Accession Number : AD0756869

Title :   Residual Stress Measurement Using Surface Displacements Around an Indentation.

Descriptive Note : Technical rept.,

Corporate Author : WATERVLIET ARSENAL N Y

Personal Author(s) : Underwood,John H.

Report Date : DEC 1972

Pagination or Media Count : 30

Abstract : An experimental method is described which can measure the direction and applied stress in metals. The method uses optical interference to measure the permanent surface deformation around a shallow spherical indentation in a polished area on the metal specimen. The deviation from circularly symmetrical surface deformations is measured at known values of applied stress in calibration specimens. This deviation from symmetry can then be used to determine the direction and magnitude of tensile residual stress in specimens of the same material. Determination of compressive residual stress is more limited. A model of the indentation process is offered which qualitatively describes experimental results in 4340 steel for both tensile and compressive stress. Various conditions are discussed which affect the indentation process and its use to measure stress, including (a) the rigidity of support of the indentor and specimen (b) the size and depth of the indentation (c) the uniaxial stress-strain behavior of the specimen material. (Author Modified Abstract)

Descriptors :   (*STEEL, STRESSES), (*STRESSES, DEFORMATION), MEASUREMENT, TEST METHODS, PHOTOELASTICITY

Subject Categories : Metallurgy and Metallography
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE