|
Manufacturing of Stress Physical Scale Models (SPSMs) for Signature Reduction and Resistance to Environmental Stress
Navy SBIR 2011.2 - Topic N112-153 ONR - Mrs. Tracy Frost - [email protected] Opens: May 26, 2011 - Closes: June 29, 2011 N112-153 TITLE: Manufacturing of Stress Physical Scale Models (SPSMs) for Signature Reduction and Resistance to Environmental Stress TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes OBJECTIVE: Develop a low cost capability to manufacture physical scale models of Navy vessels that are dimensionally accurate, have electromagnetic signatures representative of the full-scale model, and react magnetically exhibiting magnetization change and hysteresis behavior properties to physically applied (environmental) stress forces as would a full-scale vessel. DESCRIPTION: Typical scale models of ships and submarines focus on the aesthetic quality of the model and the rough scale of their major exterior features. However, scale models are crucial in the early stages of design and analysis of ship features and characteristics well before beginning production of the actual vessel. Physical scale models (PSMs) are made to be dimensionally accurate and represent the physical signatures of the vessels in a high-fidelity environment for test and evaluation. Stress physical scale models (SPSMs) mimic the effects of structure and materials in response to physical stimuli, e.g., wave action, vibration, seaway and environmental stress hull loadings, acoustic and electromagnetic (EM) propagation. This requires the model to have high-fidelity key features. The Navy is interested in studying the magnetic effects of ship hulls and hull forms that have been exposed to stresses typical of seaway loads and other environmental stress loadings along all or part of the hull structure. For this purpose, studies of SPSMs are important. SPSMs are 1/30 to 1/60 the size of full-scale with EM signatures corresponding to the full-scale structure. SPSMs need to be representative of a ship�s structure including medium-to-detailed interior structure, be able to accept degaussing coils for magnetic compensation, and be instrumented with sensors for physical data acquisition during high-fidelity testing conditions involving high stress. SPSM test results are important and influence the design of ships, especially in cases when SPSM results arrive late in the design of a ship and significant design changes and extensive re-work of the ship design are necessary. Currently SPSMs are manually assembled from sheet metal that is cut and welded and manual insertion of degaussing coils. Making a SPSM is very labor intensive, expensive, and lengthy, requiring long lead times. Few models are actually available for test. The current process is slow to respond to design changes. Manufacturing of SPSMs would benefit from an integrated approach to design, modeling, physical testing, and analysis that leverages advanced information technology and fabrication technologies. Ship acquisition would greatly benefit by a capability to more rapidly and easily test more design alternatives with more and different kinds of materials while still meeting its EM objectives before committing to a final design. The goal is to reduce cost by one-half, reduce build-time from months to a few days, and allow degaussing coils be made in situ or inserted later. New technologies such as solid freeform fabrication, additive manufacturing and direct digital manufacturing, which are suitable for "art-to-part" approaches, mass customization, flexibility in design changes, automation, and robotic assembly, can be explored for their usefulness for SPSM development. PHASE I: Develop the design of a capability and technical justification of its feasibility to prototype a SPSM with representative EM signatures and mechanical durability. PHASE II: Develop the technology capability to make a SPSM, based the design from phase 1, and demonstrate that it meets the desired goals. Provide a significant SPMS sample, based on a drawing in a standard CAD system such as, e.g., AutoCAD or CATIA, for independent testing of EM signatures, especially under mechanical stress. PHASE III: Transition the SPSM manufacturing technology to critical military use and the civilian sector. Build marketable manufacturing units and demonstrate the fabrication of a test model. For example, construct a SPSM of a complex Navy ship/submarine with degaussing coils. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: A successful SPSM fabrication system would be useful for a variety of commercial applications. An example could be an underwater exploratory vessel. Its affordability and versatility will result in new businesses and industries, and high value jobs. REFERENCES: 2. John J. Holmes, Modeling a Ship's Ferromagnetic Signatures, 1st ed., Morgan & Claypool, 2007. 3. ASNE Ships & Ship Systems Technology (S3T) Symposium, "The Role of Physical Scale Models in the Design of Ship Degaussing Systems in the Age of Computer Modeling" (Mr. William Gay & Mr. Robert Wingo), 13-14 November 2006. KEYWORDS: Stress Physical Scale Model; Electromagnetic Signature; Environmental Stress; Additive Manufacturing; Cost Reduction.
|