Slave node is not constrained since it is not found on a segment.
Wong Edward
l...@schwer.net
In my experience when using *CONTACT_TIED_SURFACE_TO_SURFACE it is best to use node sets for the nodes you wanted tied together. Using Part Set IDs involves too many nodes interior to parts that you do not want to be considered in the TIED nodes definition.
I now nothing about spotwelds. --len
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James M. Kennedy
Dear Edward,
*MAT_100 or *MAT_SPOTWELD_{OPTION}
This is Material Type 100. The material model applies to beam element type 9 and to solid element type 1 with type 6 hourglass controls. The failure models apply to both beam and solid elements. The beam elements, based on the Hughes-Liu beam formulation, may be placed between any two deformable shell surfaces and tied with constraint contact, *CONTACT_SPOTWELD, which eliminates the need to have adjacent nodes at spot weld locations. Beam spot welds may be placed between rigid bodies and rigid/deformable bodies by making the node on one end of the spot weld a rigid body node which can be an extra node for the rigid body, see *CONSTRAINED_ EXTRA_NODES_{OPTION}. In the same way rigid bodies may also be tied together with this spot weld option. This weld option should not be used with rigid body switching. The foregoing advice is valid if solid element spot welds are used; however, since the solid elements have just three degrees-of-freedom at each node, *CONTACT_TIED_SURFACE_TO_SURFACE must be used instead of *CONTACT_SPOTWELD.
In flat topologies the shell elements have an unconstrained drilling degree-of-freedom which prevents torsional forces from being transmitted. If the torsional forces are deemed to be important, brick elements should be used to model the spot welds.
Beam and solid element force resultants for *MAT_SPOTWELD are written to the spot weld force file, SWFORC, and the file for element stresses and resultants for designated elements, ELOUT.
It is advisable to include all spot welds, which provide the slave nodes, and spot welded materials, which define the master segments, within a single *CONTACT_SPOTWELD interface for beam element spot welds or a *CONTACT_TIED_SURFACE_TO_ SURFACE interface for solid element spot welds. As a constraint method these interfaces are treated independently which can lead to significant problems if such interfaces share common nodal points. An added benefit is that memory usage can be substantially less with a single interface.
Available options include: <BLANK>, DAMAGE-FAILURE.
The DAMAGE-FAILURE option causes one additional line to be read with the damage parameter and a flag that determines how failure is computed from the resultants. On this line the parameter, RS, if nonzero, invokes damage mechanics combined with the plasticity model to achieve a smooth drop off of the resultant forces prior to the removal of the spot weld. The parameter OPT determines the method used in computing resultant based failure, which is unrelated to damage
*MAT_100_DA or *MAT_SPOTWELD_DAIMLERCHRYSLER
This is Material Type 100. The material model applies to solid element type 1 with type 6 hourglass control. Spot weld elements may be placed between any two deformable shell surfaces and tied with constraint contact, *CONTACT_TIED_SURFACE_TO_ SURFACE, which eliminates the need to have adjacent nodes at spot weld locations. Spot weld failure is modeled using this card and *DEFINE_CONNECTION_ PROPERTIES data. Details of the failure model can be found in Seeger, Feucht, Frank, Haufe, and Keding [2005].
It is advisable to include all spot welds, which provide the slave nodes, and spot welded materials, which define the master segments, within a single *CONTACT_TIED_SURFACE_TO_SURFACE interface. This contact type uses constraint equations. If multiple interfaces are treated independently, significant problems can occur if such interfaces share common nodes. An added benefit is that memory usage can be substantially less with a single interface.
In this paper the modeling possibilities in LS-DYNA were investigated for a self piercing riveted joint of aluminium sheets. Beams, eight-noded hexahedrons, hexahedron clusters and constrained elements were used for a simplified modeling of the riveted connection. The material models *MAT_SPOTWELD, *MAT_SPOTWELD_DAIMLER, *MAT_ ARUP_ADHESIVE, *MAT_COHESIVE_MIXED_MODE_ELASTOPLASTIC_RATE and the constrained models *CONSTRAINED_SPR2 and _SPR3 were tested with the simplified rivet model. The failure models were based on forces and moments, on normal, shear and bending stresses, on stresses and fracture energies and on forces and displacements for the constrained SPR models. The model parameters were determined by simulation of specimen tests under tension, lap-shear, peel and combined loading and by fitting the measured force vs. displacement curves. The different numerical results were compared concerning the measured load bearing capacities and energy absorption:
Sommer, S., and Maier, J., "Failure Modeling of a Self Piercing Riveted Joint Using LS-DYNA", 8th European LS-DYNA Users Conference, Strasbourg, France, May, 2011.
