3D hybrid particle contact method for ignition response of high explosives and high velocity impact

The contact method is required in the smoothed particle hydrodynamics to prevent virtual shear and tensile stresses when the effects of relative motion at the solid object interfaces are not negligible. In this study, we propose a three-dimensional hybrid contact method combining particle-surface contact and particle-particle contact for smoothed particle hydrodynamics. First, an improved high accuracy free-surface particle detection method is developed, including optimization of the detection process to reduce the detection time and consideration of the effect of material compressibility to extend the existing semi-geometric method from the incompressible (weakly-compressible) field to the compressible field. Then, a novel three-dimensional local surface reconstruction method is developed based on the free-surface particles and region growing method, including the selection of the initial edge, the principle of triangle extension, and the evaluation function, followed by the particle-surface contact detection and enforcement of normal penalty force and tangential friction force according to the penalty function method and Coulomb friction law, respectively. Finally, the particle-particle contact is added to deal with cases where particle-surface contact fails, e.g., some particles cannot reconstruct the local surface when the material undergoes extreme deformations. Several numerical tests show that the proposed free-surface particle detection method is successfully applied to the compressible field while reducing the detection time, the proposed local surface reconstruction method is easy to parallelize, and the proposed hybrid contact method is capable of handling frictionless and friction problems under various deformation conditions.