JP3909843B2 - Coupled vibration tester - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coupled vibration experimenter used for experimentally learning coupled vibrations, and more particularly to a coupled vibration experimenter using a coupled pendulum.
[0002]
[Prior art]
In general, a phenomenon in which two or more vibrators vibrate while acting on each other is called coupled vibration. Coupled vibration is one of the basic concepts of mechanics and is an important vibration phenomenon for understanding various phenomena in nature. Therefore, it is important for science and engineering students to quantitatively measure these vibration phenomena and deepen their understanding by considering the results in professional education such as universities and colleges of technology. The coupled vibration tester is used in such cases.
[0003]
FIG. 6 is a schematic perspective view of a general coupled vibration experimental device 10 that has been conventionally used (see, for example, Patent Document 1 and Non-Patent Document 1). This experimental apparatus 10 is of a two-coupled vibration system, and the first and second pendulums 11 and 13 are swung by a fulcrum 12 and 14 by a knife edge with respect to a support (not shown). Suspended freely. The first and second pendulums 11 and 13 are connected to each other via a cylindrical coil spring 15. In conducting the experiment, for example, when the first pendulum 11 is swung in the direction A in the figure, the vibration energy is propagated to the second pendulum 13 through the cylindrical coil spring 15, thereby causing the second pendulum 13 to move. Swing. The amplitude and phase of the pendulums 11 and 13 at this time are measured, and the angular frequency of each is calculated from them, or the time required for the vibration energy to move is measured.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 59-231578 (FIG. 2)
[Non-Patent Document 1]
“Rigidly Coupled Pendulum PT-60”, No. 500 (Educational physics and chemistry instrument) General Catalog 2001-2002, p. 230, Shimadzu Rika Instruments Co., Ltd. [0005]
[Problems to be solved by the invention]
However, in the conventional coupled vibration experimental device as described above, the cylindrical coil spring 15 not only expands and contracts in a direction parallel to the axis, but also bends or twists in a direction perpendicular or oblique to the axis. Further, collision and friction between the rings of the spring 15 also occur. All of these factors cause loss of vibration energy, which can contribute to errors in measurement. Further, in order to perform vibration analysis, a spring constant is required as one of the parameters. However, calculation of the spring constant of the cylindrical coil spring is complicated and very difficult to calculate with high accuracy. As another problem, in the conventional coupled vibration experimental device as described above, since the degree of freedom of the experiment is low, it is very difficult to measure in a state where various parameters of the coupled vibration system are changed.
[0006]
The present invention has been made to solve such a problem, and an object of the present invention is to provide a coupled vibration experimental device that can be easily handled while being easy to handle. Another object of the present invention is to provide a coupled vibration tester in which various parameters of the coupled vibration system can be easily changed and measurement can be performed in a variety of ways.
[0007]
[Means for solving the problems and effects]
The coupled vibration experiment device according to the present invention, which has been made to solve the above-mentioned problems, includes at least two pendulums that are spaced apart from each other by a predetermined distance and are swingable in a direction substantially perpendicular to the separation direction. A torsion bar that connects the at least two pendulums, and a position adjustment mechanism that enables the position of the connecting part between the pendulum and the torsion bar to move in the extending direction of the torsion bar. It is a feature.
[0008]
As is well known, the torsion bar utilizes a spring action caused by torsional deformation, and is a rod-shaped body having a cross section of a circle (hollow or solid), a rectangle, a hexagon, or the like. For example, when there are two pendulums, the pendulum is fixed at two locations on the torsion bar. When one pendulum is swung in the direction perpendicular to the extending direction of the torsion bar with the fixed portion as a fulcrum, vibration energy propagates through the torsion bar and moves to the other pendulum. The other pendulum swings in the same direction.
[0009]
Since the deformation mode of the torsion bar is limited only to the twisting direction, there is little loss during the propagation of vibration energy, and highly accurate measurement can be performed. Further, since the spring constant can be obtained with high accuracy and relatively easily from the dimensions and the elastic coefficient, the vibration analysis accuracy is also improved. Furthermore, since the structure and movement are simple, the learner can easily understand intuitively, and the learning effect as an experimental device is high.
[0011]
As a specific aspect, the beam laid substantially horizontally, the torsion bar support part movable in the extending direction of the beam, and the torsion bar support part extended in the same direction as the extending direction of the beam. A pendulum fixing portion for movably fixing the pendulum to the torsion bar supported in a state, and the position adjustment mechanism is configured by the torsion bar support portion and the pendulum fixing portion. it can.
[0012]
In this configuration, the fixed position of the pendulum can be easily changed by the position adjusting mechanism, so that the effective length of the torsion bar connecting the two pendulums, which is one of the important parameters of the coupled vibration system, is appropriately set. It can be changed freely. In addition, since the torsion bar itself can be easily replaced, it can be replaced with one having a different material or size (cross-sectional diameter, cross-sectional area, etc.). Furthermore, it is easy to mount not only two pendulums on one torsion bar but also three or more pendulums. Accordingly, not only two-coupled experiments but also three or more coupled vibration experiments can be easily performed.
