Photo-Elastic Investigation of Stresses in the Heads of Thick Pressure-Vessels

Abstract

The frozen stress photo-elastic technique is used to study the stresses in four different shapes of full drumheads and in five drumheads with circular or elliptical manholes. Circumferential and meridional stresses on inside and outside surfaces are presented, and some of these are compared with stresses calculated from different thin shell theories. These theories were modified to be more realistic for thick shells by considering the pressure to act on the inside instead of the middle surface of the shell. The wall thickness of every drum was one-tenth of the mean diameter of the drum. The effect of large elastic strains was studied by means of two identical models tested at different pressures. Calculations showed that the stresses were slightly decreased when Poisson's ratio was changed from 1/2 to 1/4. The effect of a reduction of the wall thickness of hemispherical heads was calculated and was found to be in good agreement with experimental results. The stress distribution in the walls of the shells was also determined for some critical sections.