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Axisymmetric and three-dimensional smoothed particle hydrodynamics (SPH) models are developed to simulate normal and oblique perforation of 12 mm-thick Weldox 460 E steel plates. In the models, a particle-to-particle contact algorithm including friction effect is employed to model interactions between projectile and target plate. A constitutive model coupling viscoplasticity and ductile damage is implemented to describe material behaviors of target plate. Both axisymmetric and three-dimensional SPH models are validated by existing experimental results. By using axisymmetric models, effects of projectile structure on normal perforation are systematically studied. Two factors of projectile structure, nose shape and aspect ratio, are considered. Residual velocities, ballistic limits and failure modes are obtained for different projectile nose shapes and aspect ratios. Effects of nose shape and aspect ratio on ballistic limits predicted by SPH simulations are compared with those obtained by an analytical equation. By using three-dimensional models, oblique perforation is simulated. Effects of oblique angle on impact processes are analyzed. Intervals of critical oblique angle of ricochet are obtained for different impact velocities and caliber-radius-head values of ogival projectile. The results obtained in this work can provide reference for the design of protective structures with steels and similar materials. The SPH with contact algorithm including friction effect is proved to be a very effective method for ballistic impact simulation.

Purpose – The purpose of this paper is to confirm that the axisymmetric finite element and smoothed particle hydrodynamics (FE-SPH) adaptive coupling method is effective to solve explosion problem in concrete based on the experiments. Design/methodology/approach – Axisymmetric FE-SPH adaptive coupling method is first presented to simulate dynamic deformation process of concrete under internal blast loading. Using calculation codes of FE-SPH coupling method, numerical model of explosion is approximated initially by finite element method (FEM), and distorted finite elements are automatically converted into meshless particles to simulate damage, splash of concrete by SPH method, when equivalent plastic strain of elements reaches a specified value. Findings – In this paper, damage process and pressure curve of concrete around explosive are analyzed and buried depth of explosive in concrete influence on damage effect under internal blast loading are obtained. Numerical analyses show that FE-SPH coupling method integrates high computational efficiency of FEM and advantages of SPH method, such as natural simulation to damage, splash and other characteristics of explosion in concrete. Originality/value – This work shows that FE-SPH coupling method has good performance to solve the explosion problem.

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Smoothing length plays a significant role in smoothed particle hydrodynamics (SPH). Inappropriate smoothing length will result in problems of stability, accuracy and efficiency. Updating smoothing length with time is very important for SPH modeling of large deformation problems. In this work, an effective smoothing length updating method is proposed. The method works in the framework of SPH with scalar smoothing length. It is quite simple in implementation and is computationally efficient. The method updates smoothing length according to maximum local particle spacing and inhomogeneity of material deformation. Numerical examples in both 2D and 3D which involve large deformation are calculated to validate the effectiveness of the proposed method. A comparison between the proposed method and several traditional methods is performed. Numerical results show that the present method can adapt to the simulation of severely inhomogeneous deformation and produce better stability and accuracy than the traditional methods for SPH modeling of large deformation problems.