Numerical Simulation For Explosion Dynamic Dynamic Responses And Thermal Buckling Of Large Steel Tanks

Tank structures are widely used for fluid and bulk storage, such as oil, gas, and grain in industrial and agricultural plants. The welded steel oil tanks are most common among these. Due to the special application of steel oil tanks, they are vulnerable to explosion and fire accident, which cause damage to the tanks. A deep investigation into the dynamic responses and failure modes of steel tanks under explosion and fire helps to prevent and cut the loss caused by explosion and fire.Numerical simulations for dynamic responses under internal explosion and thermal buckling under external fire of big steel ranks are conducted. The layout is organized as follows:Chapter1introduces the background of this dissertation. Researches on load simulation and structural dynamic response of steel tanks under explosion and fire are reviewed and the arguments and ideas of this thesis are given.Chapter2specifies and validates the parameters of Johnson-Cook thermal viscoplastic material constitutive model by conducting numerical simulations on two examples. In this part, Johnson-Cook material constitutive model is compared with Cowper-Symonds viscoplastic model on the performance in simulating the explosion dynamic responses.Chapter3briefly introduces the basic principles of computational fluid dynamics (CFD). Simulations for internal vapor cloud explosion of steel tanks are conducted with FLUENT, and the overpressure time histories of different points on the tanks are calculated. Several equivalent-load areas are divided on the tanks according to the distribution characteristics of the overpressure, providing a simplified explosion load model for numerical simulating the explosion dynamic responses of the tanks.Chapter4simulates the internal explosions of the steel tanks with LS-DYNA based on the parameters of Johnson-Cook material constitutive model and explosion load model provided by the previous chapters. Structural dynamic responses and failure modes of tanks differed in geometric size and forms of roofs under internal explosions are also discussed in this part.Chapter5conducts numerical simulations for thermal buckling of steel tanks induced by external fire. The buckling modes and influential factors of thermal buckling are also discussed.Chapter6summarizes some important conclusions and indicates some further work on the topic in this dissertation.