JP2009036600A - Elastic modulus measuring method and instrument, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an elastic modulus measuring method capable of precisely measuring bending elastic modulus by reducing the error of a measuring system in the measurement of the bending elastic modulus due to a three-point bending method. <P>SOLUTION: The displacement quantities ΔW<SB>1</SB>and ΔW<SB>2</SB>of the central parts of test pieces X and Y, both of which are made of the same material, equal in length and different in width, with the respect to the change quantity ΔP of the stress applied to the central parts of the test pieces X and Y are measured with respect to the test pieces X and Y. The bending elastic moduli E of the respective test pieces are calculated from these measuring values, the interval S between the two supports, the thicknesses h<SB>1</SB>and h<SB>2</SB>of the test pieces X and Y, the widths b<SB>1</SB>and b<SB>2</SB>of the test pieces X and Y and the width ratio 1:A of the test pieces X and Y. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an elastic modulus measuring method and an elastic modulus measuring device for measuring a bending elastic modulus of a solid specimen such as ceramics represented by a refractory.

  A three-point bending method is widely known as a method for measuring the static elastic modulus of a solid (see Non-Patent Documents 1 and 2). The three-point bending method is a method for calculating a flexural modulus from the relationship between strain and stress generated in a specimen by three-point bending.

  FIG. 8 is a diagram illustrating an elastic modulus measuring apparatus that measures a flexural modulus by a three-point bending method (see Non-Patent Document 1). The elastic modulus measuring apparatus in FIG. 8 includes an elastic modulus measuring apparatus 101 and a control computer 102, both of which are connected by a cable via an interface 103.

  In the elastic modulus measuring apparatus 101, four column bodies 105 are erected on the upper surface of the gantry 104 installed on the floor surface, and the test specimen is installed on the upper surface of the gantry 104 surrounded by these column bodies 105. A support base 106 is installed. Further, a chamber 107 is installed surrounding the upper portion of the support base 106. The inside of the chamber 107 is isolated from the outside, and the temperature and atmosphere inside the chamber can be freely adjusted.

  On the upper surface of the support base 106, supports 108 and 108 made of two round bars are installed in parallel. The specimen A is placed on the two supports. The specimen A is a rod-shaped body having a predetermined rectangular cross-sectional shape (30 × 30 mm in the example of FIG. 8), and the bottom surfaces near both ends thereof are supported by the two supports 108 and 108.

  Further, a cross head 109 for generating a pressurizing force is disposed directly above the chamber 107, and a pressurizing body 110 for pressurizing the central portion of the upper surface of the specimen A is provided below the crosshead 109. Is provided. The pressurizing body 110 is a flat plate-like body, the lower cross-sectional shape is tapered, and the tip is formed in an arc shape. The upper end portion of the pressing body 110 is pressed by the cross head 109, and the center of the upper surface of the specimen A is pressed.

  In addition, each part is arrange | positioned so that the distance of the contact point of the pressurization body 110 of the specimen A upper surface and the contact point of each support body 108,108 of the specimen A lower surface may become equal.

  Although not shown in FIG. 8, the elastic modulus measuring device is a pressure sensor such as a load cell that detects the stress applied to the pressurizing body 110 by the crosshead 109 and a displacement that detects the displacement of the pressurizing body 110. And a detector. Then, the stress applied to the pressing body 110 and the displacement data of the pressing body 110 are sent to the computer 102 via the interface 103 and stored in real time.

  When actually measuring the bending elastic modulus in the elastic modulus measuring apparatus as described above, first, the stress P applied to the pressing body 110 by the cross head 109 is gradually increased. Then, the displacement W of the pressurizing body 110 at each time point is measured while increasing the stress P. Thereby, the relationship between the stress P and the displacement is obtained. Then, the computer 102 calculates the bending elastic modulus E at the time when the data on the relationship between the stress P and the displacement is obtained.

  In the case of the three-point bending test, as shown in FIG. 9, when the distance between the two supports 108, 108 is S, the thickness of the specimen A is h, and the width is b, the displacement of the central portion of the specimen A W is expressed as the following equation (1).

  Here, I is a cross-sectional secondary moment of the specimen A, and is represented by the following equation (2).

  Therefore, from (1), the bending elastic modulus E of the specimen A is expressed as the following equation (3) as a function of the ratio P / W of the stress P and the displacement W.

Therefore, if the gradient P / W is obtained from the data of the relationship between the measured stress P and the displacement W, the bending elastic modulus can be obtained from the equation (3). In actual measurement, generally, the relationship between the stress P and the displacement W is not a direct proportional relationship, but draws a curve as shown in the graph in FIG. In such a case, normally, the data of the portion closest to the straight line is cut out and approximated by a straight line, and the bending elastic modulus is obtained by the equation (3) with the gradient of the approximate straight line as P / W.
JP-A-2-108942 JP-A-63-311143 JP 58-92930 A Japanese Patent Publication No. 6-41900 Japanese Patent Publication No. 3-59374 Toshihiro Suruga, Toshiyuki Hokii, Keisuke Asano, “Hot Static Elastic Modulus Properties of MgO-C Refractories”, Refractory Materials, Kurosaki Harima Co., Ltd., December 20, 2001, No.149, pp.62- 67. Hideo Asakura, Hiroshi Minamizono, Masayuki Nakajo, “Development of Hot Static Elastic Modulus Measuring Device”, Shinagawa Technical Report, Shinagawa White Brick Co., Ltd., March 20, 2000, No. 43, pp.83-90.

  However, the displacement of the central part of the specimen A obtained in the measurement system detects the distance traveled by the pressurizing body 110 and does not directly detect the displacement of the specimen A. In addition to the displacement due to the distortion of the specimen A, the displacement of the specimen 110 is a change in minute irregularities on the contact surface between the specimen A and the specimen 110, and the contact between the specimen A and the specimen 110. Since it includes various factors such as changes in the state, cavitation crushing inside the specimen, distortion due to the pressure of the pressurized body 110 itself, rigidity of the pressure device, the displacement W due to the distortion of the true specimen A is calculated. It is difficult to find. Further, when actual measurement is performed, the values of these factors change with each measurement, and thus cannot be easily corrected.

  On the other hand, when the specimen A is a substance having high rigidity such as a refractory or ceramic, the displacement value with respect to the stress applied to the specimen A is extremely small. Therefore, even if the value of factors other than the displacement due to distortion of the specimen A included in the measured displacement value is small, the error given to the calculation result of the bending elastic modulus of the specimen becomes large.

  Therefore, the conventional method for measuring the flexural modulus by the three-point method has a problem that an accurate value of the flexural modulus cannot be measured in the case of a material having high rigidity such as a refractory or ceramic.