http://www.dynalook.com/8th-european-ls-dyna-conference/session-2/Session2_Paper2.pdf
Flow-drill screws (FDS) are used in the automotive industry to join parts in load-bearing structure of cars. In large-scale finite element simulations point connections such as FDS connections cannot be modeled with accurate geometry with a reasonable simulation run-time due to limitations in computer power. Hence simplified models are required to include connections is such simulations. The focus of this study was modeling of FDS connections in large-scale shell analysis. Five macroscopic connection models were investigated: two element-bases models (*MAT_SPOTWELD and *MAT_240) and three constraint-based models (*CONSTRAINED_SPR2 and two versions of *CONSTRAINED_INTERPOLATION_SPOTWELD):
Sonstabo, J.K., Morin, D., and Langseth, M., "Macroscopic Modeling of Flow-Drill Screw Connections", 10th European LS-DYNA Users Conference, Wurzburg, Germany, May, 2015.
Seegar, F., Feucht, M., Frank, T., Keding, B., and Haufe, A., "An Investigation on Spot Weld Modelling for Crash Simulation with LS-DYNA", 4th German LS-DYNA Forum, Bamberg, Germany, October, 2005.
http://www.dynamore.de/documents/papers/forum2005/an-investigation-on-spotweld-modeling-for-crash
Seegar, F., Michel, G., and Blanquet, M., "Investigation of Spot Weld Behavior Using Detailed Modeling Technique", 7th German LS-DYNA Forum, Bamberg, Germany, October, 2008.
http://www.dynamore.de/documents/papers/conference-08/B-I-03.pdf
Microsoft Word - Seeger_spotweld-at-DCX-final.doc (roadsafellc.com)
example
Spotweld I — Welcome to LS-DYNA Examples
Sincerely,
James M. Kennedy
KBS2 Inc.
February 18, 2022
From: ls-d...@googlegroups.com [mailto:ls-d...@googlegroups.com] On Behalf Of Wong Edward
Sent: Friday, February 18, 2022 8:59 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>
--
James M. Kennedy
Dear Edward,
The Hughes-Liu spot weld element formulation (elform=9) has 6 degrees-of-freedom per
node. It uses *MAT_SPOTWELD which offers material plasticity and failure. Selected
quadrature rules (one point, Gauss, and Lobatto) are available plus a user defined option f
or the numerical integration.
---------------------------------------------
Suri Bala provided some notes on mass scaling of deformable spot welds:
Bala, S., "Mass Scaling for MAT_SPOTWELD Elements", Livermore Software Technology
Corporation, Livermore, California, April, 2010.
http://blog2.d3view.com/?p=509
---------------------------------------------
Haufe, A., Pietsch, G., Feucht, M., and Kolling, S., "FE-Modeling of Spotwelds and
Adhesive Joining for Crashworthiness Analysis", 6th European LS-DYNA Users Conference,
Gothenburg, Sweden, May, 2007.
http://www.dynalook.com/european-conf-2007/fe-modeling-of-spotwelds-and-adhesive-joining-for.pdf
---------------------------------------------
The following presentations involving beam element modeling of a pre-tensioned bolt.
In particular, please see the comments regarding number of beam elements in the shank of
the bolt, beam element type, material behavior, and force application.
Karajan, N., Gromer, A., Borrvall, T., and Pydimarry, K., "Modeling Bolts in LS-DYNA
using Explicit and Implicit Time Integration", 15th International LS-DYNA Users Conference,
Dearborn, Michigan, June, 2018.
Karajan, N., Schenke, M., Borrvall, T., and Pydimarry, K., "Modeling Bolts in LS-DYNA
using Explicit and Implicit Time Integration", 15th German LS-DYNA Forum, Bamberg,
Germany, October, 2018.
Examples for those models can be found in https://www.dynaexamples.com/show-cases/bolts/
Bolt Type A
This bolt type uses one beam element along with a head and nut represented by circular
beam spider meshes. This model is beneficial due to the fact that it is simple and fast to
design. The drawbacks of this model are that slipping motion cannot be captured between
the nut or head. Also, the connection could be too stiff for loads above the service load of
the bolt. Other considerations are that only one element can be used for the shank and the
material card is limited to *MAT_SPOTWELD.
https://www.dynaexamples.com/show-cases/bolts/typea
Bolt Type B
This bolt type uses a beam element for the shank and shell elements for the head and nut.