[0013]
On the other hand, if only one pendulum is attached to one torsion bar, and the torsion bar is fixed at the torsion bar support part located away from the torsion bar, the weight attached to the pendulum is not a coupled vibration system. A torsional vibration system based on the moment of inertia can be configured. This makes it possible to measure characteristics such as Young's modulus of the torsion bar.
[0014]
In addition, when the lateral rigidity of the torsion bar is not so large, it is preferable to provide a pair of the torsion bar support portions with the pendulum fixing portion interposed therebetween. Thereby, the swinging of the pendulum is stabilized, and the measurement accuracy is improved.
[0015]
As described above, according to the coupled vibration experimental device according to the present invention, a highly accurate experiment can be easily performed as compared with the conventional case. Further, various parameters of the coupled vibration system (and torsional vibration system) can be easily and widely changed. As a result, the experiment level in the education field, for example, from the purpose of observing elementary phenomena as high school students, to the creation of training reports that require advanced analysis as high as science graduate students, It can be used in a wide range.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a coupled vibration experimental device according to the present invention will be described with reference to FIGS. 1 is an external perspective view of the coupled vibration experimental device 20 of the present embodiment, FIG. 2 is a partial top view seen from the direction of arrow a in FIG. 1, and FIG. 3 is a line bb in FIG. It is sectional drawing in '.
[0017]
In this coupled vibration tester 20, a pair of support columns 23 are erected on both ends of a base plate 21 supported by four leg portions 22 that can be adjusted in height to ensure horizontality. A beam 24 is laid horizontally on the upper ends of these two columns 23 in a state where the beam 24 can be removed by screws 25. The cross section of the beam 24 in this installed state is a ◇ shape (see FIG. 3). It is possible to mount an arbitrary number of clampers 26 at an arbitrary position in the extending direction of the beam 24, but as a basic configuration, as shown in FIG. Two to four clampers 26 are fixed to the beam 24 with clamper fixing screws 27, respectively. If the tightening of the clamper fixing screw 27 is loosened, the clamper 26 can be moved along the beam 24 to an arbitrary position.
[0018]
A U-shaped metal fitting 28 formed in a U-shaped groove 28 a whose upper surface is recessed in a U shape is detachably fixed to each clamper 26 by a metal fitting fixing screw 29. The four U-shaped brackets 28 are arranged in a substantially straight line along the extending direction of the beam 24, and the torsion bar 30 is supported horizontally by the four U-shaped grooves 28a. The torsion bar 30 is, for example, a cylindrical rod body having a diameter of φ2.0 mm, and the groove diameter of the U-shaped groove 28a is set to φ3.5 mm that is slightly larger than that. Accordingly, the torsion bar 30 is movable within the U-shaped groove 28a although it is a slight range, and since the contact area between the two is narrow, the friction is small and the loss of vibration energy here can be very small.
[0019]
A pendulum fixing bracket 31 is provided at each of the upper ends of the first and second pendulums 33 and 35 each having a weight 34 and 36 mounted at a position close to the lower end. The pendulum fixing bracket 31 has a deep vertical groove on the upper surface, and a fixing screw 32 is screwed from the front so as to protrude into the vertical groove. The upper ends of the pendulums 33 and 35 are fixed to the torsion bar 30 by fitting the torsion bar 30 into the vertical groove of the pendulum fixing bracket 31 from above and tightening the fixing screw 32. The vicinity of the contact portion between the torsion bar 30 and the fixing screw 32 becomes a fulcrum when the pendulums 33 and 35 swing.
[0020]
As described above, the clamper 26 can be moved to any position along the beam 24. Preferably, as shown in FIGS. 1 and 2, the pendulums 33 and 35 have two clampers attached in close proximity. 26 to be sandwiched between. As a result, the torsion bar 30 is supported by the U-shaped bracket 28 at positions relatively close to both sides across the fulcrum of the pendulums 33 and 35. Although the torsion bar 30 used here has a small cross-sectional area and is not so high in lateral rigidity, the swinging of the pendulums 33 and 35 can be prevented by supporting one fulcrum from both sides with two U-shaped brackets 28. It can be prevented from becoming stable.
[0021]
The basic swing direction of the first and second pendulums 33 and 35 is the A direction orthogonal to the extending direction B of the torsion bar 30. A scale 37 for measuring the swing amplitude of the pendulums 33 and 35 as described above is mounted on the base plate 21 directly below the both pendulums 33 and 35 in the A direction. Since the pendulums 33 and 35 can be slid in the extending direction B of the beam 24 and the torsion bar 30, the scale 37 can be similarly moved in the B direction by loosening the screw 38 fixing the scale 37. .
[0022]
When conducting an experiment using the coupled vibration experiment device 20 of the present embodiment, one of the first pendulums 33 is swung in the A direction shown in the figure. Then, this vibration energy propagates to the torsion bar 30 via the fulcrum, and propagates from the other fulcrum to the second pendulum 35 via the torsion bar 30. As a result, the second pendulum 35 starts to swing in the A direction. The amplitude of the swing of the pendulums 33 and 35 is measured by the scale 37, or the phase difference of the swing of the pendulums 33 and 35 is measured.
