PSI - Issue 60

Prince Jeya Lal Lazar et al. / Procedia Structural Integrity 60 (2024) 185–194 Author name / Structural Integrity Procedia 00 (2019) 000–000

193

9

-0.16

-0.16

100 mm 125 mm 150 mm

(a)

1 kg TNT 2 kg TNT 3 kg TNT

(b)

-0.14

-0.14

-0.12

-0.12

-0.10

-0.10

-0.08

-0.08

-0.06

-0.06

-0.04

-0.04

-0.02

-0.02

Front face mid point deflection (m)

Front face mid point deflection (m)

0.00

0.00

0.0000

0.0005

0.0010

0.0015

0.0000

0.0005

0.0010

0.0015

Time (s)

Time (s)

-0.16

-0.16

t=0.76 mm t=1.00 mm t=1.50 mm

S1 S2 S3 U1 U2 U3

(c)

(d)

-0.14

-0.14

-0.12

-0.12

-0.10

-0.10

-0.08

-0.08

-0.06

-0.06

-0.04

-0.04

-0.02

-0.02

Front face mid point deflection (m)

Front face mid point deflection (m)

0.00

0.00

0.0000

0.0005

0.0010

0.0015

0.0000

0.0005

0.0010

0.0015

Time (s)

Time (s)

Fig. 8 Front face mid-point deflections of square honeycomb sandwich panels for (a) SoD = 100 mm and t = 0.76 mm (b) TNT mass = 1 kg and t = 0.76 mm (c) SoD = 100 mm and TNT mass = 1 kg (d) Comparison of Surface vs Underwater explosion for SoD = 100 mm, t = 0.76 mm, and TNT mass = 1 kg The structural response of honeycomb sandwich panels under surface and underwater explosions can be significantly different due to the distinct characteristics of these two explosion scenarios. In a surface explosion, the blast wave travels through the air and impacts the panel. The blast wave spreads radially from the point of detonation. The primary loading mechanism is air blast, which can result in a sudden increase in pressure. In an underwater explosion, the blast wave propagates through water before impacting the panel. The primary loading mechanisms include the underwater shockwave and, to a lesser extent, the subsequent air blast. Surface explosions can cause significant front-face deformation due to the abrupt increase in pressure. The panel's response is characterized by bending, deflection, and stretching as the blast wave impinges on it. Underwater explosions can lead to severe front-face deformation. The panel may experience more complex deformation patterns, including bulging and buckling due to the water pressure. The high-speed jet of water generated by the explosion can also impact the front face. While core crushing may occur in surface explosions, it is typically less severe than in underwater explosions because the core material absorbs some of the blast energy. The core serves as a buffer and absorbs some of the shock. Panels designed for underwater explosion resistance may incorporate additional design features, such as pressure-resistant skins and core materials specifically chosen for their ability to withstand high underwater pressures.