Smaaart task order. Task title: acoustic panel fabrication. 1.0 introduction/background: due to their lightweight and high stiffness characteristics, composite structures are very efficient in…

Smaaart task order. Task title: acoustic panel fabrication. 1.0 introduction/background: due to their lightweight and high stiffness characteristics, composite structures are very efficient in radiating and transmitting noise. The structural concept under development in this task is the pultruded rod stitched efficient unitized structure (prseus) which is stitched together and then infused with resin to create a continuous CO-cured composition. The noise transmission characteristics of the prseus structure may be even more pronounced than other composite structures. Since such structures can exhibit noise radiation patterns that are very different from other bolted or bonded composite skin-stringer and/or sandwich panels, the vibro-acoustic behavior of such structures must be examined using analytical and experimental techniques. The intent is to understand the fundamental panel response for noise attenuation, and then to develop techniques that could be used to mitigate vibration and noise problems that may arise in their full-scale applications. 2.0 scope / objectives: the main objectives of this task order shall be to define the desired noise transmission properties and environments for the hybrid wing body (HWB) structure and cabin, investigate alternate noise mitigation strategies, and to fabricate a prseus test panel that shall be delivered to NASA larc for testing in the structural acoustics loads and transmission (salt) acoustics test facility. 3.0 description of the work/tasks to be performed: the contractor shall perform the following tasks: 3.1 advanced concept development the contractor shall include write-UPS for each of the following areas to be included in the final report. (deliverable item 4.5) 3.1.1 noise constraints and requirements - vibro-acoustic behavior of prseus composite structures is not fully understood. In this task, noise and vibration attenuation constraints and requirements for prseus structures in terms of sound power and radiation when compared with metallic structures, shall be described. Experimental techniques and parameters to quantify noise and vibration characteristics of a composite prseus panel shall also be described. 3.1.2 analysis model the contractor shall use nastran finite element model deck typical of hybrid wing body aircraft fuselage construction to be used as a starting point for development of a NASA derived structural acoustic model. Note: the contractor previously developed this model and fuselage construction under NASA contract NNL07AA48C. 3.1.3 control concepts due to the unique geometry and construction techniques employed to build prseus structures, the potential exists to include advanced noise treatments as an integral element of the load-bearing structure. The contractor shall use integral dampening techniques, such as vibro-acoustic layers and/or rigid core materials in the skin, to conceptually develop and exhibit different alternatives for efficiently reducing sound transmission through prseus structures. 3.2 acoustic test panel - the contractor shall design and build a 4-FT by 4-FT prseus acoustic test panel with 2 frames 24 inches apart and 8 rod stiffeners 6 inches apart that is representative of a HWB fuselage shell and deliver that article to NASA larc for testing as follows: 3.2.1 design and analysis - a detailed drawing of the test panel and a test specification write-up shall be prepared and included in the final report (deliverable item 4.5). The panel geometry shall be designed for installation into the test window frame at the salt facility at NASA larc (see SOW 5.1 GFI). 3.2.2 tooling preparation - an existing tool set (see SOW 6.0 GFP) shall be modified to fabricate the panel. New disposable stringer mandrels shall be fabricated to accommodate for the unique doubler build-UPS around the entire perimeter of the panel. 3.2.3 panel fabrication - the cont