Issue 50

O. Mouhat et alii, Frattura ed Integrità Strutturale, 50 (2019) 126-140; DOI: 10.3221/IGF-ESIS.50.12



N x

                      

                          

i

0 0 0 0 0



i N y N N y x 

i

0

0 0 0 0

    

i

0 0 0 0



N x

i

0 0 0 -

0 0





N

  0 B

i

0 0 0 0 -

0



(11)



y

- N N y x N N y N N x      i i i i i

i

0 0 0 -

0



0 0

0 - 0



0 0

- 0 0



  

N

0 0 0 0 0

i

Matrix required for the stability analysis The pre-buckling can be given by this precautionary measure:       0 0 0 = K q f

(12)

The second phase is the detection of critical states on the fundamental path reason, it is important to calculate the geometry of the stiffness matrix   K  this can be done as follows:        = d T K G G      (13)

And matrix G, which is formed by:   =   i T N G x

(14)

Where    is the stress vector, stress reorganized in the form of a matrix according to Taylor [20].

N

0 0 0

     

      

y

N

0

0 0 N N N N x xy

  

x

 

(15)

0 0 0 0

xy

y

The linear Eigenvalue problem is:

131