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Record 24 of 3337
Tethers as Debris: Simulating Impacts of Kevlar Tethers on Shuttle Tiles
Author and Affiliation:
Evans, Steven W.(NASA Marshall Space Flight Center, Huntsville, AL, United States)
Abstract: In a previous paper I examined the effects of impacts of polymer tethers on aluminum plates using the SPHC hydrodynamic code. In this paper I apply tether models to a new target - models of Space Shuttle tiles developed during the STS 107 accident investigation. In this three-dimensional simulation, a short tether fragment strikes a single tile supported on an aluminum backing plate. A tile of the LI-900 material is modeled. Penetration and damage to the tile and the backwall are characterized for three normal impact velocities. The tether is modeled as a bundle of eight 1-mm strands, with the bundle having dimensions 2-mm x 4-mm x 20-cm. The bulk material properties used are those of Kevlar(TradeMark) 49, for which a Mie-Gruneisen multiphase equation of state (eos) is used. In addition, the strength model is applied in a linear sense, such that tensile loads along the strand length are supported, but there is no strength in the lateral directions. Tile models include the various layers making up the tile structure. The outermost layer is a relatively dense borosilicate glass, known as RCG, 0.5-mm thick. The RCG layer is present on the top and four sides of the tile. Below this coating is the bulk of the tile, 1.8- in thick, made of LI-900, a product consisting of rigidized fiberous silica with a density of 9 lWft3. Below the main insulating layer is a bottom layer of the same material that has been treated to increase its density by approximately 69% to improve its strength. This densified layer is bonded to a Strain Isolation Pad (SIP), modeled as a refractory felt fabric. The SIP is bonded to an aluminum 2024 wall 0.1-in thick. The tile and backwall materials use a Me-Gruneisen multiphase eos, with the exception of the SIP felt, which uses a fabric equation of state. Fabrics must be crushed to the full bulk material density before bulk material properties and a Mie-Gruneisen eos are applied. Tether fragment impact speeds of 3,7, and 10 km/s are simulated, with impact velocities normal to the tile face. Damage results are presented in tabular format.
Publication Date: Jan 01, 2004
Document ID:
20040070911
(Acquired Jun 10, 2004)
Subject Category: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
Document Type: Conference Paper
Meeting Information: 45th AIAA/ASME/ASCE/AHS Structures, Structural Dynamics, and Materials Conference; 19-24 Apr. 2004; Palm Springs, CA; United States
Meeting Sponsor: American Inst. of Aeronautics and Astronautics;
American Society of Mechanical Engineers;
American Society of Civil Engineers; New York, NY, United States
American Helicopter Society, Inc.
Financial Sponsor: NASA Marshall Space Flight Center; Huntsville, AL, United States
Organization Source: NASA Marshall Space Flight Center; Huntsville, AL, United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: KEVLAR (TRADEMARK); COMPUTERIZED SIMULATION; TETHERING; TILES; DEBRIS; SPACE TRANSPORTATION SYSTEM; SPACE SHUTTLES; THREE DIMENSIONAL MODELS; IMPACT VELOCITY; ACCIDENT INVESTIGATION; EQUATIONS OF STATE; BOROSILICATE GLASS; FABRICS; INSULATION
Availability Source: Other Sources
Availability Notes: Abstract Only
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