Exploratory Investigation of Rapid Crack Propagation and Crack Arrest
Report Number: AFFDL TR 73-95
Author(s): Shah, R. C.
Corporate Author(s): Boeing Aersopace Company
Laboratory: Air Force Flight Dynamics Laboratory
Date of Publication: 1973-08
Pages: 102
Contract: F33615-72-C-1063
DoD Project: None Given
Identifier: AD0778822
Abstract:
This experimental program was undertaken to study and investigate the effects of crack velocity and maetrial parameters on the crack characteristics of aircraft structural alloys. Materials tested included 2219-T851 and 7075-T6 Aluminum, 6Al-4V beta-annealed Titanium, 9Ni-4Co-0.2C and 4340 steel alloys. Tests were conducted with radially flared and uniform height DCB (Double Cantiler Beam) specimens containing either sharp cracks or notches with finite root radii. The specimens were instrumented to measure crack velocity, crack length, crack opening displacement, instantaneous load, strain and crack lengths and the stress intensity factors at the initiation and the arrest of the crack propagation. An instrumentation system for the measurement of crack velocities from zero to several thousands of feet per second is presented. Experimental results are presented and are evaluated with fracture mechanics parameters. The test results indicate that a cracked DCB specimen of any configuration under static loading is not suitable for investigating the dynamic behavior of rapidly running cracks or crack arrest conditions. Recommendations for suitable test specimens are provided.
Provenance: Bombardier/Aero
Author(s): Shah, R. C.
Corporate Author(s): Boeing Aersopace Company
Laboratory: Air Force Flight Dynamics Laboratory
Date of Publication: 1973-08
Pages: 102
Contract: F33615-72-C-1063
DoD Project: None Given
Identifier: AD0778822
Abstract:
This experimental program was undertaken to study and investigate the effects of crack velocity and maetrial parameters on the crack characteristics of aircraft structural alloys. Materials tested included 2219-T851 and 7075-T6 Aluminum, 6Al-4V beta-annealed Titanium, 9Ni-4Co-0.2C and 4340 steel alloys. Tests were conducted with radially flared and uniform height DCB (Double Cantiler Beam) specimens containing either sharp cracks or notches with finite root radii. The specimens were instrumented to measure crack velocity, crack length, crack opening displacement, instantaneous load, strain and crack lengths and the stress intensity factors at the initiation and the arrest of the crack propagation. An instrumentation system for the measurement of crack velocities from zero to several thousands of feet per second is presented. Experimental results are presented and are evaluated with fracture mechanics parameters. The test results indicate that a cracked DCB specimen of any configuration under static loading is not suitable for investigating the dynamic behavior of rapidly running cracks or crack arrest conditions. Recommendations for suitable test specimens are provided.
Provenance: Bombardier/Aero