Hybrid Particle-finite Element Research Articles

A hybrid particle-finite element method for impact dynamics

An attachment algorithm for the coupling of smoothed particle hydrodynamics (SPH) and finite element method (FEM) is proposed to take advantage of the best properties of both methods. In the SPH-FEM attachment algorithm, SPH particles are attached to finite element nodes in the coupling interface. Any FE node that is in the support domain of SPH particle is added to the SPH neighbor list in the mode of background particle, and the continuity of coupling interface is guaranteed. The attachment algorithm allows for the use of accurate and efficient finite elements in mildly distorted regions and SPH particles in highly distorted regions within a Lagrangian framework. The perforation of a cylindrical Arne tool steel projectile impacting a Weldox 460 E steel target plate is simulated in 3D to demonstrate the performance of the SPH-FEM attachment algorithm. A corrected Johnson–Cook model containing damage variable is adopted for the target plate, with a Gruneisen EOS for the volumetric response. A birth and death particle algorithm is adopted to remove the damage particle from the model. Good agreement between numerical simulations and experimental observations is obtained.

Another approach to a hybrid particle-finite element algorithm for high-velocity impact

This article presents a hybrid particle-finite element algorithm for high-velocity impact. In the hybrid approach, both finite elements and meshless particles represent the same material simultaneously. The initial hybrid concept was introduced and developed by Fahrenthold and others. It is based on a Hamiltonian formulation for both the particles and elements, and it has used a structured arrangement for the finite elements. The work presented here is based on the Generalized Particle Algorithm, and it can be used with a variety of element types and arrangements. A finite element mesh is generated as it would be for a traditional finite element computation (except that contact surfaces do not need to be defined), and the hybrid algorithm simply becomes another option for the user. The hybrid algorithm of Fahrenthold computes the compressive pressure at the nodes (particles), with the strength and tensile pressure computed in the elements. This approach allows large distortions and fragmentation to be represented, it eliminates tensile instabilities in the particles, and it allows the contact to be performed within the particle algorithm. There are additional advantages and disadvantages of the hybrid approach when compared to other techniques, such as the automatic conversion of distorted finite elements into meshless particles, and these are discussed. The new hybrid algorithm is demonstrated in both 2D and 3D geometries with a range of example computations. Comparisons to computations performed with a conversion (of elements into particles) algorithm are also presented.

Hypervelocity impact simulation using membrane particle-elements

A series of three-dimensional simulations have been performed to evaluate the use of membrane particle-elements to model hypervelocity impact effects in fabrics. The simulations employed an improved hybrid particle-finite element method and material models recently developed for conventional Kevlar and for Kevlar treated with a shear thickening fluid. The simulation results were compared with experimental data from tests conducted by NASA Johnson Space Center. The results suggest that membrane particle-elements can provide a computationally efficient description of hypervelocity impact dynamics in flexible multi-layered structures.

Simulation of orbital debris impact on the Space Shuttle wing leading edge

A series of three dimensional hypervelocity impact simulations has been performed to study the effects of orbital debris impact on the Space Shuttle wing leading edge. The simulations employed an improved hybrid particle-finite element method and an orthotropic elastic-plastic material model recently developed for reinforced carbon–carbon. The simulation results are consistent with the available experimental data, and suggest the use of momentum scaling to estimate damage effects for impact conditions outside the range of current light gas gun technology. Projectile shape and orientation effects appear to be modest for flat plate projectiles at impact velocities above the ballistic limit.

Simulation of hypervelocity impact on aluminum-Nextel-Kevlar orbital debris shields

An improved hybrid particle-finite element method has been developed for hypervelocity impact simulation. The method combines the general contact-impact capabilities of particle codes with the true Lagrangian kinematics of large strain finite element formulations. Unlike some alternative schemes which couple Lagrangian finite element models with smooth particle hydrodynamics, the present formulation makes no use of slidelines or penalty forces. The method has been implemented in a parallel, three dimensional computer code. Simulations of three dimensional orbital debris impact problems using this parallel hybrid particle-finite element code, show good agreement with experiment and good speedup in parallel computation. The simulations included single and multi-plate shields as well as aluminum and composite shielding materials. at an impact velocity of eleven kilometers per second.

Extention and validation of a hybrid particle-finite element method for hypervelocity impact simulation

The hybrid particle-finite element method of Fahrenthold and Horban [1], developed for the simulation of hypervelocity impact problems, has been extended to include new formulations of the particle-element kinematics, additional constitutive models, and an improved numerical implementation. The extended formulation has been validated in three dimensional simulations of published impact experiments. The test cases demonstrate good agreement with experiment, good parallel speedup, and numerical convergence of the simulation results.

An improved hybrid particle-element method for hypervelocity impact simulation

An improved hybrid particle-finite element method has been developed for hypervelocity impact simulation. The method combines the general contact-impact capabilities of particle codes with the true Lagrangian kinematics of large strain finite element formulations. Unlike some alternative schemes which couple Lagrangian finite element models with smooth particle hydrodynamics, the present formulation makes no use of slidelines or penalty forces.

Orbital debris impact simulation using a parallel hybrid particle-element code

Simulations of three dimensional orbital debris impact problems, using a parallel hybrid particle-finite element code, show good agreement with experiment and good speedup in parallel computation. The simulations included single and multi-plate shields as well as aluminum and composite shielding materials, at an impact velocity of eleven kilometers per second.

Numerical simulation of oblique impact on orbital debris shielding

Hybrid particle-finite element methods have been proposed as a modeling methodology well suited to the problem of hypervelocity impact simulation. To evaluate the use of such numerical methods for orbital debris shielding design, a series of simulations have been conducted using a three dimensional hybrid particle-finite element code now under development. Two sets of oblique impact simulations, one for a single bumper Whipple shield and one for a dual bumper or stuffed Whipple shield, have been compared to published ballistic limit equations, the latter derived from experiment. The results indicate that hybrid particlefinite element methods can provide an accurate and computationally tractable approach to the simulation of orbital debris shield performance.

A hybrid particle-finite element method for hypervelocity impact simulation

Coupled particle-finite element methods have been suggested as an approach to modeling particular impact problems not well suited to simulation with conventional Eulerian, Lagrangian, or particle codes. An alternative hybrid particle-finite element technique has been developed, in which particles are used to model contact-impact and volumetric deformation while finite elements are employed to represent interparticle tension forces and elastic-plastic deviatoric deformation. The method has been implemented in a three dimensional code and applied to simulate representative hypervelocity impact problems.