Contact type circumferential strain measuring device and measuring method

Abstract

The invention belongs to the technical field of geotechnical engineering, and particularly relates to a contact type circumferential strain measuring device and a measuring method. Comprising an elastic piece sleeving a sample body; a plurality of groups of measuring assemblies are sleeved on the elastic piece, are in contact with the sample body and move along the outline track of the elastic piece; the multiple sets of measuring assemblies measure different point positions of the sample body, and meanwhile in the deformation process of the sample body, the measuring assemblies are driven to rotate around the elastic pieces, so that data of the different point positions are collected in real time, and the measuring accuracy is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering, and in particular relates to a contact type annular strain measuring device and a measuring method. Background Art

[0002] Poisson's ratio is an important property of various materials. The determination of Poisson's ratio requires the axial and hoop strain values ​​of the specimen to be obtained through experiments. However, due to the different deformation properties, various types and complex properties of materials, it is difficult to obtain the hoop deformation of cylindrical specimens, and the experimental research on hoop deformation started late.

[0003] At present, the measurement of hoop strain in indoor tests can be divided into two types: contact type and non-contact type. The non-contact type mainly uses digital imaging technology to measure lateral deformation, which has high accuracy but high cost. However, since the image of the specimen needs to be collected by a camera, it occupies a large space and cannot be used in triaxial tests, and its application range is relatively limited. The contact type usually uses resistance strain gauges, improved resistance strain gauges and LVDT (linear variable differential transformer) strain gauges. The existing strain gauge method can only measure the local strain at the location of the strain gauge, with a small measurement range and complex operation; some other improved resistance strain gauges have low sensitivity, short life, large measurement errors and inconvenient operation. The existing LVDT strain gauge fixing method generally adopts chain type, wire rope type and hoop type. Due to the poor deformation performance of chains and steel ropes, when conducting tests with large material deformation, the chains and steel ropes are often damaged or hurt to the LVDT sensor, which leads to high measurement costs. At the same time, due to the large difference in the deformability of different materials, such as the strong deformation performance of asphalt, the hoop strain measurement range needs to be larger.

[0004] Therefore, the measurement of circumferential strain in indoor tests has become a constraint in the study of various material properties. An instrument and method that can accurately and simply test the circumferential deformation of the specimen is needed to solve such problems. Summary of the invention

[0005] In view of the above problems, the present invention provides a contact type hoop strain measuring device, comprising an elastic member sleeved on a sample body;

[0006] The elastic member is sleeved with a plurality of measuring components, which are in contact with the sample body. When the sample body is loaded and deformed, the measuring components are driven to move along the outer shape track of the elastic member to measure various points on the sample body.

[0007] Furthermore, multiple groups of the measuring components are connected end to end in sequence to form a complete ring shape.

[0008] Furthermore, the measuring component comprises an adjusting component and a measuring component; the measuring component is mounted on the adjusting component, the adjusting component is used to adjust the distance inside the measuring component, and the adjusting component is sleeved on the elastic member.

[0009] Furthermore, the measuring component comprises two groups of adjusting components, the two groups of adjusting components are distributed in upper and lower layers, and the measuring components and the elastic member are both installed between the two groups of adjusting components.

[0010] Furthermore, the adjustment component includes a No. 1 rotating shaft and a No. 2 rotating shaft; a No. 1 connecting plate is rotatably installed between the No. 1 rotating shaft and the No. 2 rotating shaft; the two groups of measuring components are respectively installed between the two groups of No. 1 rotating shafts and the two groups of No. 2 rotating shafts.

[0011] Furthermore, the adjustment component includes two No. 1 rotating shafts and one No. 2 rotating shaft, and is distributed in the shape of an isosceles triangle; a No. 2 connecting plate is rotatably connected between adjacent No. 1 rotating shafts between adjacent measuring components.

[0012] Furthermore, the measuring component includes a No. 1 sensor and a No. 2 sensor; the No. 1 sensor is installed between the two groups of No. 1 rotating shafts, and the No. 2 sensor is installed between the two groups of No. 2 rotating shafts.

[0013] Furthermore, the two groups of the No. 1 rotating shaft are coaxially arranged with the No. 1 sensor; and the two groups of the No. 2 rotating shaft are coaxially arranged with the No. 2 sensor.

