Optimum strain gage locations for accurate determination of the mixed mode stress intensity factors

Assessment of proper radial location for strain gages is extremely important in accurate experimental determination of mixed mode stress intensity factors (SIFs) and is an open problem. The present work proposes a methodology for accurate estimation of maximum permissible radial location (rmax) and also suggests a new strain gage method for experimental determination of the mixed mode SIFs (KI and KII). The effect of crack length to width ratio and state of stress on the rmax has also been investigated in this work. Numerical results obtained from the present investigation are observed to be in accordance with the theoretical predictions.

► Existence of optimal strain gage locations is presented for finding mixed mode SIFs.
► A procedure for estimation of optimal strain gage locations is presented.
► A modified Dally–Berger technique for estimation of mixed mode SIFs is presented.
► The upper bound on gage locations is a function of geometry of the cracked body.