Issue 63

Z. Najat et alii, Frattura ed Integrità Strutturale, 63 (2023) 61-71; DOI: 10.3221/IGF-ESIS.63.06

To extract the field of displacement and deformation. In our study, a developed open-source software based on a 2D subset (Ncorr) is used to export the displacement and deformation fields. In Ncorr, the subsets are primarily a continuous circular group of points on integer pixel positions in the reference configuration. The transformation of the coordinates of these points from the reference to the current configuration is a first-order linear transformation:

u

u

  

  ) ref

cur x x u

ref x x

y

y

(

(

)

ref

rc

ref

ref

i

x

y

i

i

c

i

c

rc

rc

 ( , ) i j S

(1)

v

v

 y

   y v

  ) ref

ref x x

y

y

(

(

)

ref

rc

ref

ref

cur

x

y

i

i

c

i

c

i

rc

rc

where x refi and y refj are the x and y coordinates of an initial reference subset point, x refc and y refc are the coordinates of the center of the initial reference subset. Ncorr is using Green-Lagrangian constraints, with the following three displacement gradients generated:

    2 2 1 (2 ( ) ( ) ) 2 u u v x x x                 u v u u v v x x y x y 1 ( 2 y     

E

(2)

xx

E

)

(3)

xy

    2 2 1 (2 ( ) ( ) ) 2 u u v y y y    

E

(4)

yy

Figure 3: The flowchart of the proposed measuring method.

Identification of crack length Accurate crack tip position estimation is problematic for fracture mechanics researchers, particularly in the case of materials made of polymers Measuring fracture propagation is challenging in such materials due to extreme necking at the crack tip and considerable plastic deformation.

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