PSI - Issue 47

G. Morettini et al. / Procedia Structural Integrity 47 (2023) 296–309 Author name / Structural Integrity Procedia 00 (2019) 000–000 � ���� � �� � � � � � (3)

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In the specific case we are analyzing, considering a blunt V-shaped notch geometry and adopting a reference system as shown in Fig.1, where the z direction is pointing out of the plane, the total strain energy can be expressed by equation (4).

Fig. 1. Geometric description and reference system of the considered V-notched geometry with critical volume (yellow area). � , �� � � � � � � � �� � � � � 2 � � � � � � � � � �� 2 � 1 � � � � � � (4) In which ν represents the Poisson's ratio of the material. This equation simplifies in the case of plane strain deformation assumption, in fact � � � � � � � , while in the case of plane stress � � 0 . The choice of which simplifying assumption to use is dictated by the geometric conditions of the component (e.g. thickness, height...) combined with the type and arrangement of external forces acting on the component. For example, it is common in the scientific community (Yosibash at al. (2012)) to consider a dominant plane strain condition when the fracture toughness � (a unique property of the material) reaches the limit imposed by Eq. (5). � � � � � � . � � � . � ��������� �⎯⎯⎯⎯⎯⎯� � � � � � � � (5) where � is the yield strength, and the specimen thickness. Instead, the plane stress hypothesis is satisficed when � exceeds the limit defined by Equation (6) (Yosibash at al. (2012)). � � � �� � � . � ��������� �⎯⎯⎯⎯⎯⎯� � � 0 (6) Considering that, for this research activity, a standard PLA material for additive manufacturing with nominal material data of fracture toughness �� �� 3.5 � 4.5 �√ 1000 √ and yield strength � � 49.5 MPa (Morettini et al. (2022)) will be used, and the thickness of the test specimens to be manufactured is � 5 (as illustrated in the following paragraphs), then it will be appropriate to consider a plane strain condition since Equation (5) will be satisfied. Moreover, this choice of assumption is not contradictory to the load tests (in tension) that will be performed.

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