摘要：

The use of composite sandwich construction is rapidly increasing in current and211u001efuture airframe designs especially for general aviation aircraft and rotorcraft. 211u001eTypically, sandwich constructions for these applications use thin-gage composite 211u001efacesheets (0.020 in to 0.045 in) which are cocured to honeycomb and foam cores. 211u001eDue to the nature of these structures, damage tolerance is more complex than 211u001econventional laminated structures. Besides typical damage concerns such as 211u001ethrough penetration and delamination, additional modes including core crushing 211u001eand facesheet debonding must also be addressed. This complicates the 211u001ecertification process by introducing undefined Allowable Damage Limits (ADL) and 211u001eCritical Damage Thresholds (CDT) as related to the ultimate and limit load 211u001ecarrying capability of the structure. This document provides a background review 211u001eof previous damage tolerance investigations including an overview of traditional 211u001emetallic damage tolerance methodologies.

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