Residual tension strength study of fatigued open-hole titanium-graphite hybrid composite laminates

摘要

This study addresses the potential advantage with respect to damage tolerance for Ti-Gr laminates by demonstrating the residual tension strength capabilities of fatigued open-hole tension (OHT) laminates with cracks in the titanium layers. ^Ti-Gr laminates are precracked in fatigue cycles until the cracks in the outer layer of titanium reach predetermined lengths of 1.27, 3.18, 6.35, and 12.70 mm. ^Three lay-ups are used, including titanium dominant (4Ti-2C-2C), 0-deg polymer matrix composite (PMC) dominant (2Ti-6C-2C), and thick laminate (7Ti-12C4C) lay-ups. ^For specimens containing a 12.70-mm precrack, the titanium dominant lay-up demonstrates an 81 percent strength retention relative to baseline specimens of no precracks. ^The 0-deg PMC dominant and the thick Ti-Gr lay-up demonstrate a retention of 98 and 92 percent respectively. ^Retention strengths for shorter precrack lengths, representative of lesser damage cases, are equivalent to or higher than those previously listed. ^Results show that limited fatigue cracks in the titanium layers of Ti-Gr laminates do not significantly affect the residual tension strength of the material. ^(Author)