  In order to solve this problem, the measurement of the displacement of the central portion of the specimen A is not indirectly obtained from the displacement of the pressurizing body 110, but a strain gauge is attached to the specimen A to directly measure the amount of strain. You can ask for. Such a method is effective for measurement at room temperature.

  However, since the elastic modulus measurement of refractories and ceramics is performed for the purpose of evaluating heat-resistant spalling properties in hot conditions, it is often necessary to test the elastic modulus in hot temperatures of several hundred degrees Celsius or higher. . Under such a high temperature, it is impossible to measure by attaching a strain gauge to the specimen A, and it is necessary to indirectly measure the displacement of the central part of the specimen A from the displacement of the pressurizing body 110. I do not get. Therefore, the problem of the influence of the measurement error of the distortion amount due to various factors as described above still remains.

  Therefore, the object of the present invention is to measure the bending elastic modulus by the three-point bending method, change in minute irregularities on the contact surface between the specimen and the pressure body, change in the contact state between the specimen and the pressure body, Elastic modulus measurement that enables accurate measurement of bending elastic modulus by removing factors caused by measurement devices such as crushing of cavitation inside the specimen, distortion due to pressure of the pressurized body itself, rigidity of the pressure device, etc. It is to provide a method and an elastic modulus measuring apparatus.

[1] Principle of bending elastic modulus measurement test in the present invention First, the principle of measuring the bending elastic modulus by the three-point bending method used in the present invention will be briefly described. In an ideal measurement system free from errors caused by the measuring apparatus, the relationship between the stress P applied to the specimen and the strain W of the specimen is as shown in Equation (1).

  However, when the relationship between stress and strain is actually measured by a three-point bending method as a refractory material specimen, a measurement result as shown in FIG. 1 is obtained. 1 (a) and 1 (b) show the experimental results obtained by the three-point bending method for specimens made of the same material. 1A shows a specimen width b of 20 mm, and FIG. 1B shows a specimen width b of 40 mm. The horizontal axis represents the displacement of the pressurized body. The vertical axis represents the load applied to the pressurized body. Since the specimen of FIG. 1 (b) has a width twice that of the specimen of FIG. 1 (a), the load applied in FIG. 1 (b) to apply the same stress is shown in FIG. ) Is twice the load applied.

  As can be seen from FIG. 1, the relationship between the actually measured stress of the pressure body and the displacement of the pressure body is not a straight line but a curve. Further, it is generally observed that the curve when the first pressurization is largely deviated from the curve after the first pressure drop.

  Based on the above experimental results, the present inventor has modeled a measurement system for a flexural modulus test by a three-point bending method using a simple model such as the following equation (4).

  In Expression (4), the second term on the right side includes the influence of a disturbance factor such as a measurement device (crushing cavitation inside the specimen, or a minute unevenness on the contact surface between the specimen and the pressurized body). It represents the term of displacement caused by "measurement device system". In the equation (4), the measuring device system including the pressurizing body is replaced with one elastic body, and the measuring device system assumes that the strain of the measuring device system increases in proportion to the stress.

Furthermore, as a result of various experiments, it has been found that the second term on the right side of Equation (4) also changes depending on the hardness of the specimen. That is, when the specimen is soft and the flexural modulus E is small, the measuring apparatus system is sufficiently harder than the specimen, so there is almost no distortion of the measuring system and the measurement is not affected. On the other hand, when the specimen is as hard as the measurement system, that is, when the flexural modulus of the specimen is large, the distortion of the measurement system becomes large, and the influence thereof also appears in the displacement measurement value. In order to incorporate such a phenomenon into the model formula, it is assumed that the second term on the right side is inversely proportional to the magnitude of S ³ / EI of the first term, and formula (4) is further replaced by the following formula (5).

ここで、ｋは測定装置に固有の定数である。図７にＥＩ／Ｓ^３と装置変位Ｗとの関係を測定した結果を示す。

Here, k is a constant specific to the measuring apparatus. FIG. 7 shows the results of measuring the relationship between EI / S ³ and the apparatus displacement W.

  This k is the sum of the clearance and distortion between the joints of each component of the device (and the joint with the measurement sample), the distortion of these components themselves, and the variation of factors such as temperature affecting them. It is thought that it appears as.

  Next, a method for obtaining the flexural modulus E after eliminating the influence of the measurement system after modeling the measurement system as shown in Equation (5) will be described. In the following description, the bending tester is the same as the bending tester shown in FIG.

First, rod-shaped specimens X and Y having the same material and the same length L but different widths b are prepared. The width of the specimen X is b ₁ , the thickness is h ₁ , the width of the specimen Y is b ₂ , and the thickness is h ₂ . Further, the ratio of the widths b ₁ and b ₂ is set to A = b ₂ / b ₁ . Then, with respect to the two specimens X and Y, the stress is changed in the same range, and the stress change ΔP applied to the pressurizing body and the displacement amount ΔW of the pressurizing body relative thereto are measured. For example, the stress was varied between the sigma _s0 from _{σ s2 (σ s0 <σ s2} ), stress sigma _s1 and _{σ s2 (σ s0 <σ s1} <σ s2) become displaced at two points .delta.W _1, .delta.W ₂ And ΔP = σ _s2 −σ _s1 and ΔW = δW ₂ −δW ₁ . The relationship between the observed stress and strain for each specimen X and Y is expressed by the following equations (6a) and (6b) from the equation (5).

Here, ΔW ₁ and ΔW ₂ are displacement amounts measured for the specimens X and Y, respectively, and I ₁ and I ₂ are cross-sectional secondary moments of the specimens X and Y, respectively. 6c).

By substituting b ₂ = Ab ₁ into equation (6b) and eliminating the term k from equations (6a) and (6b), the flexural modulus E can be obtained as follows.

  Since the above equation (7) does not include the constant k inherent to the measurement apparatus, it can be understood that the influence of the distortion of the measurement apparatus is eliminated by this.

[2] Configuration and operation of the present invention The first configuration of the present invention relating to the elastic modulus measuring method is to support the lower part near both ends of the rod-shaped specimen at two points supported horizontally. The elastic modulus is measured by measuring the displacement of the central part of the specimen by measuring the displacement of the central part by pressing the central part of the specimen with a pressurized body and measuring the displacement of the pressurized body. A measurement method for each of the first and second specimens made of the same material and having the same length and different widths, and the center of the change ΔP of the stress applied to the center of the specimen. Displacement measuring step for measuring the displacement amounts ΔW ₁ , ΔW ₂ of the portion, the distance between the two supports is S, the thicknesses of the first and second specimens are h ₁ , h ₂ , the first and _second the width of the second specimen b _1, b _2, a ratio of the first and second specimen width was 1: a To come formula (7), and having a an elastic modulus calculating step of calculating by calculation, each specimen of the flexural modulus E of (6c).

