3D printing concrete material shear test mold

Abstract

The invention discloses a 3D printing concrete material shear test mold, and relates to the technical field of test piece shear tests.The 3D printing concrete material shear test mold comprises a fixed supporting piece and a pressing piece, the fixed supporting piece is provided with a containing cavity used for containing a transverse part of a to-be-sheared sample, and the pressing piece and the containing cavity are arranged in a staggered mode; the pressing piece moves towards or away from the fixed supporting piece through the regulation and control mechanism, rolling pieces are rotationally arranged on the opposite faces of the pressing piece and the fixed supporting piece, and a clamping space used for clamping a vertical part of a to-be-sheared sample is formed between the rolling pieces of the pressing piece and the rolling pieces of the fixed supporting piece; the vertical part of the to-be-sheared sample is in rolling contact with the rolling pieces on the two sides; the vertical part of the to-be-sheared sample is stably clamped by the pressing piece and the fixed supporting piece, a pure shear test can be realized, and the vertical part of the to-be-sheared sample is in rolling contact with the pressing piece and the fixed supporting piece, so that the influence of friction force on the shear test is reduced, and the accuracy of a test result is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of specimen shear testing, and in particular to a 3D printing concrete material shear testing mold. Background Art

[0002] With the rapid development of additive manufacturing in construction, 3D printed concrete, as a new type of engineering construction method, has been applied in many countries and regions. This technology constructs the overall structure by layer-by-layer deposition, and has the advantages of high degree of construction automation, saving formwork costs, and large design freedom. However, the interlayer interface area formed during the 3D printing process often has defects such as insufficient bonding, pores or microcracks, which become the weak link in structural performance.

[0003] In order to study the interfacial bonding performance of 3D-printed concrete layers, it is necessary to conduct interfacial shear tests on the specimens. In the currently widely used oblique shear test, the normal stress component formed by the inclination angle will actively apply uncontrollable lateral pressure. According to the MOHR-COULOMB theory, this additional stress will significantly change the characterization values ​​of the interfacial cohesion and internal friction angle; and although the double shear test has better symmetrical loading characteristics, the coexistence of double shear surfaces in its parallel interfaces makes it difficult to accurately peel off the true mechanical response of a single interface in the failure mode; the above-mentioned systematic deviations have seriously restricted the basic research on the interfacial bonding mechanism of 3D-printed materials.

[0004] As for the shear device, existing concrete shear fixtures generally adopt a surface contact clamping mechanism. Such rigid fixtures apply high-strength clamping force to ensure the stability of the specimen, which interferes with the test loading path and reduces the accuracy of the test results.

[0005] Therefore, people are in urgent need of a 3D printing concrete material shear test mold with high test accuracy. Summary of the Invention

[0006] The purpose of the present invention is to provide a 3D printed concrete material shear test mold to solve the problems existing in the above-mentioned prior art. On the basis of using a clamping member and a fixed support member to clamp the vertical part of the sample to be sheared to realize a pure shear test, the surface is changed to a rolling clamping to reduce the influence of clamping friction on the test results, thereby improving the test accuracy.

[0007] To achieve the above-mentioned objectives, the present invention provides the following solution: The present invention provides a 3D printing concrete material shear test mold, comprising a fixed support member and a pressing member, wherein the fixed support member is provided with an accommodating cavity for accommodating the transverse portion of the sample to be sheared, the pressing member and the accommodating cavity are staggered, and the pressing member moves toward or away from the fixed support member through a regulating mechanism, and rolling members are rotatably provided on the opposite surfaces of the pressing member and the fixed support member, and a clamping space for clamping the vertical portion of the sample to be sheared is formed between the rolling member of the pressing member and the rolling member of the fixed support member, and the vertical portion of the sample to be sheared is in rolling contact with the rolling members on both sides.

[0008] Preferably, along the direction of the vertical portion of the sample to be sheared, a plurality of rolling members are provided on both the pressing member and the fixed support member.

