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Investigation of cracks found in helicopter longerons
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Wallace, Terryl A. Newman, John A. Baughman, James M. |
| Copyright Year | 2009 |
| Description | Four cracked longerons, containing a total of eight cracks, were provided for study. Cracked regions were cut from the longerons. Load was applied to open the cracks, enabling crack surface examination. Examination revealed that crack propagation was driven by fatigue loading in all eight cases. Fatigue crack initiation appears to have occurred on the top edge of the longerons near geometric changes that affect component bending stiffness. Additionally, metallurigical analysis has revealed a local depletion in alloying elements in the crack initiation regions that may be a contributing factor. Fatigue crack propagation appeared to be initially driven by opening-mode loading, but at a crack length of approximately 0.5 inches (12.7 mm), there is evidence of mixed-mode crack loading. For the longest cracks studied, shear-mode displacements destroyed crack-surface features of interest over significant portions of the crack surfaces. |
| File Size | 6141741 |
| Page Count | 29 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20100011385 |
| Archival Resource Key | ark:/13960/t5p898959 |
| Language | English |
| Publisher Date | 2009-07-15 |
| Access Restriction | Open |
| Subject Keyword | Nonmetallic Materials Depletion Length Helicopters Fatigue Materials Bending Stiffness Surface Cracks Displacement Loads Forces Crack Initiation Crack Propagation Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
