How do you assess impact damage in composite structures?

Composite impact damage assessment considers: Barely Visible Impact Damage (BVID) threshold - typically 50-100 J creating dent just visible to the eye; Internal damage extent (delamination, matrix cracking) often larger than visible indication; Inspection methods (detailed visual, tap test, ultrasonic for damage mapping); Residual strength analysis - Compression After Impact (CAI) is critical as delamination causes buckling; and Hot-wet property knockdown. Damage tolerance requires demonstrating limit load capability with BVID anywhere. Visible Damage (VID) requires repair before continued flight. Design allowables include impact knockdowns; CAI strength may be 40-60% of undamaged strength.