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Moawez Zamir Awan

ERROR # 312 *** In static load case 1 the compliance is negative or large 1.52002e+09. Optimization/buckling analysis cannot be performed. due to possible rigid body model.

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Hi,

This error occurs when a model is under constrained or incorrect material property definition or contact definitions are incorrect or missing.

error 312.JPG

In your case (the units are tonne, MPA, mm) the pressure loading of 24000 MPA is causing excessive deformations.  You should review the unit consistency and/or pressure load magnitude.

Moawez Zamir Awan likes this

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Hi! Thanks for answering my query. I wanted to ask for the Moment my units would be Nmm or Nm? Because I figured it would be Nmm since length is in mm but this is giving me an error due to large static compliance. 

Also when I apply pressure should I calculate according to units in tonnes and mm? or I can directly apply the MPa unit as PA in N/m^2? I am a little confused by the units here.

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Glad to help.

 

Hypermesh is unitless and it is the user's responsibility to follow a consistent set of units.

Force unit? - Altair HyperMesh - Altair Forum

https://www.altairuniversity.com/wp-content/uploads/2012/04/Student_Guide_55-57.pdf

Since the material properties are consistent with the tonne, MPA, mm unit system, the model dimensions and loads should follow the same units. So yes, the moment should be Nmm. You are getting a compliance error because of the unrealistically high pressure load of 24000 MPa. Applying only the moment load in the model you shared, the displacement is actually minimal (0.0068 mm). The pressure load should be calculated according to unit system (1 MPa = 1 N/mm2 = 1000000 Pa)

 

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please, always check if your model is properly constrained, as suggested.

Large compliance is often related to lack of constraints.

 

Always perform an analysis only run to check your model, before going to optimization.

 

In a few scenarios, lrge compliance might also be related to use of gap elements.

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