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Load-Acceleration application NX Nastran

Pioneer
Pioneer

Hi 

I have Bracket Holder mounted on to a frame and would like to accelerate the Holder to 2.5g and look the results.I have contacts in the Bracket Holder and few Bolted Connections in the assembly.

Which would be the best way to test it?

1)Should i have to select all the Bracket Holder except the frame and apply 2.5 g .Will this solve my problem?

2)Should i have to apply 2.5g at its COG and solve it?

3)Which would be the best solver to do it like SOL101,601 and so on...

 

Thanks

 

4 REPLIES

Re: Load-Acceleration application NX Nastran

Pioneer
Pioneer

Hi there.

 

I see it is a while since you posted your question. Not sure if it is still valid, but I can try to help Smiley Happy

 

If you explain a bit about what creates this acceleration load it may be easier to help. It may effect the way you apply the load. I am familiar with the marine industry where the ship motion creates "acceleration" loads in longitudinal, transverse and vertical direction on the structures. Normally we apply these loads as a gravity where we modify the gravity value. The load will be applied to the COG.

 

For example 2.5g equals approx 24.5 m/s^2.  If normal gravity needs to be included you need to define both gravity (1g) + acceleration load (2.5g) and assign the load direction.

 

Thomas

 

 

Re: Load-Acceleration application NX Nastran

Pioneer
Pioneer

Hi Thomas

Thanks for your reply though a bit late.

Load Case:2.5+1 g in vertical direction 

Questions:

1.In earlier versions of NX Nastran i was comfortable in applying "g" value to the point which is  at its COG.

2.In newer versions i think i am unable to apply to its COG  ie its COG point and now i had to pick the complete body to  subject it to  "g".

 

Even i have a practice of applying vertical,longitudinal,Transverse loads.

 

3.Say if both ways are possible in newer versions 1 and 2 will that change my results .I am no more using

NX 8 and i have my  Load cases defined at its COG i.e 2.5+1 g at its COG.

I need to justify that to my client.

 

Please suggest answers for 1,2,3.

 

Thanks

 

 

 

 

Re: Load-Acceleration application NX Nastran

Pioneer
Pioneer

Hi again.

 

1. When you say applying 'g' value at COG, do you mean force/point load applied at COG?

 

The manual says that GRAV load applies a force at every point in the model that has mass (see page 8-30). My understanding is that adding a force/point load at COG is not the same at applying a GRAV load.

 

So I believe that if you apply 1g+2.5g as force/point load at the COG , you will not get the same result when using GRAV load. So yes, I believe that will change your result.

 

Anyone else here that can confirm this?

 

Thomas

 

 

 

 

 

 

 

Re: Load-Acceleration application NX Nastran

Pioneer
Pioneer

Hello Thom,

 

So Accelaration 3.5g at its COG  as a point load will give me a different result than that of selecting the complete body and apllying it as cumulative load.

This what you are saying right.

 

If yes why are they varying literally both has to be same.Right?

 

Thanks