[0009] Preferably, a groove body for accommodating the rolling member is provided on the opposing surfaces of the clamping member and the fixed support member, and the rolling member is rotatably arranged in the groove body. A pressure plate groove is vertically provided on the opposing surfaces of the clamping member and the fixed support member, and an isolation pressure plate is vertically slidably provided in the pressure plate groove. One end face of the isolation pressure plate contacts the vertical part of the sample to be sheared, and the other end face contacts the rolling member.

[0010] Preferably, the width of the isolation pressure plate along the axial direction of the rolling element is not less than the width of the vertical portion of the sample to be sheared along the axial direction of the rolling element.

[0011] Preferably, the width of the pressure plate groove along the axial direction of the rolling element matches the width of the isolation pressure plate along the axial direction of the rolling element.

[0012] Preferably, the upper surface of the isolation pressure plate is flush with the lower surface of the accommodating cavity.

[0013] Preferably, the upper surface of the pressing member is flush with the lower surface of the accommodating cavity.

[0014] Preferably, the regulating mechanism includes at least two adjusting screws, the axis of the adjusting screw is parallel to the movement direction of the clamping member, one end of the adjusting screw passes through the clamping member and is threadedly connected to the first adjusting nut, and the other end passes through the fixed support member and is threadedly connected to the second adjusting nut.

[0015] Preferably, washers are provided between the first adjusting nut and the pressing member, and between the second adjusting nut and the fixing support member.

[0016] Preferably, a positioning member with vertical movement function is provided in the accommodating cavity.

[0017] Compared with the prior art, the present invention mainly achieves the following technical effects:

[0018] The horizontal portion of the sample to be sheared is placed in the accommodating cavity, and the vertical portion of the sample to be sheared is stably clamped by the clamping member and the fixed support member. At this time, a shear force is applied to the vertical portion of the sample to be sheared, which can realize a pure shear test and improve the accuracy of the test results. Moreover, the vertical portion of the sample to be sheared is in rolling contact with the clamping member and the fixed support member, which can effectively reduce the friction force generated during the clamping process that prevents the vertical portion of the sample to be sheared from moving vertically, that is, reduce the influence of friction on the shear test, and further improve the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 Schematic diagram of the structure of the 3D printing concrete material shear test mold in an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of the structure of the 3D printing concrete material shear test mold clamping the sample to be sheared in an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of the cross-sectional structure of a 3D printed concrete material shear test mold in an embodiment of the present invention;

[0023] Figure 4 This is a schematic structural diagram of a fixed support member in an embodiment of the present invention;

[0024] Figure 5 Schematic diagram of the structure of the pressing member in an embodiment of the present invention;

[0025] Figure 6 Schematic diagram of the structure of a rolling element in an embodiment of the present invention;

[0026] Figure 7 Schematic diagram of the structure of the isolation pressure plate in an embodiment of the present invention;

[0027] Figure 8 This is a schematic structural diagram of a control mechanism in an embodiment of the present invention;