[0014] Furthermore, the width of the elastic member is smaller than the distance between the two groups of adjusting components; the No. 2 connecting plate is composed of two No. 2 plates, one end of the two No. 2 plates is detachably connected, and the other ends of the two No. 2 plates are respectively rotatably connected to the adjacent No. 1 rotating shaft.

[0015] The present invention provides a measurement method of a contact type annular strain measuring device, which uses the contact type annular strain measuring device and specifically includes the following steps:

[0016] The strain measuring device is mounted on the specimen body;

[0017] Obtaining angle data a measured by the first sensor and the second sensor in the loading state and angle data b measured by the first sensor and the second sensor in the deformed state;

[0018] According to the angle data a and the length of the No. 1 connecting plate, the length distance c between the No. 2 sensor and the sample body in the loading state is obtained; according to the angle data b and the length of the No. 1 connecting plate, the length distance d between the No. 2 sensor and the sample body in the deformed state is obtained;

[0019] According to the difference between the length distance c and the length distance d, the radius deformation data of the sample body at the corresponding point position is obtained;

[0020] Generate a curve set based on the radius deformation data of multiple points on the specimen body

[0021] Beneficial Effects

[0022] The beneficial effects of the present invention compared to the prior art are as follows:

[0023] 1. The present application arranges a corresponding number of measuring components on an elastic member as required, and installs the measuring components on a sample body through the elastic member; multiple groups of measuring components measure different points of the sample body, and at the same time, during the deformation of the sample body, the measuring components are driven to rotate around the elastic member, thereby collecting data at different points in real time to improve the accuracy of the measurement.

[0024] 2. In the present application, after the elastic part is put on the sample body, the No. 1 rotating shaft and the No. 1 sensor are in contact with the surface of the sample body; when the surface of the sample body is deformed, the No. 1 sensor and the No. 1 rotating shaft are driven to rotate, and the No. 2 sensor is driven to rotate through the No. 1 connecting plate, and the elastic part expands outward at the same time; the No. 1 sensor and the No. 2 sensor convert the circumferential displacement into angular rotation, thereby realizing multi-point, high-precision deformation measurement.

[0025] 3. The present application connects the two measuring components through a No. 2 connecting plate, and at the same time, the No. 2 connecting plate is detachably connected to the No. 2 plate, so that the two measuring components can be disassembled by disassembling the No. 2 plate, so that the number of measuring components can be increased or decreased accordingly according to the diameter of the sample body to adapt to the corresponding sample body.

[0026] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A schematic diagram of the structure in an embodiment of the present invention is shown.

[0029] Figure 2 A top view of an embodiment of the present invention is shown.

[0030] Figure 3 A front view of an embodiment of the present invention is shown.

[0031] Figure 4 It shows a schematic structural diagram of the strain measuring device before being installed on the surface of the sample body in the embodiment of the present invention.

[0032] Figure 5 The schematic diagram shows the structure of the strain measuring device installed on the surface of the sample body in the embodiment of the present invention.

[0033] Figure 6 A schematic diagram showing angle measurement conversion between sensor No. 1 and sensor No. 2 in an embodiment of the present invention is shown.

[0034] In the figure, 10, sample body; 127, adjustment component; 46, measurement component;

[0035] 1. No. 2 rotating shaft; 2. No. 1 connecting plate; 3. No. 2 connecting plate;

[0036] 4. Sensor No. 1; 5. Elastic part; 6. Sensor No. 2; 7. Rotating shaft No. 1. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The present application provides a contact type hoop strain measuring device, referring to Figure 1 and Figure 5 It includes an elastic member 5 sleeved on a sample body 10;

[0039] The elastic member 5 is sleeved with a plurality of measuring components, the measuring components are in contact with the sample body 10 , and the measuring components move along the outer shape track of the elastic member 5 .

[0040] The multiple groups of measuring components are connected end to end in sequence.

