Issue 48

F. V. Antunes et alii, Frattura ed Integrità Strutturale, 48 (2019) 676-692; DOI: 10.3221/IGF-ESIS.48.64 679 Figure 3 : Loading and boundary conditions of the CTS specimen. Figure 4 : Typical finite element mesh (x=52.5; y=0;  =20º). P RESENTATION AND ANALYSIS OF NUMERICAL RESULTS he stress intensity factors (K I , K II ) depend on: - the geometry of the specimen, characterized by its width, W; - the geometry of the crack, characterized by the Cartesian coordinates of its tip (x P , y P ) and by the slope at its tip (  in Fig. 1); - the magnitude and direction of the load, which can be characterized by  (=F/(w  t), being t the thickness of the specimen) and  (Figs. 2 and 3), respectively: , ( , , , , , ) K K f W x y I II P P      (2) The number of independent variables can be reduced using Buckingham’s theorem of non dimensional analysis  17  . Considering  and x the primary variables, the following non-dimensional relations can be obtained: K x y I Y f( , , α β,β) I W W σ. π.x     (3) K x y II Y f( , , α β,β) II W W σ. π.x     (4) This approach reduces the number of independent variables, and Y I , Y II are independent of unit system and can be used to specimens similar to present one, which is interesting since CTS specimen is not a standard geometry. To obtain relations 3 and 4 several numerical analyses were performed in order to obtain Y I and Y II for the different independent parameters. The values considered for x were 32.5, 37.5, 42.5, 47.5, 52.5, 57.5, 62.5 and 67.5 mm, and for y were 0, 5, 10 and 15 mm. Only zero and positive values were considered for y because crack deflects always towards mode T