CompositesWorld
Issue link: https://cw.epubxp.com/i/450689
11 CompositesWorld.com Ensuring Dimensional Fidelity during heat ramp-up. When a process model is created for the part, tool and process of interest, it can be used to predict the expected mean dimensional change (Fig. 3) and to identify param- eters that drive process variability. Often, the most efective way to address the part's mean dimensional change is by geometric compensation of the tool surface because it can be done without changing laminate or process parameters. Using the COMPRO/ CATIA/ABAQUS solution set, geometric compensation of the tool can be performed automatically by transferring the calculated dimensional change back to the CATIA design environment and morphing the tool surface so that dimensional conformance is achieved. Altering the layup sequence and/or modifying the cure cycle are alternatives that can be developed and evaluated in the same simulation environment. Once the system parameters have been adjusted to give a mean dimensional outcome that matches the nominal dimensions, the model can be used to identify and set bounds on the allowed vari- ability of systems parameters, such that the dimensional variability of the part is within dimensional tolerances. Te technology and methodology presented here is routinely employed by large aerospace OEMs, and it is clear we have reached a tipping point: Powerful and efective process simu- lation tools and inexpensive, fast computational power are converging. Composites fabrication need no longer be treated as an art and should leave the domain of empiricism. Processing can be approached with the same analytical mindset and design and simulation tool sets as any other aspect of engineering. Tis is critical if we are to build large, complex composite structures that can compete with metal structures. Te era of simulation- supported, knowledge-based composites manufacturing is here, and there is no turning back if we want to remain competitive. REFERENCES 1 Nelson, R. H., & Cairns, D. S. (1989). "Prediction of dimensional changes in composite laminates during cure," Tomorrow's Materials: Today, 34, 2397-2410. 2 Johnston, A., Vaziri, R., & Poursartip, A. (2001). "A plane strain model for process-induced deformation of laminated composite structures." Journal of Composite Materials, 35(16), 1435-1469. 3 Fernlund, G., Floyd, A., Shewfelt, M. & Hudek, M. (September 2007). "Process analysis and tool compensation for a complex composite panel," Proceedings of the 22 nd American Society for Composites Technical Conference (Seattle, WA, US). ABOUT THE AUTHORS Dr. Göran Fernlund (top) and Dr. Anoush Poursartip (bottom) are the engineering director and research director, respectively, and co-founders of Convergent Manufacturing Technologies (Vancouver, BC, Canada), established in 1998 on the basis of process simulation software developed at the University of British Columbia (UBC).