[0041] First, the elastic member 5 is stretched manually so that the measuring range inside the strain measuring device reaches the diameter of the sample body 10, and then the elastic member 5 is sleeved on the sample body 10 from top to bottom. The elastic member 5 is an annular elastic band, and nine groups of measuring components are arranged on the elastic member 5, so that multiple groups of measuring components can be fixed on the sample body 10; the elastic member 5 makes the measuring components in close contact with the sample body 10 at all stages during the entire measurement process to ensure the accuracy of the measurement; when the sample body 10 undergoes circumferential strain, the nine groups of measuring components are closely attached to the surface of the sample body 10, and the measuring components will be forced to move outward, and the movement of one group of measuring components will drive the nine groups of measuring components to rotate synchronously; the measuring components perform multi-point measurements on different positions on the sample body 10; the measuring components are connected to external sensors to transmit the measured data; and then the specific data and deformation curve of the circumferential strain of the sample body 10 during the loading process are obtained by calculation.

[0042] The present application arranges a corresponding number of measuring components on the elastic member 5 as needed, and installs the measuring components on the sample body 10 through the elastic member 5; multiple groups of measuring components measure different points of the sample body 10, and at the same time, during the deformation of the sample body 10, the measuring components are driven to rotate around the elastic member 5, so as to collect data at different points in real time and improve the accuracy of the measurement.

[0043] In one embodiment of the present invention, the measuring component includes an adjusting component 127 and a measuring component 46 ; the measuring component 46 is mounted on the adjusting component 127 , the adjusting component 127 is used to adjust the distance inside the measuring component, and the adjusting component 127 is sleeved on the elastic member 5 .

[0044] In one embodiment of the present invention, the measuring assembly includes two groups of adjusting components 127 , the two groups of adjusting components 127 are distributed in two layers, and the measuring component 46 and the elastic member 5 are installed between the two groups of adjusting components 127 .

[0045] In one embodiment of the present invention, reference Figure 2-4 The adjusting component 127 includes a No. 1 rotating shaft 7 and a No. 2 rotating shaft 1; a No. 1 connecting plate 2 is rotatably installed between the No. 1 rotating shaft 7 and the No. 2 rotating shaft 1; two groups of the measuring components 46 are respectively installed between the two groups of No. 1 rotating shaft 7 and the two groups of No. 2 rotating shaft 1.

[0046] By rotating the first rotating shaft 7 and the second rotating shaft 1 , the inner diameters of the multiple measuring components can be expanded, so that the hoop strain measurement can be performed on the sample bodies 10 with different diameters.

[0047] In one embodiment of the present invention, reference Figure 4The adjusting component 127 includes two No. 1 rotating shafts 7 and one No. 2 rotating shaft 1, and is distributed in the shape of an isosceles triangle; two groups of No. 1 connecting plates 2 and the No. 1 rotating shaft 7 are symmetrically distributed on both sides of the No. 2 rotating shaft 1; and the No. 2 connecting plates 3 are rotatably connected between the adjacent No. 1 rotating shafts 7 between adjacent measuring components.

[0048] In one embodiment of the present invention, the measuring component 46 includes a No. 1 sensor 4 and a No. 2 sensor 6 ; the No. 1 sensor 4 is installed between two groups of No. 1 rotating shafts 7 , and the No. 2 sensor 6 is installed between two groups of No. 2 rotating shafts 1 .

[0049] The upper and lower ends of the No. 2 sensor 6 are detachably connected to the two No. 2 rotating shafts 1, and the elastic member 5 can be placed between the two groups of adjustment components 127 before the No. 2 sensor 6 is installed; then the No. 2 sensor 6 is installed on the No. 2 rotating shaft 1 in turn to realize the installation and disassembly of the elastic member 5, which is convenient for the later replacement of the elastic member 5.

[0050] In one embodiment of the present invention, the two groups of the No. 1 rotating shaft 7 and the No. 1 sensor 4 are coaxially arranged; the two groups of the No. 2 rotating shaft 1 and the No. 2 sensor 6 are coaxially arranged.

[0051] After the elastic member 5 is put on the sample body 10, the No. 1 rotating shaft 7 and the No. 1 sensor 4 are in contact with the surface of the sample body 10; when the surface of the sample body 10 is deformed, the No. 1 sensor 4 and the No. 1 rotating shaft 7 are driven to rotate, and the No. 2 sensor 6 is driven to rotate through the No. 1 connecting plate 2, and the elastic member 5 expands outward at the same time; the No. 1 sensor 4 and the No. 2 sensor 6 convert the circumferential displacement into angular rotation, thereby realizing multi-point, high-precision deformation measurement;

[0052] In one embodiment of the present invention, the width of the elastic member 5 is smaller than the distance between the two groups of adjusting components 127; the No. 2 connecting plate 3 is composed of two No. 2 plates (not shown in the figure), one end of the two No. 2 plates is detachably connected, and the other ends of the two No. 2 plates are respectively rotatably connected to the adjacent No. 1 rotating shaft 7.

