JPH11218483A - Viscoelasticity measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure static and dynamic viscoelasticities of a sample without receiving an influence from an elastic modulus of an elastic material which is supporting a detecting bar. SOLUTION: A part of a sample 1 is held by a detecting bar 6 elastically held by a support 12 variable at its opposed position to a sample holder 2 for holding an end of the sample 1. When a force of a DC or an AC is applied to the bar 6, a displacement of the bar 6 to the support 12 is detected. In this case, a position of the support 12 is altered or the force of the DC is changed so that the displacement is reset to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring static and / or dynamic viscoelasticity of a material.

[0002]

2. Description of the Related Art Conventionally, this type of invention has been disclosed in Japanese Patent Publication No. 57-40963 (hereinafter referred to as a first conventional example).
There is an apparatus for measuring the relationship between stress and strain of a material as seen in the above. Further, as disclosed in JP-A-63-139232 (hereinafter referred to as a second conventional example), by simplifying the mechanical system, the mechanical strength is increased, the weight of the vibration system is reduced, and the mechanical resonance is reduced. There is an improved device that can mitigate the effect of the stress and measure the dynamic viscoelasticity of the material. Furthermore, as disclosed in JP-A-3-82934 (hereinafter referred to as a third conventional example), an AC force obtained by adding a DC is applied to the material, and the DC distortion component of the distortion generated in the material is mechanical. There is an improved device which can measure the dynamic viscoelasticity of the material from only the AC component by the tension method.

In these conventional devices, force is transmitted to a sample via a detection rod, and distortion of the sample is detected by a displacement detector provided between the detection rod and an external support. They have something in common. On the other hand, the detection rod in these devices needs to be supported by a support in the device in some form, and in the first conventional example, a balance support mechanism is used,
In the second and third conventional examples, the leaf spring is fixed to the support.

[0004]

In each of the above-mentioned conventional devices, a characteristic generally required for each method of supporting the detection rod is that the friction between the detection rod and the support is small (between the detection rod and the support). Has low viscous resistance). In addition, for the purpose of measuring the static viscoelasticity of the sample, a small elastic coupling constant (spring constant) between the detection rod and the support is required.

[0005] For the purpose of measuring the dynamic viscoelasticity of a sample,
In order to minimize the measurement error due to inertia, the mass of the vibrating part including the detection rod must be small. In addition, since the resonance frequency of the vibrating part determined by the ratio of the elastic coupling constant and the mass of the vibrating part needs to be higher than the measurement frequency, the elastic coupling constant between the detection rod supports needs to be large to some extent. That is, measuring the static viscoelasticity of a sample and measuring the dynamic viscoelasticity both have a common point in measuring the relationship between stress and strain generated in the sample, but only in the above conventional example. In such a method of supporting a detection rod, there are conflicting requirements regarding the elastic coupling constant between the detection rod and the support.Therefore, there are devices that can accurately measure both the static viscoelasticity and the dynamic viscoelasticity of the sample. Did not.

Actually, static viscoelasticity can be measured using the device shown in the first conventional example, but due to the large mass of the balance mechanism, the measurement of dynamic viscoelasticity is limited to an extremely low frequency region of 1 Hz or less. Is done. On the other hand, in the devices shown in the second and third conventional examples, dynamic viscoelasticity measurement up to a high frequency of about several hundred Hz can be performed, but simultaneous measurement of stress and strain when measuring the static viscoelasticity of the sample is performed. Since it is difficult to separate the spring constant of the leaf spring from the change, there is a drawback that the measurement accuracy cannot be obtained.

[0007]

SUMMARY OF THE INVENTION The present invention has been developed to solve the above problems quickly. A sample holder supporting both ends or one end of the sample, a sample chuck supporting a part of the sample, a detector support capable of changing a relative position with respect to the sample holder, and connected to the sample chuck and A detection rod elastically supported by the detector support, and a displacement detector that captures a change in a longitudinal position of the detection rod with respect to the detector support;
A force generator that is fixed to the detector support and applies a force to one end of the detection rod in a longitudinal direction and that applies stress to the sample via the detection rod and the sample chuck; and a force generator connected to the force generator. A function generator for setting a DC component and an AC component of a stress applied to the sample, and a machine for changing a relative position of the detector support with respect to the sample holder so that a DC component output of the displacement detector approaches zero. Negative feedback control means, negative feedback control means for changing the DC output of the force generator so that the DC component output of the displacement detector approaches zero, and the detector support for the output of the force generator and the sample holder Recording means for recording the relative movement amount of the body, and a Fourier transform process for a periodic function signal of the periodic function generator and a periodic function component of the displacement signal captured by the displacement detector. Cormorants and calculator, and a.

