  Two different mechanisms may act to induce quasi-periodic pulsations (QPP) in
whole-disk observations of stellar flares. One mechanism may be
magneto-hydromagnetic (MHD) forces and other processes acting on flare loops as
seen in the Sun. The other mechanism may be forced local acoustic oscillations
due to the high-energy particle impulse generated by the flare (known as
`sunquakes' in the Sun). We analyze short-cadence Kepler data of 257 flares in
75 stars to search for QPP in the flare decay branch or post-flare oscillations
which may be attributed to either of these two mechanisms. About 18 percent of
stellar flares show a distinct bump in the flare decay branch of unknown
origin. The bump does not seem to be a highly-damped global oscillation because
the periods of the bumps derived from wavelet analysis do not correlate with
any stellar parameter. We detected damped oscillations covering several cycles
(QPP), in seven flares on five stars. The periods of these oscillations also do
not correlate with any stellar parameter, suggesting that these may be a due to
flare loop oscillations. We searched for forced global oscillations which might
result after a strong flare. To this end, we investigated the behaviour of the
amplitudes of solar-like oscillations in eight stars before and after a flare.
However, no clear amplitude change could be detected. We also analyzed the
amplitudes of the self-excited pulsations in two delta Scuti stars and one
gamma Doradus star before and after a flare. Again, no clear amplitude changes
were found. Our conclusions are that a new process needs to be found to explain
the high incidence of bumps in stellar flare light curves, that flare loop
oscillations may have been detected in a few stars and that no conclusive
evidence exists as yet for flare induced global acoustic oscillations
(starquakes).