[0053] When the number of measuring components needs to be adjusted according to the diameter of the sample body 10, the existing nine measuring components have a diameter adjustment range that can meet the measurement of the sample body 10 within a diameter of 50-70 units; when the diameter of the sample body 10 is 100 units, several more measuring components need to be added;

[0054] Therefore, it is only necessary to disassemble the two No. 2 plates of one of the No. 2 connecting plates 3 based on the initial strain measurement device, and connect the No. 2 plate on the added measurement component to it, so as to realize the measurement of the sample body 10 that is not directly required; at the same time, the No. 2 sensor 6 can be disassembled and replaced with the elastic member 5 (elastic ring) of the corresponding diameter, thereby improving the applicability of the strain measurement device.

[0055] refer to Figure 6 , from left to right are the initial state, the sample loading state and the deformed state; from top to bottom are the main body of the strain measuring device, the top view of a single measuring component and the simplified diagram of the distance between half of the measuring component and the sample body 10; showing the process of converting the measured values ​​of the No. 1 sensor 4 and the No. 2 sensor 6 into the hoop strain;

[0056] The center of the circle of the measuring component in different states is the same, and the center of the circle is the center of the sample body 10; then Figure 6 A, E, and J in the figure are the center points of the same position. The measurement component is symmetrical, so half of it is selected for calculation. Sensor No. 1 4 (located at Figure 6 The angle changes in the three states can be measured at points B, F, and K in the middle; the second sensor 6 (located at Figure 6 The C, G, and L points in the middle can measure the angle changes here in three states;

[0057] Since the length of the No. 1 connecting plate 2 is constant, it is assumed that the length of the No. 1 connecting plate 2 is O, that is, BC = FG = KL = O;

[0058] Then in the initial state, we can get: BD = O × sin ∠ BCD, DC = O × cos ∠ BCD, ∠ CAB = 180° - ∠ BCA - ∠ ABC, but

[0059] Similarly, the lengths of EG and JL can be obtained. Therefore, at different times, the radius deformation of the annular circle of the specimen body at this point is: EG-JL, and the angle change at the center of the specimen is: ∠KJL-∠GEF. Through the diameter change of the annular circle at multiple points and the angle change at the center of the specimen, the real-time circle at the measurement point can be drawn, thereby obtaining the annular deformation of the entire specimen body 10;

[0060] Sensor No. 1 4 and Sensor No. 2 6 are angle measuring sensors, which can obtain the angle value at each moment in the entire loading process. Therefore, according to the above conversion process, the specific data of the hoop strain in the entire loading process can be obtained, and then the deformation curve can be obtained after statistically arranging the data;

[0061] The present application provides a measurement method of a contact type annular strain measurement device, which uses the above-mentioned contact type annular strain measurement device and specifically includes the following steps:

[0062] The strain measuring device is mounted on the sample body 10;

[0063] Acquire the angle data a measured by the first sensor 4 and the second sensor 6 in the loading state and the angle data b measured by the first sensor 4 and the second sensor 6 in the deformed state;

[0064] According to the angle data a and the length of the first connecting plate 2, the length distance c between the second sensor 6 and the sample body 10 in the loading state is obtained; according to the angle data b and the length of the first connecting plate 2, the length distance d between the second sensor 6 and the sample body 10 in the deformed state is obtained;

[0065] According to the difference between the length distance c and the length distance d, the radius deformation data of the sample body 10 at the corresponding position point is obtained;

[0066] A set of curves is generated based on the radius deformation data of more than 10 points on the specimen body.

