Axial tensile constitutive test device for steel fiber reinforced concrete
By designing dog-bone specimens and dog-bone fixtures, combined with displacement meter measurement, the stress concentration problem in the axial tensile test of steel fiber reinforced concrete was solved, and the axial tension of the specimen and the precise constitutive curve measurement were achieved.
Patent Information
- Application Number
- CN202422650064.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2034-10-31
AI Technical Summary
In the axial tensile test of steel fiber concrete using existing test equipment, stress concentration is prone to occur at the clamping point of the specimen, causing cracks to appear within non-measurement gauge lengths, affecting the accuracy of the test results.
A dog-bone specimen and a relatively set dog-bone fixture are used. An extension block with an inner convex and arc-shaped structure is used to connect the middle and head parts of the specimen. The displacement meter is combined with the fixed plate and the base plate to ensure that the axis of the specimen is tensile to avoid stress concentration. The relative displacement of the specimen is measured by the displacement meter to obtain an accurate constitutive curve.
It effectively avoids stress concentration at the clamping point of the specimen, ensures that cracks appear in the middle of the specimen cross section, improves the test success rate, and obtains accurate tensile constitutive curves.
Smart Images
Figure CN223449670U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to test equipment technical field, concretely relates to a kind of steel fiber reinforced concrete axial tensile constitutive test device. BACKGROUND
[0002] Concrete axial tensile test is the most suitable and most basic test to obtain concrete tensile strength index, and is the method to accurately obtain full constitutive curve, so developing axial tensile test device has very important theoretical significance and engineering application value.Steel fiber reinforced concrete axial tensile constitutive is the relationship between tensile stress and tensile strain in measuring gauge after concrete test piece is subjected to tension until fracture.Due to steel fiber reinforced concrete does not sharply destroy like ordinary concrete after appearing tensile main crack, still has good residual strength, resulting in that steel fiber reinforced concrete tensile ultimate strain is far greater than ordinary concrete, if more complete tensile constitutive curve is obtained, test measurement in larger deformation range is needed, but due to the randomness of concrete crack development, it is difficult to guarantee that test piece is absolutely axially tensioned in later stage of tensile test, the monitoring precision of test force of existing test device is acceptable, but deformation monitoring error is larger under certain eccentricity condition.On the other hand, in order to facilitate mold production and test piece pouring, the shape of existing variable cross-section clamping type test piece is mostly linear combination, test device clamps test piece, so that stress concentration phenomenon easily occurs at clamped part of test piece in tensile process, resulting in that crack appears at variable cross-section clamping part instead of measuring gauge, and then affect test result. SUMMARY
[0003] The utility model discloses to solve the problem that clamped part of prior art test piece is prone to stress concentration and steel fiber reinforced concrete tensile constitutive curve is difficult to obtain, provide a kind of steel fiber reinforced concrete axial tensile constitutive test device, which can effectively guarantee that test piece is axially tensioned, avoid stress concentration phenomenon at clamped part of test piece, so that test piece crack appears in the middle of test piece section and measuring gauge, improve test success rate;At the same time, accurate steel fiber reinforced concrete tensile constitutive curve is facilitated to obtain.
[0004] In order to achieve the above object, the technical scheme of the utility model is: a kind of steel fiber reinforced concrete axial tensile constitutive test device, including dog bone type test piece, further including measuring assembly and two oppositely arranged, and the same size structure of dog bone type clamp, the dog bone type clamp includes U-shaped seat, extension block and pull head, the both ends of U-shaped seat are equipped with the extension block being inclined inward, the inside of the extension block is outwardly convex arc structure, the pull head is fixedly connected with U-shaped seat. Two dog bone type clamps are connected with MTS testing machine by pull head, so as to carry out axial tensile test on steel fiber reinforced concrete by the cooperation of MTS testing machine and dog bone type clamp;Wherein the middle part and head of dog bone type test piece are connected by the extension block of inside convex and arc structure, so that dog bone type test piece is smooth and continuous when being pulled in axial center, and crack is more likely to occur in the middle part of smaller cross section of dog bone type test piece.
[0005] The measuring assembly includes displacement meter fixing plate, displacement meter base plate and displacement meter, the displacement meter fixing plate and the displacement meter base plate are sleeved at the middle part of the dog bone type test piece, and the displacement meter is arranged on the displacement meter fixing plate and contacts the displacement meter base plate.
[0006] Further, the two ends of the dog bone type test piece are located inside the two dog bone type clamps respectively, and the end of the dog bone type test piece is matched with the dog bone type clamp, so as to carry out axial tensile test on the dog bone type test piece.
[0007] Further, the pull head is vertically arranged at the center position of the horizontal part of the U-shaped seat, and a drill hole is formed in the pull head, so as to connect the pull head with the MTS testing machine through the drill hole.
[0008] Further, the dog bone type clamp further includes two symmetrically arranged clamp baffles, the two ends of the clamp baffle are bolted with the two extension blocks respectively, and the clamp baffle plays a positioning role on the dog bone type test piece.
[0009] Further, convex grooves are formed in the displacement meter fixing plate and the displacement meter base plate, and the displacement meter fixing plate and the displacement meter base plate are fixedly arranged on the dog bone type test piece through the convex grooves.
[0010] Further, the convex slot comprises a test piece slot and a positioning slot, the test piece slot is matched with the middle part of the dog bone type test piece, the length of the test piece slot is less than the thickness of the dog bone type test piece; the positioning slot is detachably provided with a positioning plate, and the displacement meter fixing plate and the displacement meter bottom plate are fixed on the dog bone type test piece under the action of the positioning plate.
[0011] Further, the number of the displacement meters is two, and the displacement meters are located on both sides of the dog bone type test piece, circular holes matched with the displacement meters are formed in the two ends of the displacement meter fixing plate, and the displacement meters are sleeved in the circular holes to be installed on the displacement meter fixing plate through the circular holes.
[0012] Further, a bolt hole is formed in the position corresponding to the circular hole on one side of the displacement meter fixing plate, and a jacking bolt is threadedly connected in the bolt hole to achieve the purpose of fixing the displacement meter.
[0013] Through the above technical scheme, the steel fiber reinforced concrete axial tensile test device has the following beneficial effects:
[0014] The steel fiber reinforced concrete axial tensile test device has the advantages of simple structure, good use effect, effective guarantee of the axial tension of the dog bone type test piece, avoidance of the stress concentration phenomenon of the clamped part of the dog bone type test piece, appearance of the crack in the middle part of the cross section of the dog bone type test piece and the measurement gauge length, improvement of the test success rate, and convenient acquisition of the accurate tensile constitutive curve of the steel fiber reinforced concrete test piece.
[0015] The steel fiber reinforced concrete axial tensile test device has the advantages of simple structure, good use effect, effective guarantee of the axial tension of the dog bone type test piece, avoidance of the stress concentration phenomenon of the clamped part of the dog bone type test piece, appearance of the crack in the middle part of the cross section of the dog bone type test piece and the measurement gauge length, improvement of the test success rate, and convenient acquisition of the accurate tensile constitutive curve of the steel fiber reinforced concrete test piece.
[0016] The steel fiber reinforced concrete axial tensile test device has the advantages of simple structure, good use effect, effective guarantee of the axial tension of the dog bone type test piece, avoidance of the stress concentration phenomenon of the clamped part of the dog bone type test piece, appearance of the crack in the middle part of the cross section of the dog bone type test piece and the measurement gauge length, improvement of the test success rate, and convenient acquisition of the accurate tensile constitutive curve of the steel fiber reinforced concrete test piece. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 is a structural diagram of the steel fiber reinforced concrete axial tensile test device of the utility model Figure 1 ;
[0018] Figure 2 is a structural diagram of the steel fiber reinforced concrete axial tensile test device of the utility modelFigure 2 ;
[0019] Figure 3 is a structural schematic of the steel fiber reinforced concrete axial tensile constitutive test device Figure 3 ;
[0020] Figure 4 is a structural schematic of the dog bone type clamp Figure 1 ;
[0021] Figure 2 is a structural schematic of the dog bone type clamp Figure 6 ;
[0022] Figure 7 is a structural schematic of the displacement meter fixing plate
[0023] Figures 1 to 7 is a structural schematic of the displacement meter base plate.