In the operation of the above configuration, first, one or both of a DC force and an AC force are applied to the sample held by the sample holder and the sample chuck via a detection rod from a force generating unit. At this time, reflecting the linear viscoelasticity of the sample and the elastic support, a DC distortion occurs for a DC force, and an AC distortion occurs for an AC force, all of which are captured by the displacement detector.

The AC distortion detected by the displacement detector is detected as a synthesized dynamic viscoelasticity of the sample and the elastic support by comparison with the applied AC force. If the sample and the elastic support are connected in parallel, the dynamic viscoelasticity of the sample can be known by simply subtracting the elastic modulus of the elastic support from the synthesized dynamic viscoelasticity. On the other hand, the applied DC force and the DC component of the distortion captured by the displacement detector are:
Measured by passing the displacement signal through a low-pass filter (low-pass filter) or by continuously applying a DC wave and applying an AC wave intermittently to measure the displacement when no AC wave is applied Is done. At this time, according to the measured value, the measured value of the DC component of the displacement signal approaches zero.
Either move the detector support or change the DC force. At this time, the amount of movement of the detector support indicates the deformation of the sample, and no deformation occurs in the elastic support.
Therefore, all the applied DC force is distributed to the sample. That is, since the applied DC force and the amount of movement of the detector support respectively represent the static stress and the static strain of the sample, the static viscoelasticity of the sample can be measured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. In FIG. 1, reference numeral 1 denotes a sample,
Is fixedly held by the sample holder 2 via the screw 2a. The sample holder 2 is fixed below the outer side of the detector box 4 by a column 3. The other end of the sample 1 is held by a chuck 5, and the chuck 5 is fixed to one end below a vertically arranged detection rod 6. The attachment of the sample 1 to the sample holder 2 and the chuck 5 is not limited to the above embodiment, but may be simply supported depending on the purpose of measurement.

The detection rod 6 extends vertically through a hole provided below the detector box 4. A coil 7 is fixed to the other end above the detection rod 6, and a permanent magnet 8 fixed to a detector support 12 is arranged around the coil 7. By the cooperation, a force is applied in the longitudinal direction of the detection rod 6. That is, the coil 7 and the permanent magnet 8 form an electromagnetic force generator for applying an axial force to the detection rod 6.

The detection rod 6 is elastically fixed to the detector support 12 by two leaf springs 9 so that it can move only in the longitudinal direction. The two leaf springs 9, 9 are
Can move in the longitudinal direction (axial direction), and the detection rod 6 restricts the movement in the radial direction. The two leaf springs 9 and 9 and the detection rod 6 may be fixed and detachably mounted or slidably mounted.

A core 10 is fixed to a part of the detection rod 6 between the two leaf springs 9. In addition, core 1
0 is located in the inner part of the detector box 4. Core 10
A differential transformer 11 is arranged around the periphery of the core 10 with a gap provided with the core 10. The differential transformer 11 includes the detector support 1
2, is held in a fixed state, and the relative displacement of the core 10 is detected as distortion of the sample 1. That is, the core 10 and the operation transformer 11 constitute a distortion detector for detecting distortion. The detector support 12 is axially movably engaged with a ball screw 14 and a guide rod 15 by bearings 13, 13. The ball screw 14 and the guide rod 15 are held by the detector box 4 in a direction parallel to and perpendicular to the detector box 4. Reference numeral 16 denotes a step motor mounted on the detector box 4, and pulleys 17 are fixed to the shaft of the step motor 16 and the tip of the ball screw 14, respectively. A drive belt 18 is hung between the two pulleys 17. The ball screw 14 rotates by the movement of the pulleys 17 and 17 and the drive belt 18 accompanying the rotation of the step motor 16, and the detector support 12 can be moved via the bearings 13 and 13 while keeping the detector support 12 horizontal in the vertical direction. it can. That is, the coil 7, the differential transformer 11, and the leaf springs 9, 9 can be simultaneously moved in the vertical direction by the same amount.