[0028] Among them, 1. horizontal part; 2. vertical part; 3. fixed support part; 4. pressing part; 5. accommodating cavity; 6. rolling part; 7. trough body; 8. pressure plate groove; 9. isolation pressure plate; 10. adjusting screw; 11. first adjusting nut; 12. second adjusting nut; 13. washer. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0030] The purpose of the present invention is to provide a 3D printed concrete material shear test mold to solve the problems existing in the prior art. On the basis of using a clamping member and a fixed support member to clamp the vertical part of the sample to be sheared to realize a pure shear test, the surface clamping is changed to a rolling clamping to reduce the influence of clamping friction on the test results, thereby improving the test accuracy.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Please refer to Figures 1 to 8 As shown, a 3D printing concrete material shear test mold is provided, which is suitable for 3D printing concrete material samples with a T-shaped, L-shaped and cross-shaped lateral portion 1 and a vertical portion 2 distributed at 90 degrees, including a fixed support member 3 and a pressing member 4. The fixed support member 3 is provided with a receiving cavity 5 for accommodating the lateral portion 1 of the sample to be sheared. The pressing member 4 is staggered with the accommodating cavity 5. The pressing member 4 moves toward or away from the fixed support member 3 through a regulating mechanism. Rolling members 6 are rotatably provided on the opposite surfaces of the pressing member 4 and the fixed support member 3 through bearings. A clamping member for clamping the vertical portion 2 of the sample to be sheared is formed between the rolling member 6 of the pressing member 4 and the rolling member 6 of the fixed support member 3. Space, the vertical part 2 of the sample to be sheared is in rolling contact with the rolling members 6 on both sides. The shear test principle and effect of this mold are as follows: the horizontal part 1 of the sample to be sheared is placed in the accommodating cavity 5, and the vertical part 2 of the sample to be sheared is stably clamped by the clamping member 4 and the fixed support member 3. At this time, shear force is applied to the vertical part 2 of the sample to be sheared, which can realize a pure shear test and improve the accuracy of the test results. Moreover, the vertical part 2 of the sample to be sheared is in rolling contact with the clamping member 4 and the fixed support member 3, which can effectively reduce the friction force generated during the clamping process to prevent the vertical part 2 of the sample to be sheared from moving vertically, that is, reduce the influence of friction on the shear test, and further improve the accuracy of the test results.

[0033] In some embodiments, multiple rolling members 6 are provided on the clamping member 4 and the fixed support member 3 along the upward direction of the vertical portion 2 of the sample to be sheared, and both sides of the vertical portion 2 of the sample to be sheared are in contact with the multiple rolling members 6, thereby increasing the contact area and avoiding the problem of damage to the vertical portion 2 of the sample to be sheared due to the small contact area when the clamping member 4 cooperates with the fixed support member 3 to press the vertical portion 2 of the sample to be sheared.

[0034] In some embodiments, grooves 7 for accommodating rolling members 6 are provided on the opposing surfaces of the clamping member 4 and the fixed support member 3, and the rolling members 6 are rotatably provided in the grooves 7. Pressure plate grooves 8 are vertically provided on the opposing surfaces of the clamping member 4 and the fixed support member 3, and an isolation pressure plate 9 is vertically slidably provided in the pressure plate groove 8. One end face of the isolation pressure plate 9 contacts the vertical portion 2 of the sample to be sheared, and the other end face contacts the rolling member 6. The isolation pressure plate 9 is utilized to replace the rolling member 6 in contacting the vertical portion 2 of the sample to be sheared. The vertical sliding characteristic of the isolation pressure plate 9 can ensure that the vertical portion 2 of the sample to be sheared is actually in rolling contact with the rolling members 6 on both sides when it moves downward under the shear force, and it is also equivalent to increasing the contact area between the rolling member 6 and the vertical portion 2 of the sample to be sheared, which can further avoid the problem of the vertical portion 2 of the sample to be sheared being damaged during the clamping process.

[0035] The width of the isolation pressure plate 9 along the axial direction of the rolling element 6 is not less than the width of the vertical portion 2 of the sample to be sheared along the axial direction of the rolling element 6, so that only the sliding isolation pressure plate 9 is in contact with the vertical portion 2 of the sample to be sheared, and the vertical portion 2 of the sample to be sheared does not come into contact with any fixed structure, ensuring that only a small rolling friction force exists during the shear test.

[0036] Of course, an isolation pressure plate 9 can also be set to extend out of the pressure plate groove 8 near the end face of the vertical part 2 of the sample to be sheared. This can also ensure that only the sliding isolation pressure plate 9 is in contact with the vertical part 2 of the sample to be sheared. In this case, the width of the isolation pressure plate 9 along the axial direction of the rolling element 6 can be set to be smaller than the width of the vertical part 2 of the sample to be sheared along the axial direction of the rolling element 6. However, in order to increase the contact area, it is preferred that the width of the isolation pressure plate 9 along the axial direction of the rolling element 6 is greater than or equal to the width of the vertical part 2 of the sample to be sheared along the axial direction of the rolling element 6.

