Sach's boring

The Sachs method also known as the boring method is applied to cylindrical geometries.  Conventionally stressed material is bored out from the centre and relived strains are measured using strain gauges instrumented in the axial and circumferential directions on the outside surface of the cylinder or tube. Alternatively the method can be used by machining away the stressed material from the outside surface of a tube and recording the relaxed strains on the inside surface of the tube.  The relaxed strain readings are then used to calculate the through thickness distribution of residual stresses.