Research On Dynamic Responses And Design Methods Of Discrete Multi-layered Explosion Containment Vessels

Explosion containment vessel is a device used for confining potential danger.It can restrict shock wave and production of explosion,effectively protect the personnel and equipment near from the explosion,and facilitate the observation and testing of the explosion and detonation process.Therefore,it is widely used in national defense, fabrication using explosion process,storage and transportation of dangerous substances, scientific research and other fields.Because of the development of military,fabrication and scientific research,there is a larger capacity trend existing in explosion containment vessels. With the capacity development of explosion containment vessels,the inherent shortages of the currently widely used single shell explosion containment vessels gradually reveal themselves.For instance,the manufacturing difficulties,high costs,and difficult quality assurance of the thick steel plate(forge).Therefore,it is a very important to develop new type explosion containment vessel to fulfill the requirement of large capacity.Based on the National Natural Science Foundation″Analysis of Dynamic Elastic Response and Lifetime of Confined Discrete Multi-Layered Explosion Containment Vessel(DMECV) under Strong Dynamic Load″(No.10372091) and″Investigation on Method for Design of Multilayered Cylindrical Explosion Containment Vessels″(No.50675195),the elastoplastic dynamic response and design methods for DMECV under explosion loading were deeply studied in this thesis.The main researches are as follows:(1) A theoretical elastic-dynamic response calculation model has been developed.The displacement solution of the dynamic equilibrium equations of both inner shell and outer ribbon layer can be decomposed into two parts,i.e.,a elastic solution for inhomogeneous stress boundary conditions,and an elastic-dynamic solution for homogeneous stress boundary conditions under given initial conditions.The quasi-static elastic solution is determined by linearity method and stress boundary conditions,while the dynamic solution is worked out by means of finite Hankel integral transformation and Laplace integral transformation.Under the same internal dynamic loads,the dynamic responses of DMECV and monobloc explosion vessel with the same geometry and material have been comparative analyzed,and the effect of winding angle,inner and outer shell thickness ratio and material composition on the dynamic response have also been studied. (2) A theoretical calculation model for rigid plastic dynamic response has been established. By using a rigid plastic constitutive material model,the dynamic response of DMECV under the overall uniformly distributed rectangular load and partial load have been studied. Through the introduction of ribbon effective quality factor,the largest displacement and dynamic response time calculation formula for the inner shell and outer ribbon layer have been deduced,which are with high accuracy.Two modes of shell movements,i.e.,moving separately and moving together,are revealed,and the conversion conditions of the two movement modes are also given.(3) Three-dimensional numerical simulation method for calculating the rigid plastic dynamic response of DMECV has been developed.Finite element analysis models are established based on LS-DYNA and ABAQUS.Through comparing and analyzing the LS-DYNA and ABAQUS simulation results,the key parameters for exposure calculation have been determined.Based on the results of the former analysis,the numerical dynamic responses of DMECV are calculated,and the numerical calculation results fit with the theoretical analysis results very well,which further prove the existence of the two movement modes of DMECV.(4) Considering the strain strengthening effect and strain rate effect of the material,the model for calculating the plastic dynamic response has been established.Corresponding for each of the two movement modes,the maximum displacement formula and the equivalent plastic strain formula are derived.By calculating the theoretical formulas and comparing the result with numerical simulation results,it verifies that the largest displacement formula and equivalent plastic strain formula are with fine precision.(5) Considering the material strain strengthening effect and strain rate effect,the numerical simulation model for calculating the plastic dynamic response of DMECV under partial load has been established in LS-DYNA.According to the combination of different materials,the two movement modes of DMECV are confirmed again.Under partial load,in the latter part of a movement,the existence of non-membrane movement pattern of the outer ribbon layer is found.Under the condition of all layers together movement,it is found that the largest equivalent plastic strain of the vessel is always in the cross-section of the cylinder centre,and that the equivalent plastic strain of the ribbon shell don't change with the non- membrane movement. (6) The methods for design of multiple-used and single-used DMECV have been developed. For a multiple-used DMECV,in order to facilitate the engineering application,a group of theoretical formulae for easily calculating stresses and displacements of the inner shell and outer ribbon shells have been derived.By introducing a safety factor,the largest allowable explosive load for the DMECV is obtained.For a single-used DMECV,the equivalent plastic strains of inner shell and layered ribbons are the most important indicator for vessel strength is clarified,and a limit strain design rule is carried out.At last,selection principle of ribbon winding angle,inner and outer shell thickness ratio and material compositions are narrated.