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How To Run FEA on Nut-Bolt Assembly

How To Run FEA on Nut-Bolt Assembly

How To Run FEA on Nut-Bolt Assembly

(OP)
Hey,

I am trying to run a simulation for a nut-bolt assembly. The nut and bolt are connected to a c-channel beam, I want to run a vibration simulation to find out the clamping force between the nut and bolt after a certain number of vibrations/oscillations. Can anyone give me any tips for how to go about this? I haven't really done much simulations/FEA since I finished my undergrad last year so any info will be helpful.

Thanks

RE: How To Run FEA on Nut-Bolt Assembly

What is the nature of vibration (steady-state, transient, random) ? How is the structure supposed to be supported and loaded ?

RE: How To Run FEA on Nut-Bolt Assembly

(OP)
I am thinking of applying a cycle of steady-state vibrations (i.e. apply steady-state vibration n amount of times and see the affect it has on the clamping force). The c-channel beams are used for warehouse racking, the nut-bolt assemble 2 safety bars perpendicular to the c-channel, so there are 2 c-channels with 2 safety bars perpendicularly assembled to the c-channels. The loads are applied to the safety bars.

RE: How To Run FEA on Nut-Bolt Assembly

Then harmonic analysis will do the job. You just have to connect the parts (with bonded contact), apply boundary conditions and loads. They will be harmonic by default and you can also define their variation with frequency. Then specify the range of frequencies to do the sweep.

RE: How To Run FEA on Nut-Bolt Assembly

What mechanism do you suppose will change the clamping force?

RE: How To Run FEA on Nut-Bolt Assembly

The goal is not to have me read the paper and extract the mechanisms you are looking for. The goal is for you to decide what factors there are so you can match them to what an FEA can actually simulate.

RE: How To Run FEA on Nut-Bolt Assembly

To give a hint - the major reason for loss of tension is embeddment - randomly located variations in high spots on the order of 0.0001 inch take the majority of the initial load. Repeated high loads cause these highly stressed points to deform, lowering the overall separation and the preload. To simulate that you need to have the ability to generate a randomly rough surfaces and allow for incremental deformation, possibly with very small areas of fatigue failure. The overall stress levels will remain in the elastic region so a typical FEA will never detect/simulate the effect.

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