A METHOD FOR DETERMINING STRAINS IN SHELLS BASED ON THE IN-FOCUS IMAGE HOLOGRAPHIC INTERFEROMETRY

The results of the investigation of a cylinder shell loaded by a concentrated force normal to the surface are presented. The triple-exposure in-focus image method of holographic interferometry was utilized to obtain holographic interferograms and speckle-photographs which then were used to identify three components of the displacement vector on the illuminated surface. Approximating (on a personal computer) the discrete identified values of the displacements by polynomials of high degree (5 or 6) and using known differential relations of the classical theory of shallow shells, we defined the strains on the illuminated surface of a cylindrical shell. Then the calculations for the separation of the bending and membrane strains were performed to determine the stress-strain state in the shell under investigation.