Abstract
A special subset of pressures vessels are required to fully contain internal explosive blasts for commercial and government agencies conducting blast-related research and testing. In some cases these blast chambers must also safely contain the impact of high-speed fragments that may be created from cased munitions and devices. Both of these loading conditions require specific analysis methods, for example penetration mechanics and specialized dynamic finite element simulation. Careful attention must also be paid to the construction of these blast chambers, which typically utilize very thick steel plate, large forgings and pressings, and thorough weld procedure and inspection development. Beside the typical steel pressure vessel body, many ports are needed in such vessels, including those that house thick windows. These elements are typically the areas of highest stress concentration. Fatigue analysis is also conducted, using the predicted stress states, to ensure the pressure vessel will survive the required number of tests. Due to the potentially hazardous operation of the vessel, they must also undergo extensive post-construction proof testing to verify their safety and to validate the design/analysis approach. Methods to address the repetitive impulsive loading and fatigue failure are described in ASME BPVC Code Case 2564-5 Impulsively Loaded Pressure Vessels. An approach taken to satisfy those guidelines is described in this paper.
Southwest Research Institute (SwRI) has designed, constructed, and tested many blast chambers in the last 30 years. This paper discusses the specialized work needed for this class of vessel, including dynamic finite element analysis that accounts for shock pressure and quasi-static pressure. To illustrate the different steps specific examples are provided for key areas such as entry doorways and the viewports. Evaluation of internal shielding and transparency materials that must withstand impact are described. Example proof test methods are described and data obtained during recent projects will be included to demonstrate results.
