PSI - Issue 14

C.Jayarami Reddy et al. / Procedia Structural Integrity 14 (2019) 634–641 C.Jayarami Reddy / Structural Integrity Procedia 00 (2018) 000–000

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2.4 Experimental Set-up The explosive air blast experiments were conducted at DMRL, Hyderabad using an experimental set up shown in Fig. 2. As shown in figure, the target sample of 250mmx250mmx5mm dimensions was positioned in the centre of FRP spacer of same thickness. The target sample mounted between the spacer was sandwiched between two rigid flanges of the stand through circumferential bolting using 8 bolts. Bolting was done through the spacer. The FRP spacer and the rigid flange are also shown in figure. The area of 210mmx210mm on the target sample was used for exposure of blast load. The stand-off distance (SoD) which is defined as the distance between the target plate and the centre of the explosive charge was varied in different experiments. The experimental details are given in Table 2. The explosive charge was kept on a card board maintaining the SoD from target plate. The pencil probes and plate deployed with pressure sensors were also kept at same SoD from explosive charge to measure incident and reflected pressure, respectively. The positions of the sensor plate and pencil probes are also shown in figure. Two pencil probes are positioned perpendicularly to each other to determine the spherical form of the wave, propagating after detonation. As the sensors were not deployed directly on the target sample, these sensors will only provide representative pressures on the target sample. All these pressure sensors and pencil probes were connected to two signal conditioners through long input cables. The outputs of the signal conditioners were given to data acquisition system. The explosive charges were detonated from the control room using electric detonator-33.

Fig. 2. Experimental set- up of Air blast experiments with spacer and rigid flanges

Table 2. Details of Air blast experiments. Sl.No. Target Plate Charge mass (gms)

SoD (mm)

Peak Pressure (bar)

Final Displacement (mm)

Incident Reflected Front

Back

01 02 03 04

E2 H2 E3 H4

142 142 142 142

400 400 300 300

9.51 9.58 9.66 9.70

75.4 76.0 92.8 92.0

1 3

1 4

12 13

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