Total energy does not remain constant (Abaqus Explicit)

[sanju261991]

I am simulating a sphere bouncing of a rigid plane in Abaqus Explicit as seen in the assembly below,

It consists of a axisymmertic semi circle for the sphere, with a velocity in th-y direction and an analytical ridig for the plane. The material is elastic, with E=9.3Gpa, Mass Density=900kg/m3 and poission's ratio 0.33

When the timestep is reduced to the range if 1e-10 the total energy varies greatly as seen in the image below,

Please help me understand this. The total energy must remain constant throughtout the simulation. THe simulation result are as expected when the timestep is set to automaotic, but incorrect for fixed timesteps of the range 1e-10.

 

[btrueblood]

Yes. But is your plotted value "total energy" (i.e. kinetic plus strain energy plus potential energy plus heat dissipated) or just total strain energy?

 

[sanju261991]

It is total energy, all energies added together and have not included heat dissipation in the simulation. Abaqus has the option of plotting total energy. The total energy should be constant.

 

[IceBreakerSours]

You have to look at such plots in a larger context: i.e., the physical energies of the system. What is the max. potential energy and, in relation to that energy, is the total energy more or less flat? Think about it. I bet there is nothing funny going on here.

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