CN212045402U - A Specimen Slotting Device for Bending Element Test - Google Patents

Abstract

The utility model discloses a sample fluting device for crooked unit is experimental, including lid shape nut, logical nut, packing ring, screw rod, sleeve and gasket, the sleeve sets up to hollow structure, and the structure of gasket cooperatees with the inside hollow structure's of sleeve cross section, sets up the horizontal location hole of number to running through the section of thick bamboo wall in sleeve horizontal direction, vertical locating hole has been seted up to the center department of gasket, the upper and lower both ends at the screw rod are installed to lid shape nut, and lid shape nut still supports on telescopic upper and lower terminal surface. The utility model provides a naked eye rough observation of traditional fluting method be difficult to guarantee that two on the crooked first sample of reserving the cavity are parallel to each other, the difficult problem of accurate counterpoint, through guaranteeing the controllability to sample fluting degree of depth, can realize the inseparable laminating of crooked component insert and sample reservation cavity high-efficiently, the accurate crooked first reservation cavity that satisfies the experimental requirement of digging, improve the efficiency and the success rate of sample preparation.

Description

A Specimen Slotting Device for Bending Element Test

Technical field:

The utility model belongs to the technical field of bending element test, in particular to a sample slotting device used for bending element test.

Background technique:

Bending element test is a non-destructive testing method for determining the shear modulus, elastic modulus and Poisson's ratio of materials in a small strain range of the order of 10-6 by using the propagation theory of elastic waves in a medium. This experiment uses a pair of bending elements as the transmitting end and the receiving end, respectively. Because the bending elements have the same structure, each bending element can be used as both the transmitting end and the receiving end. Bending elements can be mounted both vertically at the top and bottom of the specimen, as well as horizontally, allowing a quantitative study of the difference between the axial stiffness and the horizontal stiffness due to the specimen's anisotropy. The bending element is a piezoelectric ceramic bimorph composed of two piezoelectric ceramic sheets bonded together, and a conductor (metal spacer) is installed between the two sheets and their outer surfaces. Since piezoelectric ceramics have piezoelectric properties, which can realize the mutual conversion of electrical energy and mechanical energy, a signal generator can be used to apply voltage to the two piezoelectric ceramic sheets on the bimorph to make them expand and contract at the same time or one by one, so as to make the pressure The electric ceramic bimorph exhibits slight expansion deformation or bending deformation as a whole and generates corresponding vibrations in the embedded sample, that is, compression waves (longitudinal waves) or shear waves (shear waves) are generated. After the body wave emitted by the bending element at the transmitting end propagates in the sample, it drives the piezoelectric ceramic sheet of the receiving bending element to generate corresponding vibration, and converts the mechanical energy into an electrical signal. By comparing the transmitted and received signals stored and displayed in the storage oscilloscope, the propagation time of the body wave in the sample can be determined. the propagation speed in the sample. Because the wave velocity and propagation path of the body wave are only controlled by the density and stiffness, the small strain stiffness of the sample can be calculated from the body wave velocity and the density of the sample, and the seismic response of the site and the small strain state under the working load can be analyzed and calculated. practical engineering problems. In addition, the bending element test can also be used as a non-destructive test method to evaluate the uniformity of the specimen by the difference in the measured stiffness in different directions.

In the bending element test, the bending element is inserted into the sample as an insert and cannot be directly pressed into hard and rigid samples such as soft rock, cement-stabilized soil, high-density thawed soil, and frozen soil. Therefore, a pair of precisely aligned cavities must be excavated in the sample for insertion of the curved elements serving as the transmitter and receiver to avoid damage to the elements during installation and testing. If the receiving end element and the transmitting end element after inserting the sample are not coplanar, that is, there is a non-zero angle between the receiving end and the transmitting end or there is a parallel spacing, the received signal is not clear and there are many clutter, especially It is theoretically that when the two are perpendicular, no signal will be received, causing the test to fail. Therefore, a pair of accurately aligned reserved cavities are excavated on the sample, so that the transmitting end element and the receiving end element after inserting the sample are coplanar on the premise of having the same phase direction, which is very important for obtaining an accurate and clear maximum signal and It is critical to ensure that test results are accurate and reliable.

At present, for the bending element test of hard and rigid samples such as soft rock, cement-stabilized soil, high-density thawed soil, and frozen soil, the reserved cavity of the sample is only marked with the naked eye and marked with a knife, hand, etc. Drills and other tools are used to make grooves by hand.

