PSI - Issue 56

Mihai Marghitas et al. / Procedia Structural Integrity 56 (2024) 26–32 Author name / Structural Integrity Procedia 00 (2019) 000–000 The experimental results expressed in terms of / versus / for the different fracture criteria reported in Table 2 are plotted in Fig. 5. It could be observed that the SED, MTS and ESIF criteria are in good agreement with the experimental results. 31 6

Table 2. Mixed mode fracture criteria Fracture criterion

Formulation

Eq. (3)

2 3

c θ 2

c θ 2

K IC

−  

  

MTS Erdogan – Sih (1963)

2

cos

cos

sin

F

K

K

K

c θ

=

−

cr σ = =

σ θθ

,

I

II

IC

,max

2

r π

( 2 1 1 − κ

[

(

)

(

)

(

)

(

) 2 K

2

1 cos +

cos

2sin 2cos θ

1 κ θ

F

K θ κ θ +

K K

=

−

− +

+

1

κ −

)

SED Sih (1974)

c

c

I

c

c

I II

S S

= =

cr

IC

) ] 2 II K K −

8

πµ

(

(

)( 1 1 cos

) (

)(

)

2

1 cos 3cos θ

1

+ + − κ

c θ

+ +

c θ

−

c

IC

c θ

c θ

     

     

π

1 1

−

2

[

(

)

   

   

3 cos 1 +

π

2

K

2

2

1 3cos

8 K K K +

sin cos

4

F

c θ

+ θ θ

⋅ +

=

Gmax Hussain (1974)

( ) G G

IC

I

I II

c

c

c θ

= = θ

2

c θ

+

c

Ic

E

π

) ] 2 II

(

2

2

9 5cos

K K −

c θ

+ −

IC

2 1

K

(

)

ESIF Richard (1985)

2

K K K − + 2 4 α

I = +

eq K K =

F

IC

I

II

IC

2

1.4

Experiment MTS SED Gmax ESIF

1.2

1

0.8

K II /K IC

0.6

0.4

0.2

0

0 0.2 0.4 0.6 0.8 1 1.2

K I /K IC

Fig. 5. The fracture criteria and experimental results.

4. Conclusions The following conclusions of this study could be drawn:

• The semi-circular bend specimen loaded asymmetric was adopted to investigate mixed mode fracture of DLP additive manufactured specimens made of translucent green photo-polymerization resin. The advantages of this specimen are the simple geometry, the use of classic bending fixtures for loading the specimens and the ability to produce full range of mixed modes, from pure mode I to pure mode II, only by changing the position of one support.