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Cui X.X.,Tsinghua University | Zhang X.,Tsinghua University | Zhou X.,Beijing Institute of Special Engineering Design and Research | Liu Y.,Tsinghua University | Zhang F.,Tsinghua University
CMES - Computer Modeling in Engineering and Sciences | Year: 2014

The material point method (MPM) discretizes the material domain by a set of particles, and has showed advantages over the mesh-based methods for many challenging problems associated with large deformation. However, at the same time, it requires more computational resource and has difficulties to construct high order scheme when simulating the fluid in high explosive (HE) explosion problems. A coupled finite difference material point (CFDMP) method is proposed through a bridge region to combine the advantages of the finite difference method (FDM) and MPM. It solves a 3D HE explosion and its interaction with the surrounding structures by dividing the problem domain into FDM region and MPM region in space. FDM is employed to simulate the region where the detonation products disperse into the surrounding air, while the FSI region is simulated by MPM. A bridging region is employed to exchange the information. In the bridge region, MPM provides the boundary condition for FDM region by mapping the variables from MPM background grid nodes to FDM fictitious points, while FDM provides the boundary condition for MPM region by mapping the variables from FDM cell-centre points to MPM interface grid nodes. The transportation between the two computational regions is implemented by moving particles in the bridge region. Numerical results are in good agreement with those of theoretical solutions, empirical formula and experiments. No obvious interface effect are observed in the bridge region in numerical tests. Copyright © 2014 Tech Science Press. Source


Cui X.X.,Tsinghua University | Zhang X.,Tsinghua University | Sze K.Y.,University of Hong Kong | Zhou X.,Beijing Institute of Special Engineering Design and Research
CMES - Computer Modeling in Engineering and Sciences | Year: 2013

Based on the material point method (MPM), an alternating finite difference material point (AFDMP) method is proposed for modeling the 3D high explosive (HE) explosion and its interaction with structures nearby. The initiatory detonation and eventual fluid structure interaction (FSI) are simulated by the standard MPM. On the other hand, the finite difference method (FDM) is employed to simulate the dispersion of the detonation products into the surrounding air where the particles degenerate to marker points which track the moving interface between detonation products and air. The conversion between MPM and FDM is implemented by the projection between the particles variables in MPM and the cell centers variables in FDM. In several numerical tests, predictions of the proposed method tests are in good agreement with theoretical solutions or empirical formulae. They illustrate that the method can yield good prediction for the entire HE explosion process. Copyright © 2013 Tech Science Press. Source


Lian Y.P.,Tsinghua University | Zhang X.,Tsinghua University | Zhou X.,Beijing Institute of Special Engineering Design and Research | Ma Z.T.,Tsinghua University
Computer Methods in Applied Mechanics and Engineering | Year: 2011

The material point method (MPM) takes advantages of both the Eulerian and Lagrangian methods, so it is capable of handling many challenging engineering problems, such as the dynamic responses of reinforced concrete (RC) subjected to blast and impact loadings. However, it is time-consuming to discretize the steel reinforcement bars (" rebars" ) in RC by using MPM because the diameter of the steel bar is very small compared with the size of concrete. A hybrid finite element-material point (FEMP) method is proposed, in which the truss element in the traditional finite element method (FEM) is incorporated into the MPM to model the rebars. The proposed FEMP method is implemented in our three-dimensional material point method code, MPM3D®, and validated by several benchmark problems. Finally, it is applied to simulate the dynamic response of RC slab penetrated by projectile, and the numerical results are in good agreement with the experimental data reported in the literature. The proposed idea is applicable to incorporate other types of finite elements into MPM to take advantages of both FEM and MPM. © 2011 Elsevier B.V. Source


Lian Y.P.,Tsinghua University | Zhang X.,Tsinghua University | Zhang X.,Dalian University of Technology | Zhou X.,Beijing Institute of Special Engineering Design and Research | And 2 more authors.
International Journal of Impact Engineering | Year: 2011

The material point method (MPM) fully takes the advantages of both Lagrangian method and Eulerian method, and can be capable of simulating high explosive explosion problems and impact problems involving large deformation and multi-material interaction of different phases. In this paper, MPM is extended to simulate the explosively driven metal problems, and two typical explosive/metal configurations, open-faced sandwich and flat sandwich, are analyzed in detail using MPM, and numerical results are compared with Gurney solution and its corrections. Based on our MPM results, a new correction to Gurney solution is proposed to account for the lateral effects for flat sandwich configuration. MPM provides a powerful tool for studying the explosively driven metal and other explosive problems. © 2010 Elsevier Ltd. All rights reserved. Source


Yang P.,Tsinghua University | Liu Y.,Tsinghua University | Zhang X.,Tsinghua University | Zhou X.,Beijing Institute of Special Engineering Design and Research | Zhao Y.,Beijing Institute of Special Engineering Design and Research
CMES - Computer Modeling in Engineering and Sciences | Year: 2012

The material point method is extended to the simulations of fragmentation driven by detonation. A crack modeling scheme based on contact algorithm with material failure process is developed to study the dynamic crack propagation in plastic media. When considering microscopic damage of material, the plastic behavior is described by Gurson model with randomly-distributed initial void of material points. Gurson model can degenerate to J2 plastic theory while the microscopic void is ignored, in which situation the Weibull random failure scheme will be used. Meanwhile, a background-grid-based searching method is proposed to capture the statistical feature of the fragmentation. The scaling of the fragments in simulation tends to exhibit the same law as that in the experiment. It is found that the material point method possesses great potential for simulating high strain-rate, large deformation fragmentation phenomena. Copyright © 2012 Tech Science Press. Source

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