抄録
When the structural response of a submerged structure subjected to UNDerwater EXplosion (UNDEX) loads is calculated, the shock loading from UNDEX must be estimated accurately. In this paper, firstly, characteristics of free field pressure and those of surface pressure on a cylindrical shell structure are discussed through experimental results. Secondly, through the comparison of numerical simulation results with the experimental results, the capability of simulating UNDEX phenomena is shown. And also, it is shown that fluid-structure interaction plays an important role in UNDEX phenomena. Main conclusions can be summarized as follows.
(1) Doubly exponential function proposed here can be fitted to measured free field pressure with accuracy better than 5%for impulse and energy flux density of free field pressure.
(2) The reflection factor seems to depend on the distance between explosive and a structure. In these experiments, the shadow effects of the test model to shock wave is so remarkable that the reflection factor of the back surface of the test model becomes about 0.3.
(3) There are some occasions that sharp peak pressure is generated on the back surface of a cylindrical shell structure, where elastic stress waves through different paths meet.
(4) Fluid-structure interaction greatly influences peak value, impulse and energy flux density of shock loading to the test model. Therefore, it is necessary to take it into account when estimating the shock loading by numerical simulation.
(5) Using axis-symmetric numerical simulation model, efficient and reasonably accurate estimation of shock loading to a cylindrical shell structure can be performed.