In this way, for the first and second specimens made of the same material and having the same length but different widths, the applied stress change amount ΔP and the displacement amounts ΔW ₁ and ΔW ₂ are measured, and the equation (7 ) And (6c) to obtain the flexural modulus, the change in minute irregularities on the contact surface between the specimen and the pressure body, the change in the contact state between the specimen and the pressure body, the specimen Factors caused by the measuring device such as crushing of the internal cavitation, distortion due to the pressure of the pressurizing body itself, and rigidity of the pressurizing device are eliminated, and the bending elastic modulus can be measured with high accuracy.

The thicknesses h ₁ and h ₂ of the specimen may be the same value or different values. However, from the viewpoint of sharing the measurement conditions and eliminating the extra error factors as much as possible, the thicknesses h ₁ and h 2 ₂ is preferably the same value.

According to the second configuration of the present invention relating to the elastic modulus measuring method, in the first configuration, in the displacement measuring step, two different stresses σ _s1 and σ _s2 (which are applied to the central portion of the first specimen) a first measurement step of measuring the displacement ΔW ₁ of the central portion of the specimen between σ _s1 <σ _s2 ) and the stresses σ _s1 and σ _s2 applied to the central portion of the second specimen. And a second measuring step for measuring a displacement amount ΔW ₂ of the central portion of the specimen between the two.

  Thereby, since the relationship between stress and displacement is measured under the same stress condition in the first and second specimens, measurement errors due to nonlinear deformation phenomena with respect to stress can be suppressed as much as possible.

Here, the values of the applied stresses σ _s1 and σ _s2 may be arbitrarily set within the required range in consideration of the fracture stress of the specimen, the necessary measurement range, the magnitude of creep deformation of the specimen, and the like. it can. However, the values of the applied stresses σ _s1 and σ _s2 need to be within the range in which the displacement can be measured, the low pressure value σ _s1 is 0 [Pa] or more, and the high pressure value σ _s2 is the bending fracture stress of the specimen. Is set to a smaller value. When σ _s1 = 0 [Pa], a clearance is generated again between the pressurizing body in the pressurizing device and other parts during decompression, or the crushed cavitation in the test specimen is restored, Since the influence of the delay elastic component (in the case of a viscoelastic body) of the specimen increases, the low pressure value σ _s1 is preferably set to a value larger than 0 [Pa].

Note that the high pressure value σ _s2 is the elasticity of the stress region according to individual needs and given conditions, such as the method of use of the material used as the specimen, that is, its use conditions, equipment conditions, characteristics, etc. It can be set individually to obtain the rate.

According to the third configuration of the present invention relating to the elastic modulus measurement method, in the first or second configuration, in the first and second measurement steps, before the displacement amounts ΔW ₁ and ΔW ₂ are measured. The pressure applied to the central part of the first or second specimen is increased to a predetermined pressure not higher than the bending strength of the specimen and then reduced or reduced to the stress σ _s1 or lower. It is characterized in that an error removing step is performed more than once.

As described above, by performing the error removal step before measuring the displacement amounts ΔW ₁ and ΔW ₂ of the central part of the specimen, the clearance existing between the specimen and the pressurizer and other in the pressurizer machine can be obtained. Error factors with various irreversible changes superimposed, such as crushing, crushing irregularities on the surface of the specimen, crushing cavitation existing inside the specimen (FIGS. 1A and 1B) Irreversible factors as appearing in the first step-up process).

According to the fourth configuration of the present invention relating to the elastic modulus measurement method, in the second or third configuration, in the first and second measurement steps, with respect to the first or second specimen,
(1) The stress applied to the central portion of the specimen is changed from σ _s1 to σ _s2 (σ _s1 <σ _s2 ) according to a predetermined time function σ _s (t) defined by the time interval [0, T]. While increasing the pressure at T, the displacements δW ₁ ^(up) and δW ₂ ^(up) of the specimen are measured at each time point when the stress becomes σ _s1 and σ _s2, and the difference (δW ₂ ^(up) −δW ₁ ^{( up)} ) ⁾ as a pressure increase displacement ΔW ^(up) between the stresses σ _s1 and σ _s2 ;
(2) The stress applied to the central portion of the specimen is _lowered from time σ _s2 to σ _s1 and time T according to the function σ _s (T−t) obtained by reversing the time function σ _s (t). The displacements δW ₂ ^(down) and δW ₁ ^(down) of the specimen are measured at each time point when the stress becomes σ _s2 and σ _s1, and the difference (δW ₂ ^(down) −δW ₁ ^(down) ) is determined as the stress σ. a step-down process measuring step for calculating as step-down displacement ΔW ^(down) between _s1 and _σs2 ;
(3) The average value of the step- ^up displacement ΔW ^(up) and the step-down displacement ΔW ^(down) is calculated as the displacement amount ΔW ₁ or ΔW of the central portion of the specimen between the stresses σ _s1 and σ _s2. An average displacement calculating step of calculating as ₂ .

As described above, for the first and second specimens, the applied stress σ _s is increased at the time T according to the time function σ _s (t) in the pressure increasing process, and the stress σ _s (t) is converted to the time reversal function in the pressure decreasing process. The pressure is decreased at time T according to σ _s (T−t), and average values ΔW ₁ , ΔW of the pressure increase displacement displacements δW ₁ ^(up) , δW ₂ ^(up) and the pressure decrease displacements δW ₂ ^(down) , δW ₁ ^(down) By calculating ₂ and calculating the flexural modulus E according to equation (7) using these average values, the influence of plastic deformation can be canceled and the influence of delayed elasticity can be reduced.

The first configuration of the present invention relating to the elastic modulus measuring apparatus is a pair of supports that support lower portions near both ends of a rod-shaped specimen, and a central portion of the specimen placed above the two supports on the top surface. A pressure body that pressurizes the pressure body, a pressure cylinder that applies pressure to the pressure body, a displacement detector that measures the displacement of the pressure body, and a pressure sensor that measures the stress generated by the pressure cylinder; Storage means for storing the measurement condition data and measurement data, output means for outputting the measurement result of the flexural modulus, pressurizing control of the pressurizing cylinder, and measurement control of displacement and generated stress of the pressurizing body. An elastic modulus measuring device for measuring the flexural modulus of a specimen material, the control device being made of the same material to be tested and having equal length and width different first and second specimen of width _b 1, _{b 2}及The thickness h _1, h _2, and sets the values of both interval S of the support, as well as the variation ΔP of the stress applied to the specimen when performing displacement measurement, the measurement condition setting means for storing in the storage means, In the state where the first or second specimen is placed on both the supports, the pressure cylinder changes the stress applied to the central part of the specimen by the change amount ΔP, and the change the specimen displacement amount [Delta] W 1 of the central portion of between _measures the [Delta] W _2, the displacement amount [Delta] W _1, a displacement measuring means for storing [Delta] W ₂ in the storage means, the storage means stored in the two of the Specimens used when measuring the distance S between the supports, the thicknesses h ₁ and h ₂ of the first and second specimens, the widths b ₁ and b _{2 of} the first and second specimens, and the displacement The amount of change ΔP in the stress to be applied and the central part of the first and second specimens Based on the displacement amounts ΔW ₁ and ΔW ₂ , the bending elastic modulus E of each specimen is calculated by executing the following expressions (3), (4), and (5), and output to the output means: And an elastic modulus calculating means.

