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

混合模式载荷下胶粘剂粘结断裂：双作动器载荷框架试验与数值模拟[j]。在美国国家科学基金会（NSF）的支持下，一种新型的双致动器负载框架被开发出来，它能够很容易地改变断裂模式（施加的剪切和开放位移的相对量），用于粘合梁的断裂测试。其独特的性能允许广泛的研究粘合剂系统和实际工程接头的断裂。目前的项目将研究在缓慢、循环疲劳和冲击载荷情况下，改变不同的断裂模式对断裂能和裂纹扩展的影响；施加应力状态如何与化学表面处理相互作用以确定失效；裂缝包络层的开发对工程设计有一定的指导意义。新的数值技术将被开发和用于模拟材料在加载条件下的响应，并指导具体的实验，以获得对不同加载条件下粘结梁断裂的新见解。在汽车、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，粘合剂粘合已成为连接部件的重要手段。通过本研究获得的对粘结破坏的更好理解为更安全、更耐用的粘结结构提供了机会。两名博士和几名本科生将参与拟议的实验和数值模拟工作，在测试、数学建模、数值分析以及加载速率和附着面预处理对粘结接头性能的影响方面获得丰富的经验。这项研究将培养科学家设计出更安全、更轻、更坚固、更经济的粘合接头。结果将通过主要的技术期刊、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.