DYNAmore GmbH LS-DYNA – Anwendungsmöglichkeiten für die Fügesimulation Thomas Klöppel DYNAmore GmbH 1
DYNAmore GmbH Agenda ■ Introduction to LS-DYNA ■ Clinches and Rivets ■ Friction Stir Welding ■ Inductive Welding ■ Resistive Welding 2
DYNAmore GmbH LS-DYNA – LSTC – DYNAmore History 1976: John Hallquist develops DYNA3D at Lawrence Livermore National Laboratories 1987: John Hallquist founds LSTC in Livermore CA, DYNA3D becomes LS-DYNA3D 1988: Prof. Schweizerhof + co-workers start with crash simulations in Germany 2001: DYNAmore is established 2011: DYNAmore acquires ERAB Nordic 2011: DYNAmore assigned as Master distributor 2011: DYNAmore SWISS established 2013: DYNAmore Italia S.r.l. established 3
DYNAmore GmbH LSTC Product Range LS-PrePost LS-OPT/LS-TaSC LS-DYNA USA Dummies & Barriers FREE OF CHARGE! 4
DYNAmore GmbH LS-DYNA R8 – The Applications Automotive Civil Engineering Crash and Safety Concrete structures NVH Earthquake safety Durability Wind- & Waterpower Aerospace Elektronics Bird strike Drop analysis Containment Package analysis Crash Thermal Manufacturing Defense Detonations Stamping Penetrations Forging Biomechanics Consumer Products 5
DYNAmore GmbH LS-DYNA R8 – The Multiphysics Solver ■ Combine the capabilities ■ Explicit/ Implicit structural solver ■ Thermal solver & heat transfer ■ Incompressible fluid solver (ICFD) ■ Compressible fluid solver (CESE) ■ Electromagnetics solver (EM) ■ Frequency domain, acoustics, modal analysis ■ Finite elements, iso-geometric elements, Heart valve: ALE, EFG, SPH, DEM, CPM, … Courtesy of H. Mohammadi, ■ User elements, materials, loads McGill University ■ Into one scalable code for ■ highly nonlinear transient problems ■ static problems ■ To enable the solution of ■ coupled multi-physics and ■ multi-stage problems ■ On massively parallel systems [coil heating water] 6
DYNAmore GmbH LS-DYNA R8 – The Multiphysics Solver ■ No need for co-simulation, as all solvers are included! Thermal Solver Implicit Double precision EM Solver Fluid Solver Displacement Temperature Plastic Work Implicit Implicit / Explicit Air (BEM) ICFD / CESE Conductors (FEM) ALE / CPM Double precision Double precision Mechanical Solver Implicit / Explicit Double precision / Single precision 7
DYNAmore GmbH LS-DYNA R8 – Continuum Meshfree Methods Material law for stress tensor Equation of State F T p Material Fluid Gas Solid Strength Metal Forming EFG Extrusion CPM Incompressible Forging SPG fluids Foam packing ICFD Kinetic Molecular theory MEFEM (Maxwell-Boltzman Equ.) Crashworthiness Airbag Sloshing Fracture MLPG Hydroplaning Bird strike SPH Explosion/ Splashing Penetration Momentum 8
DYNAmore GmbH Agenda ■ Introduction to LS-DYNA ■ Clinches and Rivets ■ Friction Stir Welding ■ Inductive Welding ■ Resistive Welding 9
DYNAmore GmbH Clinches and Rivets ■ 2 or more sheets are to be joined together ■ Highly distorted structures ■ Topology changes for self piercing rivets 10
DYNAmore GmbH 2D axisymmetric model ■ METHOD 1: Use 2D axisymmetric remeshing: ■ Switch on R-adaptivity in *PART set adpopt=2 ■ Use volume-weighted axisymmetric solid in *SECTION_SHELL set eltyp=15 ■ Use reasonable values for adaptivity *CONTROL_ADAPTIVE *PART_ADAPTIVE_FAILURE 11
DYNAmore GmbH Extension to 3 blanks ■ Simulation not restricted to 2 blanks 12
DYNAmore GmbH Serviceability analysis ■ Cross tension test ■ Tension test 13
DYNAmore GmbH Serviceability analysis ■ Cross tension test ■ Tension test 14
DYNAmore GmbH Modeling Clinches and Rivets in 3D with EFG ■ For a 3D representation adaptive EFG seems to be promising ■ Basic ideas ■ Replace the continuum by a set of particles ■ Construction of shape functions without a mesh [ Lucy 1977, Gingold & Monaghan 1977, Liu 2003] ■ In contrast to other element-free methods, a background mesh (or integration cells) is needed SPH nodal ■ Define the physical domain integration ■ Contact conditions ■ Impose boundary conditions e ■ Perform volume integration via “stress points” EFG stress point integration ■ Based on Galerkin weak form of the problem 15
DYNAmore GmbH Adaptive EFG ■ Adaptive EFG might be needed to deal with „ severe material deformation ■ Current numerical limitations ■ RH-adaptivity for solids (H-adaptivity is limited to shells) ■ Failure analysis is limited to metal cutting problems ■ Not applicable to rubber-like materials 16
