Title: Rapid Cure Honeycomb Sandwich Composite Repair

Authors: Elizabeth J. Andrew, Luke Colone, Simon Chung

DOI: 10.33599/nasampe/c.25.160

Abstract: With the increased reliance on enhanced composite material system capabilities to meet the operational demands of the 21st century warfighter, the Navy has a critical operational requirement for a lightweight honeycomb core filler for repairs. The current repair and maintenance approach requires a short, room-temperature cure in order to maximize the life of these high-performance composite components and structures. There are two general repair approaches for sandwich structures: core fill and replacement honeycomb. For large repairs, replacing the honeycomb is currently required due to the weight and structural performance attributes associated with state-of-the-art (SOTA) materials. As such, a novel, light-weight, fastcuring filler material, dubbed HexHeal Pro, is being developed with enhanced mechanical properties to facilitate larger potting repairs that would eliminate the need to replace the honeycomb. The material formulation features fire retardancy not currently characteristic of comparable legacy systems, and minimizes downtime by curing swiftly, enabling faster repairs and reduced operational disruptions: 1 hour time to sand (finishing operation) versus 8 hours for the incumbent, legacy material. HexHeal Pro also cures across a broad temperature range, which means assets can be reliably used for repairs in diverse environmental conditions and operational settings including exposure to freezing temperatures (0°C, 32°F). These improvements enable a 70% reduction in repair time and 50% increase in the diameter of repairs. Streamlining larger honeycomb repairs has the potential to return a significant cost-savings to the Navy and also positively impacting the operating tempo (OPTEMPO) of the associated platforms.

References: 1. NAVAIR 01-1A-21, TECHNICAL MANUAL, ORGANIZATIONAL AND INTERMEDIATE MAINTENANCE, GENERAL COMPOSITE REPAIR, 01 AUG 2015 2. Andrew, A., “Room-Temperature Filler for Honeycomb Repairs – Technical Progress Report,” MSC TPR 23787/AA47, Contract No. N68335-23-C-0523, SBIR Topic Number N221-006, Oct 2024 3. ASTM D 792-20. "Standard Test Method for Density and Specific Gravity (Relative Density) of Plastics by Displacement." Annual Book of ASTM Standards. ASTM. Philadelphia, PA. 04/2019. 4. ASTM D 695-15. "Standard Test Method for Compressive Properties of Rigid Plastics." Annual Book of ASTM Standards. ASTM. Philadelphia, PA. 07/01/2020. 5. Andrew, A., “Room-Temperature Filler for Honeycomb Repairs – Technical Progress Report,” MSC TPR 23699/AA47, Contract No. N68335-23-C-0523, SBIR Topic Number N221-006, July 2024 6. Andrew, A., “Room-Temperature Filler for Honeycomb Repairs – Technical Progress Report,” MSC TPR XXXX/AA47, Contract No. N68335-23-C-0523, SBIR Topic Number N221-006, April 2025

Conference: CAMX 2025

Publication Date: 2025/09/08

SKU: 160

Pages: 7

Price: $14.00