Digital Repository, Youth Symposium on Experimental Solid Mechanics

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Fracture mechanics analyses of the slip-side joggle regions of wing-leading edge panels
Ivatury S. Raju, Norman F. Knight, Jr., Kyongchan Song, Dawn R. Phillips

Last modified: 2010-09-06


ach Space Shuttle Orbiter wing is comprised of 22 leading edge panels. These panels are part of the thermal
protection system that protects the Orbiter wings from extreme heating that take place on the reentry in to the
earth atmosphere. On some panels that experience extreme heating, liberation of silicon carbon (SiC) coating
was observed on the slip-side regions of the panels. Global structural and local fracture mechanics analyses were
performed on these panels as a part of the root cause investigation of this coating liberation anomaly. The wing-leadingedge
reinforced carbon-carbon (RCC) panels, Panel 9, T-seal 10, and Panel 10, are shown in Fig. 1, and the progression of
the stress analysis models is presented in Fig. 2. The global structural analyses showed minimal interaction between
adjacent panels and the T-seal that bridges the gap between the panels. A bounding uniform temperature is applied to a
representative panel and the resulting stress distribution is examined. For this loading condition, the interlaminar normal
stresses showed negligible variation in the chord direction and increased values in the vicinity of the slip-side joggle
shoulder. As such, a representative span–wise slice on the panel can be taken, and the cross section can be analyzed
using plane strain analysis.

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