PSI - Issue 60

S.K. Pandey et al. / Procedia Structural Integrity 60 (2024) 665–677 S. K. Pandey/ Structural Integrity Procedia 00 (2023) 000 – 000

669

5

4.1. Analysis with varying young modulus of elasticity

The analysis of Split-Hopkinson Pressure Bar is performed with varying modules of elasticity and the specimen is also model as linear elastic. The strain signals is plotted in Fig.2. The pulse velocity with varying elastic modulus, travel time of wave in bars and pulse duration is provided in Table 1. The first observation: increasing elastic modules the velocity of wave is increasing hence time required to reach the wave at the first strain gauge which is at 0.65 m (situated at the mid of incident bar) is decreasing. Second observation: The pulse duration, which is equal to the duration of time to travel the wave in to the double length of striker, is decreasing with increasing elastic modulus. Since the compressive wave pulse start at the striking end of striker and travel to the other end and reflect back as tensile wave pulse at the striking end. Third observation: The amplitude of incident strain signal increase with decreasing value of elastic modulus. The strain is the ratio of particle velocity and wave velocity. The particle velocity is constant because same velocity of strike (12 m/s) is imposed during every analysis. Wave velocity is decreasing hence the amplitude of strain is increasing.

Fig. 2. Strain signal with varying elastic modulus (E) during elastic analysis.

Table 1. Pulse velocity with Elastic modulus

Time to reach the pulse at strain gauge (microsecond)

length of incident bar (m)

Velocity of wave (m/s)

Pulse duration (microsecond)

Length of striker (m)

Elastic modulus (N/m 2 )

density

0.5

1.3

7800

2.00E+11 1.80E+11 1.60E+11

5064 4804 4529

128 135 144

197 208 221