TRL-7 is a major step from TRL 6, requiring the demonstration of
an actual prototype in an operational environment.
The fabrication of a series of structural performance models was
completed under shipyard welding conditions. Holding bulkhead panel models,
foundation models, and a full-scale foundation were evaluated and demonstrated
satisfactory structural performance.
The Electric Boat Division [General Dynamics Corporation]
fabricated the full-scale foundation and a small, heavy-gage tank model. NNS
partially completed the fabrication of a full-scale hard tank; however, a
funding shortage precluded tests. In these shipyard fabrication exercises, all
weld cracking was related to SMAW and SAW consumables (where cracking occurred
even when HY-100 preheat temperatures were used) or to improper welding
practices. No HAZ cracking occurred in HSLA-100.
Hydrostatic tests of full-gage bulkhead panel models are an
extreme test of platingto-stiffener strength and HAZ ductility. The HSLA-100
panel models exceeded anticipated holding pressure levels, withstanding over
twice the holding pressure of identical HY-100 panel models. A series of
foundation beam elements (full-scale) and the full-scale SSN 688-type AC
foundation were installed and tested on a floating shock platform. The
structures were subjected to a series of underwater explosion (UNDEX) shock
tests. For a series of 3 UNDEX events, the structural response of the HSLA-100
items indicated no cracking or excessive deformation in any structural
Czyryca, E.J., Assessment of HSLA-80 and HSLA-100 Steels for
Submarine Non-Pressure Hull Applications, CARDIVNSWC-TR-61-94/38,
Preliminary, February 1995.
Fugate, S.P., Fabrication of the HSLA-100 Foundation
Structure, Electric Boat Division of General Dynamics Corporation, Report
No. 276, Contract No. 00024-86-C-2059, June 1988.
Kenney, D.P., and S.P. Fugate, Fabrication of an HSLA-100
Model Structure, Electric Boat Division Report No. PDE-279, NAVSEA
Contract No. N00024-86-C-2059, July 1989.
Knight, D.E., and J.R. Carlberg, Shock Performance Evaluation
of HSLA-100 Foundation Structures, DTRC/SSPD-90-172-1, October 1989.
Spaulding, R.S., P.D. Thomas, and R.A. Spitzer, HSLA-100 Hard
Tank Fabrication and Fatigue Model, Design and Fabrication Report, Newport
News Shipbuilding and Drydock Company, Report G2001- 0059, Contract No.
N00024-87-C-2012, 9 September 1988.
Thomas, P.D., HSLA-100 Hard Tank Fabrication and Fatigue
Model Construction, Newport News Shipbuilding and Drydock Company, Report
No. ES10-1, Contract No. 00024-85-C-2056, 29 July 1988.