Issue 75

P. Grubits et alii, Fracture and Structural Integrity, 75 (2026) 124-156; DOI: 10.3221/IGF-ESIS.75.10

   

, E if

 

y

    

, f if



y

y

h





 

C     

E  

f

if

,



  

(24)

y

sh

sh

sh

u

1

 

f

f





u 

u

C

 

  

    

f

, C if C

1

u 

C

u

u

u

1

1

u 

u 

 

C

1

1

Figure 10: Distribution of cross-sectional areas assigned to each member in the initial configuration of the 37-bar truss structure.

Figure 11: The illustration of the quad-linear material model of steel.

where  denotes the stress and  the corresponding strain. The yield stress and its associated strain are expressed as y f and y  , whereas the ultimate tensile stress and strain are given by u f and u  . The elastic modulus of the material is designated as E . Furthermore, the strain-hardening modulus is represented by sh E , and sh  indicates the onset of strain hardening. The strain and stress corresponding to the intersection of the third segment of the idealized model with the actual stress–strain curve are denoted as 1 u C  and 1 u C f  , respectively, where 1 C is a material-dependent coefficient. These quantities can be evaluated using the following equations:

f

0.6 1         y u f 

u 

(25)

0.06

f

0.1 0.055 y 

sh   

sh  

and 0.015

0.03

(26)

f

u









  

0.25

sh

u

sh



C

(27)

1

u 

140