Thick, 3D woven carbon/phenolic composites offer potential improvement over legacy thermal protection systems (TPS) for re-entry vehicle heat shield applications. However due to the scale and complexity of typical re-entry vehicle structures, it is likely that multiple 3D woven panels would need to laid up to create the overall heat shield, creating potential weak spots at the panel joints. In Phase I T.E.A.M., Inc. addressed the joint issue by developing an innovative stitching process capable of forming mechanically reinforced joints between densely woven, 3D carbon fiber pre-forms up to 3" thick. The Phase I scope included design, model and fabrication of multiple stitched joint specimens with anticipated strength / stiffness properties multiple times higher than baseline, un-stitched joints. In Phase II T.E.A.M. proposed a parallel manufacturing scale-up and D&A/testing effort to mature the MRL/TRL of the developed technology. The high level goals of Phase II are A) To scale the developed stitching process to the size, geometry and repeatability representative of that required for fabrication of net shape re-entry vehicle structure (i.e. ~1.5m base diameter cone + nose cap will be demonstrated), and B) To optimize the stitched joint configuration (i.e. stitch site frequency, orientation and tow size) for performance in a re-entry environment by analytical modeling and mechanical and LHMEL testing of stitched and un-stitched joints using a representative 3D woven carbon/phenolic material system.
Potential NASA Commercial Applications: (Limit 1500 characters, approximately 150 words) The proposed innovation is directly relevant as a joining technology for NASA Ames' 3D-woven carbon/phenolic thermal protection system (3D-TPS) for the Heatshield for Extreme Entry Environment Technology (HEEET) program, which is currently targeting delivery of heat shield solutions for mission programs including for future Venus, Saturn, high speed sample return, and human missions beyond lunar or Mars Sample Return (MSR) missions. Similarly, the technology will enable joining of thinner and thicker 3D woven carbon and ceramic fabrics relevant to NASA's Adaptable, Deployable Entry and Placement Technology (ADEPT) program, and the Hypersonic Inflatable Aerodynamic Decelerator (HIAD) program.
Potential NON-NASA Commercial Applications:
: (Limit 1500 characters, approximately 150 words) The proposed innovation will create the capability to stitch/join together carbon fiber preform assemblies with geometries too complex for existing textile processes, including 3D weaving, to achieve. Potential commercial applications thus include those composite applications where through thickness strength AND complex geometry are both required. Examples include composite armor for military vehicles and structural composites for aerospace including stitched skin + core assemblies, stitched joint assemblies and stitched skin + web-stiffener assemblies.
Technology Taxonomy Mapping: (NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.) Composites Joining (Adhesion, Welding) Passive Systems Textiles
