Issue 47

Yu. G. Matvienko et alii, Frattura ed Integrità Strutturale, 47 (2019) 303-320; DOI: 10.3221/IGF-ESIS.47.23 308 is made for the notch of current length 1 n a  (n = 1, 2, 3). After that, the notch length is increased by a small increment and the second exposure is made for the notch of final length. Constancy of acting force during the process of notch length increase lies in the interval P –0.01 P with a warranty. Initial experimental information for each measurement step has a form of two interference fringe patterns related to in-plane displacement components u and v as it shown in Fig. 1. Presented interferograms are obtained for specimen T5_13H after applying N = 1000 cycles. Initial experimental information Initial experimental information has the form of interference fringe patterns, which describe the distributions of both in- plane displacement components near the crack tip. These interferograms correspond to increasing the length of the central symmetrical crack of mode I in thin rectangular plate under constant tensile load. The total crack length consists of three prolongation increments. Typical interference fringe patterns obtained for different notch length increments in specimens of T5-H1 and T5-H2 group are shown in Figs. 1, 2, and 3, 4, respectively. High quality of presented interferograms is quite evident. a b c d Figure 2 : Specimen T5_18H. Interference fringe patterns obtained in terms of in-plane displacement component u (a, b) and v (c, d); a, c – initial crack length 0 a = 0 with the increment 1 a   = 1.97 mm (left) and 1 a   = 2.18 mm (right); b, d – initial crack length 1 a  = 1.97 with the increment 2 a   = 1.87 mm (left) and initial crack length 1 a  = 2.18 mm with the increment 2 a   = 1.70 mm (right).