Purpose
Perform fatigue crack growth and fracture mechanics research on aerospace alloys, simultaneously mimicking service loads and environments; provide relevant information needed to characterize material performance in service-like environments, including crack growth rates, fracture loads, strain field data (digital image correlation), and high-fidelity characterization of the test environment.
Equipment/Test Method
Typical/Recent Experiments
- Small crack tests on aluminum alloy coupons containing countersunk fastener holes
– Geometry selected to mimic aircraft lap-splice joints
– Cracks monitored using potential difference
– Tests conducted in a saline solution created to be identical to fluid found in lap-splice joints during destructive teardowns.
- Near-threshold fatigue crack closure
– Tests conducted to isolate dominant near-threshold crack closure mechanisms
– Testing in vacuum to eliminate oxide-induced crack closure
– Digital image correlation used to characterize crack closure
- Fatigue crack growth tests in vacuum to mimic space environments
– Testing done in a Mars-like atmosphere by back filling with appropriate gases