PSI - Issue 61

Koji Uenishi et al. / Procedia Structural Integrity 61 (2024) 108–114 Uenishi et al. / Structural Integrity Procedia 00 (2024) 000 – 000

110

3

When the static strain is slightly increased, in the second case shown in Fig. 2, dynamic fracture evolves totally a

External loading (tension or compression)

b

Primary fracture

Projectile

0  s

20  s

40  s

60  s

80  s

100  s

120  s

140  s

160  s

10 mm

c

Tension

180  s

440  s

Projectile

Fig. 1. (a) Typical specimen with multiple preexisting small-scale parallel cracks with an inclination (dip) angle of 45 degrees. In addition to uniaxial static tension or compression, the specimen is subjected to dynamic impact. Thickness of the polycarbonate specimen is 2 mm. The mass density, shear modulus and Poisson’s ratio of the polycarbonate are 1,200 kg/m 3 , 820 MPa and 0.37, respectively [unit: mm]. (b) Development of dynamic impact-induced fracture in the specimen under static tensile strain equal to 0.027. The impact velocity of the projectile is roughly 66 m/s, and the time of impact is regarded as 0 microseconds (  s). The photographs are taken by a high-speed video camera at a frame rate of 100,000 frames per second (fps). (c) Dynamic fracture indicated in red develops in a prograde fashion from bottom near the point of impact upwards to the top surface to result in the total split of the specimen into two. However, the dynamic fracture does not “unzip” the perforation lines of small-scale cracks with an inclination angle of 45 degrees.