User Element (UEL) Based Process Model for Prediction of C/C Dimensional Changes During Manufacturing

The process of manufacturing phenolic-derived structural carbon-carbon composites is one fraught with variability. Many of the standard practices employed by fabricators have, in some way, been derived from both experience and tribal knowledge, with little consideration for the underlying physics. While this has been sufficient for the manufacture of prototype hardware, there exists a need for a better understanding of how carbon-carbon behaves during processing as manufacturing shops transition to higher rate, production-focused facilities. In a production environment, process optimization is critical to reducing fabrication times and minimizing scrap rates; this type of optimization can be achieved through execution of physics-based models of the manufacturing process. In the effort proposed herein, Materials Research & Design will work with Carbon-Carbon Advanced Technologies (C-CAT) and Allcomp to develop, demonstrate, and validate a processing model designed to predict the physical and mechanical properties of structural carbon-carbon materials and components. Specifically, this model will take the form of a custom user element (UEL) capable of interfacing with the commercial-off-the-shelf (COTS) finite element code, Abaqus. The Phase I effort demonstrated the feasibility of using a UEL to predict the temperature and rate-dependent response of C/Ph as it converts to C/C. The UEL accuracy was verified by comparing its predictions to the legacy Process Environment Model (PEM). The Phase II effort will use additional measured in-process data supplied by Southern Research to continue development of the physics-based UEL which aims to predict residual stress, shape change, and material properties of complex carbon-carbon geometries. This program will also enlist the help of Southwest Research Institute (SwRI) to leverage their expertise in the area of verification and validation (V&V), probabilistic analysis, and uncertainty quantification (UQ). SwRI's support and involvement will be integral in ensuring that the Phase II program results in a software tool which is ready for transition to industry.