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Multi-physics


Electromagnetics (EM)


The LS-DYNA® Electromagnetic solver (EM) combines the Finite Element Method (FEM) and the Boundary Element Method (BEM) in a way that allows robust, scalable, and accurate simulations of electromagnetic processes. Strong coupling between the EM solver with the structural, thermal and Computational Fluid Dynamics (CFD) solvers makes LS-DYNA an excellent option for multi-physics problems.


    Applications:

      • Magnetic metal forming/welding

      • Induced heating

      • Rail gun

      • Resistive spot welding

      • Battery cells

      • Cardiac electro-physiology

Magnetic forming of a metallic plate against a conical die.


    Features:

      • FEM and BEM based

      • 2 and 3 dimensional

      • Available for solids, shells and composite thick shells

      • EM contact

      • Computation of inductances

      • EM equations-of-state

      • Circuit models for electro-chemistry in batteries

      • Cell ionic models for electro-physiology

      • Electrophysiology mono and bi-domain models


Resistive spot welding simulation, where the Joule heating due to the material and contact resistances gives the temperature needed for the weld.


Evolution of the potential during the crush by a sphere of a module of 10 Li-ion cells.

Coupled electrophysiology-mechanical-CFD simulation of a heart ventricle showing the propagation of the cell transmembrane potential, wall deformation and blood flow.



Arbitrary Lagrange-Eulerian (ALE)

LS-DYNA ALE (Arbitrary Lagrange-Eulerian Method), coupled with its embedded fluid-structure interaction, aims to solve a series of transient engineering problems characterized by large momentum and energy transfer between Lagrange structures and ALE fluids.

LS-DYNA ALE multi-material formulation solves multiple species of fluids in one ALE mesh. Its versatile fluid-structure interaction algorithm is used to study the interactions between structures and those individual fluids. The multi-material capability, together with its embedded coupling to structures, has been utilized by users from various engineering application areas.

LS-DYNA ALE/FSI package excels in simulating engineering problems in which fluids carrying large momentum or high energy density impact, penetrates Lagrange structures. For examples, explosions, tank sloshing, container dropping, bird strike, projectile-hitting-target, aircraft water landing, tire hydo-planing, etc.

The newly developed ALE essential boundary feature greatly reduced the simulation time by eliminating the needs for fluid-structure interactions between rigid structures and fluids. We expect it is going to be explored by users in packaging, petroleum, chemical, manufacturing industries to study problems like pipe-flow, resin molding.



Corpuscular Particle Method (CPM)

The CPM (Corpuscular Particle Method) is a muti-scale method developed for gas dynamics simulation. It is based on the kinetic molecular theory, where molecules are viewed as rigid particles obeying Newton’s laws of mechanics. Each particle in the corpuscular method represents a group of gas molecules.  Pressure is built up by discrete particle-fabric impacts, and the dynamical behavior of the gas is simulated by particle-particle collisions. The Lagrangian description of gas dynamics makes the method simple, numerical robust, and CPU efficient compared to the ALE approach, and it is potentially capable of simulating out-of-position deployment, gas flow in curtain airbag, and multiple-chamber system, etc.


Discrete Element Sphere (DES)

The DES (Discrete Element Sphere) is a particle-based solver that implements the Discrete Element Method (DEM), a widely used technique for modeling processes involving large deformations, granular flow, mixing processes, storage and discharge in silos or transportation on belts. In LS-DYNA, each DE particle is a FEM node, making it easy to couple with other rigid or deformable structures by using penalty-based contact algorithms. The DE is highly parallelized and is capable of simulating systems containing over several hundred-million particles.


A bond model has been developed to bond particles and form “continuum” materials. The behavior and stiffness of these bonded particles match those of the solid mechanics of the same material, such as Bulk and Shear Moduli and deformation energy. The fractural energy is captured over all broken bond for crack initialization, propagation and fragmentation

during dynamic and impact analysis. This bond model bridges the continuum mechanics and the DEM, and enables seamless transition crossing multi-physics analyses. Here are some distinct features of the bond model:


·The stiffness of the bond between particles is determined automatically from Young’s Modulus and Poisson’s Ratio.

·The crack criteria are directly computed from the fracture energy release rate.

·The behavior of bond particles is particle-size independent.


Smoothed Particle Hydrodynamics (SPH)

Smooth particle hydrodynamics, as a meshfree, Lagrangian, particle method, has its particular characteristics. As a meshfree method, it can naturally handle problems with extremely large deformation, moving boundary, free surface and deformable boundary. As a Lagrangian method, the entire time history of all the field variables at a material point can be easily tracked and obtained, and the boundary conditions at free surfaces, moving boundaries and material interfaces are automatically imposed. As a particle method, it can handle the interaction with solid parts or fluid parts naturally through contacts.


Smooth particle hydrodynamics has been extensively used in the following applications: high velocity impact, high explosive detonation, HE explosion, underwater explosion, water mitigation of shocks, soil penetration, metal cutting, forging, composite, bird strike testing, incompressible flows, free surface flows, multi-phase flows, tank sloshing, tank dropping testing, fluid-structure interaction coupling, heat conduction, friction stir welding, fracture of brittle solid, and so on.


Additionally, the 2D-capabilities were used to investigate axi-symmetric problems. The Lagrangian kernel was adopted in the code to avoid the tensile instability problem. More recently, new hybrid elements for SPH were developed to couple with solid elements easily, and node to node contact was developed to handle the interaction between two SPH parts with high density ratio. An explicit formalism to model heat conduction with Smoothed Particle Hydrodynamics method was introduce in the code recently, heat transfer with explicit SPH method can be coupled with structure for thermal stress and thermal structure coupling analysis.

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