customized load frame complete with dual actuators, load cells, displacement transducers, controllers, and data acquisition system. By independently adjusting the magnitude and phase of the actuators, any desired fracture energy and mode mixity may be applied to commonly used, ASTM standard, double cantilever beam specimens. Because the mode mixity can be easily changed during a test, one can investigate the effects of mode mix, even as a debond propagates within a single specimen. The instrument will have unique scientific and engineering capabilities for characterizing mixed mode fracture, developing fracture envelopes, and investigating the complex interactions between stress state and spatially varying material properties and how they affect locus of failure. The unit is expected to be useful in many areas of adhesive utilization and can also be readily extended to other disciplines, such as the study of interlaminar properties of composites or other laminated materials, important for many aerospace, automotive, and infrastructure applications. In addition to the scientific merits, companies producing or using adhesives and composite materials for many industrial fields are expected to gain from the insights that can conveniently be obtained with this simple unit. Because the specimens are already an ASTM standard and are easily fabricated, barriers will be reduced for the use and broader adoption of this technology. In essence, we will be able to gain a great deal of additional information about the material performance using specimens that are already in common use. A graduate student and an undergraduate student will participate in the development effort, obtaining significant experience in instrument design, construction, and calibration, along with computer interfacing and programming skills. The unit will be used by a diverse group of students and faculty associated with our interdisciplinary Center for Adhesive and Sealant Science. This unique research capability will nicely complement the wide array of equipment we have available for characterizing adhesion and composite properties, and is expected to attract significant interest from current sponsors as well as potential sources of future funding, including industry and government laboratories. The unit will offer a very flexible instrument to enhance the research of mechanical properties of adhesives, and also provide useful new insights related to polymer and surface science in this interdisciplinary field of adhesion.%%% Adhesive bonding has become an essential means for joining components in a wide range of applications, including automotive, aerospace, civil infrastructure, biomedical, and microelectronic fields. Satisfactory performance of these bonds requires retaining structural integrity over the service life where they are often subjected to dead loads, impact, and/or fatigue, while exposed to environmental challenges such as temperature and humidity. A significant need exists for improved understanding of the fracture resistance of bonded joints, and how these properties can be incorporated into meaningful and robust design procedures for bonded structures. Joints often fail by fracture propagating under some combination of tensile and shear mode loadings. Because fracture energies depend on mode combinations, comprehensive failure envelopes for a range of mode combinations are generated by conducting pure and mixed mode tests. These provide important understanding of the failure process, and avoid non-conservative design space. This proposal seeks funding to develop a unique instrument capable of easily varying the mode mix for fracture testing of adhesively bonded beam specimens. Currently, different mode combinations are achieved by using different test configurations, increasing complexity and obscuring meaningful comparisons. Several fixtures have been developed to vary the mode combination over a limited range for a given specimen geometry, but these techniques are cumbersome to use and limited in their applicability. These limitations will be largely overcome by the unit proposed herein, which offers significant potential for new scientific insights gained through use of a convenient and efficient test method relevant to many fields. The proposed instrument will be built around a customized load frame complete with dual actuators, load cells, displacement transducers, controllers, and a data acquisition system. By independently adjusting the magnitude and phase of the actuators, any desired fracture energy and mode mix may be applied to commonly used, double cantilever beam specimens. The instrument will have unique scientific and engineering capabilities for characterizing mixed mode fracture for design and scientific applications. The unit is expected to be useful in many areas of adhesive utilization and can also be readily extended to other disciplines, such as the study of interlaminar properties of composites or other laminated materials, important for many aerospace, automotive, and infrastructure applications. In addition to the scientific merits, companies producing or using adhesives and composite materials for many industrial fields are expected to gain from the insights that can conveniently be obtained with this simple unit. Because the specimens are already an American Society for Testing and Materials standard and are easily fabricated, barriers will be reduced for the use and broader adoption of this technology. In essence, we will be able to gain a great deal of additional information about the material performance using specimens that are already in common use. The development of the device will promote the training and research effort in adhesion science, scientific instrument design and programming for a diverse group of undergraduate and graduate students associated with faculty in our interdisciplinary Center for Adhesive and Sealant Science.