[0037] The width of the pressure plate groove 8 along the axial direction of the rolling element 6 matches the width of the isolation pressure plate 9 along the axial direction of the rolling element 6 , preventing the isolation pressure plate 9 from sliding in the pressure plate groove 8 along the width direction.

[0038] The upper surface of the isolation plate 9 is flush with the lower surface of the accommodating cavity 5, which can achieve clamping and supporting the vertical portion 2 of the sample to be sheared from the shearing position, and maximize the contact area between the isolation plate 9 and the vertical portion 2 of the sample to be sheared.

[0039] In some embodiments, a pressure sensor for detecting the clamping force can be provided on the isolation plate 9 to obtain the current clamping force of the vertical portion 2 of the sample to be sheared, thereby determining the clamping state and avoiding damage to the sample to be sheared caused by excessive clamping force.

[0040] The upper surface of the pressing member 4 is flush with the lower surface of the accommodating cavity 5 , so that the upper surface of the pressing member 4 can also support the transverse portion 1 of the sample to be sheared, thereby improving the supporting effect on the transverse portion 1 of the sample to be sheared.

[0041] In this embodiment, the regulating mechanism includes at least two adjusting screws 10, the axis of the adjusting screw 10 is parallel to the movement direction of the clamping member 4, one end of the adjusting screw 10 passes through the clamping member 4 and is threadedly connected to the first adjusting nut 11, and the other end passes through the fixed support member 3 and is threadedly connected to the second adjusting nut 12. By screwing the adjusting screws 10 on both sides to move relative to each other on the adjusting screws 10, the distance between the clamping member 4 and the fixed support member 3 can be controlled to shorten, thereby achieving clamping of the vertical portion 2 of the sample to be sheared.

[0042] In some embodiments, one of the first adjusting nut 11 and the second adjusting nut 12 can be replaced by a fixing member fixedly provided on the adjusting screw 10. In this structure, when clamping is required, it is sufficient to control the only remaining adjusting nut.

[0043] In some embodiments, a linear motion mechanism such as an electric push rod, a hydraulic push rod or a pneumatic push rod can also be used as a regulating mechanism to directly drive the pressing member 4 to move.

[0044] Washers 13 are provided between the first adjusting nut 11 and the pressing member 4 and between the second adjusting nut 12 and the fixing support member 3 , which can improve the protection effect of the pressing member 4 and the fixing support member 3 .

[0045] In some embodiments, a positioning member with a vertical movement function is provided in the accommodating cavity 5, and the lateral part 1 of the sample to be sheared can be positioned from above by the positioning member, so as to prevent the lateral part 1 of the sample to be sheared from tilting upward during the shearing process, thereby affecting the normal vertical shearing. The positioning member is controlled by a linear motion mechanism such as an electric push rod, a hydraulic push rod or a pneumatic push rod; or a screw rod with a threaded connection is provided on the upper surface of the fixed support member 3, and the screw rod extends through the fixed support member 3 into the accommodating cavity 5 and is fixedly connected to the positioning member. At this time, the vertical position of the positioning member can be adjusted by screwing the screw rod, or other mechanisms that can control the vertical movement of the positioning member in the accommodating cavity 5 can be used.

[0046] In order to accommodate more specimens of different specifications, a accommodating chamber 5 can be set to pass through the entire fixed support member 3 horizontally, which can be adapted to specimens to be sheared with transverse portions 1 of different lengths. At the same time, the accommodating chamber 5 can also be set to pass through the entire fixed support member 3 axially along the rolling member 6, which can be adapted to specimens to be sheared with transverse portions 1 of different widths. However, it is necessary to ensure that there is a fixed connection between the upper wall plate and the lower wall plate used to form the accommodating chamber 5 to ensure the stable existence of the accommodating chamber 5; the upper wall plate and the circumferential wall plate of the accommodating chamber 5 can also be directly eliminated, and the positioning member can be used as the upper wall plate. In this case, the positioning member and the upper surface of the fixed support member 3 form a circumferentially unrestricted accommodating chamber 5. In this case, the positioning member needs to be controlled by a linear motion mechanism such as an electric push rod, a hydraulic push rod or a pneumatic push rod above. This structure can be adapted to specimens to be sheared with transverse portions 1 of different lengths and widths.

