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# ABAQUS unit conversion for nanometer length.

Hi all,

I ran a pre-buckling analysis using ABAQUS. I chose nanometer as my length unit. So for the Young's modulus, since my sample has 100 GPa for the Young's modulus, I put 0.0000001 as the value for the Young's modulus under the material property in the ABAQUS.

However, the resulted eigenvalue (~2 nN) was not as what I expected (~2uN). Based on the calculation based on the Euler buckling theory, the critical load should be around 2 uN.

In the pre-buckling analysis using ABAQUS, I use 1 as my load value. This unity value for the force should make the resulted eigenvalue to have the same value as the critical load.

I plan to run a post-buckling analysis by using the IMPERFECTION command and RIKS analysis. But first, I need to get the correct eigenvalue from my pre-buckling analysis.

Please advise me where I did wrong. Thank you in advance for your kind attention.

Wanbot

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## Comments

## Are you running it in

Are you running it in Standard or Explicit? I think you need to check the units of density too, if it is a dynamic analysis !! Make sure the units of density and stress (modulus) are consistent!

## I need the same help!

Same problem with me , but at micro level, and am unable to figure it out (may be it simple and I am not getting it :-) ) . I draw a circle with 10 units radius . (Since my cirlce is 10 microns radius). Then what will be the input values of the stress and Pressure to be applied, if problem values are given as Stress=400 Pascals and Pressure=900 Pascals.

Regards

P M G

## I think I have solved the

I think I have solved the problem. The problem was indeed due to the unit inconsistency.

This time I choose micrometer as the unit length. Then, the units for force and Young's modulus are uN and MPa respectively.

By using the above unit, the resulted eigenvalue is quite reasonable.

Am I correct?

Thanks.

Wabot

## How? After taking Approximate

How? After taking Approximate size of 20, I made a cell, in micro meters obviously. Now the shear modulus is 400 GPa, so should I have to convert it into other untis? Regards

## How? After taking Approximate

How? After taking Approximate size of 20, I made a cell, in micro meters obviously. Now the shear modulus is 400 GPa, so should I have to convert it into other untis? Regards