  A few-degrees-of-freedom Hamiltonian model exhibiting one-directional
long-term trends in energy exchange flows is introduced. The model includes a
massive potential well - a container with one or few relatively light
non-interacting particles \ - attached to a linearly elastic spring. No
phenomenological dissipation is imposed, nevertheless, due to a similarity of
the container shapes to typical stochastic soft-wall billiards, the energy is
transferred from the container (donor) to the inner particles (acceptor) in
almost irreversible way during physically reasonable time intervals. The
potential well is introduced in such a way that, in the rigid-body limit, it
resembles either Sinai billiards or the so-called Buminovich stadiums as the
main geometrical parameter of the well switches its sign. In particular, using
the nonlinear normal mode stability concept reveals conditions of stochasticity
and determines the analogy with the dynamic properties of billiards. Possible
applications to the design of macro-level energy absorbers, harvesters, and
energy absorbing materials are discussed.
