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Unit of rotation (output)

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01-22-2019 03:30 AM

Hello,

Femap Nastran NX analysis is unitless. But we should be consisitant with the units. Can anyone tell me if I apply a moment at a node about one axis what will be the unit of rotation obtained as the out put?

I am keeping the solid geometry scale factor in meters ( in File--Preferences--Geometry/model), which means am following a N-m-s unit system (then moment will be in Nm). Is the rotation will be in radians?

Regards,

Muhammed sadique

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Re: Unit of rotation (output)

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01-22-2019 05:18 AM

Re: Unit of rotation (output)

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01-22-2019 05:40 AM

Okay. Thank you

Re: Unit of rotation (output)

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01-22-2019 08:13 AM

There is an option in preferences to show "Angles as 0 -> 360".

I know this affects the measurment of angles.

I don't know if if affects output.

Test models, like Karachun says, are always a great check.

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Re: Unit of rotation (output)

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01-22-2019 08:27 AM

Nastran output for displacement rotations is always in radians.

However, on the input side:

1) defining node locations in a cylindrical system, then the angle is in degrees.

2) enforced displacements when using rotation dof's, then Nastran expects radians.

Regards,

Joe

Re: Unit of rotation (output)

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01-22-2019 01:37 AM - edited 01-23-2019 04:44 AM

Hello every one,

I think it is in angles. I did a manual calculations by considering the distance between nodes. First I took coordinates of the point and node as shown the attahced file (see the white circles). The coordintes were the same. the pink colored model is the deflected version of the transparant model (tansparant blue). As it gives the same coordinates I understood that the femap doesn't give the coordinates for the defelcted model.

Then i checked the distance between the points in undeflected model (shown in the green circle) and used that to calculate the angle manually. The angle was 18.772 and then I used the femap to check the angle between the points in femap. I got 18.77282. From that I concluded that femap is showing the angles in degrees.

Hello Fembrackin,

I imported the solid model to the femap and did the meshing. When I am supposed to define the coordinte system ? I do have a independent node on which the moment is applied. The indepentend node is defined in rectangular coordinte system. Also on the independent node the constraint were applied to restrict 5 DOFs except the rotation about x axis(the moment was applied about this axis).

Regards,

Sadique

Re: Unit of rotation (output)

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01-22-2019 01:47 AM

Emm... I think that we are talking about different angles.

Re: Unit of rotation (output)

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01-23-2019 04:40 AM - edited 01-23-2019 04:41 AM

My question is this.

In postprocessing, in countour when I select rotation R1 (about x axis-about this axis I gave the moment 1 unit value (Nm) I am getting a countour plot as shown below. Please find the image for your references. The moment was applied on an independent node which is connected to the solid using rigid elements (see the images).What is the unit of the output am getting in the countours?

Re: Unit of rotation (output)

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01-23-2019 09:24 AM

Re: Unit of rotation (output)

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01-23-2019 12:48 AM

Could you please give the equations (or some reference) for the theoretical calculation for the rotation.

Is there any way in Femap to apply a torque (in Nm/revolution) about some axis instead of moment?

Regards,

Sadique

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