According to this configuration, first, the measurer uses the measurement condition setting means to measure the thicknesses h ₁ and h ₂ , the length L, the widths b ₁ and b _{2 of} the first and second specimens, The interval S and the amount of change ΔP of the stress applied to the specimen when performing displacement measurement are set and stored in the storage means. Next, displacement amounts ΔW ₁ and ΔW ₂ of the central portion with respect to a change amount ΔP of stress applied to the central portion of the specimen are measured for each of the first and second specimens by the displacement measuring means. Then, the elastic modulus calculating means calculates the bending elastic modulus E of each specimen by the calculation of the equations (7) and (6c). Due to this, due to changes in minute irregularities on the contact surface between the specimen and the pressurized body, changes in the contact state between the specimen and the pressurized body, crushing of cavitation inside the specimen, the pressure of the pressurized body itself Factors caused by the measuring device such as strain and rigidity of the pressing device are eliminated, and the bending elastic modulus can be measured with high accuracy.

The second configuration of the present invention relating to the elastic modulus measuring apparatus is the first configuration, wherein the measurement condition setting means includes widths b ₁ and b ₂ and a thickness h _{1 of} the first and second specimens. , H ₂ , the distance S between the two supports, and two different stress values σ _s1 , σ _s2 (σ _s1 <σ _s2 ) applied to the specimen when measuring the displacement are set in the storage means The displacement measuring means applies stress applied to the central portion of the specimen by the pressure cylinder in a state where the first or second specimen is placed on both supports. varied between sigma _s1 and sigma _s2, the displacement amount [Delta] W 1 of the central portion of the specimen during the _change, the [Delta] W ₂ is measured and stored displacement amount [Delta] W _1, the [Delta] W ₂ in the storage means It is characterized by being.

According to a third configuration of the present invention relating to the elastic modulus measuring device, in the first or second configuration, the control device controls the pressurizing cylinder before the displacement measuring unit measures the amount of displacement. Then, after increasing the stress applied to the central portion of the first or second specimen to a predetermined pressure below the bending strength of the specimen, the step-up / step-down process of reducing the pressure to the stress σ _s1 or less is at least It is characterized by having an error removing means for performing at least once.

According to a fourth configuration of the present invention relating to the elastic modulus measuring device, in the second or third configuration, the displacement measuring means controls the piston, thereby controlling the central portion of the first or second specimen. Boosting control means for boosting the stress applied to σ _s1 to σ _s2 (σ _s1 <σ _s2 ) at time T according to a predetermined time function σ _s (t) defined by time interval [0, T]; When the stress is boosted by the boost control means, the displacements δW ₁ ^(up) and δW ₂ ^(up) of the specimen are measured at each time point when the stress becomes σ _s1 and σ _s2, and the difference (δW ₂ ^{(up) )} −δW ₁ ^(up) ) is calculated as the pressure increase displacement ΔW ^(up) between the stresses σ _s1 and σ _s2 , and the pressure increase process measurement means stored in the storage means and the piston are controlled to Pair with the center of the 1st or 2nd specimen Stresses sigma _s1 from the sigma _s2 addition, the step-down control means for step-down in the time function sigma _{s (t)} the time function was reversed σ _{s (T-t)} according to the time T, the step-down of the stress due to the step-down control unit In time, the displacements δW ₂ ^(down) and δW ₁ ^(down) of the specimen are measured at each time point when the stress becomes σ _s2 and σ _s1, and the difference (δW ₂ ^(down) −δW ₁ ^(down) ) Is calculated as a step-down displacement ΔW ^(down) between the stresses σ _s1 and σ _s2 and stored in the storage unit, and the step- ^up displacement ΔW ^(up) and the step-down stored in the storage unit An average displacement calculating means for calculating an average value of the displacement ΔW ^(down) as a displacement amount ΔW ₁ or ΔW ₂ of the central portion of the specimen between the stresses σ _s1 and σ _s2 and storing it in the storage means; With It is characterized by that.

  According to the first configuration of the present invention relating to the program, a pair of supports that support lower portions near both ends of a rod-shaped specimen and a central portion of the specimen placed above the two supports are pressurized from above. A pressure body, a pressure cylinder that applies pressure to the pressure body, a displacement detector that measures the displacement of the pressure body, a pressure sensor that measures the stress generated by the pressure cylinder, and measurement conditions Storage means for storing data and measurement data, output means for outputting the measurement result of the flexural modulus, computer for controlling the pressurizing force of the pressurizing cylinder, and measuring and controlling the displacement and generated stress of the pressurizing body, An elastic modulus measurement system for measuring a bending elastic modulus of a specimen material, comprising: a computer that reads and executes the elastic modulus measurement device according to any one of claims 5 to 8. Wherein the function as location of the control device.

As described above, according to the elastic modulus measuring method and the elastic modulus measuring apparatus according to the present invention, the applied stress of the first and second specimens made of the same material and having the same length and different widths can be obtained. By measuring the change ΔP and the displacements ΔW ₁ and ΔW ₂ and calculating the bending elastic modulus by calculating the equations (7) and (6c), the contact surface between the specimen and the pressurizing body is obtained. There are factors due to the measuring device such as minute irregularities, changes in contact state between the specimen and the pressurized body, crushing of cavitation inside the specimen, distortion due to the pressure of the pressurized body itself, and rigidity of the pressurized device. This eliminates the need to accurately measure the flexural modulus.

Further, by performing an error removal step before measuring the displacement amounts ΔW ₁ and ΔW ₂ of the central part of the specimen, an error factor in which various irreversible changes are superimposed is removed. Therefore, it is possible to measure the elastic modulus with high accuracy.

