Issue 50

O. Mouhat et alii, Frattura ed Integrità Strutturale, 50 (2019) 126-140; DOI: 10.3221/IGF-ESIS.50.12 139 Figure 8 : Von Mises stresses obtained for the various ply layout sequences. C ONCLUSION ccording to the study of the three previous cases, we observed that when the skin and the stiffener are made of the Kevlar, the panel has better resistance compared with the other studied composites. The ply sequence (60/- 30/90/0)S has the maximum critical buckling load. When the panel and the stiffener contain different composites, the Kevlar skin and the CFC stiffener has a maximum buckling load with orientation (45/-45/90/0)S. After this work, we would like to study complex aircraft structures with both material and geometric imperfections and validate finite element models through experiments. The next work we want to extend the current techniques to complicated structures like the airplane wing and validate the FE results with practice. We will consider a stiffened panel composite with having local geometric and material imperfections and to evaluate the effects of damage in composite stiffened panel using lamb wave propagation. A CKNOWLEDGEMENTS his work is sponsored by Structure LGCE ,EST Sale -CED of Mohammadia Engineering School Mohammed V University, Rabat. These supports are gratefully acknowledged. The authors also wish to thank the anonymous reviewers for their thorough review of the article and their constructive advice. R EFERENCES [1] Abramovich, H., Weller, T. (2005). Buckling until collapse of a damaged panel. COOCMAT - Technion. Technical Report, Tel Aviv. [2] Degenhard, R., Rolfes, R., Zimmerman, R., (2006). Improved material exploitation of composite airframe structures by accurate simulation of post-buckling and collapse. Composite Structures (73), pp. 175-178. DOI: 10.1.1.567.5341. [3] Zimmermann, R., Rolfes, R. (2006). POSICOSS - Improved post-buckling simulation for design of fibre composite stiffened fuselage structures. Composite Structures (73), pp. 171-174. DOI: 10.1016/j.compstruct.2005.11.041. [4] Ravi, B., Deo, James, H., Starnes, Jr., Holzwarth, R.C. (2001). Low-Cost Composite Materials and Structures for Aircraft Applications.RTO AVT Specialists’ Meeting on “Low Cost Composite Structures”, Loen, Norway, published in RTO-MP-069(II). [5] Budarapu, P.R., Sudhir, Y.B., Javvaji, B., Mahapatra, D.R. (2014). Vibration Analysis of Multi-walled Carbon Nanotubes Embedded in Elastic Medium. Frontiers of Structural and Civil Engineering, 8(2), pp. 151-159. A T