[0024] The figure is marked: 1 is a dog bone type test piece, 2 is a U-shaped seat, 3 is an extension block, 4 is a pull head, 5 is a drilling hole, 6 is a clamp baffle, 7 is a displacement meter fixing plate, 8 is a displacement meter base plate, 9 is a convex groove, 901 is a test piece groove, 902 is a positioning groove, 10 is a positioning plate, 11 is a circular hole, 12 is a displacement meter, 13 is a bolt hole, 14 is a jacking bolt. DETAILED DESCRIPTION
[0025] The utility model will be further described in connection with the drawings and specific embodiments:
[0026] As shown, a steel fiber reinforced concrete axial tensile constitutive test device, including dog bone type test piece 1, still including measurement subassembly and two opposite settings, and the same size structure dog bone type clamp that is arranged, the dog bone type clamp includes U-shaped seat 2, extension block 3 and pull head 4, U-shaped seat 2 both ends are equipped with the extension block 3 that is inwardly inclined arrangement, the inside of extension block 3 is the outward convex arc structure, pull head 4 is fixedly connected with U-shaped seat 2. In the embodiment, the extension block 3 of U-shaped seat both ends is " eight " character structure, U-shaped seat 2 and extension block 3 are integrally formed structure, pull head 4 is vertically fixed on U-shaped seat 2;Wherein dog bone type test piece 1 is steel fiber reinforced concrete test piece, it is poured by mould, through the cooperation of dog bone type test piece 1 end and dog bone type clamp, and through the extension block 3 of inside convex and arc structure connects the middle part and head of dog bone type test piece 1, so that dog bone type test piece 1 is under the tension of the axial force smooth and continuous, avoid the stress concentration phenomenon of the clamped place of dog bone type test piece 1, crack more easily appears in the middle part of the smaller section of dog bone type test piece 1, thereby improve the test success rate.
[0027] The measurement assembly comprises a displacement meter fixing plate 7, a displacement meter base plate 8 and a displacement meter 12, the displacement meter fixing plate 7 and the displacement meter base plate 8 are sleeved at the middle part of the dog bone-shaped test piece 1, the displacement meter fixing plate 7 and the displacement meter base plate 8 are located between the two dog bone-shaped clamps, and the displacement meter 12 is arranged on the displacement meter fixing plate 7 and the head part is in contact with the displacement meter base plate 8. In this embodiment, when the dog bone-shaped test piece 1 is subjected to axial tensile test by the MTS testing machine, the displacement meter 12 cooperates with the displacement meter fixing plate 7 and the displacement meter base plate 8 to measure the relative displacement in the length between the displacement meter fixing plate 7 and the displacement meter base plate 8, and the displacement meter fixing plate 7, the displacement meter base plate 8, the displacement meter 12 and the dog bone-shaped test piece 1 remain relatively static, wherein the gauge distance between the displacement meter fixing plate 7 and the displacement meter base plate 8 is 100 mm, and the measured relative displacement divided by the gauge distance 100 mm can be converted into the strain of the dog bone-shaped test piece 1; the middle part of the dog bone-shaped test piece 1 has a constant cross-sectional size of 50 mm*50 mm, and the windows software matched with the MTS testing machine can monitor and record the tension (N) in real time, and the tension divided by the cross-sectional area of the middle part of the dog bone-shaped test piece 1 can obtain the stress (MPa) of the dog bone-shaped test piece 1, so as to obtain the tensile constitutive curve of the dog bone-shaped test piece 1.
