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

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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.