PSI - Issue 60

674 10 S.K. Pandey et al. / Procedia Structural Integrity 60 (2024) 665–677 S. K. Pandey/ Structural Integrity Procedia 00 (2023) 000 – 000 the test at quasi-static ( ̇ = ̇ ) and at reference temperature ( = ) respectively. The flow stress equation can be written as Eq. 18. In this present study, for material SS 316LN, the reference strain rate and reference temperature have been taken as 10e-3 and 25 °C respectively. The values of Johnson-Cook parameters A, B and n are found to be 256 MPa, 1100 MPa and 0.75 respectively. The experimental and Johnson-Cook stress-strain curve at quasi-static loading condition (strain rate of 1e-3 /s) and at the temperature of 25 °C is provided in Fig. 11. The Johnson-Cook strain hardening paramete r ‘C’ has been found by experiment and finite element analysis. Generally parameter ‘C’ is found by considering the experiment data as constant strain rate data but in actual strain rate varies during the test (Samal et al. 2021) hence constant strain rate condition cannot be considered for evaluating the parameter ‘C’. In the present study FEA has been used to evaluate the parameter - C. The finite element analysis of Split-Hopkinson Pressure Test has been carried out for the SS316LN cylindrical specimen of diameter and length equal to 5 mm and 5 mm respectively. The FE analysis have been performed with different values of parameter ‘C’ (from 0.01 to 0.05). The reflected and transmission signal by FEA have been compared with experimental signal. FEA signal with C= 0.03 is closely matching with experimental signal data as provided in Fig.12. The engineering strain (Eq.16) is found from the integration of engineering strain rate (Eq. 15) which is the function of reflected wave. Displacement is found by multiplying the engineering strain with the initial length of specimen. The load is found from experimental transmission signal using Eq. 11. The load and displacement have also been estimated by using FEA result. The displacement by FEA is found by the difference of left and right ends displacements of specimen and the load is found by adding the axial contact forces of all nodes of one of the end of specimen. The signal (experimental) and FEA load displacement curves is provided in Fig.13. There is fluctuation in the load displacement curve from signal due to fluctuation in wave but load displacement curve from FEA indicates that no fluctuation in actual specimen. = [ + ( ) ] (18)

Fig.11. Experimental and Johnson Cook Stress-strain curve at quasi-static loading and at 25 °C