[0047] If there is no application scope requirement, the accommodating cavity 5 can be directly set as a cavity that matches the transverse portion 1 of the sample to be sheared, and there is no need to set a positioning piece.

[0048] During actual use, the horizontal portion 1 of the sample to be sheared is placed in the accommodating cavity 5, and the vertical portion 2 is placed between the isolation pressure plate 9 of the clamping member 4 and the isolation pressure plate 9 of the fixed support member 3. Then, by adjusting the first adjusting nut 11 and the second adjusting nut 12, the clamping member 4 and the fixed support member 3 are clamped to the vertical portion 2 of the sample to be sheared. At this time, shear force can be applied to the vertical portion 2 of the sample to be sheared from above and a pure shear test can be performed.

[0049] Adaptive changes based on actual needs are all within the scope of protection of the present invention.

[0050] It should be noted that it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0051] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A 3D printing concrete material shear test mold, characterized in that: The invention comprises a fixed support member and a pressing member, wherein the fixed support member is provided with an accommodating cavity for accommodating the transverse portion of the sample to be sheared, the pressing member and the accommodating cavity are staggered, and the pressing member moves toward or away from the fixed support member through a regulating mechanism, and rolling members are rotatably provided on the opposite surfaces of the pressing member and the fixed support member, and a clamping space for clamping the vertical portion of the sample to be sheared is formed between the rolling member of the pressing member and the rolling member of the fixed support member, and the vertical portion of the sample to be sheared is in rolling contact with the rolling members on both sides.

2. The 3D printing concrete material shear test mold according to claim 1, characterized in that: Along the direction of the vertical portion of the sample to be sheared, a plurality of rolling members are provided on both the pressing member and the fixed support member.

3. The 3D printing concrete material shear test mold according to claim 1, characterized in that: A groove body for accommodating the rolling member is provided on the opposing surfaces of the clamping member and the fixed support member, and the rolling member is rotatably arranged in the groove body. A pressure plate groove is vertically provided on the opposing surfaces of the clamping member and the fixed support member, and an isolation pressure plate is vertically slidably provided in the pressure plate groove. One end face of the isolation pressure plate contacts the vertical part of the sample to be sheared, and the other end face contacts the rolling member.

4. The 3D printing concrete material shear test mold according to claim 3, characterized in that: The width of the isolation pressure plate along the axial direction of the rolling element is not less than the width of the vertical portion of the sample to be sheared along the axial direction of the rolling element.

5. The 3D printing concrete material shear test mold according to claim 3, characterized in that: The width of the pressure plate groove along the axial direction of the rolling element matches the width of the isolation pressure plate along the axial direction of the rolling element.

6. The 3D printing concrete material shear test mold according to claim 3, characterized in that: The upper surface of the isolation pressure plate is flush with the lower surface of the accommodating cavity.

7. The 3D printing concrete material shear test mold according to claim 1, characterized in that: The upper surface of the pressing member is flush with the lower surface of the accommodating cavity.

8. The 3D printing concrete material shear test mold according to claim 1, characterized in that: The regulating mechanism includes at least two adjusting screws, the axes of the adjusting screws are parallel to the movement direction of the pressing member, one end of the adjusting screw passes through the pressing member and is threadedly connected to the first adjusting nut, and the other end passes through the fixed support member and is threadedly connected to the second adjusting nut.

9. The 3D printing concrete material shear test mold according to claim 8, characterized in that: Washers are provided between the first adjusting nut and the pressing member, and between the second adjusting nut and the fixing support member.

10. The 3D printing concrete material shear test mold according to claim 1, characterized in that: A positioning piece with a vertical movement function is arranged in the accommodating cavity.

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