Issue 29

S.K. Kudari et alii, Frattura ed Integrità Strutturale, 29 (2014) 419-425; DOI: 10.3221/IGF-ESIS.29.37 420 stress ratio (  /  y ) which shall be a great help in estimating maximum magnitude of K I in a SENB specimen without complex 3D FE analysis. F INITE ELEMENT ANALYSIS series of 3D finite element analyses have been made on SENB specimens using ABAQUS 6.5 [7] finite element software. The dimensions of SENB specimen has been computed according to ASTM standard E1290 [8] considering width of the specimen W =20mm. Figure1 shows the geometry of the SENB specimen used in this analysis. Finite element computations were carried- out considering only one-half of the specimen due to the geometric and loading symmetry. The analysis domain is descritized using 20-noded quadratic brick finite elements using reduced integration. This kind of elements were used in the work of Moreira et al. [6], Qu and Wang [9], Kim et al. [10], Courtin et al. [11], Kudari and Kodancha [12]. In this analysis, the number of elements in the analysis domain varied with the thickness ( B ) of the specimen. The specimen thickness modeled by considering 11 layers in the thickness direction. A typical mesh used in the analysis for specimen thickness B =4 mm is shown in Fig. 2. The stress distributions in the specimen and magnitudes of K I have been extracted by using ABAQUS post processor. The variation of stress components and K I along the crack-front has been studied for different specimen thickness and crack length to width ratio ( a/W =0.45-0.70). Figure 1 : The geometry of the SENB specimen used in the analysis ( W =20 mm). Figure 2 : 3D Specimen FE mesh used for the analysis. In this work the magnitude of applied stress (  ) is computed using the relation [13]: 2 ) (2 3 WB PS   (1) where, P is applied load, B is thickness of the specimen, W is width of the specimen, S=4W, the span of the specimen. The specimen thicknesses ( B ) considered in this analysis is 2 to 20 mm ( B/W =0.1-1.0) in steps of 2 mm. In these finite A