  Impacting mechanical systems with suitable parameter settings exhibit a large
amplitude chaotic oscillation close to the grazing with the impacting surface.
The cause behind this uncertainty is the square root singularity and the
occurrence of dangerous border collision bifurcation. In the case of one degree
of freedom mechanical systems, it has already been shown that this phenomenon
occurs under certain conditions. This paper proposes the same uncertainty of a
two-degree freedom mechanical impacting system under specific requirements.
This paper shows that the phenomena earlier reported in the case of one degree
of freedom mechanical systems (like narrow band chaos, finger-shaped attractor,
etc.) also occur in the two degrees of freedom mechanical impacting system. We
have numerically predicted the narrowband chaos ensues under specific parameter
settings. We have also shown that the narrowband chaos can be avoided under
some parameter settings. At last, we demonstrate the numerical predictions
experimentally by constructing an equivalent electronic circuit of the
mechanical rig.
