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RBE2 adds infinite stiffness to attached nodes which means both nodes to exactly the same displacement whereas RBE3 is an interpolation element and distributes the loads and the mass depending on the length. Depending on the application one of these rigid elements should be used.

zerodof, for a better explanation, take a look at: msc.nastan 2004 release guide chapter 7 talks about how to use ACMODL find it at mscsoftware.com

Remark: The numbers shifted !

Hi zerodof, I was looking at the ACMODL, I did not use it before as our nastran decks are slightly different and as we are using AKUSMOD. I am not sure if you have the any kind of guide, but I am using quick reference quide and the format is as follows, 1 2 3 4 5...

Manual mesh will have a better quality since the mesh size will be adaptive not fixed. It may be time consuming though. I will take a look at ACMODL.

I use RBE2 elements for simulating bolts. And constrain all 6 dofs. RBE3 actually distributes the forces to the connection points by inversly propotional to the RBE3 element length. So I would not prefer using RBE3s. Depending on the stiffness of the materials, only rotational dofs can be...

I have been working on similar things for about a year now. One thing I want to point out; I understand that you want to fill and couple the air with the BIW structure. I use akusmod (msc software) to generate air. However, you should need a trim body model in which no openings are available and...

I have realized something. Actually, I want to hit the middle point and want the other nodes to depend on the center point. In this case, exactly the reverse is happening. So I guess the weighting at the center should be 1 and the rest should be some other value close to zero. However, the...

What would be the alternative then?

This is a bracket that holds(carries) the driveline shaft. Bracket is a circular piece and the shaft passes through the bracket and there is rubber between the shaft and the bracket. I am doing a point mobility analysis. Only the parts on the exterior side of rubber is modeled. So, in the model...

I am trying to model a distributed load for Nastran analysis. The shape is a hollow cylinder covered with rubber from inside. I have no idea about the rubber stiffness properties and thats why I ingore the rubber part and would like to use RBE2, RBE3 or some other element to simulate the force...

I am trying to find the direction or coordinates of TRA. Lets say you have an engine and have all the properties including mass, com, inertias and directions. How can I find the coordinates or direction cosines for TRA?

If I have the inertia, inertia axis and mass properties of an engine, how can I calculate the roll axis when a torque in some direcion (which I have the data for) is applied ?

I mean if there is any relation between the two?

So if these make sense, how can I correlate PM to NTF? or can I?

I meant VTF to PM and NTF to PM. VTF to PM seems reasonable. What about PM to NTF? For NTF I assume you hit the structure with an impact hammer and collect the pressure at the drivers ear.

I think there is a relationship between a NTF/VTF (noise transfer function/vibration transfer function and point mobility). Is it only because of the body sensitivities (resonances) or is there any other correlation between the two?

I am trying to determine the first couple of frequencies of a drive shaft. It consists of three seperate pieces connected with elastic couplings. It is attached to the vehicle, so that the boundary conditions as in real life. How can I do the test? for example, could I do a hammer test and get...

Is there any way to determine the cut-off frequency with tests or taking measurements? Thanks

How can I calculate the lower cut-off frequency of an anechoic room? Thanks.