K&C’s innovative Meshfree Computation Solid Dynamics (CSD) solver.

K&C is developing FEMFRE with the vision of a genuinely predictive, large-deformation, solid mechanics solver for simulating materials and structures in extreme environments. Originally designed as a hybrid Finite Element and Meshfree solver, K&C has since focused FEMFRE development towards an advanced meshfree solid dynamics solver that can also be coupled with other codes for fluid-structure interaction, and an option to include a fully coupled thermo-mechanical solution.

Features & Benefits

  • Flexible commercial code input format facilitates the quick exploration of FEMFRE by current users of CSD software.
  • There is no need to generate and ensure a high-quality mesh to guarantee accuracy. We are currently working towards a completely meshfree solver workflow, where only CAD geometry is required for use with FEMFRE, and no meshing is necessary.
  • Extreme distortions can be pushed infinitely farther than Lagrangian FEM. The problem of element erosion in large-deformation problems is circumvented, and there is no mass loss or erosion criteria to be tuned or selected.
  • Implements the latest techniques in stabilized nodal/particle integration schemes and enhanced nodal/particle method shock treatments [4-7]. Our goal is to remove, or at least minimize, the need to tune ad-hoc numerical controls that challenge predictive capability in solid mechanics codes (e.g., erosion, hourglass, artificial viscosity).
  • A fully thermomechanical meshfree solver [5] is available for coupled analysis.
  • OpenMP and MPI solver parallelization. FEMFRE executables are consequently suitable for both local workstations and high-performance computing platforms.
  • FEMFRE is powered by K&C’s material library, ExML (Extreme Material Library), which includes Release IV of the K&C Concrete Model and K&C’s adaptation of the Johnson-Cook model for metals, among others current in the library. Each material in ExML has material parameters that are already fit to material characterization data and ready for use. Our Dynamic Material Characterization laboratory (DMC) can also generate new ones.
  • Automatic contact detection and mechanics. Both automatic traditional contact and a physics-based particle contact algorithm free of tunable parameters are available.
  • Binary VTU output files for visualization using Paraview. There is no need to learn any new post-processing software.
  • No cost user license for collaborators and development partners, and a simplified, low-cost license model for users interested in exploring simulations with a new powerful meshfree solver. Toward our vision to increase safety, security, and affordability, we are committed to making FEMFRE available to the modeling and simulation community interested in advancing this technology.
  • Access to FEMFRE’s source code repository for selected collaborators, partners, and co-developers.

By implementing and maturing state-of-the-art meshfree methods [1-3] with advanced nodal integration [4-7], we have developed FEMFRE to solve problems that remain incredibly challenging for finite element mesh-based solvers. These include simulations involving [8-10]:

  • Materials and structures undergoing extremely large deformations
  • Materials exhibiting complex nonlinear behaviors up to and beyond failure
  • Responses governed by evolving surfaces and contact conditions
  • Structures that are difficult or time-consuming to discretize with hexahedral finite elements

FEMFRE can now be used as a tool and research platform for those in the modeling and simulation community interested in supporting the vision for this powerful solver. FEMFRE is powered by K&C’s Extreme Materials Library (ExML), which includes a host of common solid materials characterized in our Dynamic Material Characterization laboratory. FEMFRE is therefore applicable to many challenging blast, shock, impact, and intense fluid-structure interaction problems.

K&C’s current efforts for FEMFRE development are refining, extending, and validating the solver toward the vision of highly robust prediction capability.

FEMFRE USER’S MANUAL

REFERENCES

[1] T. Belytschko, J.S. Chen, and M. Hillman, Meshfree and particle methods: Fundamentals and applications, John Wiley & Sons, 2023.

[2] J.S. Chen, M. Hillman, and S. Chi, “Meshfree Methods: Progress Made after 20 Years,” J. Eng. Mech. 143(4) p. 04017001, 2017.

[3] J.S. Chen, W.K. Liu, M. Hillman, S.W. Chi, Y. Lian, and M.A. Bessa, Reproducing kernel particle method for solving partial differential equations, Encyclopedia of Computational Mechanics Second Edition, 2017.

[4] J. Wang, M. Hillman, D. Wilmes, J. Magallanes, and Y. Bazilevs, “Smoothed naturally stabilized RKPM for nonlinear explicit dynamics with novel stress gradient update,” Comput. Mech. https://doi.org/10.1007/s00466-024-02494-0, 2024.

[5] M. Hillman, and K.C. Lin, Nodally integrated thermomechanical RKPM: Part II—generalized thermoelasticity and hyperbolic finite-strain thermoplasticity, Comput. Mech. 68 pp. 821–844, 2021.

[6] M. Hillman, and  J.S. Chen, An accelerated, convergent, and stable nodal integration in Galerkin meshfree methods for linear and nonlinear mechanics, Int. J. Numer. Meth. Eng. 107 pp. 603–630, 2016.

[7] M.J. Roth, J.S. Chen, K.T. Danielson, and T.R. Slawson, “Hydrodynamic meshfree method for high-rate solid dynamics using a Rankine–Hugoniot enhancement in a Riemann-SCNI framework,” Int. J. Numer. Meth. Eng. 108 pp. 1525–1549, 2016.

[8] Y. Wu, J. Magallanes, and J. Crawford, “Fragmentation and debris evolution modeled by a point-wise coupled reproducing kernel/finite element formulation,” Int. J. of Dam. Mech. 23(7), pp. 1005-1034, 2014.

[9] Y. Wu, and J. Crawford. Numerical modeling of concrete using a partially associative plasticity model. J. Eng. Mech. 141(12), p. 04015051, 2015.

[10] Y. Wu, J. Magallanes, H. Choi and J. Crawford, “Evolutionary Coupled Finite Element Meshfree Formulation for Modeling Concrete Behaviors under Blast and Impact Loadings,” J. Eng. Mech. 139(4), pp. 525-536, 2013.

Contact Us