Description: Smoothed particle hydrodynamics (SPH) is a particular Lagrangian mesh-free numerical method. You define the model using 1-node PC3D elements (commonly referred to in the literature as particles) that are placed in space much like nodes of the usual finite elements. Abaqus/Explicit searches for neighboring particles based on a radius of influence (smoothing length) and computes kinematic quantities (such as strains, deformation gradients, etc.) based on contributions from this cloud of particles centered at the particle of interest. Every increment Abaqus/Explicit recomputes the local connectivity; thus, there are no restrictions on the movement of the particles with respect to each other. Consequently, the method can accommodate very large strain gradients that are usually not possible to account for when using regular Lagrangian finite elements.

While the method tends to address modeling needs similar to the coupled Eulerian-Lagrangian method, it is likely to be more efficient in cases where the material to void ratio is small. Fragmentation, where chunks of material move significantly through space before the secondary impact of interest occurs, is a prime example. The method can be used with all materials available in Abaqus/Explicit (including user materials). Contact with other meshed Lagrangian bodies is defined as for any other node-based surfaces. Boundary conditions, initial conditions, and constraints are defined as usual.

Figure 6–3 shows an example of ballistic impact. The projectile penetrates the plate, causing material failure and fragmentation. The impact area is modeled with particle elements.