The detector box 4 is supported by a support mechanism 19. The bottom of the detector box 4 is provided with a hole through which the detection rod 6 passes. On the other hand, a heating / cooling furnace 20 is provided around the sample 1 for the purpose of changing the temperature of the sample 1.
The heating / cooling furnace 20 is attached to the support mechanism 19 via a moving mechanism 21. The moving mechanism 21 includes the heating / cooling furnace 20
Can be moved up and down. The heating / cooling furnace 20 can change the temperature of the sample 1 by an arbitrary temperature program. Between the lower outer side of the detector box 4 and the upper end of the heating / cooling furnace 20, a tubular bellows 2 is provided.
2 is inserted, and the upper end of the tubular bellows 22 is fixed to the bottom of the detector box 4. That is, the heating / cooling furnace 2
0, the detector box 4 and the tubular bellows 22
Since a substantially closed space in the apparatus including the heating and cooling furnace 20 is formed, small holes for introducing and exhausting gas are provided in the tubular bellows 22, respectively, and gas flow is performed. Can be set to, for example, a nitrogen atmosphere. In addition, by moving the heating / cooling furnace 20 downward, a gap is generated between the upper end of the heating / cooling furnace 20 and the lower end of the tubular bellows 22, so that the sample 1 can be detached and replaced.

Reference numeral 31 denotes an AC function generator. The AC function generator 31 sets a waveform (for example, a sine wave) and a frequency of an AC force generated by the electromagnetic force generator formed by the permanent magnet 8 and the coil 7, and generates a waveform signal thereof. An amplifier 32 for setting and amplifying the amplitude of the AC force is connected to the AC function generator 31. An optimum DC value calculator 33 is connected to the amplifier 32. Optimal DC force calculator 3
A DC voltage generator 35 is connected to 3 via a switch 34, and the DC voltage generator 35 sets the DC force generated by the electromagnetic force generator. The DC voltage generator 35 is connected to an adder 36, and the amplifier 32 is also connected to the adder 36 via a switch 37. When the switch 37 is closed, the adder 36 generates a DC voltage with AC superposition. I do. The coil 7 is connected to the adder 36, a force is generated in the coil 7 according to the output of the adder 36, and a stress is applied to the sample 1 via the detection rod 6.

The distortion generated in response to the stress applied to the sample 1 is detected by the differential transformer 11 as the displacement of the detection rod 6 and sent to the distortion measuring circuit 40. The distortion signal of the sample 1 measured by the distortion measurement circuit 40 is transmitted to the low-pass filter 41 and the high-pass filter 45 connected to the distortion measurement circuit 40.
, And are taken out. The low-frequency component that has passed through the low-pass filter 41 is sent to the zero distortion control circuit 42, and the AC component that has passed through the high-pass filter 45 is sent to a Fourier calculator 47 via an analog-to-digital converter 46.

The sample 1 which is the output of the amplifier 32
Is also sent to the Fourier calculator 47 via the analog-to-digital converter 48. The Fourier calculator 47 calculates and outputs the strain amplitude, the stress-strain amplitude ratio, and the stress-strain phase difference of the sample 1. A distortion amplitude controller 49 is connected to the Fourier calculator 47, and a distortion amplitude measurement signal is sent to the amplitude controller 49. The distortion amplitude controller 49 is connected to a target distortion amplitude input device 50, and the measurement signal of the distortion amplitude transmitted from the Fourier calculator 47 is many times larger than the target value of the distortion amplitude transmitted from the target distortion amplitude input device 50. The function is to calculate whether the gain is smaller or smaller and to change the amplification factor of the amplifier 32 by the reciprocal multiple. That is, the distortion amplitude controller 49 sets the value of the amplifier 32 so that the distortion amplitude of the sample 1 becomes the target amplitude.

