Expression for the Dynamic Yield Stress from Instrumented Dynamic Tear Specimens and Plastic η-Factor for Three-Point Bend Specimens: Results for AISI 308 Weld and AISI 316 Stainless Steels

An empirical expression for computing the dynamic yield stress, σyd, from the general yield load, PGY, of dynamic tear (DT) specimens has been derived by comparing the results from instrumented drop-weight/impact tests of DT and Charpy V-notch (CVN) specimens of AISI 308 weld and AISI 316 stainless steels. This is based on the following assumptions: the functional expression relating σyd to PGY is the same for both DT and CVN specimens except for a dimensionless proportionality constant: and σyd from both the specimens has the same value. Plastic η-factors obtained by analyzing instrumented DT test results are also presented. The work reported earlier by the authors based on instrumented CVN and precracked Charpy specimen test results showed the dependence of the plastic η-factor on the crack aspect ratio; the present results indicate that the plastic η-factor shows an additional specimen size dependence. However, the new estimates based on the larger size specimens are only slightly larger than the lower-bound estimates reported earlier, but much below the upper-bound curve reported at the same place. Similar size dependence has been reported in the literature.