For the first and second specimens, the applied stress σ _s is boosted at time T according to the time function σ _s (t) in the pressure increasing process, and the stress σ _s (t) is converted to its time reversal function σ _s in the pressure decreasing process. According to (T−t), the pressure is decreased at time T, and average values ΔW ₁ and ΔW ₂ of the pressure increase displacement displacements δW ₁ ^(up) and δW ₂ ^(up) and the pressure decrease displacements δW ₂ ^(down) and δW ₁ ^(down) are obtained. By calculating and calculating the flexural modulus E according to Equation (7) using these average values, the influence of plastic deformation can be canceled and the influence of delayed elasticity can be reduced. Accordingly, it is possible to measure the elastic modulus with higher accuracy.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 2 is a diagram illustrating the overall configuration of the elastic modulus measuring apparatus 1 according to the first embodiment of the invention. The elastic modulus measuring apparatus 1 is composed of two parts: a mechanical component part 2 that applies three-point pressurization to the specimen TP and measures the bending displacement of the specimen TP, and a control constituent part 3 that controls the measurement. ing. The mechanical component 2 is the same as that of a conventional pressurizing device that performs a three-point bending test, and an example thereof is shown in FIG.

  The mechanical component 2 includes a press lower plate 4, a press upper plate 5, a support column 6, a loading table 7, a hydraulic ram cylinder (pressure cylinder) 8, a hydraulic ram piston 9, a sample support table 10, a pressure body 11, and a load cell. (Pressure sensor) 12, displacement detector 13, heat-insulated airtight container 14, heater 15, and temperature sensor 16 are provided.

  The press lower plate 4 forms a base portion for fixing the elastic modulus measuring device 1 to the floor surface. The press upper plate 5 forms a ceiling portion of the elastic modulus measuring device 1. The press lower plate 4 and the press upper plate 5 are firmly connected to each other on the left and right sides by support columns 6 and 6.

A loading table 7 is installed at the center of the upper surface of the press lower plate 4. On the other hand, a hydraulic ram cylinder 8 and a hydraulic ram piston 9 are firmly fixed to the center of the lower surface of the press upper plate 5. The hydraulic ram cylinder 8 and the hydraulic ram piston 9 are devices that generate a pressing force that pressurizes the specimen TP. The hydraulic ram piston 9 moves up and down in the barrel of the hydraulic ram cylinder 8. Further, pressurizing pipes 9 a and 9 b for transmitting pressure to the working liquid are communicated with the upper and lower barrels of the hydraulic ram cylinder 8. The pressurizing tubes 9a and 9b are provided with pressurizing devices 9c and 9d for pressurizing the working liquid. Pressure device 9c, 9d, respectively, by applying a pressure P _1, P ₂ to the working liquid in the lower inner upper and a barrel the barrel, to generate a pressure in the hydraulic ram piston 9.

  A sample support 10 is installed at the center of the upper surface of the loading table 7. A pressure body 11 is provided on the lower surface of the hydraulic ram piston 9 via a load cell 12 so as to face the sample support 10. The upper surface of the sample support 10 is configured to protrude left and right and the center portion is recessed. The upper surfaces of the left and right protrusions are formed flat, and a groove having a semicircular cross section is formed on the flat surface. Yes. And in the groove | channel, round bar-shaped support body 10a, 10b which supports the both ends of specimen TP is installed. In the installed state, the supports 10a and 10b are parallel. The specimen TP is formed in the shape of a rod having a rectangular cross section, and is installed in the heat insulating and airtight container 14 with the lower surfaces near both ends thereof supported by the supports 10a and 10b. On the other hand, the pressurizing body 11 has a slightly flat shape in the front-rear direction, the lower cross-sectional shape is tapered, and the tip is formed in an arc shape. The lower end of the arcuate pressure member 11 is in contact with the center of the upper surface of the specimen TP. Moreover, the sample support 10 and the pressurization body 11 are comprised with the refractory member with high hardness of silicon nitride and silicon carbide.

  The upper surface of the specimen TP is pressurized by the hydraulic ram piston 9 via the pressurizing body 11. Further, the lower surface of the specimen TP is held down by the loading table 7 through the supports 10a and 10b and the sample support 10. The load cell 12 detects the pressure applied to the specimen TP by the hydraulic ram piston 9.

  On the bottom surface of the hydraulic ram piston 9 and the top surface of the loading table 7, horizontal extending members 13a and 13b are extended. And then. A displacement detector 13 is installed between the ends of the extending members 13a and 13b. The displacement detector 13 is a gauge that measures the distance between the extending members 13a and 13b. Here, a linear gauge is used. Thereby, the displacement of the distance between the upper end of the pressurizing body 11 and the lower end of the sample support 10 can be accurately measured.

  The lower part of the pressurizing body 11 and the upper part of the sample support 10 are surrounded by a heat-insulating and airtight container 14, and the inside of the heat insulating and airtight container 14 is in a semi-airtight state. An air supply pipe 14a and an exhaust pipe 14b are communicated with the heat insulating airtight container 14. From the air supply pipe 14a, an inert gas such as argon, nitrogen gas, or the like is supplied into the heat insulating airtight container 14. Moreover, the excess gas in the heat insulation airtight container 14 is discharged | emitted from the exhaust pipe 14b. Thereby, the inside of the heat insulation airtight container 14 can always be kept in an inert atmosphere.

  Further, a heater 15 is provided in the heat insulating and airtight container 14 so as to surround the entire side surface of the specimen TP. Further, a temperature sensor 16 for measuring the ambient temperature in the vicinity of the specimen TP is provided. The heater 15 heats the air around the specimen TP to bring the specimen TP into an overheated state. Thereby, the bending test in the state which heated test piece TP to high temperature is attained.

  On the other hand, the control component 3 includes a control board 21 and a computer 22. The control board 21 controls the pressure output of the pressure devices 9c and 9d, detects the stress by the load cell 12, detects the displacement by the displacement detector 13, controls the heating by the heater 15, detects the temperature in the vicinity of the specimen TP by the temperature sensor 16, and the like. A circuit for controlling the above is mounted. Further, the computer 22 executes control and measurement control by the control board 21 according to the program.

  FIG. 3 is a block diagram illustrating a functional configuration of the elastic modulus measuring apparatus 1 according to the first embodiment of the present invention. In FIG. 3, the mechanical component 2 and the control component 3, the heater 15, the load cell 12, the temperature sensor 16, the pressurizing devices 9c and 9d, and the displacement detector 13 are the components having the same reference numerals in FIG. It corresponds.

  Functionally, the control component 3 includes an input device 31, measurement condition setting means 32, measurement condition storage means 33, heating control means 34, error removal means 35, displacement measurement means 36, measurement result storage means 37, elastic modulus. A calculation means 38, an output control means 39, and a display 40 are provided.

  The input device 31 is a device by which a measurer inputs an instruction to the computer 22 and includes a keyboard, a mouse, and the like.

