Method of measuring stress with x-rays

Claim 1

A method of measuring stress in a material comprising the steps of a. projecting an X-ray beam upon the surface of an article under test at a predetermined angle of incidence, b. sensing the intensity of a resultant diffracted X-ray beam with means movably disposed with respect to said articles, c. generating a first electrical signal, in counts per second, proportional to said sensed intensity with means connected to said sensing means, said first electrical signal representing the intensity of the diffracted X-ray beam and the value of sin2 Psi , where Psi represents the angle between a line normal to said surface and a bisector of an angle subtended by said incident X-ray beam and the direction of maximum diffraction, d. moving said sensing means in an arc with respect to said article, e. generating a second electrical signal proportional to the angle of said sensing means along said arc, f. recording said sensed diffraction beam intensities on a display of an electrical XY recording means by applying said first electrical signal to an ordinate input to said recording means, and applying said second electrical signal to an abscissa input to said recording means, g. repeating steps a-f at different incidence angles of projection while superimposing said recordings to yield a composite recording, h. and determining the peak values of said counts per second for respective curves; calculating values of sin2 Psi for respective peak values; drawing a straight line connecting said calculated values of sin2 Psi ; and determining the slope of said straight line with respect to said abscissa, said slope being directly proportional to said stress.

Claim 2

A method of measuring stress in a material comprising the steps of a. projecting an X-ray beam upon the surface of an article under test at a predetermined angle of incidence, b. sensing the intensity of a resultant diffracted X-ray beam with means movably disposed with respect to said articles, c. generating a first electrical signal, in counts per second, proportional to said sensed intensity with means connected to said sensing means, said first electrical signal representing the intensity of the diffracted X-ray beam and the value of sin2 Psi , where Psi represents the angle between a line normal to said surface and a bisector of an angle subtended by said incident X-ray beam and the direction of maximum diffraction, d. moving said sensing means in an arc with respect to said article, e. generating a second electrical signal proportional to the angle of said sensing means along said arc, f. recording said sensed diffraction beam intensities on a display of an electrical XY recording means by applying said first electrical signal to an ordinate input to said recording means, and applying said second electrical signal to an abscissa input to said recording means, g. repeating steps a-f at different incidence angles of projection while superimposing said recordings to yield a composite recording, h. and determining the peak values of said counts per second for respective curves; calculating values of sin2 Psi for respective peak values; drawing a straight line connecting said calculated values of sin2 Psi ; and determining the slope of said straight line with respect to said abscissa, said slope being directly proportional to said stress.