Optimal design of variable stiffness laminated composite truncated cones under lateral external pressure

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ÇAĞDAŞ İ. U.

OCEAN ENGINEERING, cilt.145, ss.268-276, 2017 (SCI-Expanded, Scopus) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 145
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1016/j.oceaneng.2017.09.011
  • Dergi Adı: OCEAN ENGINEERING
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.268-276
  • Anahtar Kelimeler: Cone, Buckling, Pressure stiffness, Finite elements, Design optimization, TAILORED CONICAL SHELLS, HYDROSTATIC-PRESSURE, FIBER ORIENTATION, AXIAL-COMPRESSION, LOAD, OPTIMIZATION, CYLINDERS, PANELS
  • Akdeniz Üniversitesi Adresli: Evet

Özet

The purpose of this pater is to present optimal designs for variable stiffness laminated composite truncated cones under lateral external pressure. The objective is to maximize the failure load which is defined as the minimum of the buckling load and the first-ply failure (FPF) load. The numerical results are obtained using a semi-analytical degenerated shell element based on a refined first-order shear deformable shell theory and the influences of the pressure stiffness (PS) and the thickness/radius ratio are taken into account. A 2D degenerated shell element is also used for verification purposes. Results are presented for the related verification problems solved and the semi-analytical shell element is validated. Optimal designs, where FPF and buckling are imposed as design constraints, are presented for laminated composite thin and relatively thick cones having variable thickness and ply-angle. A simple graphical optimization technique and a modified Micro-Genetic Algorithm are employed. It is shown that, FPF constraint may be active for thicker cones having lower cone angles, PS slightly decreases the buckling pressures, and the stacking sequence has considerable influence on the failure load. The numerical results presented show that restraining the large end against rotation significantly increases the failure load.

In this study, filament wound truncated cones under axial compression are optimized with the objectives of maximizing the failure load, which is defined as the minimum of the buckling load the first-ply failure (FPF) load, and minimizing the total weight. The numerical results are obtained using an axisymmetric degenerated shell element based on a refined first-order shear deformable shell theory and a 2D degenerated shell element is used for verification purposes. It is shown that, FPF is more critical than buckling for thicker cones with lower cone angles.

Optimal designs, where FPF and buckling are imposed as design constraints, are presented for filament wound cones using Micro-Genetic Algorithms. The results show that the total number of wound up layers having different winding angles has negligible influence on the failure load and the optimal design is not FPF critical for moderate levels of axial compression. The influence of the rotational boundary conditions on the optimal failure load is also demonstrated.