PSI - Issue 51

Hugo Vidinha et al. / Procedia Structural Integrity 51 (2023) 9–16

12 4

H. Vidinha et al./ Structural Integrity Procedia 00 (2022) 000–000

� � � �� � �� � �� � �� � �� � ���

⎪⎧ � � �� ��

� � 2 � � � � � � 0

�� ⎭⎪⎬ ⎪⎫

� ⎪⎨ ⎩

(3)

where c=cos �� and s=sin �� . To determine IFF, the fracture plane must be known a priori. In order to find the fracture plane, the stress exposure must be measured for all sections comprising θ angles in the range: [-90º, 90º]. The fracture plane is defined as the action plane with the maximum local stress exposure, i.e. � � � �� �� � � � � �� ��� (4) and the stress exposure can be obtained as follows: For �� : ����� � � � ��� 1 ⏊�� � ⏊� � ⏊� � � � � �� � �� �� � � ⏊� ⏊ � � �� �� � � ⏊� ‖ � � � ⏊� � ⏊� � � � � (5) For σ � � � ����� � � � �� ⏊� � ⏊�� � � � �� � �� �� � � ⏊� ⏊ � � �� �� � � ⏊� ⏊ � � � ⏊� � ⏊� � � � � (6) where: ⏊� � ⏊� � � ⏊� ⏊ ⏊� ⏊ � � ⏊� ‖ ⏊� ⏊ � (7) � � �� � �� � � �� � (8) � � �� � �� � � �� � (9) where ⏊� ⏊ , ⏊� ‖ or ⏊�� are the fracture resistances of the action plane to a single transverse shear stressing ⏊⏊ , longitudinal shear stressing ⏊‖ , or transverse tensile stressing ⏊� , acting on the action plane, respectively. ⏊‖ and ⏊� are the longitudinal shear strength, and the transverse shear strength of the lamina, respectively, while p ⏊ � ‖ , p ⏊� ‖ p ⏊ � ⏊ and p ⏊� ⏊ are experimentally determined inclination parameters provided by Puck et al. (Deuschle and Puck, 2013). The IFF can be verified with the expressions of the stress exposure if ����� � ��1 . The chosen path to predict IFF failure does not provide direct information about the IFF failure modes. However, that information is not relevant to this study.