Browsing by Author "Wang, Guoping"

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    Dynamically Enriched MPM for Invertible Elasticity
    (© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Zhu, Fei; Zhao, Jing; Li, Sheng; Tang, Yong; Wang, Guoping; Chen, Min and Zhang, Hao (Richard)
    We extend the material point method (MPM) for robust simulation of extremely large elastic deformation. This facilitates the application of MPM towards a unified solver since its versatility has been demonstrated lately with simulation of varied materials. Extending MPM for invertible elasticity requires accounting for several of its inherent limitations. MPM as a meshless method exhibits numerical fracture in large tensile deformations. We eliminate it by augmenting particles with connected material domains. Besides, constant redefinition of the interpolating functions between particles and grid introduces accumulated error which behaves like artificial plasticity. We address this problem by utilizing the Lagrangian particle domains as enriched degrees of freedom for simulation. The enrichment is applied dynamically during simulation via an error metric based on local deformation of particles. Lastly, we novelly reformulate the computation in reference configuration and investigate inversion handling techniques to ensure the robustness of our method in regime of degenerated configurations. The power and robustness of our method are demonstrated with various simulations that involve extreme deformations. We extend the material point method (MPM) for robust simulation of extremely large elastic deformation. This facilitates the application ofMPMtowards a unified solver since its versatility has been demonstrated lately with simulation of variedmaterials. Extending MPM for invertible elasticity requires accounting for several of its inherent limitations. MPM as a meshless method exhibits numerical fracture in large tensile deformations. We eliminate it by augmenting particles with connected material domains. Besides, constant redefinition of the interpolating functions between particles and grid introduces accumulated error which behaves like artificial plasticity. We address this problem by utilizing the Lagrangian particle domains as enriched degrees of freedom for simulation. We also novelly reformulate the computation in reference configuration and investigate inversion handling techniques to ensure the robustness of our method in regime of degenerated configurations
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    Peridynamics‐Based Fracture Animation for Elastoplastic Solids
    (© 2018 The Eurographics Association and John Wiley & Sons Ltd., 2018) Chen, Wei; Zhu, Fei; Zhao, Jing; Li, Sheng; Wang, Guoping; Chen, Min and Benes, Bedrich
    In this paper, we exploit the use of peridynamics theory for graphical animation of material deformation and fracture. We present a new meshless framework for elastoplastic constitutive modelling that contrasts with previous approaches in graphics. Our peridynamics‐based elastoplasticity model represents deformation behaviours of materials with high realism. We validate the model by varying the material properties and performing comparisons with finite element method (FEM) simulations. The integral‐based nature of peridynamics makes it trivial to model material discontinuities, which outweighs differential‐based methods in both accuracy and ease of implementation. We propose a simple strategy to model fracture in the setting of peridynamics discretization. We demonstrate that the fracture criterion combined with our elastoplasticity model could realistically produce ductile fracture as well as brittle fracture. Our work is the first application of peridynamics in graphics that could create a wide range of material phenomena including elasticity, plasticity, and fracture. The complete framework provides an attractive alternative to existing methods for producing modern visual effects.In this paper, we exploit the use of peridynamics theory for graphical animation of material deformation and fracture. We present a new meshless framework for elastoplastic constitutive modelling that contrasts with previous approaches in graphics. Our peridynamics‐based elastoplasticity model represents deformation behaviours of materials with high realism. We validate the model by varying the material properties and performing comparisons with finite element method (FEM) simulations. The integral‐based nature of peridynamics makes it trivial to model material discontinuities, which outweighs differentialbased methods in both accuracy and ease of implementation.
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    Reformulating Hyperelastic Materials with Peridynamic Modeling
    (The Eurographics Association and John Wiley & Sons Ltd., 2018) Xu, Liyou; He, Xiaowei; Chen, Wei; Li, Sheng; Wang, Guoping; Fu, Hongbo and Ghosh, Abhijeet and Kopf, Johannes
    Peridynamics is a formulation of the classical elastic theory that is targeted at simulating deformable objects with discontinuities, especially fractures. Till now, there are few studies that have been focused on how to model general hyperelastic materials with peridynamics. In this paper, we target at proposing a general strain energy function of hyperelastic materials for peridynamics. To get an intuitive model that can be easily controlled, we formulate the strain energy density function as a function parameterized by the dilatation and bond stretches, which can be decomposed into multiple one-dimensional functions independently. To account for nonlinear material behaviors, we also propose a set of nonlinear basis functions to help design a nonlinear strain energy function more easily. For an anisotropic material, we additionally introduce an anisotropic kernel to control the elastic behavior for each bond independently. Experiments show that our model is flexible enough to approximately regenerate various hyperelastic materials in classical elastic theory, including St.Venant-Kirchhoff and Neo-Hookean materials.
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    Semi-analytical Solid Boundary Conditions for Free Surface Flows
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Chang, Yue; Liu, Shusen; He, Xiaowei; Li, Sheng; Wang, Guoping; Eisemann, Elmar and Jacobson, Alec and Zhang, Fang-Lue
    The treatment of solid boundary conditions remains one of the most challenging parts in the SPH method. We present a semianalytical approach to handle complex solid boundaries of arbitrary shape. Instead of calculating a renormalizing factor for the particle near the boundary, we propose to calculate the volume integral inside the solid boundary under the local spherical frame of a particle. By converting the volume integral into a surface integral, a computer aided design (CAD) mesh file representing the boundary can be naturally integrated for particle simulations. To accelerate the search for a particle's neighboring triangles, a uniform grid is applied to store indices of intersecting triangles. The new semi-analytical solid boundary handling approach is integrated into a position-based method [MM13] as well as a projection-based [HWW*20] to demonstrate its effectiveness in handling complex boundaries. Experiments show that our method is able to achieve comparable results with those simulated using ghost particles. In addition, since our method requires no boundary particles for deforming surfaces, our method is flexible enough to handle complex solid boundaries, including sharp corners and shells.