Naval Surface Warfare Center, Carderock Division’s Naval Architecture and Engineering Department is conducting a Large-Scale Additive Manufacturing (LSAM) model feasibility study to assess the accuracy of using additively manufactured (AM) models for future experiments. The study, which also includes resistance testing on Carriage 1 in Carderock’s David Taylor Model Basin (DTMB), will determine if AM models can withstand the typical stresses of a carriage test and match the results from the same hull design manufactured from fiberglass material.
Carderock’s Surface Ship Hydromechanics Division is leading the study with the support of the Naval Innovative Science and Engineering (NISE) program as part of the LSAM FY 21-23 testing environment task proposal. Testing in Carderock’s DTMB, in West Bethesda, Maryland, took place in September 2023.
Discussions about the idea to test LSAM technology at the command began in late 2019 to early 2020. As a proof of concept, Carderock’s Facility Engineering and Operations Division 3D printed a model-scale submarine bow. Encouraged by the results, the Naval Architecture and Engineering Department head instructed Carderock’s Surface Ship Hydromechanics Division to pursue printing a full-size surface ship model to see if this approach was worth further pursuit. The group submitted their proposal to NISE in 2021 and was funded to proceed.
“I think one of the big interests within Carderock as a whole, and especially our department, is wanting to transition this technology for practical use,” Engineer Kyle Mosqueda said. “We could build models a lot faster and a lot cheaper.”
If this experimentation is successful, it could provide the U.S. Navy significant cost and time savings in manufacturing, rigging and testing capabilities. It is also possible it could change the way Carderock designs its models for testing and influence the next generation of model making.
The hull set to be tested at the DTMB is a pre-contract representation of the Arleigh-Burke class destroyer (DDG 51). This hull form is widely utilized as a benchmark geometry for engineering and scientific investigation in the naval hydrodynamics community.
Some of the specific model characteristics the group will be observing are water absorption changing the geometry of the model, hull crack development and the magnitude of hull deformation while underway.
The ship model was designed at Carderock and contracted out for 3D printing to Airtech International, Inc. in Springfield, Tennessee. It is 20.23 feet in overall length with a beam of 2.49 feet.
Mosqueda and his team have high expectations for the result of this trial. The model underwent a calm water tow tank test at a maximum Froude scaled speed of 6.4 knots, which is equivalent to a little more than 7 miles per hour.
“I’m curious to see if the DDG 51 model deflects while underway,” Mosqueda said before the test in September. “I am testing the fiberglass model and the LSAM model one after the other, and then comparing the results. I have high confidence that they will be comparable and will further validate this great piece of technology for future implementation.”
Preliminary results from the study indicate that the LSAM model compares well to the fiberglass model in terms of total resistance and underway deformation observed while testing. Because of this, Mosqueda and his team believe that LSAM technology is a feasible alternative to model making for calm water resistance testing. As part of the continued feasibility experimental testing, Mosqueda was awarded funding through a FY 24 NISE proposal to structurally evaluate the LSAM model. The team expects to put the model through a seakeeping and loads experiment in FY 25 at the Maneuvering and Seakeeping Basin where the model will be exposed to scaled sea states.
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