CompositesWorld
Issue link: https://cw.epubxp.com/i/487531
APRIL 2015 38 CompositesWorld By Ginger Gardiner / Senior Editor A DARPA program aims for certification via a Bayesian process control system for the factory floor, bounding uncertainty and predicting reliability in real-time. » Unitized, adhesively bonded composite primary structures on aircraft could ofer substantial cost savings by dramatically reducing part and fastener counts, as well as time and labor for airframe fabrication and assembly. Lockheed Martin Skunk Works (Palmdale, CA, US) demonstrated the possibilities in 2009, during develop- ment of the Advanced Composite Cargo Aircraft (see "Learn More," p. 42), with a 90% part count reduction in its bonded composite fuselage and vertical tail. But redundant mechanical fastening is currently required for certifcation of adhesively bonded primary structures on military and commercial aircraft (see "Learn More"). Lockheed Martin Aeronautics Co. (LM Aero Palmdale), however, now leads the Transition Reliable Unitized STructure (TRUST) project, part of the Defense Advanced Research Projects Agency's (DARPA, Washington, DC, US) Open Manufacturing (OM) program. An efort to reduce cost and speed delivery of high-quality parts with predictable performance for defense systems, OM seeks to do so by reducing the uncertainties that cause cost overruns and delays during development, testing and early production. Te purpose of TRUST is to develop the manufacturing process control necessary for certifcation of unitized bonded composite primary structures without redundant fasteners. "Te goal is bonded primary structure," says Skunk Works program manager Brad Hanson, "but no one is yet confdent we can eliminate bad bonds." In response, TRUST is taking a Big Data approach, attempting to build such confdence through Bayesian process control (BPC). "Te overall goal is to create a framework that captures factory-foor variability and leverages probabilistic compu- tational tools to characterize and reduce the risk of manufacturing technologies — in this case, bonded composite structures," says Mick Maher, DARPA program manager. Fig. 1: Bayesian process control is at the heart of DARPA's TRUST program, leveraging information science to gain control over the bonding process and the ability to confdently predict the reliability of bonded structures. Source | DARPA Manufacturing Data Pedigree Protocols & environment Process data Bond preparation method In Process Inspection NDI FTIR WCA DCB & Data Pedigree Test methodology Da ta reduction F ailure mode Input Models SP + SB + O T + L + SB:H + SP:SB + SP:O T Regression Model Informatics Database & Probabilistic Analysis Bayesian Process Control Reliability Analysis Informatics Reliability: 96.20% CDF Probability of Mean G R > 5.0 R-curves Known Quality Building TRUST in bonded primary structures