Durability of Continuous Fiber Reinforced Metal Matrix Composites

The objective of this program was to develop the test data and analysis techniques required to insure the structural integrity of fiber reinforced metal matrix composites FRMMC when applied to airframe structures. Approximately 300 tests of unidirectional boron6061 aluminum, B4C15-3-3-3 titanium, and crossplied boron6061 aluminum were performed. Testing was concentrated on notched central hole specimens to evaluate the notch sensitivity of these materials and to discriminate between the failure modes of aluminum and titanium matrix composites. It was found that the relative fiber and matrix stiffnesses and strengths determine primary failure modes in fatigue. Analysis methods were developed based on fiber and matrix properties to predict notched and unnotched static strength, crack initiation, fatigue failure mode, life to failure, and residual strength. One half of the tests 150 specimens were performed to verify the predicted properties of the aluminum and titanium matrix composites.