Time evolution of the kinetic, potential, and dissipated energy during collisions of two aggregates with a diameter of 60  μm and filling factor φ ≈ 0.59. Left: a bouncing collision between two CPE aggregates. A sufficient amount of the impact energy is temporarily stored in the potential U_normal of the normal interaction. Right: during a sticking collision of two BAM aggregates most of the kinetic impact energy is dissipated.