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

light surface panels Benecor, Inc. makes titanium wing panels itanium door panels

Brazed Inconel and Stainless Steel Panels

Benecor, Inc. makes inco 625 brazed heat shields Benecor manufactures rib junctions Spool Insert welded panel assembly

Bonded Stainless Panels

Benecor, Inc. manufactures bonded stainless 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