PSI - Issue 14

Neelanchali Asija Bhalla et al. / Procedia Structural Integrity 14 (2019) 564–570 Neelanchali et al/ Structural Integrity Procedia 00 (2018) 000–000

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where, ε r is reflected strain pulse, ε t is transmitted strain pulse, C o is elastic wave velocity in the bars, L s is the specimen length, A B is cross-section area of bar, A S is cross-section area of specimen, ‘t’ is time duration and ‘E’ refers to Young’s modulus of elasticity of the bar material. The SHPB experimental parameters are given in Table 2. Table 2: SHPB Experimental Parameters Parameters Values Length of the Barrel 2000 mm Incident Bar (IB) , Transmission Bar (TB) and Striker Bar (SB) Material Al6063 alloy Length of Incident and Transmission (LTB) Bars 1200 mm Length of the striker bar (LSB) 85 mm Diameter of Incident and Transmission bars 15.5 mm Elastic Modulus of the bar material, E 68.9 GPa Density of the bar material 2.7 g/cc Velocity of sound, in the bar material (C) 5052 m/s Thickness of the specimen 0.35 mm Diameter of the specimen 15.50 mm The low strain rate testing of the synthesized samples was conducted on cone and plate rheometer. The cone and plate dimensions were; cone angle 0.01 radians and plate diameter 50 mm. The gap between cone and plate surface was kept fixed at 0.05 mm. All the samples were subjected to steady shear testing in which the shear rate was linearly ramped up from 0 to 1000 s -1 and torque response was measured at discrete shear rates in succession, to give a flow curve of viscosity versus shear rate for each of the samples. Prior to rheological testing, samples were pre sheared at a shear rate of 1 s -1 for 25s followed by 60s rest period to erase any previous shear histories on the sample and to ensure that the sample establishes its equilibrium structure, before taking any readings. This helped to achieve repeatability in results. 4.2. High Strain Rate Testing The high strain rate testing was conducted on Split Hopkinson Pressure Bar (SHPB) apparatus. Fig.2 shows the sample loaded between the incident and transmission bars just before firing. 4. Testing of Samples 4.1. Low Strain Rate Testing

Fig.2: Test specimen between the incident and transmission bars