| Explosion is widely used in the engineering technology, such as demolition blasting, explosion forming, explosion welding, rock and ice breaking, et al. Explosion problems usually accompanied by high temperature and pressure, strong shock and large deformation, material fragmentation and splash phenomenon. Besides, the conventional experimental study of explosion is expensive, long cycle and difficult in getting enough details of the explosion processes. With the development of computational technology, numerical simulation has become an important approach to explosion study. At present, the numerical simulation of aluminized explosive’s explosion is mainly based on the traditional finite element mesh, but the finite element method(FEM) in modeling large deformation problems tends to generate element distortion and its accuracy and efficiency is significantly decreased. Smooth particle method(SPH) has a certain advantage in solving large deformation problems and is easy to simulate material fragmentation and splash, but in terms of computational efficiency and ability in dealing with the boundary conditions is not as good as FEM. Coupling FEM and SPH can make use of the advantages of the two methods and provides an effective approach for the simulation of large deformation problems.Firstly, the two-dimensional axisymmetric FE-SPH method is applied to simulate the explosion process of aluminized explosives in concrete. Explosion process of aluminized explosive is described by JWL equation of state and Miller reaction rate equation. In order to avoid non-physical penetration of particles that formed from FE elements after the explosion, the contact method is adopted. The explosion processes of aluminized explosives with different aluminum content in different depth of concrete are simulated. Numerical results show that the FE-SPH method can stably reproduce the explosion process of aluminized explosives in concrete. The characteristic parameters of explosive response obtained by FE-SPH method are in good agreement with experiment results.Secondly, this thesis researches the damage effect of aluminized explosive’s explosion in multilayer compact medium by numerical simulation. The numerical simulation is based on the 3D FE-SPH coupling method and turns out to be effective by comparing with the experiments. Moreover, the pressure characteristics in the explosion process, the effect on explosion damage law of the aluminum powder content and the buried depth are researched. Research results show that the multilayer compact medium’s damage is greatly influenced by aluminum powder content and the buried depth when the explosive dosage is given.Finally, this thesis introduces the model validation method to validate the simulation model of aluminized explosive’s explosion in concrete when the concrete parameters exists uncertainty. The uncertain parameters are described by probability model and the target response of impact radius in concrete is established by using surrogate model technique. And then, using the validation metric based on the area between the numerical calculation and experiment results’ cumulative probability distribution functions to quantize and evaluate the error. Results show that the simulation model is effective when the concrete parameters exists uncertainty. It is offers a new viewpoint and strategy for solving the model validation problems when consider the material parameter uncertainty. |
