PSI - Issue 50

Alexander Eremin et al. / Procedia Structural Integrity 50 (2023) 73–82 Alexander Eremin / Structural Integrity Procedia 00 (2019) 000 – 000

79

7

CS=0.13%

(a)

NOPD=0.04

CS=0.24%

(b)

NOPD=0.5

CS=0.33%

(c)

NOPD=1

Fig. 6. Changes in the shape and longitudinal strain fields within the compression of the plate impacted by 17.1 J. Figures are rotated by 90° counterclockwise.

Before the final fracture the third specimens demonstrate partial failure that is accompanied by the jumps of deformation with stress relaxation that can be seen in Fig. 4a,b. This results in the significant change of the shape in Fig. 7c. The right part of the plate is deflected in the opposite direction and compressive strains occur near it. Thus the plate buckling induced and the shape have changed forming an area with alternating tensile and compressive strains on one side. In order to study the process of buckling in details five optical extensometers were placed during DIC data processing. The (0- 0’) extensometer is placed in the middle of the specimen having a length corresponding to the nearly full plate height. Four remaining are placed in the corners of the plate and have short gage lengths (1- 1’, 2 - 2’, 3- 3’ and 4- 4’). These simulate the traditional strain gages which are recommended by ASTM D7137 to reveal buckling. The results are shown in Fig. 8. The observations obtained in Figs. 5,6, and 7, are confirmed herein as well. The first specimen is deformed quite uniformly (Fig. 8a). After the 0.18% buckling occurs which leads to bending so the extensometers located in the bottom of the plate are compressed more intensively than the upper ones.