Robot model very sensitive with deflections when minor changes made

[giles_broome-ogden]

Hi there,

I am designing a gate with non-linear plastic deformation with hardening properties and am struggling to understand why the model is so sensitive when it comes to deflections.

The gate consists of 2 vertical posts and a single horizontal beam spanning between them.

I am targeting a deflection of 1500mm as this defined by the fixed force applied of 312 kN/m.

I have then used different RHS sections to try and achieve the target deflection. However, the difference in deflection values from two relatively similar sections is huge.

So, does anyone know why the model is so sensitive when these minor changes have been made?

Model included: Looking at Load case 3: Post

See current results below:

Thank you!

[Krzysztof_Wasik]

Hi @giles_broome-ogden 

You are using elastoplastic section properties. For section 300x200x10 post have plastic hinge

[giles_broome-ogden]

Thank you for your response. I have it working the way I want now.