The existing grooving method can neither control the size and depth of the grooving, so that the bending element and the sample cannot be closely fitted, nor can the two reserved cavities be coplanar and precisely aligned. In order to prevent the sample from moving or rotating when grooving by hand, it is also necessary to firmly hold the sample, which may cause disturbance or even damage to the sample. In addition, because the existing grooving process is time-consuming, time-consuming and labor-intensive, and needs to be adjusted repeatedly, the moisture content of the sample will change, and the temperature of the sample will also be disturbed for frozen soil. Therefore, using the sample slotted by the prior art to perform the bending element test will not only cause great disturbance to the sample during the slotting process, but also the waveform of the obtained test result is cluttered, there are many interference signals, and the reliability is poor, making it difficult to judge the accepted signal. Therefore, the shear wave propagation velocity in the sample cannot be calculated correctly and the stiffness of the sample can be determined accordingly.

Invention content:

The technical problem to be solved by the present invention is to provide a device that can precisely align and slot the sample in its horizontal and vertical directions while preventing the sample from moving or rotating.

In order to solve the above-mentioned technical problems, the utility model is realized by the following technical solutions: a sample slotting device for bending element test, comprising a cap nut, a through nut, a washer, a screw rod, a sleeve and a gasket, The sleeve is set as a hollow structure, the structure of the gasket is matched with the cross section of the hollow structure inside the sleeve, and several pairs of horizontal positioning holes penetrating the cylinder wall are opened in the horizontal direction of the sleeve. A vertical positioning hole is opened, a pair of mounting holes are also opened on the gasket, threads are provided at both ends of the screw, the two gaskets are sleeved and installed on the screw, and the top surface of the gasket on the upper part passes through Through core nut and washer locking adjustment, the bottom surface of the gasket located at the lower part is adjusted by through core nut and washer locking, the gasket is placed in the sleeve, and the cap nut is installed on the upper and lower ends of the screw rod, And the cap nut also abuts on the upper and lower end surfaces of the sleeve.

Preferably, two sides of the gasket are provided with symmetrical outwardly protruding tenons, the mounting holes are opened on the protruding tenons, and the sleeve is provided with a limiting groove for limiting the tenon.

Preferably, the length direction of the vertical positioning hole is perpendicular to the direction of the connecting line of the pair of mounting holes opened on the gasket.

Preferably, the sleeve is made of hard transparent material.

Compared with the prior art, the benefits of the present utility model are:

1. The present utility model solves the problem that the traditional grooving method is difficult to ensure that the two reserved cavities on the bending element sample are parallel to each other and precisely aligned.

2. By ensuring the controllability of the groove depth of the sample, the present invention can efficiently realize the close fit between the insert of the bending element and the cavity reserved for the sample. The adjustable exposed length of the cutter head makes the device suitable for curved elements with different injection depths, and overcomes the shortcomings of the existing grooving method, which requires repeated adjustment of the grooving depth, which is time-consuming and labor-intensive. The length of the cutter head can be preset for the hole depth of the bending element, and the reserved cavity for the bending element that meets the test requirements can be accurately excavated, so as to improve the efficiency and success rate of sample preparation.

Description of drawings:

The present utility model will be further described below in conjunction with the accompanying drawings.

Figure 1 is a schematic structural diagram of the present invention.

Figure 2 is a schematic view of the structure of the sleeve.

Figure 3 is a schematic diagram of the installation structure of the gasket and the screw.

Figure 4 is a schematic diagram of the structure of the gasket.

Figure 5 is a schematic view of the structure of the detachable carving knife.

FIG. 6 is a diagram of the test results when the reserved cavity of the sample is precisely aligned after grooving using the present invention.

FIG. 7 is a graph of the test results when the sample reserved cavities are not aligned parallel to each other after grooving using the prior art.

