Inquiry Regarding *CONTACT_SLIDING_ONLY_PENALTY in LS-DYNA

[Milestone]

Hi Dear all,

I am using *CONTACT_SLIDING_ONLY_PENALTY in LS-DYNA in LS-DYNA.

In my intended application, the simulation stability is affected by using MPP or SMP.

It runs on SMP but failed on MPP. 

I wonder how we can fix that?
Thanks for your insight in advance.

Best,

Chengbin

[James Kennedy]

Dear Milestone,

 

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An initial comment perhaps worth reading:

 

To run LS-DYNA in MPP (Massively Parallel Processing) mode, you need a suitable hardware setup,

a correctly installed MPI (Message Passing Interface) software, and an Ansys LS-DYNA HPC license

for each process beyond the first. LS-DYNA MPP utilizes multiple processors on a single machine or

across a cluster to handle larger and more complex simulations

 

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Another set of introductory comments:

 

In LS-DYNA, the *CONTACT_SLIDING_ONLY_PENALTY keyword is used for defining a penalty-

based contact interface where only sliding friction forces are considered, and normal contact forces are

neglected. 

 

Key characteristics and use cases

 

Penalty-based: This contact type utilizes a penalty method to handle the interaction between surfaces.

When a penetration is detected between contacting entities, a force proportional to the penetration depth

is applied to resist and eliminate it.

 

Sliding friction only: Unlike other contact types that consider both normal and tangential (frictional)

forces, *CONTACT_SLIDING_ONLY_PENALTY focuses solely on the sliding resistance between

surfaces.

 

Applications: This contact type can be useful in scenarios where the normal contact forces are negligible

or less critical, and the primary focus is on simulating friction-dominated sliding motion. For example:

 

Friction testing simulations: When simulating tests designed to measure friction coefficients or analyze

sliding behavior, isolating the effect of friction can be beneficial.

 

Assemblies with clearances: If components are designed with intentional gaps or clearances that allow

for some initial movement before significant normal contact occurs, this contact can be used to model

the initial sliding behavior.

 

Simplifying complex interactions: In situations where the normal contact behavior is complex and

computationally expensive to model accurately, *CONTACT_SLIDING_ONLY_PENALTY can

offer a simplified yet effective approach. 

 

Considerations

 

No normal force enforcement: Because this contact type ignores normal contact forces, it won' prevent

penetration of one surface into another. This means you need to be confident that your model's geometry

or other constraints will adequately handle normal contact.

 

Mesh density: As with all contact definitions, using a sufficiently fine mesh on the contact surfaces is i

mportant for accurate contact detection and force distribution.

 

Alternative Contact Options: It's important to understand the distinctions between this contact and

other available options like *CONTACT_AUTOMATIC_SINGLE_SURFACE and *CONTACT_

AUTOMATIC_GENERAL for appropriate selection based on your specific simulation needs.

 

RCFORC file: For single-surface contact types, including *CONTACT_SLIDING_ONLY_PENALTY,

you will need to define a *CONTACT_FORCE_TRANSDUCER_PENALTY to output contact forces

to the RCFORC file. 

 

It is recommended to consult the LS-DYNA Keyword User's Manual for a comprehensive understanding

of the *CONTACT_SLIDING_ONLY_PENALTY keyword, its parameters, and potential limitations. 

 

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Best,

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