Abstract:
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As polymers are made from long macromolecular chains, their deformation mechanisms
are related with the sliding between these chains as threads in a cloth, this can be a little
explanation of tearing. Now then, if during the load application the component is in
yielding and it has a stress concentrator, as a crack may be, this sliding occurs in a stable
manner and the stable crack growth is shown. In this work, complete-fracture crack tests
where carried out for an Ethylene-Propylene Block Copolymer film prepared on DDENT
specimens with two sharpening methods; by razor blade and by femtolaser beam. The
Load-Displacement plots and the ligament length evolution for all specimens were
recorded using a Digital Image Correlation System to approach the complete crack
behavior, describing the EWF conventional method in the crack extension process. The
main results of this work aim to say that the initiation of crack propagation occurs when
the area under the load-displacement curve reaches the we value. This start of
propagation shall be given by the material as a function of the initial crack conditions. |