Honeycomb Panel Structures

Brazed Titanium Panels

• Alloys: Beta 21S, Ti3AI2.5V, Ti6AI4V, TICP
• Brazing Alloys: TiCuni, NiCu
• Applications: engines nacelles, control surfaces, wing panels, air vehicle platforms

Brazed Inconel and Stainless Steel Panels

• Alloys: Inco 617, 625, 718, Stainless 304, 316, 321, 15-7 ph
• Brazing Alloys: AMS 4777, BNi-5A, and others
• Applications: nacelle, heat shields

Bonded Stainless Panels

• Alloys: 304, 316, 321, 15-7 ph
• Applications: Naval doors, Bulkheads, Transit floor panels

Graphite / Titanium Honeycomb

Titanium honeycomb core advantages in graphite bonded structures

• Low structural weight fraction (compared to stiffened or monolithic skins)
• High stiffness / panel stability / flutter resistance
• Robust designs (carries loads after high impact)
• Simplified construction (reduced fasteners / part count) equals lower assembly cost
• Impact damage easily detected and repaired
• Eliminates corrosion issues of aluminum
• Fluid intrusion / leakage can be eliminated
• Laser welded nodes & square cell yield high shear strength (with balanced L&T properties) and extremely high compressive strengths
• Broad design latitude (few restrictions)
• Ability to tailor cell size / density for optimum design
• Galvantic and thermal compatibility with graphite
• Compatible with BMI resins
• Higher temperature capability
• GR/Epoxy Laminates - 250F hot/wet
• GR/BMI Laminates - 350F hot/wet
• GR/PMR Laminates - 600F

Benecor titanium surface preparation process enhances panel bond strengths

Impact damage modes by skin design:	Damage modes:
	Impact side - very visible (local damage) Internal - core crushing (no disbonds) Back side - no damage
	Impact side - barely visible Internal - foam crushing & disbond Back side - no visible damage
	Impact side - barely visible Internal - delaminations Back side - no visible damage

Impact damage relationship

Ti-Core Sandwich	Monolithic (Solid GR/EP Laminate)
20 CM2 damage area confined to the core crush - no delamination of graphite skins	1020 CM2 damage area damage mechanism ply delamination
Graphite / Titanium - 3 point bend coupon	Graphite / Titanium Spar - Fuselage Structure
Failure in honeycomb - no delamination of graphite
Graphite / Titanium Flight Surface Skin Panel

Titanium Honeycomb Corrosion Resistance

SO2 / Salt Spray Exposure at Impact Site - Graphite / Epoxy Laminates