N251-049 TITLE: Emergency & Short-term Structural Repair System

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials

OBJECTIVE: Develop a patching and repair system able to replace or strongly reinforce the original form and function of a damaged structure or component.

DESCRIPTION: Several past incidents (e.g., collisions, fires, drone/missile hits, and general material failure) have created hull penetrations and structural failures or scenarios where internal structural repairs are required on an immediate basis. The Navy seeks the development of a cost-effective durable patching and repair system that is convenient to store, can be easily applied to a variety of surfaces, and can be set or stiffened to the extent the patch material is able to substitute or strongly reinforce the original form and function of a damaged structure or component. The Navy seeks to develop a product that functions as a temporary repair in the event of a hull penetration or structural failure. The solution must be able to be applied while underway in a wide range of environmental conditions. The primary purpose of the repair will be to allow the ship to safely return to a destination where a more permanent repair is possible. Current commercial repair methodologies are not suitable for remediation of emergent damage while underway.

The solution should be able to be applied to a range of irregularly shaped openings and provide support for structural loads and restore the environmental integrity of the space. The repair system must stiffen to form a temporary but strong, durable, and water-tight seal. Examples of repairs include but are not limited to bracing, bonding, joining, encapsulating, plugging or patching. The repair technology will be required to be applied either indoor or outdoor and should cure regardless of temperature, humidity, and dampness. The desired product should fully cure within 1 hour. The solution must not emit toxic fumes during application and curing. Innovative joining and bonding methods are expected outcomes of this SBIR topic. The developed product should be applicable to all traditional ship steel and aluminum construction materials as well as support structures. Repair work should require minimal surface preparation such as degreasing, removal of foreign matter, or smoothing to allow for maximum contact with the patch material.

The repair material once cured should be resilient against normal pressures and in-plane ship motion/system stresses/loads. Repairs should survive wave slap green sea pressures of 4.65 Pounds Per Square Inch (psi) (normal to the deck) to 14.33 psi (normal to vertical surfaces/bulkheads), weapon blast pressures up to 20 psi, and survive a lap shear strength of the joint > 3 kilopound per square inch (ksi). In-plane structural stress levels expected are 7-9 ksi for aluminum structures and 20-30 ksi for steel. The largest damage to be addressed in this topic would be a 4’ diameter hole from a missile or drone penetration. The patch may or may not employ a system of ribbing for reinforcement to achieve the necessary strength; however, the ribbing must use the same patch material (either in flat sheets or geometric configurations) and must be able to be stiffened upon application within the same hour of set-time allotted for the primary patch. In repair applications, the repair must be resilient against tensile and torque forces.

Repair materials should meet Navy Fire, Smoke, and Toxicity (FST) standards. NAVSEA has published Design Data Sheet (DDS-78-1) to facilitate the transition of the new composite materials in U.S. Navy shipbuilding [Ref 3]. The material fire performance requirements described in this design data sheet are intended to provide consistent safety criteria for the application of composites aboard ships. These requirements have been developed based on Navy fire safety policy and international maritime standards for fire safety. Fire performance requirements for surface flammability, fire growth, smoke generation, fire gas toxicity, fire resistance, and structural integrity under fire have been established. Initial FST performance testing should include flame spread testing ASTM E162, E662, E800.

PHASE I: Develop a concept for a rapid damage repair system that meets the requirements in the Description. Demonstrate the feasibility of the operational concept with development and initial testing of the repair system. Demonstrate by Modeling and Simulation (M&S) or Finite Element Analysis (FEA) of the predicted performance of the proposed repair system to meet the requirements defined in the Description. The Phase I Option, if exercised, should include the initial layout and capabilities to demonstrate the application in Phase II.

PHASE II: Develop and deliver a prototype able to demonstrate the hardened patch material to the requisite specs, and ultimately be tested to failure. Evaluate the durability and how long the patch/repair holds. Perform a test plan as defined in Phase I to include applicable FST standards. Incrementally increase the stress loads to induce a failure point while observing and recording the failure. Prepare a Phase III development plan and cost analysis to transition the technology to Navy use.

PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the Emergency & Short-term Structural Repair System for use on the Large Surface Combatant Modernization and Sustainment program. Strong temporary repairs that rapidly set have a wide range of applicability in the U.S. Navy as well as the commercial marine industry. The specifications cited are generally more rigorous and designed to allow for a strong temporary repair while a ship is underway and in a range of weather conditions. Such a repair will allow the ship to safely arrive at a destination where a more permanent repair is possible. The repair system also has universal applicability for non-maritime repairs.

REFERENCES:

1. Aabid, Abdul; Baig, Muneer and Hrairi, Meftah. "Advanced Composite Materials for Structural Maintenance, Repair, and Control." Materials 2023, 16, 743. 10.3390/ma16020743. https://www.mdpi.com/1996-1944/16/2/743

2. Cunha, L.G.; Alonso, R.C.B.; Pfeifer, C.S.C.; Correr-Sobrinho, L.; Ferracane, J.L. and Sinhoreti, M.A.C. "Contraction stress and physical properties development of a resin-based composite irradiated using modulated curing methods at two C-factor levels." Dent Mater. 2008 Mar; 24(3) :392-8. DOI: 10.1016/j.dental.2007.06.006

3. "DDS-078-1: Composite Materials, Surface Ships, Topside Structural and Other Topside Applications, Fire Performance Requirements, 11 August 2004." https://navysbir.com/n25_1/N251-049-Reference-1-Composite_Materials-Topside.pdf

KEYWORDS: Temporary Patch; Patching and Repair System; Ductile strength; Tensile strength; Emergent repair capability; Structural Patch.

TPOC 1: Nicholas Tastad
(202) 781-2652
Email: [email protected]

TPOC 2: Luis Moreno
(202) 781-537
Email: [email protected]

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