On the other hand, the stress-strain amplitude ratio and the phase difference data calculated by the Fourier calculator 47 are sent to the dynamic viscoelastic calculator 51, where the data are combined with the information on the sample shape and the dynamics of the sample 1 are combined. The viscoelasticity is determined. Reference numeral 38 denotes a function generator that allows an operator to set a desired function with respect to time, and reference numeral 39 denotes a step motor drive circuit for driving the step motor 16.

The zero distortion control circuit 42 includes a switch 4
By the operation of 3, it is connected to either the step motor drive circuit 39 or the DC voltage generator 35. Also,
By the function of the switch 44, the function generator 38 can be switched between three cases: a case where it is connected to the DC voltage generator 35, a case where it is connected to the step motor drive circuit 39, and a case where it is not connected to any other.

The step motor drive circuit 39 is connected to a static viscoelasticity calculator 53 via an analog / digital converter 56. On the other hand, the DC voltage generator 35 is also connected to the static viscoelasticity calculator 53 via the analog / digital converter 52. The static viscoelasticity calculator 53 calculates the stress of the sample 1 from the output of the DC voltage generator 35 and calculates the strain of the sample 1 from the output of the step motor drive circuit 39 in consideration of information on the shape of the sample. By the sample 1
Is determined.

The viscoelastic signal of the sample 1 calculated by the dynamic viscoelasticity calculator 51 and the static viscoelasticity calculator 53 is stored in a memory 54.
And a printer (not shown) or CR
It can be output to recording means such as T (not shown) or display means. Hereinafter, the operation of the device according to the present embodiment will be described. FIG. 1 shows the configuration of sample gripping in the case of a tensile measurement. First, the operation of the apparatus at the time of a tensile measurement will be described below.

First, the operator lowers the heating / cooling furnace 20 by the operation of the moving mechanism 21 and holds or supports the sample 1 with the sample holder 2 and the chuck 5, then raises the heating / cooling furnace 20 and sets the sample 1 in the apparatus. I do. The operator sets a desired temperature program in the temperature controller 55,
The measurement can be performed while changing the temperature of the sample 1 or maintaining it at a certain temperature.

Next, a desired measurement mode is set from dynamic viscoelasticity measurement using a sine wave, dynamic viscoelasticity measurement using a synthetic wave, creep measurement using stress control, and stress relaxation measurement using strain control. When a sine wave measurement is selected, switches 34 and 37 are closed and switch 4
By 3, the zero distortion control circuit 42 is connected to the step motor drive circuit 39, and the function generator 38 is disconnected by the switch 44, and is not connected to the other. Further, the operator sets the measurement frequency in the AC function generator 31 between 0.01 Hz and 100 Hz, inputs the target value of the distortion amplitude to the target distortion amplitude input device 50, and
In order to prevent the sample from being loosened or pulled too much, apply a DC force that is increased by a percentage to the AC force.
Set conditions such as how many grams of DC force should be applied to the AC force. When a plurality of types of measurement frequencies are set, the measurement frequencies are sequentially changed and the measurement is performed at all the set frequencies.

When the operator gives a command to start the measurement to the apparatus, first, the distortion of the leaf spring 9 is detected by the differential transformer 11, and the detected distortion signal is sent to the distortion detection circuit 40, through the low-pass filter 41. The low frequency component of the distortion is sent to the zero distortion control circuit 42. The zero distortion control circuit 42 calculates a drive amount for driving the step motor 16 based on the proportional control so that the low frequency component of the measured distortion approaches zero, and then switches the calculated drive amount signal to the switch 43. A negative feedback control is performed to move the detector support 12 up and down so that the output of the differential transformer 11 is constantly returned to zero as a whole. At this time, since the low frequency distortion is always removed from the leaf spring 9, the low frequency component of the force generated by the electromagnetic force generator of the permanent magnet 8 and the coil 7 is the low frequency component of the distortion generated in the sample 1. And perfectly balanced.

