Issue 30

W. Tao et alii, Frattura ed Integrità Strutturale, 30 (2014) 537-544; DOI: 10.3221/IGF-ESIS.30.64 543 The regions A, B, C, D, E, F, G, H, I represent the fracture fragments after extraction. Their positional relationship between endpoints corresponds to 0, 1, 2, 3, 4, 5, 6, 7, 8 in Fig. 5 (b). Set A   , Xa Ya as the right end point coordinates. The coordinates closed to the left end point B, C, D, E, F, G, H, I is,   , Xb Yb ,   , Xc Yc ,   , Xd Yd ,   , Xe Ye ,   , Xf Yf ,   , Xg Yg ,   , Xh Yh ,   , Xi Yi , respectively. Set A to represent i -th fragment, I, b, c, d, e, f, g, h, I. This means that the   1 i  -th has 8 representative kinds of fragment with a certain position of A respectively. The connection procedure of the fragments A and B is described as below. The connection process of a, c, d, e, f, g, h, I is similar. B is located right of A. A and B match so that: , Xb Xa Yb Ya   1) The right endpoint of segment A (the rightmost column A, from the top down, the first non-zero pixel) is obtained by coordinates   , Xa Ya . And the left endpoint of B (the leftmost column B, from the top down, the first non-zero pixel) is obtained through coordinates   , Xb Yb . The following method of defining the left and right endpoints of each fragment is similar to that for defining the left and right endpoints of each fragment. 2) The coordinate difference is calculated: d Yb Ya   ; e Xa Xb   and 0 d  , 0 e  , so d e  . 3) It proceeds along a route from   , Xa Ya . And 1 is close to   , Xb Yb . The pixel value of the blank during the route is set as 1. Route 1:   , 1 Xa Ya  ▁   , 2 Xa Ya  ▁   , 3 Xa Ya  ▁   , 4 Xa Ya    , 1 1 Xa Ya   ;   , 2 1 Xa Ya   ;   , 3 1 Xa Ya   ;   , 4 1 Xa Ya   Likewise, it is the same to   , Xb Yb . 4) Reach Example verification The cracks have been divided into several segments for verifying the fracture fragment through the connecting algorithm, as shown in Fig. 6 (a). The fracture fragments algorithm is connected with the neighboring fragments. The connection results are shown in Fig. 6 (b). (a) (b) Figure 6 : (a) Crack fragment image; (b) Crack fragment after connection We can see that it is correct and effective to apply the algorithm in connecting the fracture fragments. The connection of various pieces of fragments in the image forms a connected area. This paper contributes to testing the crack developments and simplifying calculation for the characteristic quantities of crack targets.