Issue 50

O. Mouhat et alii, Frattura ed Integrità Strutturale, 50 (2019) 126-140; DOI: 10.3221/IGF-ESIS.50.12 130 Total potential energy of the panel The total potential energy  is the summation of the strain energy U and external load potential  , expressed as follows:     U         1 2 T T d q f         (6)  It is assumed that the load factor to increment the load vector   f and stress vector    can be estimated from the right component:       T x y xy x y xy x y z N N N M M M Q Q M (7) With , and x y xy N N N are the stresses and , M and M x y xy M are the moments, and x y Q Q are the shear stresses, the characteristic law:       =   C (8) Where C is the material constant matrix, the paper presents the evaluation of stresses and strains, deformations for static buckling analysis   19 . 11 12 16 11 12 16 12 22 26 12 22 26 16 26 66 16 26 6 0 0 0 0 0 0 = x y xy x y xy y x z N A A A B B B N A A A B B B N A A A B B B M M M Q Q M                                   6 11 12 16 11 12 16 12 22 26 12 22 26 16 26 66 16 26 66 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 B B B D D D B B B D D D B B B D D D 44 45 45 55 * 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 C x y xy x y x A A A A                                     y yz zx z                                      (9) Where , and ij ij ij A B D are stiffened panel properties using classical lamination theory (CLT) is a commonly used predictive tool, with * C correspond the stiffness values and z  in-plane rotation. The matrices for the stability analysis Analysis of linear static buckling at the beginning of the analysis, the stiffness matrix can be formulated as:        0 0 0 = d    T K B C B (10) Matrix   0 B used in reference [22] results of the Mindlin-Reissner hypothesis as a continuation: