A hydraulic direct loading type UHPC anti-pulling test device

Abstract

The present application relates to a kind of hydraulic direct loading UHPC tensile test device, effectively solve the tensile test device partial damage to sample, the rigidity of device is poor, the problem that tension is easily eccentric;Solving technical solutions include sample, cylinder and the connecting structure located at the both ends of cylinder, cylinder is the cylinder shape of both ends opening, oil hole is equipped on the side wall of cylinder, sample is the dumbbell-shaped structure of both ends thick middle thin, sample is coaxially placed in cylinder, sample both ends are cooperated with cylinder by connecting structure, connecting structure can realize the sealing cooperation between the inner wall of cylinder and the outer wall of sample, connecting structure is relatively fixed with sample, and the connecting mechanism of each end can be axially slid outward relative to cylinder;Hydraulic oil is directly acted on sample end portion, can guarantee the uniform distribution of pressure on sample bearing surface and the direction of resultant force along sample axial direction, avoid partial damage to sample or sample to bear bending moment or shear force influence test, and make the rigidity of whole device better.

Description

TECHNICAL FIELD

[0001] The application relates to the field of concrete performance detection, and particularly relates to a hydraulic direct loading type UHPC tensile test device. BACKGROUND

[0002] UHPC is a kind of concrete material with super-high strength, high toughness and high durability, has an extremely dense microstructure, and the porosity is far lower than that of traditional concrete, the dense structure makes it have extremely strong impermeability, and the high flowability and high self-compaction performance of UHPC can avoid the defects of surface honeycomb and rough surface, and the surface after pouring is smooth like a mirror, and the surface smoothness can reach the level of decorative materials.

[0003] The tensile test is used for testing the tensile performance of UHPC, and the current tensile test device generally adopts the mode of clamping the two ends of the sample by a clamp and then simultaneously applying a tensile force; for example, the application number CN202210356394.9 discloses a clamping device for dog bone test block tensile strength detection, the sample is set as a dog bone shape with enlarged two ends, then two groups of clamps are used to clamp the two ends of the sample, and a tensile force is loaded.

[0004] The above-mentioned rigid clamping mode through the mechanical clamping mechanism concentrates the stress points in the contact local part of the clamp and the sample, the stress position is concentrated, and the sample is prone to local damage; moreover, the two groups of clamps are located outside the two ends of the sample, the axial size of the device is large, the rigidity of the whole device is poor, and the device is prone to deformation when a large load is loaded; moreover, affected by the clamping precision of the clamp and the surface position precision of the sample, the tensile direction is prone to not coinciding with the sample axis during the tensile test, so that the sample bears a bending moment or a shearing force, and the test result is affected.

[0005] Based on the above-mentioned UHPC with extremely low porosity and high-quality forming surface, it is possible to directly bear the pressure of hydraulic oil as a mechanical part during the test for a short time without transmitting the tensile force through other rigid clamps, which provides a new direction for the tensile test of the UHPC sample.

[0006] The application number: CN201310533896.5 invention patent discloses a kind of pipe forming performance testing device and method under the action of internal and external pressure, which is by the hydraulic cavity in the pipe wall The hydraulic pressure is applied to the pipe wall, the workpiece is clamped by piston and punch, and then the clamping force is applied to the test piece to exert pulling force;Although the patent directly applies hydraulic pressure to the workpiece, the hydraulic pressure is only radial force, and the axial force is still loaded by mechanical clamping of piston and punch, so it is not possible to directly load axial force on the workpiece by hydraulic pressure;In addition, UHPC test piece as a concrete pouring piece, the shape and size tolerance is much lower than that of metal test piece, and it does not have the condition of being a mechanical part, so there is no solution in the field for hydraulic pressure to act directly on the concrete test piece, especially for axial force loading. To realize this technical concept, it is necessary to break the inherent thinking in the field and overcome technical bias, and then solve the technical problems of kinematic pair design and sealing. SUMMARY

[0007] The present application provides a kind of hydraulic direct loading type UHPC tensile test device, to solve the problem that tensile test device is easy to cause local damage to test sample, the rigidity of device is poor, and the pulling force is easy to eccentric.

[0008] The technical solution includes a test sample, a cylinder and a connecting structure at both ends of the cylinder. The cylinder is a cylindrical shape with open ends. The cylinder side wall is provided with an oil hole. The test sample is a dumbbell-shaped structure with thick ends and a thin middle part. The test sample is coaxially arranged in the cylinder. The test sample is connected to the cylinder through the connecting structure at both ends. The connecting structure can realize sealed cooperation between the inner wall of the cylinder and the outer wall of the test sample. The connecting structure is fixed relative to the test sample, and the connecting structure at each end can slide axially outward relative to the cylinder.

[0009] The test sample is composed of head parts at both ends and a rod part in the middle. The rod part is a cylindrical shape with uniform diameter and is connected to the head parts at both ends. The head part includes a first cone, and the small end of the first cone is connected to the end of the rod part.

[0010] The connecting structure includes a sliding sleeve. The outer wall of the sliding sleeve is in contact with and sealed to the inner wall of the cylinder. The sliding sleeve can slide outward relative to the cylinder. The inner wall of the sliding sleeve is in sealed cooperation with the outer wall of the head part of the test sample.

[0011] Each end of the cylinder is screwed with a limiting ring. The inner wall of the limiting ring is provided with a limiting ridge. The inner diameter of the limiting ridge is smaller than the outer diameter of the sliding sleeve, and there is a gap between the limiting ridge and the outer end of the sliding sleeve.

[0012] The head part of the test sample further includes a second cone. The second cone is located at the outer end of the first cone and has a small end facing outward. The inner wall of the sliding sleeve is a conical surface with a small end facing outward. The second cone cooperates with the inner wall of the sliding sleeve.

[0013] The outer end of the sample is pre-buried with a screw rod, a limiting disc is penetrated through the screw rod, a compression nut is screwed on the outer side of the limiting disc, the limiting disc is compressed on the end of the sample, and the outer edge of the limiting disc is pressed on the outer end of the sliding sleeve.

[0014] An axial glue injection hole is opened on the outer end surface of the sliding sleeve, the lower end of the glue injection hole is located on the inner wall taper surface of the sliding sleeve, and the glue injection hole can press and inject sealing glue between the outer wall of the second taper of the head of the sample and the sliding sleeve.

[0015] The taper of the second taper is smaller than the taper of the inner wall of the sliding sleeve.

[0016] The head of the sample further comprises a connecting section between the first taper and the second taper, the connecting section is cylindrical, and a sealing ring is installed between the outer wall of the connecting section and the inner wall of the sliding sleeve.

[0017] The application utilizes the material characteristics of the UHPC sample, such as dense texture and high surface forming quality, the good filling property of the sealing layer formed by the post-pressure injection of the sealing glue, and the wedge-shaped interval between the sample and the sliding sleeve, to ensure the reliable sealing between the sample and the sliding sleeve, so that the sample can be directly used as a piston piece of the hydraulic system, the pressure of the hydraulic oil directly acts on the end of the sample, unlike the traditional rigid contact or clamping loading mode, the hydraulic oil can ensure the uniform distribution of the pressure on the bearing surface of the sample and the direction of the resultant force along the axial direction of the sample, and the local damage of the sample or the bending moment or shear force borne by the sample does not affect the test.

[0018] In addition, the application does not need to set clamping mechanisms and loading mechanisms outside the two ends of the sample, greatly reduces the axial size of the whole device, makes the rigidity of the whole device better, and does not occur flexible deformation; and the whole device has a regular columnar shape, and the structure is more simple and compact. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a front view of the application.

[0020] Figure 2 It is Figure 1 It is an enlarged view of the A position.

[0021] Figure 3 It is a top view of the application.

[0022] Figure 4 It is an assembly sequence sectional view schematic diagram of the application.

[0023] Figure 5 It is an assembly sequence perspective schematic diagram of the application.

[0024] Figure 6 It is a perspective view of the sample.

[0025] Figure 7 isometric view of the slip sleeve. DETAILED DESCRIPTION

[0026] In combination with the drawings, the present application comprises a test sample 1, a cylinder 2 and a connecting structure at both ends of the cylinder 2, the cylinder 2 is a cylinder with both ends open, the cylinder 2 is provided with an oil hole 3 on the side wall, the oil hole 3 is connected with an oil circuit, which is used to control the hydraulic oil to enter and exit the cylinder 2, the test sample 1 is a dumbbell-shaped structure with thick ends and a thin middle, the test sample 1 is coaxially arranged in the cylinder 2, the test sample 1 is matched with the cylinder 2 through the connecting structure at both ends, the connecting structure can realize the sealing cooperation between the inner wall of the cylinder 2 and the outer wall of the test sample 1, the connecting structure is relatively fixed with the test sample 1, and the connecting structure at each end can slide axially outward relative to the cylinder 2; That is, the connecting structure will not exert an axial inward restraining force on the test sample 1 to avoid affecting the test results, when the hydraulic oil is pumped into the cylinder 2 to pressurize, the hydraulic pressure will act on both ends of the test sample 1, so that both ends of the test sample 1 are simultaneously subjected to an axial outward pressure, thereby realizing the loading of the pulling force on the test sample 1.

[0027] The test sample 1 is composed of head portions 4 at both ends and a rod portion 5 in the middle, the rod portion 5 is a cylinder with uniform diameter and is connected with the head portions 4 at both ends, the head portion 4 comprises a first cone 6, the small end of the first cone 6 is connected with the end portion of the rod portion 5, and the connection is smoothly transitioned through a round corner to avoid stress concentration; the rod portion 5 is the position where the test sample 1 breaks, and the conical surface of the first cone 6 of the head portion 4 is the action surface of the hydraulic pressure.

[0028] The connecting structure comprises a slip sleeve 7, the outer wall of the slip sleeve 7 is attached to and sealed with the inner wall of the cylinder 2, the slip sleeve 7 can slide outward relative to the cylinder 2, the inner wall of the slip sleeve 7 is sealed and matched with the outer wall of the head portion 4 of the test sample 1, through the cooperation of the slip sleeve 7 with the cylinder 2 and the slip sleeve 7 with the test sample 1, the end portion of the cylinder 2 is sealed while not exerting an axial inward restraining force on the end portion of the test sample 1.

[0029] Each end of the cylinder 2 is screwed with a limiting ring 8, the inner wall of the limiting ring 8 is provided with a limiting ridge 9 at the outer end, the inner diameter of the limiting ridge 9 is smaller than the outer diameter of the slip sleeve 7, and there is a gap between the outer end of the limiting ridge 9 and the slip sleeve 7, the limiting ridge 9 can limit the sliding distance of the slip sleeve 7 outward to avoid the slip sleeve 7 from slipping out of the cylinder 2.

[0030] The head portion 4 of the test sample 1 further comprises a second cone 10, the second cone 10 is located at the outer end of the first cone 6 and has a small end facing outward, the inner wall of the slip sleeve 7 has a conical surface with a small end facing outward, and the second cone 10 cooperates with the inner wall of the slip sleeve 7; through the cooperation of the conical surface, the test sample 1 cannot move outward relative to the slip sleeve 7 when subjected to an axial pulling force, which can avoid the test sample 1 from slipping out of the cylinder 2.

[0031] The outer end of the sample 1 is pre-buried with a screw rod 11, the screw rod 11 is provided with a limiting disc 12, the screw rod 11 is provided with a pressing nut 13 which is located outside the limiting disc 12, the limiting disc 12 is pressed on the end of the sample 1, the outer edge of the limiting disc 12 is pressed on the outer end of the sliding sleeve 7; the limiting disc 12 makes the sliding sleeve 7 unable to move outward relative to the sample 1; through the cooperation of the conical surface and the limiting of the limiting disc 12, the relative position of the sample 1 and the sliding sleeve 7 is fixed, the sealing difficulty between the sample 1 and the sliding sleeve 7 can be greatly reduced, and the possibility of sealing failure can be greatly reduced.

[0032] The outer end surface of the sliding sleeve 7 is provided with an axial glue injection hole 14, the lower end of the glue injection hole 14 is located on the inner wall conical surface of the sliding sleeve 7, the glue injection hole 14 can be used to press and inject sealing glue between the outer wall of the second cone 10 of the head 4 of the sample 1 and the sliding sleeve 7, after the sealing glue solidifies, a rear filling sealing layer 15 is formed; the sealing layer 15 can densely fill the gap between the sample 1 and the sliding sleeve 7, thereby forming an effective sealing layer 15.

[0033] The taper of the second cone 10 is smaller than the taper of the inner wall of the sliding sleeve 7, so that the gap between the sample 1 and the sliding sleeve 7 is wedge-shaped with a narrow outer end and a wide inner end, and when the sealing layer 15 in the gap is pressed by the liquid pressure in the cylinder body 2, it can be further pressed, thereby ensuring the effectiveness of the sealing.

[0034] The head 4 of the sample 1 further comprises a connecting section 16 located between the first cone 6 and the second cone 10, the connecting section 16 is cylindrical, and a sealing ring 17 is installed between the outer wall of the connecting section 16 and the inner wall of the sliding sleeve 7; on the one hand, the sealing ring 17 and the sealing layer 15 formed by the glue injection form two-stage sealing, improving the sealing reliability, and on the other hand, the sealing ring 17 intercepts the sealing glue as the bottom of the gap when the glue is injected, avoiding the leakage of the sealing glue from the lower end of the sliding sleeve 7, and ensuring the dense injection of the glue in the gap.

[0035] When the present application is used for testing, the sample 1 needs to be assembled into the cylinder body 2 first, and the specific assembly sequence is as follows: first, the sample 1 is placed in the cylinder body 2, then the sliding sleeve 7 is assembled into the end of the cylinder body 2, since the sliding sleeve 7 and the cylinder body 2 are in conventional sliding fit, a conventional sealing ring can be used for sealing; while the sliding sleeve 7 is assembled into the cylinder body 2, the sliding sleeve 7 is sleeved on the head 4 of the sample 1, then the limiting disc 12 is assembled on the screw rod 11 at the end of the sample 1 and the pressing nut 13 is screwed, the limiting disc 12 is pressed on the end of the sample 1 to limit the sliding sleeve 7, finally the limiting ring 8 is screwed on the end of the cylinder body 2, and the assembly is completed.

[0036] After assembly, sealant is injected into the gap between the sleeve 7 and the sample 1 through the sealant injection hole 14 at the end of the sleeve 7, and the sealant is kept for 10 to 20 minutes during injection, so that the gap between the sleeve 7 and the sample 1 is filled densely. After the sealant solidifies, a sealing layer 15 is formed between the sample 1 and the sleeve 7. Multiple sealant injection holes 14 can be arranged circumferentially. On the one hand, the multi-point sealant injection mode is beneficial to the dense filling of the sealant, and on the other hand, the remaining sealant injection holes 14 can be used as exhaust holes when sealant is injected through one of the sealant injection holes 14.

[0037] Before assembly, waterproof paint can be applied to the outer wall of the head 4 of the sample 1 to form a waterproof layer. The waterproof paint can better fill and repair the small defects on the surface of the sample 1, and further improve the sealing effect between the sealant and the outer wall of the sample 1.

[0038] After the sealant solidifies and forms, hydraulic oil is pumped into the cylinder 2 through the oil inlet, and the hydraulic pressure acts on the end of the sample 1 through the first conical surface, and at the same time, the sample 1 is subjected to an outward axial force, thereby forming a pulling force. As the pressure in the cylinder 2 increases, the pulling force gradually increases until the rod 5 of the sample 1 breaks. The pressure sensor records the pressure in the cylinder 2 at the moment when the sample 1 breaks. The product of the pressure and the axial projection area of the conical surface of the first cone 6 of the sample 1 is the pulling force value when the sample 1 breaks.

[0039] At the moment when the sample 1 breaks, the sleeve 7 and the broken sample 1 will be ejected outward to contact the limiting edge 9. The limiting edge 9 can avoid the safety hazards and hydraulic oil leakage caused by the sleeve 7 or the broken sample 1 slipping out of the cylinder 2. After the sample 1 breaks, the pressure in the cylinder 2 can be released smoothly.

[0040] The inner wall of the sleeve 7 is injected with sealant, so after the sample 1 is removed after the test, the residual sealant on the inner wall of the sleeve 7 needs to be scraped and cleaned. The sleeve 7 can also be replaced during the next test.

[0041] In the present application, the sample 1 directly serves as a piston member of a hydraulic system, so that the pressure of the hydraulic oil directly acts on the end of the sample 1, which can ensure uniform distribution of the pressure on the bearing surface of the sample 1 and the direction of the resultant force along the axial direction of the sample 1, avoiding local damage of the sample 1 or the influence of bending moment or shear force on the test.

[0042] In addition, the present application does not need to set clamping mechanisms and loading mechanisms outside the two ends of the sample 1, which greatly reduces the axial size of the entire device, makes the rigidity of the entire device better, and avoids flexible deformation. Moreover, the entire device has a regular columnar shape, and the structure is simple and compact.

Claims

1. A hydraulic direct loading UHPC pull-out resistance test device, characterized in that, The utility model relates to a test sample (1), cylinder (2) and the connecting structure located cylinder (2) both ends, cylinder (2) is the cylinder of both ends opening, cylinder (2) side wall is equipped with oil hole (3), test sample (1) is the dumbbell structure of both ends thick middle thin, test sample (1) is placed coaxially in cylinder (2), and test sample (1) both ends are through connecting structure with cylinder (2) cooperation, and connecting structure can realize the sealed cooperation between cylinder (2) inner wall and test sample (1) outer wall, and connecting structure is fixed relative to test sample (1), and the connecting mechanism of each end can slide axially outward relative to cylinder (2), The test sample (1) is composed of head portions (4) at both ends and a rod portion (5) in the middle, the rod portion (5) is a cylindrical shape with a uniform diameter and is connected to the head portions (4) at both ends, and the head portion (4) comprises a first cone (6), and the small end of the first cone (6) is connected to the end of the rod portion (5). The connecting structure comprises a sliding sleeve (7), the outer wall of the sliding sleeve (7) is attached to and sealed with the inner wall of the cylinder (2), the sliding sleeve (7) can slide outward relative to the cylinder (2), and the inner wall of the sliding sleeve (7) is sealed with the outer wall of the head portion (4) of the test sample (1). Each end of the cylinder (2) is screwed with a limiting ring (8), the inner wall of the limiting ring (8) is provided with a limiting ridge (9) at the outer end, the inner diameter of the limiting ridge (9) is smaller than the outer diameter of the sliding sleeve (7), and there is a gap between the outer end of the limiting ridge (9) and the sliding sleeve (7). The head portion (4) of the test sample (1) further comprises a second cone (10), the second cone (10) is located at the outer end of the first cone (6) and has a small end facing outward, and the outer end of the inner wall of the sliding sleeve (7) is a conical surface with a small end facing outward. An axial glue injection hole (14) is formed in the outer end surface of the sliding sleeve (7), and the lower end of the glue injection hole (14) is located on the conical surface of the inner wall of the sliding sleeve (7), so that sealing glue can be injected between the outer wall of the second cone (10) of the head portion (4) of the test sample (1) and the sliding sleeve (7) through the glue injection hole (14), and after the sealing glue solidifies, a rear filling sealing layer (15) is formed.

2. The hydraulic direct loading UHPC pullout resistance test device of claim 1, wherein, A screw rod (11) is embedded in the outer end of the test sample (1), a limiting disc (12) is penetrated through the screw rod (11), and a pressing nut (13) is screwed on the outer side of the limiting disc (12) on the screw rod (11), so that the limiting disc (12) is pressed against the end portion of the test sample (1), and the outer edge of the limiting disc (12) is pressed against the outer end of the sliding sleeve (7).

3. The hydraulic direct loading UHPC pullout resistance test device of claim 1, wherein, The taper of the second cone (10) is smaller than the taper of the inner wall of the sliding sleeve (7).

4. The hydraulic direct loading UHPC pullout resistance test device of claim 1, wherein, The head portion (4) of the test sample (1) further comprises a connecting section (16), the connecting section (16) is located between the first cone (6) and the second cone (10), and the connecting section (16) is a cylindrical shape, and a sealing ring (17) is installed between the outer wall of the connecting section (16) and the inner wall of the sliding sleeve (7).

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