Grants and Contracts Details
The reduction of the underwater electromagnetic signature of a Navy vessel, surface or otherwise, is critical to its survivability. A steel–hulled vessel has a permanent magnetization and perturbs the Earth’s magnetic field as it moves through the water. This field disturbance is possibly detectable by a hostile ordnance or device. Degaussing systems comprising current-carrying coils can significantly reduce a vessel’s magnetic signature by partial cancellation. Since steel is a hysteretic magnetic material, changes in the magnetic field due to vessel orientation, eddy currents, onboard motors and generators, etc., alter the magnetic properties of the steel and, hence, its permanent magnetization. Furthermore, dynamic mechanical stresses, e.g., varying sea states and hydrostatic pressure, encountered by the hull change the permanent magnetization of the vessel due to reverse magnetostriction. Since such changes in the permanent magnetization cannot be well predicted currently, the vessel’s degaussing system will slowly lose calibration. The objective of the proposed research is to further develop software simulation tools that can accurately and efficiently predict changes in induced and permanent magnetization of a naval vessel undergoing dynamic changes in the applied magnetic field and mechanical stress due to hydrostatic pressure. The electromagnetics group at the University of Kentucky has been developing a software toolset (referred to as Magström/Stress3D) to model the magnetic signature of vessels as they move through the earth’s magnetic field and are subject to fluctuating stresses. Key goals are development of the Magström/Stress3D software to 1) use a new localizing mode formulation to reduce factorization memory and speed up the solve portion, 2) revise the mesh storage scheme for distributed simulations to remove the current major memory bottleneck and develop an alternative fill procedure based on equivalence boxes, 3) characterize the accuracy of the Magström solver when using non-conformal meshes and investigate techniques to mitigate any loss of accuracy, 4) stabilize transient eddy current simulations by incorporating a more robust time-stepping procedure, 5) investigate the prediction of corrosion related magnetic fields using Magström, and 6) continue transition of software to NSWCCD.
|Effective start/end date||9/1/16 → 8/31/21|
- Office of Naval Research: $649,197.00
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