Engineering Transactions, 56, 1, pp. 25–42, 2008

The First Half-Turn of an Inertial Vibrator

AGH University of Science and Technology Department of Mechanics and Vibroacoustics

The paper concerns the starting of an inertial vibrator which, due to a high value of
static unbalance, is unable to perform the first half-turn in the gravitational field of force.
The problem plays an essential role in the selection of driving units for the wide class of
over–resonance machines.
On the basis of the Pontryagin’s Maximum Principle the problem was formulated in terms
of a dynamic optimisation. Thus, the driving moment performs the function of control – which
is being looked for – while equations of motion and start-end conditions related to the position
of a vibrator, act as constrains equations and boundary conditions. The possible simplifications
in description of the motion of the vibrator, as well as the influence of the variable asynchronous
motor driving moment on the optimal solutions, are discussed in the paper. On the basis of the
work-energy equivalence principle, the minimum values of the driving moment – which warrants
the performance of the first half-turn of the vibrator at a given number of the moment switchovers
– were determined. The problem of thermal loads of the motor during the first half-turn
was also considered. The theoretical results were confirmed by the computer simulations.
Keywords: starting, vibratory machine, dynamic optimisation
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