Energy balance.

[Nikesh Kumar Ojha]

Hello all,

Greetings of the day

 

I am simulating an impact problem using a rigid projectile (velocity 2 km/s) and a deformable target plate. The contact between the target and the projectile is eroding_surface_to_surface and for self-contact of the element is eroding_single_surface_contact .                         

 The total system energy as calculated is 450 J (Initial K.E of projectile). But in the graph, it can be observed that the total energy of the system is increased (greater than 450 J). I couldn't find why the total energy of the system increases after the initial impacts beyond initial kinetic energy (Total energy = 450 J).

Please share your suggestions on the energy balance attached below. Your suggestions will be highly appreciated.

[l...@schwer.net]

Looks as if your Internal and kinetic energies are both about 225 or 450 total. The additional 50 units of energy is coming from the sliding energy.

 

Sliding energy is usually due to penetration of one contact surface through another, i.e. it is the work needed to restore the penetration.

 

                --len

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[Kara Laing]

Your total energy jumps from 450J to 500 (initial penetration - it matches the slope of the energy? Added mass on the impactor?). Then the sum of the three matches neatly: KE, IE and dissipating interface energy.

How is your added mass? If it's significant, say 11%, and mostly on your impactor, then that's your extra energy source.

Kara