  The measurement condition setting means 32 displays an input screen on the display 40 to prompt the measurer to input measurement conditions for the three-point bending test, and stores the measurement conditions input from the input device 31 in the measurement condition storage means 33. To do. The measurement condition storage means 33 is a part for temporarily storing the measurement conditions, and is constituted by a RAM, a hard disk or the like.

Here, the “measurement conditions” include the heating temperature Θ of the specimen TP in the three-point bending test, the pressure at the time of maximum pressurization (hereinafter referred to as “maximum applied pressure”) σ _s2 , and the displacement measurement at low pressure. Pressure (hereinafter referred to as “low pressure measuring point pressure”) σ _s1 , minimum applied pressure σ _s0 when the applied pressure is reduced to low pressure, the number of repetitions N of the apparatus error elimination operation, the length L of the two specimens TP to be measured, Parameters such as thicknesses h ₁ and h ₂ , widths b ₁ and b ₂ , and distance S between the supports 10a and 10b are included.

  The heating control means 34 controls the heating of the specimen TP by controlling the heater 15 with reference to the temperature detected by the temperature sensor 16 in accordance with the heating temperature Θ in the three-point bending test stored in the measurement condition storage means 33. Do.

The error removal means 35 refers to the pressure detected by the load cell 12 and controls the pressurization devices 9c and 9d to increase the pressure applied to the specimen TP to the maximum pressure σ _{s2 and} then the minimum pressure The step-up / step-down process for reducing the pressure to σ _{s0 is} executed N times. Here, N is an integer of 1 or more and can be set to an appropriate value.

  The displacement measuring means 36 performs control to measure the pressure and the displacement of the specimen TP with the load cell 12 and the displacement detector 13 while pressurizing the central portion of the specimen TP with the pressurizing body 11.

  The measurement result storage unit 37 stores measurement data and bending elastic modulus data detected by the displacement measurement unit 36.

  The elastic modulus calculation means 38 calculates the bending elastic modulus of the specimen TP based on the pressure and displacement data output from the displacement measurement means 36 and stores it in the measurement result storage means 37.

  The output control unit 39 outputs the bending elastic modulus data calculated by the elastic modulus calculating unit 38 to the display 40.

  The elastic modulus measuring apparatus 1 according to the present embodiment configured as described above will be described below with respect to an elastic modulus measuring method using a three-point bending test.

  FIG. 4 is a flowchart showing the overall flow of the elastic modulus measurement method. Here, the bending elastic modulus of the material is measured by performing a three-point bending test on two specimens TP1 and TP2 having the same material, thickness, and length but different widths.

  In step S <b> 1, the measurement condition setting unit 32 displays a measurement condition setting screen on the display 40. The measurer sets the measurement conditions for the bending test using the input device 31 in accordance with this screen. When the measurement conditions are input, the measurement condition setting unit 32 stores the measurement conditions in the measurement condition storage unit 33.

Here, the maximum pressure σ _s2 is set to be equal to or less than the bending fracture stress of the specimen TP. The bending fracture stress of the specimen TP is measured by performing a separate fracture test in advance.

Then, a specimen TP1 having a thickness h ₁ and a width b ₁ is placed on the supports 10a and 10b on the sample support 10.

  In step S <b> 2, the heating control unit 34 performs energization control of the heater 15 in accordance with the heating temperature Θ stored in the measurement condition storage unit 33. As a result, the specimen TP1 is heated to the temperature Θ.

In step S3, the error removing means 35 gradually increases the pressure applied to the specimen TP1 by the pressurizing devices 9c and 9d. The pressure increase is stopped when the pressure detected by the load cell 12 reaches σ _s2 . Next, in step S4, the error removing means 35 gradually lowers the pressure applied to the specimen TP1 by the pressurizing devices 9c and 9d. Then, the pressure reduction is stopped when the pressure detected by the load cell 12 reaches σ _s0 . The step-up / step-down process in steps S3 and S4 is hereinafter referred to as “error removal process”.

  In step S5, if the number of repetitions of the error removal processing has not reached N times, the process returns to step S3 again. If it has reached N times, the process proceeds to the next step S5. As a result, the error removal process is repeatedly executed by the number of repetitions N set initially.

In step S6, the displacement measuring means 36 applies a constant pressure increase speed v = (σ _s2 −σ) until the pressure detected by the load cell 12 becomes σ _s1 by the pressurizing devices 9c and 9d. _The voltage is increased by _s1 ) / T. In step S7, the displacement measuring means 36 takes the displacement of the specimen TP1 in pressure sigma _s1 displacement detecting meter 13 detects _{^{δW (up) (σ s1)}} , is stored in the measurement result storage unit 37. In step S8, the displacement measuring means 36 further increases the pressure applied to the specimen TP at a constant pressure increase speed v until the pressure detected by the load cell 12 reaches σ _s2 by the pressurizing devices 9c and 9d. Let Then, when the pressure detected by the load cell 12 reaches σ _s2 , the pressure increase is stopped and the pressure _decreases . In step S9, the displacement measuring means 36, the displacement detecting meter 13 captures a displacement δW (σ _s2) of the specimen TP1 in pressure sigma _s2 to detect, is stored in the measurement result storage unit 37. The process of steps S6 to S9 described above is hereinafter referred to as a “step-up measurement process”.

In step S10, the displacement measuring means 36 gradually lowers the pressure applied to the specimen TP at a constant step-down speed −v until the pressure detected by the load cell 12 becomes σ _s1 by the pressurizing devices 9c and 9d. . In step S11, the displacement measuring means 36, the displacement detecting meter 13 takes in displacement δW specimens TP in the pressure sigma _s1 detecting ^{(down) (σ _s1),} is stored in the measurement result storage unit 37. In step S12, the displacement measuring means 36 continues to apply pressure applied to the specimen TP at a constant step-down speed −v until the pressure detected by the load cell 12 becomes σ _s0 by the pressurizing devices 9c and 9d. Decrease the pressure. Then, the pressure reduction is stopped when the pressure detected by the load cell 12 reaches σ _s0 . The process of steps S10 to S12 described above is hereinafter referred to as “step-down measurement process”.

As described above, in general, even when the specimen TP is displaced at the same pressure σ _s1, the displacement δW ^(up) (σ _s1 ) measured in the pressure increase measurement process and the displacement δW ^{( down)} (σ _s1 ) is not the same value. Therefore, the elastic modulus calculation means 38 calculates the average displacement ΔW ₁ of the specimen TP1 between the pressure σ _s1 and the pressure σ _s2 by the following equation, and stores the result in the measurement result storage means 37.

  In step S13, in order to replace the specimen TP, the heating control means 34 cuts off the power supply to the heater 15 and lowers the temperature in the heat insulating and airtight container 14. In addition, the elastic modulus calculation means 38 displays on the display 40 a prompt for exchanging the specimen TP.

