Gavity and inertia

[flyforever85]

I'm getting confused on how to simulate a crash case. I have a metallic component and attached to it there is a mass of 80 lbf. I have to simulate what happens if there in an acceleration of 12g. The 80lbf-mass is attached to the main component through MPC (beams)

I thought to introduce a force 12 times higher 80lbf (so 960 lbf) for the external mass to consider the its inertia during the impact

and a gravity 12 times higher to consider the inertia of the metallic component itself.

Any thoughts?

 

[FEA way]

Usually crash simulations done in Abaqus (mainly explicit) require target abd impactor geometry (impactor can be rigid). Then you apply initial velocity to impactor and watch as it crashes into the target. This is the most realistic way. Another simplified method is to apply gravity boundary condition to the target (for example 12g) to see how it behaves in static analysis. This way is often used for complicated parts of vehicles when we know the acceleration they should resist.

 

[flyforever85]

THe component that I have is a gear box and it won't impact on anything but the acceleration due to the impact will be transferred to the BC and I want to see if the hinges can sustain this acceleration.

I used the 12g gravity for the whole model but I'd like to know also how to model the 80 lbf mass of the internal components of the gear box. IS it simply a force equal 12 times the actual mass?

 

[FEA way]

You can represent additional mass from parts with ignored geometry using point mass feature. Such point can be connected with the rest of the model using kinematic coupling.