A sine wave having a predetermined frequency is output from the AC function generator 31, amplified by the amplifier 32, and sent to the adder 36 via the switch 37. On the other hand, the optimum DC force calculator 33 connected to the amplifier 32 calculates the optimum DC force generated by the electromagnetic force generator, and
To the DC voltage generator 35, and further to the adder 36 to be added to the AC voltage. The adder 36 is connected to the coil 7, and the AC superimposed DC signal output from the adder 36 is subjected to AC superimposition applied to the sample 1 and the leaf spring 9 via the detection rod 6 by the coil 7. Is converted into a DC force. At this time, as a result of the above-described negative feedback control on the detector support 12, actually, a DC force superimposed on the sample 1 is applied, whereas only an AC force is applied to the leaf spring 9, Does not join.

The AC force applied to the sample 1 and the leaf spring 9 causes AC distortion in both. This AC distortion is detected by the differential transformer 11, converted into a digital signal via the distortion measuring circuit 40, the high-pass filter 45, and the analog-to-digital converter 46, and then sent to the Fourier calculator 47. The Fourier calculator 47 calculates the amplitude of the AC distortion generated simultaneously in the sample 1 and the leaf spring 9 by the following calculation (Equation 1).

[0027]

(Equation 1)

The measured value of the distortion amplitude obtained in this way is sent to the distortion amplitude controller 49, and is compared with the target value of the distortion amplitude sent from the target distortion amplitude input device 50 to determine the next amplification factor of the amplifier 32. Is done. As a result of the above-described distortion amplitude control, the amplitude of the AC distortion generated in the sample 1 as a whole is constantly controlled to a value close to the target value set by the operator.

The sine wave AC output from the amplifier 32 is converted into a digital signal via an analog-to-digital converter 48 and then sent to a Fourier calculator 47. The Fourier calculator 47 calculates the amplitude ratio and the phase difference between the AC stress and the AC strain generated between the sample 1 and the leaf spring 9 based on the following calculation (Equation 2).

[0030]

(Equation 2)

The information on the amplitude ratio and the phase difference obtained by the Fourier calculator 47 is sent to the dynamic viscoelastic calculator 51, and the dynamic viscoelasticity of the sample 1 is determined as follows (Equation 3).

[0032]

(Equation 3)

The dynamic viscoelasticity information of the sample 1 obtained by the dynamic viscoelasticity calculator 51 is stored in a storage unit 54 and is recorded by a recording means such as a printer (not shown) or a CRT (not shown). Of course, it can be output to the means. Next, the case where the operator selects the measurement using the synthetic wave will be described focusing on the difference from the sine wave measurement.

The combined wave used by the inventors adds a basic sine wave as shown in FIG. 2 and its second, fourth, tenth and twenty-fold waves with equal amplitudes. This is the waveform obtained. Prior to the measurement, the operator sets only one type of basic sine wave frequency of the composite wave between 0.01 Hz and 5 Hz instead of setting the frequency of the sine wave.
The setting of other conditions is exactly the same as in the case of the sine wave.

The operation of the apparatus during the measurement is slightly different from that of the sine wave measurement in that the control of the distortion amplitude is performed only on the amplitude of the fundamental wave. In the composite wave measurement mode, the amplitude ratio and phase difference of the distortion are the fundamental wave, the second harmonic, the fourth harmonic, the tenth harmonic,
It is calculated as follows for each of the 20th harmonics.

[0036]

(Equation 4)

Therefore, in the dynamic viscoelasticity calculator 51,
The dynamic viscoelasticity of the sample 1 for all five frequencies is determined by the same procedure as in the case of the sine wave measurement.
Therefore, the information efficiency per time is superior to the sine wave measurement. However, each frequency component is limited to one-fifth the amplitude of the upper limit of the force generated by the electromagnetic force generator, so that the measurement range of the elastic modulus is narrower than that of a sine wave.

Next, the operation of the apparatus when the operator selects the creep measurement mode will be described. In the case of creep measurement, the temperature of the sample 1 is kept constant by the operation of the temperature controller 55 and the heating / cooling furnace 20. When the creep measurement is selected, the switches 34 and 37 are opened, and the AC signal generated by the AC function generator 31 is not sent to the coil 7. The switch 43 connects the zero distortion control circuit 42 to the step motor drive circuit 39, and the switch 44 connects the function generator 38 to the DC voltage generator 35. The operator starts the measurement after inputting the rectangular wave function to the function generator 38.

