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Technical Director’s Innovation Challenge - Structural design optimization: producibility vs. weight

By Benjamin McKnight III, NSWC Carderock Division Public Affairs | NSWC Carderock Division | Dec. 13, 2018

WEST BETHESDA, Md. —

In April 2017, the Congressional Budget Office estimated that the U.S. Navy would have to spend an average of $26.6 billion a year in shipbuilding costs for 30 years to reach its 355-ship goal. According to the same CBO report, to build and operate those 355 ships would cost about $102 billion each year through 2047. Skylar Stephens and Nathan Hagan of the Criteria and Risk Assessment Branch at the Naval Surface Warfare Center, Carderock Division, believe that cost can be reduced.

Through the Technical Director’s Innovation Challenge, Stephens and Hagan undertook a project to determine how the Navy can save money on their ship production by changing the criteria used to make a vessel.

“We try to optimize our structures based on how low we can get the weight down and still pass all of our criteria, but that really doesn’t do us justice,” Stephens said. “It does not account for the life-cycle support cost of the ship, and it oversimplifies the contributions that are associated with acquisition cost estimates of a vessel.”

Simply put, there are a multitude of other factors that Stephens thinks need to be considered in ship building, and accounting for said factors could reduce the amount of money spent on a ship throughout its life. The project, titled “Producibility Structural Design Optimization,” looks to identify more efficient metrics of ship building standards so engineers can include them into their programming.

“As part of the effort, I interviewed lots of subject-matter experts who had written papers in this area, people like Bob Keane (a former U.S. Navy chief naval architect),” Stephens said. “What we found is different definitions of producibility.”

Stephens identified producibility as factors such as how many labor hours it would take to build a ship, how susceptible parts would be to damage and corrosion or how much it would cost the Navy for ship repairs in the long run.

“Producibility is in all of those things; it’s not just how easy it is to make, it’s also how easy it is to maintain the vessel for a life cycle support,” Stephens said.

Tackling this project included taking a human-centered design workshop at the U.S. Office of Personnel Management in Washington, D.C., a course which Stephens credited as a key factor in their research and success.

“That process of thinking and listening to people is critical and something we don’t get in our day-to-day work,” Stephens said. “Seeing people like Jeff Hough (Carderock’s distinguished engineer for ship design) and Bob Keane discuss what producibility is and what the Navy needs to do to address it, you learn a lot more in a situation like that.”

The project is far from complete, and for Stephens and Hagan, there is not a clear way forward at the moment. What they do have, however, are pieces to their puzzle that Stephens thinks he can use in his other Carderock assignments. According to Stephens, their current producibility variables can be assigned as either quantitative or qualitative metrics, with the former being the easier of the two to implement.

“To move it forward, we need to integrate it into the tools that we use here at Carderock,” Stephens said.  

With his Integrated Structural Design Environment team, Stephens is attempting to include the quantitative metrics they discovered into the software that is used for designing ships. Stephens’ hope is that showing the positive changes that can come with using the quantitative elements of producibility in programming will lead to funding for execution on a larger scale.

“It won’t necessarily be an optimization algorithm that gives me the most producible design, but at least it’s a step forward,” he said.