The following comparison shows the running costs
of two testing machines suitable for dynamic loads
in the middle to high frequency ranges.
A RUMUL high frequency resonant testing
machine TESTRONIC 250kN and a modern
servohydraulic machine are compared. The key
features are delivered from a large testing
laboratory with many years of experiences with all
kind of testing machines.
Two characteristic features mark the comparison:
A) The resonant testing machine is designed as
a mechanical oscillating system and consists of
masses and springs. Also the specimen with its
elasticity is part of this system. The natural
frequency is excited by an electromagnet. Typical
frequencies for such machines are in the range of
50-250 Hertz and the needed energy consumption
is about 0.5kW.
B) The servohydraulic testing machine loads the
specimen with a hydraulic actuator which is
operating in a servo-loop. For frequencies in the
range of 50 Hertz rather efficient equipment has to
be used. The testing load for each cycle has to be
built-up by oil pressure, which means that the
neccessary energy is needed for each cycle.
Practically all the energy is transformed into heat
and has to be carried off by an additional cooling
system.
The comparison has been simplified in serveral
points without falsifying the essential. The
amortisation has been distributed regularly to 8
years. To take into consideration the reduction of
interest for the sinking investment the interest of 12
% has been parted to 6 %. This means that for the
first years of the amortisation period the interest is
too little but this will be compensated during the last
years.
The calculation does not consider engineering- and
space-costs.
Russenberger Prüfmaschinen AG
Comparison of costs