Issue 29

S.K. Kudari et alii, Frattura ed Integrità Strutturale, 29 (2014) 419-425; DOI: 10.3221/IGF-ESIS.29.37 422 ) ( 22 11 33        p D (3) Figure 4 : Variation of K I along the crack-front for various loading. Figure 5 : Variation of K I along the crack-front for B =10 mm and various a/W. This D p  is quite complex to compute and analysis. The above limitations in fracture analysis demand the 3D analysis of fracture specimen to find the K I at the center (maximum) of the specimen. One can observe from Fig.5 that there exists a considerable difference in the magnitudes of K I between center and surface of the specimen. A typical variation of difference between the magnitude of K I at the center and on the surface (  K I ) for a specimen having B =10mm for  /  y =0.56 and various a/W is shown in the Fig. 6. This figure indicates that  K I of the specimen increases as a/W increases, which infers that higher magnitude of specimen a/W ratio provides maximum out- of-plane constraint. The magnitude of K I are also extracted for B=2 to 20 mm ( B/W =0.1 to 1) and a/W =0.45 to 0.70 for loading  /  y =0.08 to 0.80. A typical variation of K I for thicknesses B =2mm, 10mm and 20mm for a/W =0.50 and  /  y =0.56 is shown in Fig 7. This figure clearly demonstrates an interesting finding that the magnitude of K I at the center of the specimen is independent of specimen thickness ( B ). Figure 6 : Variation of  K I for various a/W ratios. Figure 7 : Variation of K I along the crack-front for B =2 mm, 10 mm and 20 mm with a/W =0.50 Fig. 4 to 7 show that K I strongly varies with distance along the crack-front and depends on the specimen thickness. Figure 4 to 7 show that the magnitude of K I is higher at the centre of the specimen than on the surface. This nature of variation