ENERGY BALANCE IN ABAQUS IMPLICIT

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I am simulating a drop test impact scenario for a hyperviscoelastic material in Abaqus Implicit. When I look at the results, I find that the total energy of the whole model reduces by 15%. The same simulation when run in Abaqus Explicit gives a constant total energy value. Which results should I trust? Is it always necessary that the total energy of the whole model has to be constant, even when there is dissipation due to viscoelastic effects?