[0028] The two ends of the dog bone-shaped test piece 1 are located in the two dog bone-shaped clamps respectively, and the end part of the dog bone-shaped test piece 1 matches with the dog bone-shaped clamp. In this embodiment, the shape of the end part of the dog bone-shaped test piece 1 matches with the shape of the dog bone-shaped clamp, so as to carry out axial tensile constitutive test on the dog bone-shaped test piece 1 by the MTS testing machine.
[0029] The pull head 4 is vertically arranged at the center position of the horizontal part of the U-shaped seat 2, and a drill hole 5 is formed in the pull head 4. In this embodiment, the pull head 4 can be connected with the MTS testing machine by bolts passing through the drill hole 5, and the axis of the pull head 4 and the U-shaped seat 2 coincides with the axis of the MTS testing machine.
[0030] The dog bone-shaped clamp further comprises two symmetrically arranged clamp baffles 6, and the two ends of the clamp baffle 6 are bolted with the two extension blocks 3 respectively. In this embodiment, after the dog bone-shaped test piece 1 is installed in the two dog bone-shaped clamps, the two clamp baffles 6 are fixed on the two sides of the two extension blocks 3 respectively, so that the clamp baffle 6 plays a limiting role on the dog bone-shaped test piece 1, limits the position of the dog bone-shaped test piece 1, and avoids the dog bone-shaped test piece 1 from being separated from the dog bone-shaped clamp.
[0031] The convex slot 9 is provided on the displacement meter fixing plate 7 and the displacement meter bottom plate 8, and the displacement meter fixing plate 7 and the displacement meter bottom plate 8 are fixed on the dog bone type test piece 1 through the convex slot 9.
[0032] The convex slot 9 comprises a test piece slot 901 and a positioning slot 902, the test piece slot 901 is matched with the middle part of the dog bone type test piece 1, and the length of the test piece slot 901 is less than the thickness of the dog bone type test piece 1; the positioning slot 902 is detachably provided with a positioning plate 10.
[0033] The number of the displacement meters 12 is two, and the displacement meters 12 are located on both sides of the dog bone type test piece 1; the two ends of the displacement meter fixing plate 7 are provided with circular holes 11 matched with the displacement meters 12, and the displacement meters 12 are sleeved in the circular holes 11.
[0034] The displacement meter fixing plate 7 is provided with a bolt hole 13 corresponding to the position of the circular hole 11 on one side, and a jacking bolt 14 is screw-connected in the bolt hole 13.
[0035] The working principle of the utility model is as follows: when the axial tensile constitutive test of the steel fiber reinforced concrete is carried out, the dog bone type test piece 1 is poured by using a mold, and after the dog bone type test piece 1 is completely solidified, the axial tensile constitutive test can be carried out. That is, the two dog bone type clamps are connected with the MTS experimental machine by the bolts respectively penetrating the drill holes 5 on the two dog bone type clamp pull heads 4, then the two ends of the dog bone type test piece 1 are clamped in the two dog bone type clamps, and then the two clamp baffle plates 6 are fixed on the two sides of the extension blocks 3 of the dog bone type clamps through the bolts, and the clamp baffle plates 6 are used for limiting the dog bone type test piece 1.
[0036] Then the displacement meter fixed plate 7 and the displacement meter bottom plate 8 are respectively clamped on the dog bone type test piece 1 through the test piece slot 901, and the two positioning plates 10 are used to fix the displacement meter fixed plate 7 and the displacement meter bottom plate 8, then the displacement meter 12 is passed through the circular hole 11 and the head of the displacement meter 12 is in contact with the displacement meter bottom plate 8, and the bolt 14 is rotated to tightly fix the displacement meter 12.
