Precision determination of strains by strain measurement method

Method for precision strain measurement determination of strains measurement determination of strains by direct measurement of the resistance of strain gauge resistors put on the sample, by constant current bridge MOD-61 of 0.05 class using a zero method by single bridge double-clamp circuit is described. Strain measurement technique was used to investigate residual stresses in tubular samples. Sample external diameter made up 30 mm, the length - 180, the wall thickness-11 mm. To evaluate the method sensitivity, annealed samples were investigated (annealing temperature-850-880 deg C, hold-up-2 h, cooling in the furnace). It is ascertained, that the method provides for 0.3-0.5 μm strain measurement accuracy even if sample strains do not exceed 3.0-3.6 μm and correspond to residual stress level of no more than 20 MPa