DYNAmore GmbH Cold forming of a pre-stressed rivet head ■ Computation times ■ LS-DYNA (explicit): 1 day on 6 CPU ■ LS-DYNA (implicit): 20 min on 6 CPU 17
DYNAmore GmbH Cold forming of a pre-stressed rivet head ■ Computation times ■ LS-DYNA (explicit): 1 day on 6 CPU ■ LS-DYNA (implicit): 20 min on 6 CPU 18
DYNAmore GmbH Agenda ■ Introduction to LS-DYNA ■ Clinches and Rivets ■ Friction Stir Welding ■ Inductive Welding ■ Resistive Welding 19
DYNAmore GmbH Friction stir welding ■ Process: ■ Two materials ■ Fast rotating cylinder ■ Cylinder is translated through the seam ■ Due to the friction, materials meld Courtesy Kirk Fraser (Predictive Engineering) ■ Rotation mixes the materials ■ Material mixing requires meshless methods ■ The SPH method is most suitable for these high velocities 20
DYNAmore GmbH Smoothed-Particle Hydrodynamics (SPH) ■ Basic ideas ■ Replace the continuum by a set of particles ■ Construction of shape functions without a mesh [ Lucy 1977, Gingold & Monaghan 1977, Liu 2003] ■ Integral interpolant as approximation function ■ Exploitation of the identities 21
DYNAmore GmbH Smoothed-Particle Hydrodynamics (SPH) ■ Approximation of the displacement/velocity ■ Approximation of the displacement/velocity gradient Kernel function θ 22
DYNAmore GmbH Friction Stir Welding Example ■ Double sided FSW @ 600 RPM, 1200 mm/min ■ Plastic work and friction energy to heat material mixing temperature contours Courtesy Kirk Fraser (Predictive Engineering) 23
DYNAmore GmbH Friction Stir Welding Example ■ Double sided FSW @ 600 RPM, 1200 mm/min ■ Plastic work and friction energy to heat material mixing temperature contours Courtesy Kirk Fraser (Predictive Engineering) 24
DYNAmore GmbH Agenda ■ Introduction to LS-DYNA ■ Clinches and Rivets ■ Friction Stir Welding ■ Inductive Welding ■ Resistive Welding 25
DYNAmore GmbH Electromagnetism (EM) Solver in LS-DYNA ■ Electro-magnetic solver at a glance and its connection to the other solvers EM Solver : rotation Ampere„s Law: : divergence : electric field Eddy-current E Faraday„s Law: formulation B : magnetic flux density Gauss law: j : total current density Maxwell Gauss flux theorem: j s : source current density Equations Continuity: ε , μ , and σ : material electrical properties j E j Ohm‟s law: s Joule heating Lorentz forces Displacement Temperature dQ 2 p j R F E j B e dt Mechanical Solver Thermal Solver 26
DYNAmore GmbH Electromagnetism ■ Subcycling for the Joule (induced) heating problem ■ Timescale of oscillating coil is much smaller than for the total problem ■ Many small EM time steps would be needed ■ Introduction of a “micro” and “macro” time step 27
DYNAmore GmbH Electromagnetism ■ Preparation for welding applications ■ Heating of a plate by induction Courtesy of Miro Duhovic LS-DYNA Experiment 28
DYNAmore GmbH Electromagnetism ■ Continuous induction welding [ Moser & Mitschang 2012] ■ Carbon-fiber reinforcements form conductive loops Courtesy of Miro Duhovic ■ Joule heating to the melting point ■ Pressure application for consolidation [ Duhovic et al. 2013] 29
DYNAmore GmbH Agenda ■ Introduction to LS-DYNA ■ Clinches and Rivets ■ Friction Stir Welding ■ Inductive Welding ■ Resistive Welding 30
DYNAmore GmbH Analysis of the welding process [tu-chemnitz] [greitmann2013] 31
DYNAmore GmbH Typical welding process ■ Typical force, current and voltage curves during the resistance spot welding [wick2012] 32
DYNAmore GmbH Aim of the process simulation ■ Determination of the nugget geometry according to DIN 4329 d eu .. indentation width e u .. indentation depth d n .. nugget width p .. penetration [DIN14329] 33
DYNAmore GmbH Aim of the process simulation ■ Influence of electrode contact angle on the nugget size and shape [zhang2005] 34
DYNAmore GmbH Geometry ■ 2 Electrods ■ only foot of the electrode meshed ■ electrode shape according DIN 5821 ■ 2 metal sheets [zhang2005] 35
DYNAmore GmbH Electro-Magnetical Input ■ Material definitions (incl. electromagnetical properties) Source (Current) MID 1 MID 2 (EM) (EM) ■ Definition of an electrical circuit MID 3 ■ Definition of an electro-magnetic contact (EM) MID 1 (EM) Output (Current) 36
DYNAmore GmbH History of the 3d temperature field 37 37
DYNAmore GmbH Contours and Vector Plot of the Current Density ■ Contours and vector plot of the current density [zhang2005] 38
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