The rectangular wave generated by the function generator 38 is sent to the coil 7 via the DC voltage generator 35 and the adder 36, and the rectangular wave force generated by the coil 7 is transmitted to the sample 1 via the detection rod 6. The distortion transmitted to the leaf spring 9 and generated in both of them is detected by the differential transformer 11. The distortion signal detected by the differential transformer 11 is applied to the distortion measurement circuit 4 as in the case of the sine wave measurement.
0, sent to the step motor drive circuit 39 via the low-pass filter 41 and the zero distortion control circuit 42, and by driving the step motor 16, the detector support 12 is moved up and down. Output is constantly approaching zero. At this time, since the distortion of the leaf spring 9 is removed, the entire output of the coil 7 is added to the sample 1,
The amount of movement of the detector support 12 by driving the step motor 16 matches the amount of deformation of the sample 1.

Therefore, the output of the DC voltage generator 35 is converted into a digital value by the analog / digital converter 52 and sent to the static viscoelasticity calculator 53, where
9 is converted into a digital value by the analog / digital controller 56 and sent to the static viscoelasticity calculator 53, so that the static viscoelasticity calculator 53 applies the stress of the sample 1 from the former and the strain of the sample 1 from the latter. Can be calculated based on the following equation.

[0041]

(Equation 5)

That is, the static viscoelasticity calculator 53 can obtain the data of the creep recovery measurement, which is the strain response of the sample 1 to the rectangular wave stress, and can measure the static viscoelasticity of the sample. Next, the operation of the apparatus when the operator selects the mode of the stress relaxation measurement will be described.

In the stress relaxation measurement, as in the creep measurement, the temperature of the sample 1 is kept constant by the operation of the temperature controller 55 and the heating / cooling furnace 20. When the stress relaxation measurement is selected, the switches 34 and 37 are opened, and the AC signal generated by the AC function generator 31 is not sent to the coil 7. The switch 43 connects the zero distortion control circuit 42 to the DC voltage generator 35, and the switch 44 connects the function generator 38 to the step motor drive circuit 39. The operator starts the measurement after inputting the rectangular wave function to the function generator 38.

The rectangular wave generated by the function generator 38 passes through a step motor drive circuit 39 to the step motor 16.
The detector support 12 moves in a rectangular wave shape by the movement of the step motor 16. At this time, the total movement amount of the detector support 12 is distributed to the deformation of the sample 1 and the deformation of the leaf spring 9, and only the distortion generated in the leaf spring 9 is changed.
Is detected by The distortion signal detected by the differential transformer 11 is sent to a zero distortion control circuit 42 via a distortion measurement circuit 40 and a low-pass filter 41. Zero distortion control circuit 4
In step 2, a DC force to be generated by the coil 7 is calculated based on proportional control so that the measured low-frequency component approaches zero, and the calculated DC force signal is transmitted via a switch 43 to a DC voltage generator. 35 to the differential transformer 1 as a whole.
Negative feedback control is performed to change the DC force generated by the electromagnetic force generator so as to constantly return the output of 1 to zero. At this time,
Since the distortion of the leaf spring 9 is removed, the entire output of the coil 7 is applied to the sample 1, and the amount of movement of the detector support 12 by the drive of the step motor 16 matches the amount of deformation of the sample 1. I have.

Therefore, the output of the DC voltage generator 35 is converted into a digital value by the analog / digital converter 52 and sent to the static viscoelasticity calculator 53, where
9 is converted to a digital value by the analog / digital controller 56 and sent to the static viscoelasticity calculator 53, so that the static viscoelasticity calculator 53 calculates the stress of the sample 1 from the former in the same way as in the creep measurement. It can be calculated similarly. That is, the static viscoelasticity calculator 53 can obtain data of stress relaxation measurement, which is a stress response to the rectangular wave distortion of the sample 1, and can measure the static viscoelasticity of the sample.

The results of the creep measurement and the stress relaxation measurement are both sent from the static viscoelasticity calculator 53 to the storage unit 54 and stored, and are also stored in a printer (not shown) or a CRT (not shown).
Can be output to recording means or display means. In the above description of the embodiments, the description has been made based on the sample gripping structure of the tensile measurement shown in FIG.

