Experimental Stress Analysis of Cylinder-to-Cylinder Shell Models and Comparisons With Theoretical Predictions

Four carefully machined cylinder-to-cylinder shell models were tested, and the experimentally determined stresses were compared with theoretical predictions obtained from a thin-shell finite-element analysis. The models were idealized structures consisting of two circular cylindrical shells intersecting at right angles. The first model tested had a nozzle-to-cylinder diameter ratio of 0.5 and a diameter-to-thickness of 100 for both nozzle and cylinder. The second model had a nozzle-to-cylinder diameter ratio of 1.0 with a diameter-to-thickness ratio of 100. The third and fourth models had a nozzle-to-cylinder ratio of 0.129. For these models the diameter-to-thickness ratio was 50 for the cylinders and 7.68 for the nozzle of model 3, while it was 20.2 for the nozzle of model 4. All models were strain gaged and subjected to 13 separate loading cases. Comparisons of measured and predicted stress distributions are presented for three of these loadings—internal pressure and in-plane and out-of-plane moments applied to the nozzle. The analytical predictions were obtained using a finite-element program that used flat-plate elements and which considered five degrees of freedom per node in the final assembled equations. The agreement between these particular finite-element predictions and the experimental results is shown to be reasonably good for the four models.