PSI - Issue 14

Hemant Chouhan et al. / Procedia Structural Integrity 14 (2019) 830–838 Author name / Structural Integrity Procedia 00 (2018) 000–000

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Kraton Polymers. Each layer of the composite comprises of four plies of 0:90 laminae. The laminas were compression molded at a pressure of 35 ± 2 bars and the molding temperature was set to 115 ± 2  C. The 300 x 300 mm 2 compression-molded laminate was having a thickness in the range of 4.5 mm - 5.0 mm with an areal density of 4.01 kg/m 2 . To get the cylindrical composite specimen of diameter 10 mm, rota broach machining was used. Rota broach uses a fringe cutting tooth having a circular saw with a hollow cavity to get the circular specimen from a thin laminate. The subsequent SHPB specimen were having an aspect ratio in the assortment of 0.45 - 0.5. 2.2. Moisture Conditioning Two types of samples were utilized for experimental works. After rota broach machining one set was weighted on the computerized measuring scale and afterwards kept in a vacuum oven at 60 ºC for 60 minutes, to quantify if there is any moisture content uptake in the specimen. There was no change in the specimen weight, showing an initial moisture free specimen. This set of the specimen was dealt with as the dry specimen. Another arrangement of the specimen was immersed in potable water according to NIJ standard by Mukasey et al. (2008). The time of holding the specimen in potable water was kept 24 hours and the specimen were kept 100 mm underneath the surface of the water and with no less than 50 mm freedom around, at 21 ºC. The testing on SHPB was performed within one hour of the removal of the specimen from the water container. Before testing the specimen, the surface of the specimen were wiped and weighed. It is noticed that Fick's law fills in as a standard for assurance of the rate of dissemination for composite frameworks, uncovering the immersion time and dampness rate as discussed by Meng et al. (2016). Be that as it may, attributable to the utilitarian necessities of ballistics testing, which is characterized by NIJ standard, the same was not fundamental for this situation. The thought process of study is to uncover the high strain rate behaviour of the composite under dynamic high strain rate loading, to mimic the genuine risk of ballistic effect.

Fig. 1. Schematic of the experimental SHPB set-up.

Table 1. Specifications of SHPB Set-up Bar properties

Material Density

Titanium (Ti6Al4V)

4430 kg/m3

Modulus of Elasticity

113.8 GPa

Elastic wave speed

5068 m/s

Bar Diameter

16 mm

Incident and transmission bar length

1200 mm

Striker length

240 mm