The measurer replaces the specimen TP1 with a specimen TP2 having a thickness h ₂ and a width b ₂ after the temperature in the heat-insulated airtight container 14 has sufficiently decreased. The elastic modulus measuring apparatus 1, now for specimen TP2, perform the operations in steps S2 through S12, similarly calculated the average displacement [Delta] W ₂ of the specimen TP2 and equation (25).

In step S < _b > 14, the elastic modulus calculation means 38 calculates the bending elastic modulus E of the specimen TP based on ΔW ₁ and ΔW ₂ stored in the measurement result storage means 37 according to the following equation, and stores it in the measurement result storage means 37. save.

  Finally, in step S15, the output control means 39 displays the calculated bending elastic modulus on the display 40, and ends the three-point bending test process.

  By the above process, the influence of the elastic deformation of the measuring device system due to the pressurization of the pressurizing body 11 is removed, the influence of the plastic deformation of the specimen TP is also removed, and the bending elastic modulus E of the substance constituting the specimen TP is removed. Can be measured.

  Finally, in order to verify the accuracy of the elastic modulus measurement method according to the present invention, experimental results obtained by actually measuring the bending elastic modulus E using a refractory material will be described.

(Experimental example)
First, in order to verify the assumption of formula (5), that is, that the strain of the measurement system increases in proportion to the bending elastic modulus of the specimen, the pressure of the pressurized body observed when stress is applied to the specimen. A comparison was made between the displacement and the displacement of the specimen measured directly with a strain gauge.

  The test conditions for the three-point bending test are as follows.

As the measurement system, the elastic modulus measuring apparatus 1 described with reference to FIG. 2 was used. The displacement W ′ detected by the displacement detector 13 and the displacement W of the specimen measured directly by the strain gauge attached to the bottom surface of the specimen were simultaneously measured and incorporated into a computer. The distortion W ″ of the measurement system is calculated by W ″ = W′−W. Further, the ratio of the strain W ″ of the measurement system to the displacement W ′ is referred to as “apparatus stiffness ratio” and is expressed as r _sys . r _sys is defined by the following equation.

装置剛性比ｒ_ｓｙｓは式（（５）の右辺全体の値に占める右辺第２項（ＥＩ／Ｓ^３ｋ）の値の割合を示している。

The device rigidity ratio r _sys indicates the ratio of the value of the second term (EI / S ³ k) on the right side to the value on the entire right side of the equation (5).

Further, the displacement W of specimen to be measured directly by the strain gage, the exact elastic modulus of the specimen which is calculated by the equation (3) is referred to as "strain gauge modulus", referred to as E _1.

FIG. 5 shows the result of measuring the relationship between the strain gauge elastic modulus E ₁ and the apparatus stiffness ratio r _sys . A refractory material was used as a specimen material. FIG. 5B shows the result of plotting the horizontal axis as E ₁ I (I is the secondary moment of section of the specimen). From the measurement results of FIG. 5, it can be considered that the apparatus stiffness ratio r _sys has a large correlation with E ₁ I, and r _sys is substantially proportional to E ₁ I / (1 + E ₁ I) in the first-order approximation.

FIG. 6 is a diagram showing a comparison between the elastic modulus obtained by the strain gauge and the elastic modulus (converted elastic modulus) obtained by the equation (7). From FIG. 6, the elastic modulus E, which is determined by measurement methods of the present invention, it is seen that a good match with the strain gauge elastic modulus E _1.

It is an example of the measurement result of the stress and displacement by a three-point bending method. It is a figure showing the whole elastic modulus measuring device 1 composition concerning Example 1 of the present invention. It is a block diagram showing the function structure of the elasticity measuring apparatus 1 of Example 1 of this invention. It is a flowchart showing the whole flow of an elastic modulus measuring method. Is the result of the relationship between the strain gauge elastic modulus E ₁ and device rigidity ratio r _sys was measured. It is the figure which showed the comparison with the elastic modulus calculated | required with the strain gauge, and the elastic modulus (converted elastic modulus) calculated | required by Formula (7). The result of measuring the relation between the EI / S ³ and the device displacement W. It is a figure which shows the elastic modulus measuring apparatus which measures the bending elastic modulus by a three-point bending method It is a figure showing the various parameters of a three-point bending test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elastic modulus measuring device 2 Mechanical component 3 Control component 4 Press lower plate 5 Press upper plate 6 Post 7 Loading platform 8 Hydraulic ram cylinder 9 Hydraulic ram piston 9a, 9b Pressurizing pipe 9c, 9d Pressurizing device 10 Sample support stand 10a, 10b Support body 11 Pressurizing body 12 Load cell 13 Displacement detectors 13a, 13b Extension member 14 Insulating airtight container 14a Air supply pipe 14b Exhaust pipe 15 Heater 16 Temperature sensor TP Specimen

Claims (9)

The lower part of both ends of the rod-shaped specimen is supported at two points by two horizontally placed supports, and the center of the specimen is pressurized with a pressurized body to measure the displacement of the pressurized body. Measuring the amount of displacement at the center of the specimen and measuring the elastic modulus of the specimen material,
For each of the first and second specimens made of the same material and having the same length and different widths, the displacement amount ΔW _{1 of the} central portion with respect to the change amount ΔP of the stress applied to the central portion of the specimen. , ΔW ₂ , a displacement measuring step;
The distance between the two supports is S, the thicknesses of the first and second specimens are h ₁ , h ₂ , the widths of the first and second specimens are b ₁ , b ₂ , the first And when the ratio of the width of the second specimen is 1: A, the elastic modulus calculation step of calculating the bending elastic modulus E of each specimen by the calculation of the following formulas (1) and (2);
A method for measuring elastic modulus.

