Issue 35

H. Dündar et alii, Frattura ed Integrità Strutturale, 35 (2016) 360-367; DOI: 10.3221/IGF-ESIS.35.41 363 C RACK PROPAGATION ANALYSES orner, surface and through-thickness cracks under mode-I conditions in different geometries are analyzed and results are compared to those from the literature which are experimental test data and/or numerical results. FCPAS results showed very good agreement with the literature data in terms of SIFs, crack profiles/paths and propagation lives. Some of these studies can be found in [13] and [14]. In addition to the above mode-I propagation analyses including multiple mode-I cracks, several multiple-non-planar crack propagation analyses are also performed using FCPAS. In this study, two different nonplanar crack propagation analyses are performed. First set of analyses represent the study by Yan [15]. A thin plate which contains two equal sized cracks is subjected to tensile stress. One of the cracks is perpendicular to the loading axis of the plate, and the second crack makes a 45-degree angle. Details of the geometry and loading conditions can be seen in Fig. 2. Figure 2 : Details of the cracked model [15]. In Fig. 2, L=4 mm,  =45 degree, h=8 mm, width and height of the plate are taken as 160 mm to simulate large plate conditions relative to the crack sizes and the thickness of the plate is taken as 5 mm to assure plane stress conditions. Load and loading ratio (R) are 150.42 MPa and 0.048, C constant of the material is 1.039E-10, constant n is 2.7438 [15]. Modulus of elasticity and Poisson’s ratio are used as 70000 MPa and 0.321 respectively. Same analysis as that of Yan’s is performed using FCPAS and results are compared. Crack path comparison is shown in Fig. 3. It should be noted that for the incremental crack propagation analyses presented in this paper, the propagation angles are computed using the maximum tangential stress (MTS) criterion proposed by Erdoğan and Sih [16]. According to this criterion, under mixed mode loading, crack extends in a direction such that mode-II SIF becomes zero. Figure 3 : Crack path comparison between FCPAS and Yan’s analysis. Although the loading is uniaxial in the problem considered, because of the shear stress which occurs on the slanted crack plane, K II stress intensity factors are generated at its crack tips causing the tips to grow initially in a non-planar manner. C