<title>Structural finite-element modeling strategies for conformal load-bearing antenna structure (CLAS) (Air Force contract F33615-C-93-3200)</title>

Abstract

As the Wright Lab Air Force military contract "Smart Skin Structures Technology Demonstration" (S3TD) Contract No. F33615-C-93-3200 draws toward conclusion, pertinent features of the program finite element modeling are presented. Analysis was performed to predict the structural performance of a complex multilayered composite panel that will be tested structurally (and electrically) for the final program deliverable.Application of finite element modeling (FEM) to predict component load path and strain distribution in sandwich panel construction has been reported elsewhere in the literature for more standard applications. However, the unauthordox sandwich configuration layup posed by the quite revolutionary S3TD CLAS aircraft fuselage panel demonstration article merits further discussion. Difficulties with material selection, the stumbling block for many programs, are further exacerbated by conflicting material properties required to support simultaneous electrical and structural performance roles. The structural analysis challenge derives from S3TD's unique program goal, namely, to investigate load bearing antenna structural configurations, rather than conventional structurally inefficient "bolt in" installations, that have been the modus operandi for tactical aircraft antenna installations to date. Discussed below is a cost saving strategy where use of linear finite element analysis has been employed in the prediction of key structural parameters, and validated with risk reduction sub panel measurements, before proceeding to the final fabrication of a full scale 36 by 36 inch CLAS panel demonstration article. IWFRODUCTIONAfter concept validation and preliminary design described previously [1], the S3TD program has selected the final CLAS demonstration article as a single broad band multifunction antenna element operating in the 0.15 to 2.0 GHz frequency bands. The program has considered and analyzed a variety of antenna apertures that could be included in a full up panel, however a single multi-arm spiral copper element, furnished by TRW, will be embedded in a complex structural panel suitable for tactical fighter fuselage installations. The CLAS panel will be capable of withstanding tactical fighter running loads and strain values of 4000 micro-strains and will be structurally tested for compression and shear properties in NGC's combined load test fixture, and finally 166 SPIE Vol. 3046 • 0277-786X/97/$10.00 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/14/2015 Terms of Use: http://spiedl.org/terms

Structural design and development of multiband aero-vehicle smart skin antenna

“…After successful substitution of Level 1 over Level 0 in military aircraft, Level 2 technology has been selected for experimental use and partially deployed in military aircraft (Callus, 2007). Lockyer et al (1997Lockyer et al ( , 2001 have done Level 2 antenna demonstration on military aircraft.…”

Antenna/sensor multifunctional composites for the wireless detection of damage

“…Conformal antenna arrays that are integrated into the composite skin of an aircraft have been proposed and demonstrated within the Smart-Skin Structure Technology Demonstration (S 3 TD) program [6,7]. Popular solutions for the load-bearing antenna system are the conformal load-bearing antenna structure (CLAS) [8][9][10][11], the composite smart structure [12,13], and the surface antenna structure [14]. In a CLAS, a strip antenna is sandwiched between layers of Nomex honeycomb, which are then laminated with glass fiber reinforced plastic layers, resulting in a planar antenna structure that has a high bending stiffness and is conformal to shell surface designs such as aircraft wings or automobile roofs.…”