[0023]
The clamper 26 can be moved to an arbitrary position of the beam 24 and the pendulum fixing bracket 31 can be moved to an arbitrary position of the torsion bar 30, so that the torsion bar 30 connecting both the pendulums 33 and 35 is effective. The length can be changed arbitrarily. Further, the torsion bar 30 is only placed in the U-shaped groove 28 a of the U-shaped metal fitting 28, and the torsion bar 30 can be pulled out from the pendulum fixing metal 31 simply by loosening the fixing screw 32. Therefore, the torsion bar 30 can be easily replaced with one having a different material, size, cross-sectional shape, or the like.
[0024]
For example, when a belt-like torsion bar having a rectangular cross section is used, the torsion bar is mounted such that the short side of the cross section is in contact with the bottom of the U-shaped groove 28a of the U-shaped bracket 28. In this case, the friction between the torsion bar and the U-shaped groove 28a becomes extremely small, and vibration energy is hardly lost. Therefore, it is very effective for performing highly accurate measurement. Of course, it is obvious that a torsion bar having any other cross-sectional shape, size, and material can be used.
[0025]
Furthermore, although FIG. 1 shows a two-coupled configuration, an arbitrary number of clampers 26 can be attached to the beam 24 as much as possible. For example, a pair of clampers and one pendulum is added. As long as it is attached, a triple coupled pendulum can be constructed. Of course, it is possible to have a multiple coupled structure if necessary.
[0026]
The positions of the weights 34 and 36 attached to the pendulums 33 and 35 can be slid up and down, and can be removed and replaced with other weights. As a result, the moment of inertia, which is one of the important parameters of the vibration system, can be easily and freely changed.
[0027]
Furthermore, the experimental device 20 can be used for an experiment of a torsional vibration system in addition to the coupled vibration system. FIG. 5 is an external perspective view showing the configuration of an experimental device 20 ′ modified for a torsional vibration system experiment, and FIG. 4 is a cross-sectional view corresponding to FIG.
[0028]
One clamper 26 is mounted near one end (the left end in FIG. 5) of the beam 24, and the torsion as shown in FIG. A bar fixing bracket 41 is attached. Like the pendulum fixing bracket 31, the torsion bar fixing bracket 41 sandwiches and fixes the torsion bar 30 by screwing a fixing screw 42. Accordingly, the vicinity of the contact point between the fixing screw 42 and the torsion bar 30 is a fixing point of the torsion bar 30.
[0029]
On the other hand, the configuration on the other end side of the beam 24 is the same as the configuration of the double coupled pendulum of FIG. Therefore, the pendulum has only the second pendulum 35. In this configuration, when the second pendulum 35 is swung in the direction A as shown in FIG. Therefore, characteristics such as the Young's modulus of the torsion bar 30 can be obtained by measuring the state of the swing amplitude and performing calculation using parameters such as moment of inertia. Thus, the coupled vibration experiment device 20 according to the present embodiment can be easily changed to a torsional vibration system test device.
[0030]
It should be noted that the above embodiment is merely an example of the present invention, and it is apparent that appropriate modifications and corrections can be made in accordance with the spirit of the present invention.
[Brief description of the drawings]
FIG. 1 is an external perspective view showing an embodiment of a coupled vibration experimental device according to the present invention.
FIG. 2 is a partial top view as seen from the direction of arrow a in FIG.
FIG. 3 is a cross-sectional view taken along line bb ′ in FIG. 2;
FIG. 4 is a cross-sectional view corresponding to FIG. 3 when an experiment of a torsional vibration system is performed.
FIG. 5 is an external perspective view when the coupled vibration experimental device of the present embodiment is changed to a torsional vibration system configuration.
FIG. 6 is a perspective view showing a conventional coupled vibration experimental device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... Coupled vibration experiment device 21 ... Base plate 22 ... Leg part 23 ... Support column 24 ... Beam 25, 38 ... Screw 26 ... Clamper 27 ... Clamper fixing screw 28 ... U-shaped metal fitting 28a ... U-shaped groove 29 ... Metal fitting fixing Screw 30 ... Torsion bar 31 ... Pendulum fixing bracket 32, 42 ... Fixing screw 33, 35 ... Pendulum 34, 36 ... Weight 37 ... Scale 41 ... Torsion bar fixing bracket

Claims (3)

At least two pendulums spaced apart from each other by a predetermined distance and arranged to be swingable in a direction substantially orthogonal to the separation direction, a torsion bar connecting the at least two pendulums, the pendulum and the torsion bar, And a position adjusting mechanism for allowing the position of the connecting portion to move in the extending direction of the torsion bar . The beam installed substantially horizontally, the torsion bar support part movable in the extending direction of the beam, and the torsion bar supported in the state extended by the torsion bar support part in the same direction as the extending direction of the beam respect, Coupling according to claim 1, wherein the pendulum includes a pendulum fixing portion for movably securing the said torsion bar bearing and the position adjusting mechanism by pendulum fixing unit characterized in that it is configured Vibration tester. The coupled vibration tester according to claim 2 , wherein two of the torsion bar support portions are paired with the pendulum fixing portion interposed therebetween.

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