An important note is that the PID of the head and nut need to be added to *CONTACT_
AUTOMATIC_SINGLE_SURFACE. Null beams can also be added to the model to help
with the contact. The benefits of this method are that it can capture the onset of slipping.
The drawbacks are that this method can be tedious if the hole bearing behavior needs to be
investigated. Also, this technique is not good for calculating bolt shear failure.
https://www.dynaexamples.com/show-cases/bolts/typeb
---------------------------------------------
To model the main effects of bolt connections in commercial vehicles, a new modeling
technique was presented and compared with conventional techniques. To describe the
bolt material, the *MAT_SPOTWELD_DAMAGE-FAILURE option was used:
Sonnenschein, U., "Modelling of Bolts Under Dynamic Loads", 7th German LS-DYNA
Forum, Bamberg, Germany, October, 2008.
http://www.dynamore.de/de/download/papers/forum08/dokumente/B-II-02.pdf
---------------------------------------------
In this paper the modeling possibilities in LS-DYNA were investigated for a self piercing
riveted joint of aluminium sheets. Beams, eight-noded hexahedrons, hexahedron clusters
and constrained elements were used for a simplified modeling of the riveted connection.
The material models MAT_SPOTWELD, MAT_SPOTWELD_DAIMLER, MAT_ ARUP_
ADHESIVE, MAT_COHESIVE_MIXED_MODE_ELASTOPLASTIC_RATE and the
constrained models CONSTRAINED_SPR2 and _SPR3 were tested with the simplified
rivet model. The failure models were based on forces and moments, on normal, shear and
bending stresses, on stresses and fracture energies and on forces and displacements for the
constrained SPR models. The model parameters were determined by simulation of specimen
tests under tension, lap-shear, peel and combined loading and by fitting the measured force
vs. displacement curves. The different numerical results were compared concerning the
measured load bearing capacities and energy absorption:
Sommer, S., and Maier, J., "Failure Modeling of a Self Piercing Riveted Joint Using LS-DYNA",
8th European LS-DYNA Users Conference, Strasbourg, France, May, 2011.
http://www.dynalook.com/8th-european-ls-dyna-conference/session-2/Session2_Paper2.pdf
---------------------------------------------
Spotweld modeling was one of the three options discussed:
Graf, T., "Workshop: Connection Modeling with LS-DYNA", 13th German LS-DYNA Forum,
Bamberg, Germany, October, 2014.
---------------------------------------------
This paper proposed a failure criterion of spot welds for combined loading condition for crash
simulation. The tests were designed to obtain the failure load of a spot weld under combined
loading condition. The seven types of experimental test were conducted for the component
of spot weld failure criterion. The failure criterion of this paper consisted of moment component
including normal and shear force. Each component of spot weld test failure was obtained from
finite element analysis results. The proposed criterion was considered to use Wung model except
torsion term. It was found that the criterion of mild steel was expressed as a function of previous
researches, however failure criterion of high strength steel and advanced high strength steel were
newly proposed:
Lim, J.-H., Ha, J, Oh, C.-Y., "Practical Failure Criterion of Spot Weld for Crash Simulation", 10th
European LS-DYNA Users Conference, Wurzburg, Germany, May, 2015.
---------------------------------------------
Some examples of the various spot weld modeling options which are available on the www.dynaexamples.com website:
http://www.dynaexamples.com/intro-by-k.-weimar/spotweld
*MAT_SPOTWELD
http://www.dynaexamples.com/intro-by-k.-weimar/spotweld/spotweld-i
*CONSTRAINED_GENERALIZED_WELD_SPOT
http://www.dynaexamples.com/intro-by-k.-weimar/spotweld/spotweld-ii
*CONSTRAINED_SPOTWELD
http://www.dynaexamples.com/intro-by-k.-weimar/spotweld/spotweld-iii
*CONSTRAINED_TIEBREAK_NODES
http://www.dynaexamples.com/intro-by-k.-weimar/spotweld/spotweld-iv
---------------------------------------------
From: ls-d...@googlegroups.com [mailto:ls-d...@googlegroups.com] On Behalf Of Wong Edward
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