[0067] The angle data a measured by the No. 1 sensor 4 and the No. 2 sensor 6 in the loading state is ∠EFG=90°, ∠EGF=45°; the angle data b measured by the No. 1 sensor 4 and the No. 2 sensor 6 in the deformed state is ∠JKL=60°, ∠JLK=60°; the length O of the No. 1 connecting plate 2 is 20 unit lengths;

[0068] In the loading state ∠GEF=180°-90°-45°=45°; but

[0069] When in the deformed state, ML=20×cos∠KLM=10;∠LJK=60°; Then JL=20;

[0070] Then the radius of the annular circle at this point is deformed to The angle change at the center of the sample body 10 is ∠LJK-∠GEF=15°;

[0071] Finally, the real-time circle at the measurement location is drawn using the diameter deformation data and angle change data at multiple points, thereby obtaining the annular deformation of the entire sample body 10 .

[0072] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A contact type hoop strain measuring device, characterized in that: It comprises an elastic member (5) sleeved on a sample body (10); The elastic member (5) is sleeved with a plurality of measuring components, the measuring components are in contact with the sample body (10), and the measuring components move along the outer shape track of the elastic member (5).

2. A contact type hoop strain measuring device according to claim 1, characterized in that: The multiple groups of measuring components are connected end to end in sequence.

3. A contact type hoop strain measuring device according to claim 1, characterized in that: The measuring component comprises an adjusting component (127) and a measuring component (46); the measuring component (46) is mounted on the adjusting component (127); the adjusting component (127) is used to adjust the distance inside the measuring component; and the adjusting component (127) is sleeved on the elastic component (5).

4. A contact type hoop strain measuring device according to claim 1, characterized in that: The measuring assembly comprises two groups of adjusting components (127), the two groups of adjusting components (127) are distributed in two layers, the measuring component (46) and the elastic component (5) are both installed between the two groups of adjusting components (127).

5. A contact type hoop strain measuring device according to claim 3, characterized in that: The adjusting component (127) comprises a first rotating shaft (7) and a second rotating shaft (1); a first connecting plate (2) is rotatably mounted between the first rotating shaft (7) and the second rotating shaft (1); and two groups of measuring components (46) are respectively mounted between the two groups of first rotating shafts (7) and the two groups of second rotating shafts (1).

6. A contact type hoop strain measuring device according to claim 5, characterized in that: The adjustment component (127) comprises two No. 1 rotating shafts (7) and one No. 2 rotating shaft (1), and is distributed in the shape of an isosceles triangle; a No. 2 connecting plate (3) is rotatably connected between adjacent No. 1 rotating shafts (7) between adjacent measuring components.

7. A contact type hoop strain measuring device according to claim 6, characterized in that: The measuring component (46) comprises a No. 1 sensor (4) and a No. 2 sensor (6); the No. 1 sensor (4) is installed between the two groups of No. 1 rotating shafts (7), and the No. 2 sensor (6) is installed between the two groups of No. 2 rotating shafts (1).

8. A contact type hoop strain measuring device according to claim 7, characterized in that: The two groups of the No. 1 rotating shaft (7) and the No. 1 sensor (4) are coaxially arranged; the two groups of the No. 2 rotating shaft (1) and the No. 2 sensor (6) are coaxially arranged.

9. A contact type hoop strain measuring device according to claim 6, characterized in that: The width of the elastic member (5) is smaller than the distance between the two groups of adjustment components (127); the No. 2 connecting plate (3) is composed of two No. 2 plates, one end of the two No. 2 plates is detachably connected, and the other ends of the two No. 2 plates are respectively rotatably connected to adjacent No. 1 rotating shafts (7).

10. A measurement method of a contact type hoop strain measuring device, characterized in that: The contact type hoop strain measuring device according to any one of claims 1 to 9 is applied, and specifically comprises the following steps: Mounting a strain measuring device on the sample body (10); Acquire angle data a measured by the first sensor (4) and the second sensor (6) in a loaded state and angle data b measured by the first sensor (4) and the second sensor (6) in a deformed state; According to the angle data a and the length of the first connecting plate (2), the length distance c between the second sensor (6) and the sample body (10) in the loading state is obtained; according to the angle data b and the length of the first connecting plate (2), the length distance d between the second sensor (6) and the sample body (10) in the deformed state is obtained; According to the difference between the length distance c and the length distance d, the radius deformation data of the sample body (10) at the corresponding point position is obtained; A set of curves is generated based on the radius deformation data at multiple points of the sample body (10).

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