The rotational inertia of complex or heterogeneous rigid body can be measured by
trifilar torsional
pendulum.The torsion pendulum period is an important parameter related to
the accuracy of the test. Manual
counting and stopwatch timing are very laborious and easy to make
mistakes.The photoelectric sensor and the measurement
are easily affected by the yawing or shaking，which will lead to the
omission of one period.To this end，a
new type of trifilar torsional pendulum periodic measuring instrument is
proposed，which consists of light source，polarizer，
detector，photosensitive resistance module，data acquisition system and
computer installed with upper computer
software.The polarization characteristics of light and Marius's law are
used to detect the torsion pendulum situation
of the trifilar torsional pendulum.We can get the period of trifilar
torsional pendulum by using the linear fitting
function of origin data processing software.Using the photoelectric
measurement device in the market and the new
trifilar torsional pendulum period measuring instrument at the same time，a
comparative experiment is carried out to
measure the moment of inertia of the lower plate of trifilar torsional
pendulum.The experimental results show that the
relative error of the existing photoelectric measuring device is 0.83%，and
the relative error of the new trifilar torsional
pendulum period measuring instrument is up to 0.11%， indicating that the
accuracy of the new type trifilar
torsional pendulum periodic measuring instrument is higher than the
existing photoelectric measuring device.Because
the intensity of the transmission light is not affected by the small range
swing or sloshing of the trifilar torsional pendulum，
the new rifilar torsional pendulum periodic measuring instrument has a
strong anti-interference ability.Besides，
the device has the advantages of fast measuring speed， simple
operation，convenience，and has certain popularization
value.
Just Accepted