[0037] The MTS experimental machine is opened, the dog bone type test piece 1 is subjected to axial tension through the cooperation of the MTS experimental machine and the dog bone type clamp, the displacement meter fixed plate 7, the displacement meter bottom plate 8, the displacement meter 12 and the dog bone type test piece 1 remain relatively static, the displacement meter 12 measures the relative displacement between the displacement meter fixed plate 7 and the displacement meter bottom plate 8, the average value of the relative displacement between the two measured by the two displacement meters 12 is taken as the final deformation value, and the deformation value is divided by the gauge length 100mm to be converted into the strain of the dog bone type test piece 1; the windows software matched with the MTS experimental machine is used to monitor and record the tension (N) in real time, the tension obtained by monitoring is divided by the cross-sectional area of the middle part of the dog bone type test piece 1, so that the stress (MPa) of the dog bone type test piece 1 is obtained, and the tensile constitutive curve of the dog bone type test piece 1 is obtained, that is, the axial tensile stress-strain curve of the steel fiber reinforced concrete is obtained.
[0038] The above-mentioned embodiments are only preferred embodiments of the utility model, and do not limit the scope of the utility model, so equivalent changes or modifications made according to the technical solutions described in the utility model patent range should be included in the patent range of the utility model application.
Claims
1. A steel fiber concrete axial tensile constitutive test device, comprising a dog-bone specimen (1), characterized in that: It also includes a measuring component and two dog-bone-shaped clamps that are arranged opposite to each other and have the same size and structure. The dog-bone-shaped clamps include a U-shaped seat (2), an extension block (3) and a pull head (4). Both ends of the U-shaped seat (2) are provided with the extension block (3) that is inclined inwardly. The inner side of the extension block (3) is an outwardly convex arc structure. The pull head (4) is fixedly connected to the U-shaped seat (2). The measuring assembly comprises a displacement meter fixing plate (7), a displacement meter base plate (8) and a displacement meter (12); the displacement meter fixing plate (7) and the displacement meter base plate (8) are spaced apart and sleeved in the middle of the dog-bone type specimen (1); the displacement meter fixing plate (7) and the displacement meter base plate (8) are located between two dog-bone type fixtures; the displacement meter (12) is arranged on the displacement meter fixing plate (7), and the head thereof is in contact with the displacement meter base plate (8).
2. The steel fiber concrete axial tensile constitutive test device according to claim 1, characterized in that: The two ends of the dog-bone-shaped test piece (1) are respectively located inside the two dog-bone-shaped clamps, and the ends of the dog-bone-shaped test piece (1) match the dog-bone-shaped clamps.
3. The steel fiber concrete axial tensile constitutive test device according to claim 1, characterized in that: The pull head (4) is vertically arranged at the center of the horizontal portion of the U-shaped seat (2), and a drill hole (5) is provided on the pull head (4).
4. The steel fiber concrete axial tensile constitutive test device according to claim 1, characterized in that: The dog-bone type clamp further comprises two symmetrically arranged clamp baffles (6), and the two ends of the clamp baffles (6) are respectively connected to the two extension blocks (3) by bolts.
5. The steel fiber concrete axial tensile constitutive test device according to claim 1, characterized in that: The displacement meter fixing plate (7) and the displacement meter bottom plate (8) are both provided with convex grooves (9), and the displacement meter fixing plate (7) and the displacement meter bottom plate (8) are fixedly arranged on the dog-bone test piece (1) via the convex grooves (9).
6. The steel fiber concrete axial tensile constitutive test device according to claim 5, characterized in that: The convex groove (9) comprises a specimen groove (901) and a positioning groove (902), wherein the specimen groove (901) matches the middle portion of the dog-bone-shaped specimen (1), and the length of the specimen groove (901) is less than the thickness of the dog-bone-shaped specimen (1); a positioning plate (10) is detachably provided at the positioning groove (902).
7. The steel fiber concrete axial tensile constitutive test device according to claim 1, characterized in that: There are two displacement meters (12) located on both sides of the dog-bone test piece (1), and circular holes (11) matching the displacement meters (12) are provided at both ends of the displacement meter fixing plate (7), and the displacement meters (12) are sleeved in the circular holes (11).
8. The steel fiber concrete axial tensile constitutive test device according to claim 7, characterized in that: A bolt hole (13) is provided on one side of the displacement meter fixing plate (7) at a position corresponding to the circular hole (11), and a tightening bolt (14) is connected to the inner thread of the bolt hole (13).