In the displacement measuring step,
A first measurement step of measuring a displacement amount ΔW ₁ of the central portion of the specimen between two different stresses σ _s1 and σ _s2 (σ _s1 <σ _s2 ) applied to the central portion of the _first specimen. When,
A second measuring step for measuring a displacement amount ΔW ₂ of the central part of the specimen between the stresses σ _s1 and σ _s2 applied to the central part of the second specimen;
The elastic modulus measurement method according to claim 1, wherein: In the first and second measurement steps, before measuring the displacement amounts ΔW ₁ and ΔW ₂ , the stress applied to the central part of the first or second specimen is applied to the bending strength of the specimen. 3. The elastic modulus measuring method according to claim 1, wherein an error removing step is performed in which a step-up / step-down process for reducing the pressure to the stress σ _s1 or less is performed at least once after the pressure is increased to the following predetermined pressure. . In the first and second measurement steps, for the first or second specimen,
(1) The stress applied to the central portion of the specimen is changed from σ _s1 to σ _s2 (σ _s1 <σ _s2 ) according to a predetermined time function σ _s (t) defined by the time interval [0, T]. While increasing the pressure at T, the displacements δW ₁ ^(up) and δW ₂ ^(up) of the specimen are measured at each time point when the stress becomes σ _s1 and σ _s2, and the difference (δW ₂ ^(up) −δW ₁ ^{( up)} ) ⁾ as a pressure increase displacement ΔW ^(up) between the stresses σ _s1 and σ _s2 ;
(2) The stress applied to the central portion of the specimen is _lowered from time σ _s2 to σ _s1 and time T according to the function σ _s (T−t) obtained by reversing the time function σ _s (t). The displacements δW ₂ ^(down) and δW ₁ ^(down) of the specimen are measured at each time point when the stress becomes σ _s2 and σ _s1, and the difference (δW ₂ ^(down) −δW ₁ ^(down) ) is determined as the stress σ. a step-down process measuring step for calculating as step-down displacement ΔW ^(down) between _s1 and _σs2 ;
(3) The average value of the step- ^up displacement ΔW ^(up) and the step-down displacement ΔW ^(down) is calculated as the displacement amount ΔW ₁ or ΔW of the central portion of the specimen between the stresses σ _s1 and σ _s2. Average displacement calculation step calculated as ₂ ;
The elastic modulus measuring method according to claim 2, wherein: A pair of supports that support the lower portions near both ends of the rod-shaped specimen;
A pressurizing body that pressurizes the central portion of the specimen placed on top of the two supports from above;
A pressure cylinder for applying pressure to the pressure body;
A displacement detector for measuring the displacement of the pressure member;
A pressure sensor for measuring the stress generated by the pressure cylinder;
Storage means for storing measurement condition data and measurement data;
Output means for outputting the measurement result of the flexural modulus;
A control device for controlling the pressurizing force of the pressurizing cylinder, and measuring and controlling the displacement and generated stress of the pressurizing body;
An elastic modulus measuring apparatus for measuring the flexural modulus of a specimen material, comprising:
The controller is
The widths b ₁ and b ₂ and the thicknesses h ₁ and h _{2 of} the first and second specimens made of the same material and having the same length but different widths, the distance between the two supports. S, and a measurement condition setting means for setting a value of a change amount ΔP of stress applied to the specimen when performing displacement measurement, and storing the value in the storage means;
In the state where the first or second specimen is placed on both the supports, the pressure cylinder changes the stress applied to the central part of the specimen by the change amount ΔP, and the change A displacement measuring means for measuring the displacement amounts ΔW ₁ and ΔW ₂ of the central part of the specimen in between and storing the displacement amounts ΔW ₁ and ΔW ₂ in the storage means;
The distance S between the two supports stored in the storage means, the thickness h of the first and second specimens, the widths b ₁ and b _{2 of} the first and second specimens, and the displacement measurement. Based on the amount of change ΔP of the stress applied to the specimen when performing and the displacements ΔW ₁ , ΔW ₂ of the central part of the first and second specimens, the following equations (3), (4), Calculating the elastic modulus E of each specimen by executing the operation of (5), and outputting the elastic modulus to the output means;
An elastic modulus measuring device.

The measurement condition setting means is used for the specimens when the widths b ₁ and b ₂ and the thicknesses h ₁ and h _{2 of} the first and second specimens, the interval S between the two supports, and the displacement measurement are performed. Two different stress values to be applied σ _s1 and σ _s2 (σ _s1 <σ _s2 ) are set and stored in the storage means,
In the state where the first or second specimen is placed on the both supports, the displacement measuring means applies stress applied to the central part of the specimen by the pressure cylinder as σ _s1 and σ _s2 . characterized in that varied between the displacement amount [Delta] W 1 of the central portion of the specimen during the _change, and measuring the [Delta] W _2, is for storing displacement amount [Delta] W _1, the [Delta] W ₂ in the storage means The elastic modulus measuring apparatus according to claim 5. Prior to the displacement measuring means measuring the displacement, the control device controls the pressure cylinder to apply a stress applied to the central portion of the first or second specimen to bend the specimen. 7. The elasticity according to claim 5, further comprising an error removing means for performing a step-up / step-down process of increasing the pressure to a predetermined pressure below the strength and then reducing the pressure to the stress σ _s1 or less at least once. Rate measuring device. The displacement measuring means includes
By controlling the piston, the stress applied to the central portion of the first or second specimen is defined from σ _s1 to σ _s2 (σ _s1 <σ _s2 ) in the time interval [0, T]. Boost control means for boosting at time T according to a predetermined time function σ _s (t);
When the stress is increased by the pressure increase control means, the displacements δW ₁ ^(up) and δW ₂ ^(up) of the specimen are measured at each time point when the stress becomes σ _s1 and σ _s2, and the difference (δW ₂ ^{(up) )} −δW ₁ ^(up) ) is calculated as the pressure increase displacement ΔW ^(up) between the stresses σ _s1 and σ _s2 , and is stored in the storage means.
By controlling the piston, the stress applied to the central portion of the first or second specimen is changed from σ _s2 to σ _s1 and the time function σ _s (t) is time-reversed function σ _s (T A step-down control means for stepping down at time T according to -t);
When the stress is lowered by the step-down control means, the displacements δW ₂ ^(down) and δW ₁ ^(down) of the specimen are measured at each time point when the stress becomes σ _s2 and σ _s1, and the difference (δW ₂ ^{(down) )} −δW ₁ ^(down) ) is calculated as a step-down displacement ΔW ^(down) between the stresses σ _s1 and σ _s2 and stored in the storage unit;
The average value of the step- ^up displacement ΔW ^(up) and the step-down displacement ΔW ^(down) stored in the storage means is the displacement amount ΔW _{1 at} the center of the specimen between the stresses σ _s1 and σ _s2. Or mean displacement calculating means for calculating as ΔW ₂ and storing it in the storage means;
The elastic modulus measuring apparatus according to claim 6 or 7, further comprising: A pair of supports that support the lower portions near both ends of the rod-shaped specimen;
A pressurizing body that pressurizes the central portion of the specimen placed on top of the two supports from above;
A pressure cylinder for applying pressure to the pressure body;
A displacement detector for measuring the displacement of the pressure member;
A pressure sensor for measuring the stress generated by the pressure cylinder;
Storage means for storing measurement condition data and measurement data;
Output means for outputting the measurement result of the flexural modulus;
A computer for controlling the pressurizing force of the pressurizing cylinder and measuring and controlling the displacement and generated stress of the pressurizing body;
In an elastic modulus measuring system for measuring a bending elastic modulus of a specimen material, comprising:
A program which causes the computer to function as a control device of the elastic modulus measuring device according to any one of claims 5 to 8 by being read and executed by the computer.

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