Experimental determination of mode I notch stress intensity factors using valid strain gage locations

Abstract

Accurate experimental determination of mode I notch stress intensity factors (NSIFs) of various sharp V-notched configurations using strain gages plays an important role in notch fracture mechanics. However, practically feasible, economical, and efficient strain gage techniques are hardly available for the sharp V-notched problems. Considering problems associated with the sharp V-notched bodies, the authors recently proposed a strong theoretical basis for an efficient single strain gage technique with valid gage locations for the accurate measurement of mode I NSIFs of sharp V-notched configurations. The main thrust of the present investigation is the experimental substantiation of the above strain gage technique using different V-notched configurations. It has been shown that these valid locations are governed by two parameters rmin and rmax of a sharp V-notched configuration. The results of the present investigation clearly demonstrate that very accurate NSIFs can be obtained from a single strain gage located at the suggested valid locations, which need not necessarily be in the vicinity of a notch tip. Further, the results also show that highly erroneous NSIFs can result if the gages are located at invalid radial locations. The results explicitly indicate that adopting the valid gage locations is beneficial rather than pasting the gages based on guesswork or other speculations.