PSI - Issue 60

Ganesh Nigudage et al. / Procedia Structural Integrity 60 (2024) 678–689 Ganesh Nigudage / Structural Integrity Procedia 00 (2023) 000 – 000

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4.1. Yield strength correlations The characteristic small punch force values used to correlate with yield strength are normalized by square of initial specimen thickness (h 0 2 ) and then empirical correlations are established of the form- = 1 × ℎ 02 + 2 (3) Correlations for yield strength are established using Fe (proj) , Fe (int) , F ho/10 , F 0.1mm,offset in eq.3. Correlations are established using linear regression ( α 1 =slope, α 2 = intⅇrcⅇpt) . Different authors use these correlations with (Garcia et al., 2014; K. Matocha, 2015) or without (Mao and Takahashi, 1987; E. Altstadt. et al., 2016;M. Moreno, G. Bertolino, A. Yawny, 2016) the constant term 2 so both the ways were employed for generating the correlations and termed as way 1 and way 2 respectively. For the steel investigated, the following correlations were obtained: =0.22× ℎ 02 +221.45 ( =0.961) (4) =0.364× ℎ 02 ( = 0.996) (5) =0.2106× ℎ 02 +216.98 ( =0.968) (6) =0.343× ℎ 02 ( =0.996) (7) =0.184× ℎ /10 ℎ 02 +198.23 ( =0.972) (8) =0.2846× ℎ /10 ℎ 02 (r = 0.997) (9) =0.17062× 0.1 , ℎ 02 +172.35 ( =0.983 ) (10) =0.2465× 0.1 , ℎ 02 (r = 0.998) (11) 4.2. Tensile strength correlations For tensile strength, correlations are established using F m , F 0.48mm , F 0.65mm in equation 12. F m normalized by h o x v m is also used to correlate with tensile strength. = 1 × ℎ 02 + 2 (12) The following correlations were obtained- =0.088× ℎ 02 +32.81 ( =0.964) (13) =0.093× ℎ 02 (r = 0.999) (14) =0.255× ℎ 0 × +8.178 ( =0.989) (15)