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Name: Strain Isolator Pad (SIP)
Database: NASA Ames Thermal Protection Materials
Category: Silicon-Based Reusable Composites: Cloths
Composition: Aramid fibers
Manufacturer: Albany International
Technical Readiness Level: 9
Last Modified: 2001-10-01

Description:

• SIP, or Strain Isolation Pad, is a Nomex felt pad used to prevent stress failure in rigid TPS ceramic tiles. The SIPs are thermal isolators typically supplied in thicknesses of 0.090, 0.115 or 0.160 inch. SIPs are bonded to the tiles, and the SIP and tile assembly is bonded to the shuttle orbiter structure using an RTV adhesive. <BR><BR> SIP can introduce stress concentrations at the needled fiber bundles. This has resulted in localized failure in the tile just above the RTV bond line causing loss of the tile during flight. To solve this problem, the inner surface of the tile is densified to distribute the load more uniformly and increase tile strength at the bondline.

Point of Contact:

• Marc Rezin
• NASA Ames Research Center
• mrezin@mail.arc.nasa.gov