However, by using the sample holding structure as shown in FIG. 3, the apparatus of the embodiment can be subjected to various deformation modes such as compression, three-point bending, double-sided burr, cantilevered burr, shearing and the like. It can also be measured. At that time, in the case of measurement in each deformation mode of double-ended burr and shear, unlike the case of pulling, the sign of the force must not be reversed during measurement (DC force must not always exceed AC force amplitude) The switch 34 is opened, and the measurement is performed under the condition that the DC force is not superimposed. Although the treatment of the sample shape is partly different in the determination of the viscoelasticity, the other conditions and the operation of the apparatus are exactly the same as in the case of the tensile measurement described above.

Also, in this embodiment, part of the analog signal processing part can be digitally processed and signal processing can be performed by the processor. Conversely, part of the digital signal processing part can be converted to analog processing. That is. Hereinafter, measurement data measured by the apparatus shown in the examples will be described. FIG. 4 shows the dynamic viscoelasticity of a thin plate of PMMA (polymethyl methacrylate) at a fundamental frequency of 0.1.
This was measured using a 5 Hz synthetic wave. The heating rate of the sample was 4 degrees per minute, and near 130 degrees, a large decrease in storage modulus (E ') and peaks of loss modulus (E ") and loss tangent (tan δ) were detected. 5
Frequency dispersion between 10 and 10 Hz was confirmed.

FIG. 5 shows the measured creep recovery characteristics of PMMA at 115 degrees. As a result of measuring the amount of deformation (strain) when the load of 50 gram weight and 500 gram weight were alternately changed at 5 minute intervals, P at this temperature was measured.
I was able to know how MMA recovered from creep. FIG.
Shows the results obtained by measuring the stress relaxation characteristics of PMMA at 140 degrees. At 2 minute intervals, the strain amount was changed to a rectangular wave shape by 4%, and the change in stress was captured. After the change in strain, the PMM
A state in which the stress was reduced as the sample A was relaxed was observed.

[0050]

As described above, according to the present invention, despite the fact that the detection rod, which is the means for transmitting the force to the sample and the deformation transmitting means for the sample, is held by the leaf spring, By performing the negative feedback control so that the deformation always returns to zero, the separation of the spring constant effect of the leaf spring becomes easy,
In addition to being able to measure the dynamic viscoelasticity of a sample in the range of 100 Hz to 100 Hz, it is also possible to measure static viscoelasticity such as creep recovery and stress relaxation, and analyze the viscoelastic properties of a material from multiple angles. I can do it. . Further, since the average displacement of the leaf spring is zero, the positional relationship between the permanent magnet forming the electromagnetic force generator and the coil hardly changes, so that the linearity between the current flowing through the coil and the generated force is well secured, The effect of improving the accuracy of the measured viscoelasticity data was also obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a waveform of one cycle of a composite wave used in the embodiment.

FIG. 3 is a cross-sectional view showing various sample supporting methods. 3A is a cross-sectional view showing compression, FIG. 3B is three-point bending, FIG. 3C is a double-sided burr, FIG. 3D is a cantilevered burr, and FIG.

FIG. 4 is data obtained as a result of dynamic viscoelasticity measurement of PMMA (polymethyl methacrylate) using synthetic waves.

FIG. 5 shows data obtained by measuring the creep recovery characteristics of PMMA at 115 degrees.

FIG. 6 is data obtained by measuring stress relaxation characteristics of PMMA at 140 degrees.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sample 2 sample holder 3 support 4 detector box 5 chuck 6 detection rod 7 coil 8 permanent magnet 9 leaf spring 10 core 11 differential transformer 12 detector support 13 bearing 14 ball screw 15 guide rod 16 step motor 17 pulley 18 drive belt DESCRIPTION OF SYMBOLS 19 Support mechanism 20 Heating / cooling furnace 21 Moving mechanism 22 Tubular bellows 31 AC function generator 32 Amplifier 33 Optimal DC force calculator 34 Switch 35 DC voltage generator 36 Adder 37 Switch 38 Function generator 39 Step motor drive circuit 40 Distortion measurement Circuit 41 Low-pass filter 42 Zero distortion control circuit 43 Switch 44 Switch 45 High-pass filter 46 Analog-to-digital converter 47 Fourier calculator 48 Analog-to-digital converter 49 Strain amplitude controller 50 Target strain amplitude input device 51 Dynamic viscoelastic Sex calculator 52 Analog-to-digital converter 53 Static viscoelasticity calculator 54 Storage device 55 Temperature controller 56 Analog-to-digital converter

