Characterization of Fatigue Behavior of Composite Sandwich Structures at Sub-Zero Temperatures
This chapter summarizes recent studies of the flexural fatigue characteristics of foam core carbon/epoxy and glass/epoxy composite sandwich beams over the temperature range from 22°C to −60°C. Core shear was found to be the dominant fatigue failure mode for the test specimens over this temperature range. Significant increases in the useful fatigue life with brittle type core shear failure were observed at low temperatures by comparison with the corresponding room temperature behavior. Fatigue failure at the subzero temperatures was catastrophic and without any significant early warning, but the corresponding failures at room temperature were preceded by relatively slow but steadily increasing losses of stiffness. Two different approaches were used to investigate stiffness reductions during fatigue tests, and both approaches led to the same conclusions. Static finite element analyses confirmed the experimentally observed locations of fatigue crack initiation.
KeywordsFatigue Life Load Level Face Sheet Sandwich Beam Subzero Temperature
This work was performed while all of the authors were located at Wayne State University. The authors gratefully acknowledge the financial support of the United States. Office of Naval Research, and the guidance of ONR Program Officers Dr. Kelly Cooper and Dr. Yapa Rajapakse.
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