Date of Award
Master of Science in Mechanical Engineering and Applied Mechanics
Mechanical, Industrial and Systems Engineering
An experimental investigation was conducted to understand the collapse mechanism of internally ring stiffened aluminum cylinders under uniform hydrostatic loading in a limited energy environment, and observe a transition of the mode of failure as the ring thickness of the stiffener is varied. The implosion of ring stiffened cylinders was studied using a combination of state-of-the-art limited energy environment facilities at DPML and 3D Digital Image Correlation (DIC). The results show that as stiffener thickness is decreased, the collapse behavior of the structure transitions from two segments collapsing in mode III with the stiffener acting as a rigid boundary to one uniform mode II collapse where the ring stiffener collapses along with the structure. Thicker stiffeners cause the long tube to behave as two distinct shorter tubes depicting their fundamental modes of collapse. The pressure signature at the confinement end consisted of a drop in pressure followed by a hammer pulse. The drop in pressure was significantly greater for mode II collapses versus mode III. While the strength of the hammer pulse approximately 0.6���� for all the experiments. The ring thickness also effects numerous other parameters such as collapse pressure, radial velocity at the location of the ring stiffener, and dwell time between the collapse of two sections. Furthermore, it was seen that as stiffener thickness increased, the behavior of the structure approached that of two isolated structures divided by a simply-supported boundary condition at the location of the stiffener. An Abaqus FEA model was developed to accurately predict the collapse pressure and mode shape of ring stiffened cylinders. The model gave roughly accurate collapse pressures and modes. The collapse pressures from the model were than used to relate the ring stiffener to the effective length. Lastly, the calculated effective length was accurate for the mode III collapses, however the predictions for a mode II collapse were significantly higher than the mode II results.
Bodurtha, Nidhi Mehta, "DYNAMIC INSTABILITY OF REINFORCED CYLINDERS IN A CONFINING ENVIRONMENT" (2019). Open Access Master's Theses. Paper 1739.