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Alternative Manufacturing Technologies for Bridging and Structural Applications

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: The objective of this SBIR is to develop parts made with alternative manufacturing technologies to be integrated into bridges or other high strength structures. 

DESCRIPTION: Typically, connections are the most difficult part to design, manufacture, and test in bridges and other structures. From a design perspective, military bridge connections are typically unique to the system due to each system having different loading requirements. As military vehicles become heavier, bridge capacities must also increase. Nearly every increase in bridge capacity requires an extensive effort to design and test a connection to support the increased vehicle weight. Typically, the connections are then designed to be the most robust and heaviest part of the system and end up with a large amount of wasted material that is not highly stressed. Traditionally, connections in military bridging are made from high strength materials and involve time-consuming manufacturing processes. For example, a bridge connection may be forged, rough machined, heat treated, final machined, assembled, line-bored, and post-processed. Each process then requires a unique fixture and typically will only work for that specific bridging system. Military bridging systems are often manufactured in relatively low volume with a large production run not exceeding 1,000 parts. These time consuming manufacturing processes are taken so that the final product is lightweight, strong, durable, and easily assembled in the field, usually by a pin/clevis type joint. This results in the connections being the most expensive part of the bridging system to manufacture. In addition, conventional manufacturing methods for these extreme conditions have been proven to fail before the threshold requirements are met. This SBIR seeks to understand the impact of using alternative manufacturing technologies on cost, strength, durability, weight, structural efficiency, and manufacturability of the bridge connection. We are looking for designs that optimize material layout within a given design space, for a given set of loads, boundary conditions and constraints with the goal of maximizing the performance of the integrated system. Technologies such as additive manufacturing allow for great flexibility in design, and complex geometry does not generally impact cost of the part. This SBIR seeks an innovative solution to develop a connection that is easily scalable to different loading requirements, is structurally efficient, and is easy to manufacture. In order to support various vehicles on a range of bridging systems, there are different load capacity requirements. On the low end, a connection should maintain a 15,000 lbs sustained tensile load representative of a dead load plus a maximum live load of 200,000 lbs. On the high end, the connection should maintain a 200,000 lbs sustained tensile load representative of a dead load plus a maximum live load of 500,000 lbs. The connection should not weigh more than 75 lbs and 250 lbs at low and high end respectively, and be no larger than 400 cubic inches for the low end and 2000 cubic inches for the high end. The connection should be able to support a minimum of 10,000 fatigue cycles, with 30,000 to 50,000 as the objective. 

PHASE I: The Phase I effort will assess the feasibility and performance characteristics for using alternative manufacturing technologies in bridging and other structural applications, specifically at the connections. These studies should include discussions with TARDEC to identify specific requirements for connections manufactured using this technology, such as strength, durability and weight of the connection. The goal would be to develop a concept for a connector design that is producible using alternative manufacturing technology, scalable to meet the different loading requirements at the high and low end of the loading spectrum, and can take advantage of the increasing geometric complexity that these technologies can accommodate. Analysis of the design concept should include plans for integration into a larger structure, to be determined as part of initial discussions with TARDEC, that could be made of various materials and the determination of techniques to reduce the amount of material wasted during manufacturing. Small scale component testing, which may include but is not limited to Fatigue, Overload, Corrosion, Finite Element Analysis, Modeling & Simulation, Tensile, Micro Structure Analysis, and Fracture Toughness may also be performed to obtain an initial assessment of the manufacturing process viability and connection design performance. Phase I should begin to analyze the effectiveness of different materials in their ability to meet the requirements and be used to manufacture connections using alternative manufacturing techniques. 

PHASE II: Phase II should further develop the concept from Phase I for a scalable connector design, to include material selection, manufacturing process selection, and geometry optimization. As part of the effort, 1 or more full scale prototype connection(s) should be manufactured and tested in overload, fatigue and environmental to verify the analysis performed in Phase I. The effort should also include information on how to integrate the new design into the larger structure identified in Phase I. Phase II shall result in a full scale prototype that meets or exceeds current connector designs, manufactured using alternative manufacturing processes, which will be delivered to TARDEC for further evaluation. 

PHASE III: Phase III work will further demonstrate the capability of the technology to be utilized for a variety of large structures. The technology will initially be used for rapid development, prototyping, and manufacturing of connections in military bridging structures. Other commercial opportunities include development and prototyping of civil structures through alternative manufacturing technologies. These connections would provide cost effective solutions that maintain high strength and durability. Due to the flexibility in alternative manufacturing techniques, the connections could be quickly optimized for different loadings and applied to different industries as applicable. 

REFERENCES: 

1: Additive consistency of risk measures and its application to risk-averse routing in networks, R. Cominetti and A. Turrico, arXiv: 1312.4193v1 [math.OC] 15 Dec 2013.

2:  Cooperative learning in multi-agent systems from intermittent measurements, N. Leonard, A. Olshevsky, arXiv: 1209.2194v2 Sept 2013.

3:  Learning of coordination: exploiting sparse interactions in multiagent systems, F. S. Melo and M. Veloso, Procs of 8th Int. Conf on Autonomous Agents and Multiagent Systems, 2009.

4:  Collaborative multiagent reinforcement learning by payoff propagation, J. R. Kok and N. Vlassis, Journal of Machine Learning Research 7, 2006.

5:  Collective decision-making in ideal networks: the speed-accuracy tradeoff, V. Srivastave, N. E Leonard, arXiv 1402.3634v1 Feb 2014.

6:  The topology of wireless communication, E. Kantor, Z. Lotker, M. Parter, D. Peleg, arXiv 1103.4566v2 Mar 2011.

7:  A review of properties and variations of Voronoi diagrams, A. Dorbin.

8:  Risk Measures for the 21st Century, Giorgio Szego (Editor), Wiley

9:  1 edition 2004.

KEYWORDS: Alternative Manufacturing, Bridging, Structures, Bridge Connections, Structural Connections, High Strength Connections 

CONTACT(S): 

Adam Henry 

(586) 282-6319 

adam.j.henry14.civ@mail.mil 

Bernard Sia 

(586) 282-6101 

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