Dahlgren Division, Naval Surface Warfare Center 17320 Dahlgren Rd, Dahlgren, VA 22448-5100

A -- LIGHTNING EFFECTS ON MULTILAYERED COMPOSITE STRUCTURES SOL N00178-96-Q-3009 DUE 112695 POC (540)653-7765; FAX (540)653-6810 CONNIE GAYLE, CONTRACT SPECIALIST. The Dahlgren Division, Naval Surface Warfare Center (NSWCDD) in collaboration with the Office of Naval Research (ONR) and Carderock Division NSWC (CDNSWC), is soliciting research and development ''white papers'' for a probability of a lightning sidestrike model, testing of composites for lightning damage and determine lightning attractiveness for Frequency Selective Surfaces (FSS). BACKGROUND: The use of multilayered composite structure is necessary to meet 21st century warfighting goals. For example, the purpose of the Advanced Enclosed Mast/Sensor (AEM/S) System program is to demonstrate the ability to reduce mast signatures and improve sensor performance by enclosing/embedding radars, communication antennas, and equipment in an advanced hybrid composite mast. The overall objective is to develop an affordable mast with enhanced warfighting capabilities by fully integrating sensor technology, electromagnetics, signature reduction, advanced materials, structures, and manufacturing technologies. This program is a necessary step in the development and deployment of next generation radar and communication systems. The AEM/S System is an advanced hybrid composite mast that is a 71 foot bi-pyramidal hexagonal structure enclosing existing radars and providing important signature and other operational benefits. The upper half of the AEM/S System mast is an advanced composite hybrid frequency selective structure (FSS). This structure is designed to allow passage of own-ship sensor frequencies while reflecting other frequencies. The lower half of the mast serves an important function; it holds up the upper half. The core of the lower half is balsa; with e-glass skins. At the base of the lower half of the mast is an EM shielded compartment which utilizes reflective metallic shielding to demonstrate the ability of a composite structure to meet realistic fleet electromagnetic interference (EMI) design requirements. The AEM/S System is a free-standing integrated composite structure; there are no ribs and panels. No such structure has ever been constructed or deployed on a Navy ship. Many composite material and structure reseach and development programs for future surface combatants are underway. These composite material systems are currently being developed and will be tested onboard surface combatants in the near future. Lightning protection systems are installed on these multilayered composite structures to prevent unwanted lightning attachment. These protection system designs typically are based on analysis tools such as the rolling sphere, the cone of protection, or finite element analysis. If the lightning protection system is designed properly, the probability of such an event is highly unlikely. However, in the event of an attachment to a structure (sidestrike), the peak current value of the lightning pulse may approach 200 kiloamperes at the point of attachment. As the impulse travels to ground, it could potentially inflict damage to a structure and the equipment housed inside. The level of damage is dependent on the electrical and mechanical properties of the materials used to fabricate the structure and the configuration of the structure. The repair task, particularly for composite structures, may be costly and labor intensive. Therefore, applied research is needed relative to the following issues: (1) Probability of strike model. Measuring the probability of a lightning sidestrike to a structure is extremely expensive and highly time consuming. Therefore, research and development is required to select an appropriate model for probabilty of sidestrike and to adapt it for shipboard composite structures. Initially, the model will be used to evaluate the probability of a lightning sidestrike to a stand alone composite structure on a ship. This will provide a worst-case probability for a lightning sidestrike attachment. The feasibility of extending the model to a more realistic multiple structure platform found on typical naval ships will be studied. Once completed, this model shall provide data necessary to perform cost/benefit analyses of competing lightning protection system designs; (2) Test composites for lightning damage. The survivability of different shipboard composites to a direct lightning attachment is unknown. Lightning qualification testing to determine how much damage each material sustains for a given lightning intensity is required. A literature search will be used to develop an understanding of the level of information already documented and reduce the likelihood of redundant testing. A est matrix of relevant materials and material systems will be developed from this database and the current shipboard composite database. Using the standardized test procedures developed by the aerospace community, an appropriate test plan for testing shipboard composites will be developed. The results of the testing will show how much damage each material sustains for a given lightning intensity. This information can be used either to select materials which will have low damage susceptibility or to show when added protection is needed for materials with high damage susceptibility; (3) Determine lightning attractiveness of Frequency Selective Surfaces (FSS). Using circuit analog theory, FSS may be modeled as a bandpass filter. Therefore, there is some speculation that FSS behaves as a capacitor. If this is true, a buildup of a static charge on an FSS surface might influence the probability of a sidestrike. Research and development is required to resolve this speculation. To that end testing composites with embedded FSS layers and comparing their lightning attraction properties to other composites shall be performed. This effort will produce the most immediately applicable results and will receive an early emphasis. Proposals shall be submitted in original and three copies to the Contracting Officer, Dahlgren Division, Naval Surface Warfare Center, Attn: S137/Connie Gayle, Room A162, Building 962, 17320 Dahlgren Road, Dahlgren, Virginia 22448-5100. Proposals and all related correspondence should reference Request for Quotation number N00178-96-Q-3009. If desired, multiple ''white papers'' addressing different areas of research and development may be submitted. Offerors are encouraged to submit a one to ten page ''white paper'' summarizing the proposed effort(s) and a rough order of magnitude of cost to obtain a preliminary indication of potential NSWCDD interest. Offerors should state whether or not their facility is cleared for storing confidential information. Offerors will be requested to submit in-depth proposal(s) should NSWCDD deem the ''white paper'' of scientific and technical merit. The format for the in-depth proposal(s), if requested, should be divided into three sections: (1) a Technical Section which includes a clear statement of objective, technical approach and methodology, supporting technical information (including an indication of proprietary aspects of the proposed effort), ad a plan of action and milestones, (2) a Management Section which includes a description of relevant corporate expertise, experience, facilities and other relevant resources, resumes of key program personnel, and (3) a Cost Section which includes a breakdown of the proposed effort described in the Technical Section. All assumptions shall be clearly identified and defined. Award decisions will be based upon competitive selection of proposal resulting from a peer and/or scientific review and availability of funds. Proposals submitted in response to this announcement will be evaluated using the following criteria: (1) overall scientific and technical merits of the proposal, (2) potential contributions of the proposed effort in the United States Navy, (3) the realism of the proposed cost and availability of funds. Technical and other questions regarding this announcement may be submitted to Connie T. Gayle, telecopier number (540) 653-6810. Multiple awards of a cost-plus-fixed-fee (completion) contract with R&D provisions may be made. This announcement shall be open through 5 January 1996. Cut off for the ''white papers'' is 5 January 1996 at 2:00 PM at the aformentioned NSWCDD address. Proposals may be submitted at any time during this period and contract award(s) may be made at any time in fiscal year 1996. Although no portion of this announcement is set aside for Historically Black Colleges/Universities and Minority participation, proposals are invited from all sources. This BAA should not be construed as commitment or authorization to incur costs in anticipation of a resultant contract. Information provided herein is subject to modification and in no way binds the Government to award a contract. As authorized by FAR 6.102(d)(2), this notice constitutes a BAA for Lightning Effects on Multilayered Composite Structures for NSWCDD. (0303)

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