Claims (5)

[Claims] 1. A sample holder for supporting at least one end of a sample, a sample chuck for supporting a part of the sample independently of the sample holder, and a detector support for changing a relative position with respect to the sample holder. A body, a detection rod connected to the sample chuck and elastically supported by the detector support, a displacement detector that captures a change in a longitudinal position of the detection rod with respect to the detector support, A force generator that is fixed to a detector support and applies a force to the sample via the detection rod and the sample chuck as a result of applying a force to one end of the detection rod in the longitudinal direction; and a force generator connected to the force generator. A program function generator that can set a target function with respect to the time of the stress applied to the sample, and the detector support with respect to the sample holder so that the output of the displacement detector approaches zero. Feedback control means for changing the relative position of the body, and recording means for recording the output of the force generator and the amount of relative movement of the detector support relative to the sample holder, from the output of the force generator to the sample A static strain applied to the sample is obtained from an applied static stress and a relative movement amount of the detector support with respect to the sample holder, and a static viscoelasticity of the sample can be measured based on a relationship between the two. Elasticity measurement device. 2. A sample holder for supporting at least one end of a sample, a sample chuck for supporting a part of the sample independently of the sample holder, and a detector support for changing a relative position with respect to the sample holder. A body, a detection rod connected to the sample chuck and elastically supported by the detector support, a displacement detector that captures a change in a longitudinal position of the detection rod with respect to the detector support, A force generator that is fixed to a detector support and that applies a force to one end of the detection rod in the longitudinal direction as a result of applying a stress to the sample via the detection rod and the sample chuck; A DC generator for generating a DC signal to output a strong force, and a program function for setting a target function with respect to time of a relative movement amount of the detector support relative to the sample holder. A number generator, a feedback control circuit for changing the output of the DC generator so that the output of the displacement detector approaches zero, and the output of the force generator and the relative displacement of the detector support with respect to the sample holder. Recording means for recording the static stress applied to the sample from the output of the force generator, and the static strain generated in the sample from the relative movement amount of the detector support with respect to the sample holder. A viscoelasticity measuring apparatus characterized in that a static viscoelasticity of a sample can be measured from the sample. 3. A sample holder for supporting at least one end of a sample, a sample chuck for supporting a part of the sample independently of the sample holder, and a detector support for changing a relative position with respect to the sample holder. A body, a detection rod connected to the sample chuck and elastically supported by the detector support, a displacement detector that captures a change in a longitudinal position of the detection rod with respect to the detector support, A force generator that is fixed to a detector support and that applies a force to one end of the detection rod in the longitudinal direction as a result of applying a stress to the sample via the detection rod and the sample chuck; A DC generator that generates a DC signal to output a strong force, a periodic function generator that generates a periodic function signal to output a periodic force to the force generator, and a displacement detector. Feedback control means for changing the relative position of the detector support with respect to the sample holder so that the average output approaches zero; and recording the DC output of the force generator and the relative movement of the detector support with respect to the sample holder. Recording means for performing a Fourier transform process on a periodic function signal of the periodic function generator and a periodic function component of a displacement signal captured by the displacement detector, and a sample is obtained from an output of the force generator. The static strain applied to the sample, the static strain generated in the sample is obtained from the relative movement amount of the detector support with respect to the sample holder, the static viscoelasticity of the sample can be measured from the relationship between the two, and the arithmetic unit Is a viscoelasticity measuring device capable of outputting a dynamic viscoelasticity of the sample as a calculation result. 4. The viscoelasticity measuring apparatus according to claim 3, wherein the periodic function generator alternately repeats generation and stop of the periodic function signal, and the feedback control means operates only during a stop period. 5. The periodic function generated by the periodic function generator is a composite wave function obtained by adding a plurality of sine waves having different frequencies from each other. 4. The viscoelasticity measuring apparatus according to claim 3, wherein a dynamic viscoelasticity value of a plurality of samples corresponding to each frequency can be output.