粘合剂粘合已成为汽车、航空航天、民用基础设施、生物医学和微电子领域等广泛应用中连接组件的重要手段。 这些粘合的令人满意的性能需要在使用寿命期间保持结构完整性，在使用寿命期间它们经常受到静载荷、冲击和/或疲劳，同时暴露于温度和湿度等环境挑战。迫切需要更好地了解粘合接头的抗断裂性，以及如何将这些特性纳入粘合结构的有意义且稳健的设计程序中。 在 I 型（张开）、II 型（前向剪切）和 III 型（撕裂）载荷的某种组合下，接头经常因断裂扩展而失效。 由于断裂能取决于模式混合度，因此通过进行纯模式和混合模式测试来生成一系列模式混合度的综合失效包络线。 该提案寻求资金来开发一种独特的仪器，能够轻松改变粘合梁试样断裂测试的模式组合。 目前，不同的模式混合是通过使用不同的测试配置来实现的，这增加了复杂性并模糊了有意义的比较。 已经开发了几种固定装置来在给定样本几何形状的有限范围内改变模式混合度，但这些技术使用起来很麻烦并且适用性有限。 这些并发症是加深对模式混合对断裂特性和失效部位影响的理解的主要障碍。 本文提出的装置将在很大程度上克服这些限制，该装置通过使用与许多领域相关的方便且有效的测试方法，为获得新的科学见解提供了巨大的潜力。 拟议的仪器将围绕定制的负载框架构建，配有双执行器、称重传感器、位移传感器、控制器和数据采集系统。 通过独立调整致动器的幅度和相位，任何所需的断裂能和模式混合都可以应用于常用的 ASTM 标准双悬臂梁样本。 由于在测试过程中可以轻松更改模式混合，因此即使脱粘在单个样本内传播，也可以研究模式混合的影响。该仪器将具有独特的科学和工程能力，用于表征混合模式断裂、开发断裂包络线、研究应力状态和空间变化材料特性之间的复杂相互作用以及它们如何影响失效位置。 该装置预计将在粘合剂应用的许多领域发挥作用，并且还可以很容易地扩展到其他学科，例如复合材料或其他层压材料的层间特性的研究，这对于许多航空航天、汽车和基础设施应用非常重要。 除了科学优点之外，在许多工业领域生产或使用粘合剂和复合材料的公司预计也能从通过这个简单的装置方便地获得的见解中获得收益。 由于样本已经符合 ASTM 标准并且易于制造，因此将减少该技术的使用和更广泛采用的障碍。 本质上，我们将能够使用已经常用的样本获得有关材料性能的大量附加信息。一名研究生和一名本科生将参与开发工作，获得仪器设计、建造和校准方面的丰富经验，以及计算机接口和编程技能。 该单元将由与我们的跨学科粘合剂和密封剂科学中心相关的不同学生和教师群体使用。 这种独特的研究能力将很好地补充我们用于表征粘合和复合材料性能的各种设备，并预计将吸引当前赞助商以及未来资助的潜在来源（包括行业和政府实验室）的极大兴趣。 该装置将提供非常灵活的仪器来加强粘合剂机械性能的研究，并在这个跨学科的粘合领域提供与聚合物和表面科学相关的有用的新见解。%%% 粘合剂粘合已成为连接组件的重要手段其应用范围广泛，包括汽车、航空航天、民用基础设施、生物医学和微电子领域。 这些粘合的令人满意的性能需要在使用寿命期间保持结构完整性，在使用寿命期间它们经常受到静载荷、冲击和/或疲劳，同时暴露于温度和湿度等环境挑战。迫切需要更好地了解粘合接头的抗断裂性，以及如何将这些特性纳入有意义且稳健的粘合结构设计程序中。 在拉伸和剪切模式载荷的某种组合下，接头经常因断裂扩展而失效。 由于断裂能取决于模式组合，因此通过进行纯模式和混合模式测试可以生成一系列模式组合的综合失效包络线。 这些提供了对故障过程的重要理解，并避免了非保守的设计空间。 该提案寻求资金来开发一种独特的仪器，能够轻松改变粘合梁样本断裂测试的模式组合。 目前，不同的模式组合是通过使用不同的测试配置来实现的，这增加了复杂性并模糊了有意义的比较。 已经开发了几种固定装置来在给定样本几何形状的有限范围内改变模式组合，但这些技术使用起来很麻烦并且适用性有限。 本文提出的装置将在很大程度上克服这些限制，该装置通过使用与许多领域相关的方便且有效的测试方法，为获得新的科学见解提供了巨大的潜力。 拟议的仪器将围绕定制的负载框架构建，配有双执行器、称重传感器、位移传感器、控制器和数据采集系统。 通过独立调整致动器的幅度和相位，任何所需的断裂能和模式混合都可以应用于常用的双悬臂梁样本。 该仪器将具有独特的科学和工程能力，用于表征混合模式断裂，以供设计和科学应用。 该装置预计将在粘合剂应用的许多领域发挥作用，并且还可以轻松扩展到其他学科，例如复合材料或其他层压材料的层间性能研究，这对于许多航空航天、汽车和基础设施应用非常重要。 除了科学优点之外，为许多工业领域生产或使用粘合剂和复合材料的公司预计也能从通过这个简单的装置方便地获得的见解中获得收益。 由于这些样本已经成为美国测试和材料协会的标准，并且易于制造，因此将减少该技术的使用和更广泛采用的障碍。 本质上，我们将能够使用已经常用的样本获得有关材料性能的大量附加信息。该设备的开发将促进与我们的跨学科粘合剂和密封剂科学中心的教师相关的各种本科生和研究生群体在粘合科学、科学仪器设计和编程方面的培训和研究工作。