Unusual force spike in the force time graph from quasi-static simulation

[Wong Ming Hao]

Hi everyone,

I’m running a quasi-static simulation on an L-shaped reinforced-concrete frame in LS-DYNA, using the Continuous Surface Cap Model (CSCM) for the concrete. The loading rate is 0.6 mm s⁻¹.

When I plot the force versus time, I see an unrealistic force spike during the very first part of the analysis (see attached curve). 

Has anyone come across this issue, and how did you solve it?





Thanks and BR,
Ming Hao

[l...@schwer.net]

More information is needed for the loading:

 

1\ Why use a ball (sphere) and a plate rather than just the plate?

 

2\ What is the loading curve history for the ball and is it force or displacement etc.?

 

3\ What type contacts are used between ball/plate and plate/concrete?

 

                --len

 

From: ls-d...@googlegroups.com <ls-d...@googlegroups.com> On Behalf Of Wong Ming Hao
Sent: Wednesday, June 4, 2025 6:18 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>
Subject: [LS-DYNA2] Unusual force spike in the force time graph from quasi-static simulation

 

Hi everyone,

I’m running a quasi-static simulation on an L-shaped reinforced-concrete frame in LS-DYNA, using the Continuous Surface Cap Model (CSCM) for the concrete. The loading rate is 0.6 mm s⁻¹.

When I plot the force versus time, I see an unrealistic force spike during the very first part of the analysis (see attached curve). 

Has anyone come across this issue, and how did you solve it?

Thanks and BR,
Ming Hao

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[l...@schwer.net]

I should have added:

 

4\ Are the ball/plate rigid or deformable?

To view this discussion visit https://groups.google.com/d/msgid/ls-dyna2/002701dbd560%2495f68760%24c1e39620%24%40schwer.net.

[Wong Ming Hao]

Hi Len,

Thank you for answering my query.

1\ Why use a ball (sphere) and a plate rather than just the plate?

 Ming Hao: It's actually a cylindrical solid on a plate. It was intended to address the unusual force spike in the force time graph, but it doesn't seem to be resolving the issue. 

2\ What is the loading curve history for the ball and is it force or displacement etc.?

 

Ming Hao: The displacement curve can be seen as above.  

3\ What type contacts are used between ball/plate and plate/concrete?

Ming Hao: CONTACT_AUTOMATIC_SURFACE_TO_SURFACE

4\ Are the ball/plate rigid or deformable?

Ming Hao: Both use rigid.

Thanks again for getting back to me, and I look forward to your reply.

BR,
Ming Hao