PSI - Issue 5

F. Romano et al. / Procedia Structural Integrity 5 (2017) 721–728 F. Romano/ Structural Integrity Procedia 00 (2017) 000 – 000

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On the other hand, by another point of view in terms of weight reduction, additional analyses have shown that if the panel is sized by using as design value that one obtained by PFA analysis, 4316  , the final panel should have a weight lower of about 9% respect to that one obtained by the traditional design, for the same design load.

4. Conclusions

This work has evaluated the amount of the weight reduction that could be obtained by releasing some traditional limitations and constraints, currently existing in the industrial design approach of aircraft composite structures. The design by supposing the presence of SHM systems has revealed that weight reductions are achievable thanks to the information given from this kind of systems. Relevant reductions could be obtained in particular for the wing stiffened panels sized at strength, instead of those ones critical at buckling. Furthermore, this study has also furnished the design requirements for the development of the SHM architecture, in terms of which parts of the stiffened panel is necessary to monitor in order to obtain significant weight reductions. On the other side, the PFA methodology has shown its effectiveness to predict the real mechanical behaviour of the stiffened panels, demonstrating to be a valid design tool for a design approach oriented to a weight saving, through the evaluation of the residual strength of panels with discrete damages. Overall, this study can give useful information to support new design approaches oriented to a higher weight reduction and/or structural performance improvement. Finally, the validation of the above approaches, based on the monitoring of the real health condition of the structure and of the related residual strength, would allow besides a reduction of the structural weight also a greater amplitude of the inspection intervals expected for the structural part in question. EASAAMC 20-29, 2010. Composite aircraft structure. Kassapoglou, C., 2010. Design and analysis of composite structures with applications to aerospace structures. John Wiley & Sons, U.K. Baaran, J., EASA Research Project: Visual inspection of composite structures, 2009. Knight, N. F. Jr, Rankin, C. C., Brogan, F. A., 2002. STAGS Computational Procedure for Progressive Failure Analysis of Laminated Composite Structures. International Journal of Non-Linear Mechanics 37, 833-849. Sleight, D. W., 1999. Progressive Failure Analysis Methodology for Laminated Composite Structures. NASA Technical Paper, NASA/TP-1999 209107. Moas, E., Griffin, O. H. Jr, 1997. Progressive Failure Analysis of Laminated Composite Structures. AIAA Journal, AIAA-97-1186, 2246-2256. Herszberg, I., Bannister, M. K., Li, H. C. H., Thomson, R. S., White, C., 2007. Structural health monitoring for advanced composite structures, 16th International Conference on Composite Materials. Kyoto, Japan. Romano, F., Mercurio U., 2017. New Design Approach for Composite Stiffened Wing Panels. Compositi Magazine, Year XII, 43, 35-42. Romano F., Di Caprio F., Mercurio U., 2016. Compression After Impact Analysis of Composite Panels and Equivalent Hole Method. Journal of Procedia Engineering 167 C, 182-189. Romano, F., 2015. Ph.D. Thesis: Design of composite stiffened panels by new design criteria and progressive failure analysis. University of Naples Federico II. Borrelli, R., Franchitti, S., Di Caprio, F., Romano, F., Mercurio, U., 2015. A numerical procedure for the virtual compression after impact analysis. Advanced Composites Letters 24, 4, 57-67. Romano, F., Di Caprio, F., Auriemma, B., Mercurio, U., 2015. Numerical investigation on the failure phenomena of stiffened composite panels in post-buckling regime with discrete damages. Journal of Engineering Failure Analysis 56, 116-130. Borrelli, R., Di Caprio, F., Mercurio, U., Romano, F., 2013. Assessment of Progressive Failure Analysis Capabilities of Commercial FE Codes. International Journal of Structural Integrity, 4, 3, 300-320. Orifici, A. C., de Zarate Alberdi, I. O., Thomson, R. S., Bayandor, J., 2008. Compression and post-buckling damage growth and collapse analysis of flat composite stiffened panels. Journal of Composites Science and Technology 68, 3150-3160. Schuecker, C., Pettermann, H. E., 2008. Constitutive ply damage modeling, FEM implementation, and analyses of laminated structures. Journal of Computers and Structures 86, 908-918. Lin, W. P., Hu, H. T., 2002. Nonlinear analysis of fiber-reinforced composite laminates subjected to uniaxial tensile load. Journal of Composite Materials 36, 1429-1450. References