Detailed ways:

Below in conjunction with specific embodiment, the present utility model is described in detail:

As shown in Figures 1 to 4, a sample slotting device for bending element test includes a cap nut 1, a through nut 2, a washer 3, a screw 4, a sleeve 5 and a washer 6. The said The sleeve 5 is set as a hollow structure, the structure of the gasket 6 is matched with the cross section of the hollow structure inside the sleeve 5, and several pairs of horizontal positioning holes 51 are opened in the horizontal direction of the sleeve 5 through the cylinder wall. The center of 6 is provided with a vertical positioning hole 61, a pair of mounting holes 62 are also provided on the washer 6, the two ends of the screw 4 are provided with threads, and the two gaskets 6 are sleeved and installed on the screw 4, and The top surface of the washer 6 located at the upper part is adjusted by the through-center nut 2 and the washer 3, and the bottom surface of the washer 6 located at the lower part is adjusted by the through-center nut 2 and the washer 3, and the washer 3 is sleeved and installed. On the screw 4, the through nut 2 is threadedly connected to both ends of the screw 4, the washer 6 is placed in the sleeve 5, the cap nut 1 is installed on the upper and lower ends of the screw 4, and the The cap nut 1 also abuts on the upper and lower end surfaces of the sleeve 5 .

As a preferred setting structure of the gasket 6, two sides of the gasket 6 are provided with symmetrical outwardly protruding tenons 63, the mounting holes 62 are opened on the protruding tenons 63, and the sleeve 5 is provided with a The limiting groove 52 of the limiting tenon 63 .

The length direction of the vertical positioning hole 61 is perpendicular to the direction of the connecting line of the pair of mounting holes 62 opened on the gasket 6 to avoid collision between the knife or the cap nut 1 when the operator is vertically grooving.

The sleeve 5 is made of hard transparent material, so as to perform horizontal alignment and grooving on the sample marked with the grooving position after adjustment.

Example 1:

A. Place a gasket 6 on each of the upper and lower ends of the prepared cylindrical sample, so that the two ends of the sample overlap with the gasket 6;

B. Insert the two screws 4 vertically into the mounting holes 62 of the tenons 63 on both sides of the upper and lower gaskets 6 respectively;

C. At both ends of each screw 4, insert a washer 3 and a through-core nut 2;

D. Tighten the through nut 2 to make it clamp both ends of the sample through the washer 3 and the upper and lower gaskets 6;

E. Set the clamped sample into the sleeve 5;

F. Then insert a cap nut 1 at both ends of each inserted screw 4, and clamp it on the sleeve 5 and tighten it;

G. Determine and adjust the exposed length of the cutter head in the detachable cutter according to the thickness of the sleeve 5, the thickness of the spacer 6 and the sample insertion depth of the actual bending element insert. When grooving in the horizontal direction, the exposed length of the cutter head is the sum of the thickness of the sleeve and the insertion depth of the insert of the bending element; when grooving in the vertical direction, the exposed length of the cutter head is the sum of the thickness of the gasket and the insertion depth of the insert of the bending element;

H. Insert the cutter 7 with the adjusted length of the exposed cutter head 73 into the horizontal positioning hole 51 on the sleeve 5 and the vertical positioning hole 61 on the gasket 6, respectively, to slot the sample; Increase, the exposed length of the cutter head 73 gradually decreases, when the casing 71 outside the cutter chuck 72 is tightly stuck on the outer side of the sleeve 5 cylinder wall or the gasket 6, it means that the groove depth has reached the required depth; finally, Move the knife 7 back and forth in the length and width directions of the positioning hole until a regular cavity is formed.

Embodiment 2:

A. First install a gasket 6 on the two screws 4 through the through nut 2 and the washer 3;

B. Then place the inside of the sleeve 5 as the lower gasket, put the sample and place another gasket 6 on the sample as the upper gasket;

C. At the upper end of each screw 4, a washer 3 and a through-core nut 2 are inserted into each;

D. Tighten the through nut 2 to make it clamp both ends of the sample through the washer 3 and the upper and lower gaskets 6;

E. Set the clamped sample into the sleeve 5;

F. Then insert a cap nut 1 at both ends of each inserted screw 4, and clamp it on the sleeve 5 and tighten it;

G. Determine and adjust the exposed length of the cutter head in the detachable cutter according to the thickness of the sleeve 5, the thickness of the spacer 6 and the sample insertion depth of the actual bending element insert. When grooving in the horizontal direction, the exposed length of the cutter head is the sum of the thickness of the sleeve and the insertion depth of the insert of the bending element; when grooving in the vertical direction, the exposed length of the cutter head is the sum of the thickness of the gasket and the insertion depth of the insert of the bending element;

H. Insert the cutter 7 with the adjusted length of the exposed cutter head 73 into the horizontal positioning hole 51 on the sleeve 5 and the vertical positioning hole 61 on the gasket 6, respectively, to slot the sample; Increase, the exposed length of the cutter head 73 gradually decreases, when the casing 71 outside the cutter chuck 72 is tightly stuck on the outer side of the sleeve 5 cylinder wall or the gasket 6, it means that the groove depth has reached the required depth; finally, Move the knife 7 back and forth in the length and width directions of the positioning hole until a regular cavity is formed.

