The deep hole drilling (DHD) measurement technique is a residual stress measurement technique used to measure locked-in and applied stresses in engineering materials and components.[1] 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. Deep hole drilling is considered deep in comparison to other hole drilling techniques such as centre hole drilling.[2]