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Mobile Metal Manufacturing Technologies For Repair And Retrofit of Infrastructure Systems



OBJECTIVE: Develop an in-situ manufacturing system for repair or retrofit of existing structures such as railways and bridges with the ability to match or improve upon existing material performance. 

DESCRIPTION: With the demand for persistent readiness of critical infrastructure such as rail and bridge structures, the need for the ability to repair and improve upon existing large metal structures becomes more crucial. These needs range from the ability to repair metal structures with the same material to retrofit with materials exhibiting improved material properties over the existing structure which impart new capabilities to carry heavier loads and/or improve durability. Recent advancements in additive manufacturing have developed several technologies such as cold spray and additive friction stir which provide unique capabilities to deposit material on existing structures and maintain or improve upon the performance characteristics of the original wrought material. The goal of this topic is to develop a system capable of rehabilitating existing structures such as railway rails and bridges using an additive process. The proposed system should not only be able to provide in-situ repair of the base material, but also be capable of improving upon the existing material properties through processes or material improvements. The additive manufacturing repair process needs to have a deposition rate of at least 80 cm3/hr. in order to be economically viable for large structures. 

PHASE I: Demonstrate the feasibility of material repair prototypes which exhibit favorable mechanical properties for structural performance. Develop a few small-scale prototypes using the proposed process for a steel structure. Demonstrate the feasibility of applying the repair/update process to existing structures. Deliver a report documenting the research and development efforts along with a detailed description of the proposed methodology. The most effective process capable of repairing/improving existing structures with the desired material properties will be determined and proposed for phase 2. 

PHASE II: Manufacture the proposed repair technology. Develop a set of small-scale mechanical tests to demonstrate the performance of the developed repair process. Apply the proposed rehabilitation methodology to a damaged steel structure as a repair method and demonstrate the repaired area has comparable properties to that of the original structure. Demonstrate that the technology could be used on a wide range of structure geometries and open environments. Determine the effects of varying specific structure/composition parameters on the mechanical performance of the prototype. Develop a parametric study which systematically varies the composition, microstructure, and processing of the material to determine the conditions for manufacturing operations. In addition, determine the environmental stability of the backing material: relevant variables to consider are temperature, corrosion resistance, and effects of strain rate. Deliver a reporting document: (1) the formulation, composition and process for fabrication of the repaired structure; (2) the experimental procedures and results that demonstrate the process meets the performance requirements; (3) the experimental procedures and results showing the repaired material meets the performance requirements. A favorable performance evaluation will lead into Phase III applications. All research, development, and prototype designs shall be documented with detailed descriptions and specifications of the composition, fabrication, microstructure, and mechanical performance of the prototype repair materials. 

PHASE III: The development of a process capable of repairing/improving on existing railway and bridge systems has a wide range of applications in both the military and civil works areas as well as in both government and private sectors. A metal repair process such as this could also potentially be used for in-situ repair of ships or complex parts such as submarine propellers, automotive parts, etc. The process could also be used in a wide range of coating applications. The ability to repair an existing structure in-situ with a metal additive process opens an endless amount of possibilities for applications. 


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