Elastic Strength of High Pressure Vessels With an Offset Elliptical Cross Bore

The purpose of this study was to establish the elastic strength of an optimum elliptical shaped cross bore at different location using elastic failure theories. Seven cross bored thick walled cylinders with different thickness ratio ranging from 1.4 to 3.0 were investigated. The study was done on two elliptical cross bores having different cross sectional areas, at 9 different locations. The cross bores were positioned between 0 and 0.9 along the longitudinal X axis plane of the cylinder. Three-dimensional elastic finite element analyses were performed on cross bored cylinders using Abaqus version 6.16 commercial software program. The analysis was done on 126 different models using an eighth structure of the cylinder. It was found that the minimum working stresses occurred at the radial position of the cross bore. The possible improvement of pressure carrying capacity when the cross bore size is chosen optimally, ranged from 20.18% to 32.69% for Von mises material, and 15.2% to 33.15% for Tresca material. On the other hand, the amount of pressure carrying capacity that can be improved when the cross bore is located optimally, ranged from 43.83% to 54.29% and 124.03% to 104.21% for Von Mises and Tresca's theories, respectively. An indication that the location of cross bore in an elliptical shaped cross bore had a more pronounced significant effect than its size. Similar to working stresses, the lowest working Stress Concentration Factor (SCF) occurred at the cross bore radial position. For cross bore size 1, the working SCF ranged from 1.630 to 1.708, and 1.417 to 1.902 for Von Mises and Tresca's materials, respectively. Whereas, that for cross bore size 2, ranged from 1.621 to 1.708, and 1.415 to 1.486 for Von Mises and Tresca's materials, respectively