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The room temperature tensile and fatigue response of non-perforated and perforated titanium for laminar flow control application was investigated both experimentally and analytically. Results showed that multiple perforations did not affect the tensile response, but did reduce the fatigue life. A two-dimensional finite element stress analysis was used to determine that the stress fields from adjacent perforations did not influence one another. The stress fields around the holes did not overlap one another, allowing the material to be modeled as a plate with a center hole. Fatigue life was predicted using an equivalent initial flaw size approach to relate the experimental results to microstructural features of the titanium. Predictions using flaw sizes ranging from 1 to 15 (μm correlated within a factor of 2 with the experimental results by using a flow stress of 260 MPa. By using two different flow stresses in the crack closure model and correcting for plasticity, the experimental results were bounded by the predictions for high gross section stresses. Further analysis of the complex perforation geometry and the local material chemistry is needed to further understand the fatigue behavior of the perforated titanium.
commercially pure titanium, tensile response, fatigue crack growth, life prediction, cracks
Resident research associate, NASA Langley Research Center, Hampton, VA
Senior scientist, NASA Langley Research Center, Hampton, VA
Professor of materials science and engineering, Georgia Institute of Technology, Atlanta, GA