PSI - Issue 28
Najat Zekriti et al. / Procedia Structural Integrity 28 (2020) 1745–1754 Najat Zekriti and al/ Structural Integrity Procedia 00 (2019) 000–000
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Whereas a sample subjected to low loading speed does not break rapidly, it slowly deforms under the action of the mechanical energy provided by the external stresses and the thermal energy due to the molecular motions. Fibrils act as energy absorbers. It can thus be concluded that the rate of loading is a parameter that controls and influences the behavior of amorphous polymers. Depending on the loading speed, the ABS adopts either a ductile or a fragile behavior. 3.3. Digital image correlation In the following, the study will focus on the analysis of cracks by means of DIC. Fig.6. shows the visualization of the displacement and stress fields obtained by the DIC method. It should be noted that a high concentration of stress is located at the bottom of the notch for both samples.
Processed image
Deplacement U
Deplacement V
Strain ε yy
Processed image
Deplacement U
Deplacement V
Strain ε yy
a.
b.
Fig.7. ABS image correlation results from horizontal mode I crack using Ncorr (a) extruded ABS; (b) printed ABS
3.4. Stress intensity factor In this study, we used the method of extrapolation of displacement fields at the crack tip. The SIF is related to the mode-I displacement fields by the relation 1
2 2 m U u u
Fig.8. Definition of the coordinate system around the tip of the crack
2 2 I K r G
( 1) k
u
(1)
2
2 2 I K r G
( 1) k
u
2
With 3 4 k
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