Design for Manufacturing Accurate Skin Panels from Fibre Metal Laminates

1. Design for Manufacturing Accurate Skin Panels from Fibre Metal Laminates PhD Candidate: Morteza Abouhamzeh Department: ASM Section: Structural Integrity & Composites Supervisor: J. Sinke Promoter: R. Benedictus Start date: 10-02-2012 Funding: Cooperations: Manufacturing Processes Generate Distortion Manufacturing Processes and effects on Residual Stress (Distortion) of FMLs • Background • Fibre metal laminates (FMLs) as a new hybrid aerospace material has found applications in structural parts of aircraft like fuselage panels. Different manufacturing processes like cure, adding doublers and splices, cut-outs and post-cure produces residual stresses and shape deviations. To have high performance and accurate skin panels made of FMLs and finally make massive production of FMLs possible without manual action and corrections, it is needed to have models that describe the manufacturing-induced phenomena and predict the final mechanical and geometric state of the structure. In this regard, no considerable research is done on FMLs. The most relevant works available are on some common processes on full composites. • If we can model these processes and predict the stresses and distortions, we can reduce them by designing revised layup tools. • Experimental Strategy • Approach 1: Direct/indirect measurement of residual strains of cured samples • Measurement of: • Curvature Calculation Residual Strain & Stress • Residual strains Calculation Residual Stress • Ply removal • Measuring TStress-Free • Approach 2: Monitoring/measurement during cure • Cure-monitoring of: • Curvature Interrupted cure • Calculation of Residual Strain & Stress • Residual strains Calculation Residual Stress • Embedded strain gages or fibre optic sensors Model Development Aerospace Engineering Manufacturing FMLs for Fuselage Research Methodology Phase 1: IntroductionandLiterature Review Phase 2: Understanding and Measurement of Residual strains (Distortion) in Simple Configurations Phase 3: Complete Cure Modeling and Measurement of Residual Strains (Distortion) During Manufacture of an FML Phase 4: Residual Stress (Distortion) in FML Skin Panels, Including Splices, Doublers and Ply-Drop-Off Phase 5: Experimental Study and Modeling of Residual Stress-Distortion in post-cure Processes of FML Skin Panels Phase 6: Combining Previous Phases to Achieve a Predictive Model for the Whole Process • Current Stage: • Modeling: Cure (cool-down process): • Linear elastic modeling (sym./unsym. GLARE panels) • Nonlinear (large-displacement) elastic • Experiments: • Manufacturing somesimplelaminatesandmeasuringcurvatureandstrains • Determination of stress-free temperature (usingcurvedunsym. panles) • Determiningcurvatureandresidualstrainsbyeliminatingoneplyfrom a symmetricFML