The utility model realizes the precise alignment of the signal transmitting end and the receiving end in the bending element test and makes them coplanar, thereby obtaining the clearest receiving waveform, accurate and reliable wave speed and sample stiffness. The device and method should not only be suitable for hard and rigid samples such as soft rock, cement-stabilized soil, high-density thawed soil and frozen soil with different heights, but also suitable for bending elements with different sampling depths. Insert, and should ensure that the sample and the bending element piezoelectric ceramic bimorph closely fit. It should not only be able to accurately align and notch the horizontal and vertical directions of the sample under the condition of preventing the sample from moving or rotating, but also effectively reduce the disturbance to the sample in terms of internal structure, moisture and temperature. At the same time, the grooving speed is greatly improved and the time for the sample to leave the curing environment is reduced.

As shown in Figure 6 and Figure 7, in order to verify the beneficial effect produced by the method of the present utility model compared with the traditional technology and the feasibility in practical application, a set of control experiments are set up below, and the test materials used are all samples with a moisture content of 18%. High-density silty clay sample, the original sample is a cylinder with a diameter of 50 mm and a height of 100 mm, and the excitation signals used at the transmitting end during the bending element test are all sinusoidal shear waves with an amplitude of 14 V and an excitation frequency of 2.5 kHz.

In the control experiment, the samples of the experimental group were precisely aligned and slotted by the device of the utility model, and the shear wave test results are shown in Fig. 6 .

The samples in the control group were grooved by traditional techniques, and the parallel alignment of the reserved cavities in the samples was not guaranteed. The shear wave test results are shown in Figure 7.

The comparison shows that the test results of the experimental group have stable waveforms, high intensity and less clutter, and it is easy to judge the initial arrival time of the received signal, so that the propagation speed of the shear wave in the sample can be accurately calculated and the shear of the sample can be determined accordingly. stiffness. However, for the control samples that were slotted by the traditional method and did not guarantee the parallel alignment of the reserved cavities, the shear wave test results showed many interference signals, and the received signals were cluttered and unstable, making it difficult to accurately determine the initial arrival time of the received waves. , the test results under the same conditions are far from the experimental group.

It should be emphasized that it is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential features of the present invention. The utility model. Therefore, the embodiments are to be considered in all respects as exemplary and not restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description, and it is therefore intended that the All changes within the meaning and range of the required equivalents are embraced within the present invention.

Claims (4)

1. A sample slotting device for bending element test, characterized in that: comprising a cap nut (1), a through nut (2), a washer (3), a screw (4), a sleeve (5) and a gasket (6), the sleeve (5) is set as a hollow structure, the structure of the gasket (6) is matched with the cross section of the hollow structure inside the sleeve (5), at the level of the sleeve (5) Several pairs of horizontal positioning holes (51) penetrating the cylinder wall are opened in the direction, a vertical positioning hole (61) is opened at the center of the gasket (6), and a pair of mounting holes (61) are also opened on the gasket (6). 62), the two ends of the screw (4) are provided with threads, the two gaskets (6) are sleeved and installed on the screw (4), and the top surface of the gasket (6) located at the upper part passes through the through nut ( 2) The washer (3) is locked and adjusted, and the bottom surface of the washer (6) located at the lower part is locked and adjusted by the through nut (2) and washer (3), and the washer (6) is placed on the sleeve ( 5), the cap nut (1) is installed on the upper and lower ends of the screw rod (4), and the cap nut (1) also abuts on the upper and lower end surfaces of the sleeve (5). 2. The sample slotting device for bending element test according to claim 1, characterized in that: both sides of the gasket (6) are provided with symmetrical outwardly protruding tenons (63), the The mounting hole (62) is opened on the raised tenon (63), and the sleeve (5) is provided with a limiting groove (52) for limiting the tenon (63). 3. The sample slotting device for bending element test according to claim 1, characterized in that: the length direction of the vertical positioning hole (61) and a pair of mounting holes opened on the gasket (6) (62) The directions of the connecting lines are perpendicular to each other. 4 . The sample slotting device for bending element test according to claim 1 , wherein the sleeve ( 5 ) is made of hard transparent material. 5 .

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