Fracture of Adhesive Bonds under Mixed Mode Loading: Experiments in a Dual Actuator Load Frame and Numerical Simulations

CMMI 0826143混合模式载荷下粘接剂的断裂：双致动器载荷框架中的实验和数值模拟D. A. Dillard，D. C.奥哈内希河C. Batra，J. G. DillardVirginia Tech，Blacksburg，Virginia在先前NSF的支持下，开发了一种新型双驱动器载荷框架，能够轻松改变断裂模式（施加的剪切和打开位移的相对量），用于粘接梁的断裂测试。独特的功能允许广泛的研究调查粘合剂系统和实际工程接头的断裂。 目前的项目将研究改变不同的断裂模式对断裂能和裂纹扩展的影响，在缓慢，循环疲劳和冲击载荷的情况下;施加的应力状态如何与化学表面处理相互作用，以确定故障;以及在工程设计中有用的断裂包络线的发展。 新的数值技术将被开发和使用，以模拟材料的响应下施加的负载条件下，也指导具体的实验，以获得新的见解在不同的负载条件下的粘结梁的断裂。 粘合剂结合已成为在广泛应用中连接部件的基本手段，包括汽车、航空航天、民用基础设施、生物医学和微电子领域。通过这项研究获得的粘结失效的更好的理解提供了更安全和更耐用的粘结结构的机会。 两名博士生和几名本科生将参加拟议的实验和数值模拟工作，获得测试，数学建模，数值分析，以及加载速率和粘附体表面预处理对粘接接头性能的影响的重要经验。这项研究将培养设计更安全、更轻、更坚固和更经济的粘合接头的科学家。 研究结果将通过主要技术期刊、会议和网站传播。

CMMI 0826143Fracture of Adhesive Bonds under Mixed Mode Loading: Experiments in a Dual Actuator Load Frame and Numerical SimulationsD. A. Dillard, D. C. Ohanehi, R. C. Batra, J. G. DillardVirginia Tech, Blacksburg, Virginia Under prior NSF support, a novel dual-actuator load frame was developed with capabilities to easily vary the fracture mode (relative amount of shear and opening displacements imposed) for fracture testing of adhesively bonded beams. The unique capabilities allow for a wide range of studies investigating fracture of adhesive systems and practical engineering joints. The current project will investigate the effect of changing different fracture modes on fracture energies and crack propagation under slow, cyclic fatigue, and impact loading situations; how applied stress state interacts with chemical surface treatments in determining failure; and the development of fracture envelopes useful in engineering design. New numerical techniques will be developed and used to model the material response under the applied loading conditions and also guide specific experiments to gain new insights into the fracture of bonded beams under different loading conditions. 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. The improved understanding of bond failure obtained through this research offers opportunities for safer and more durable bonded structures. Two doctoral and several undergraduate students will participate in the proposed experimental and numerical modeling effort, obtaining significant experience in testing, mathematical modeling, numerical analysis, and effects of loading rates and adherend surface pretreatment on bonded joint performance. The research will train scientists who will design safer, lighter, stronger and more economical bonded joints. Results will be disseminated through premier technical journals, at conferences, and a web site.