Simulation of dynamic environments for design verification

Abstract

Surveys on verification techniques are updated in this report to include recent applications in nuclear facilities that use transient methods for dynamic excitation. Also covered are brief discussions of the theoretical considerations underlying this testing approach, as well as requirements for correlation of experimentally and analytically derived data. Within the context of the experimental approach, the application of the rapidly changing technology of digital signal capture and data processing portends shorter test times, lowered costs, and more comprehensive measurements and environmental simulations. The experimental data encompass the use of structural transfer functions. This type of data may be used to extract mode shapes, modal frequencies, and damping, and can also be used directly to calculate structural system response motions to a variety of dynamic forcing functions. Force pulse generators provide large input forces over short time periods for in-place testing of very large structures and massive equipments. The pulse generators are applied in two different ways. In one they are used to excite structures for measurement of transfer functions; in another, now being developed, multiple pulse generators are attached to large structures to create a response that will closely match that predicted for the structure when subjected to an earthquake or other dynamic loads. The discussions culminate in a projection of the design and development work that will be required to meet future needs in structural response of nuclear reactors to dynamic loads. It is envisioned that the technical community will be required to focus attention on nonlinear behavior with special emphasis on how structures can be tested to yield their structural response characteristics.