Deep hole drilling

Deep hole drilling (DHD) is a residual stress measurement technique used to measure locked-in and applied stresses in engineering materials and components. DHD is a semi-destructive mechanical strain relaxation (MSR) technique, which seeks to measure the distribution of stresses along the axis of a drilled reference hole. The process is unique in its ability to measure residual stresses at a microscopic level with a penetration of over 750 millimetres (30 in), without total destruction of the original component. DHD is considered deep in comparison to other hole drilling techniques such as centre hole drilling.