Tensile fatigue testing device and method under bending action of FRP (Fiber Reinforce Plastic) rib

Abstract

The invention discloses a tensile fatigue testing device and method used under the bending effect of an FRP rib, and relates to the technical field of FRP rib mechanical testing. Comprising a steel frame, the steel frame comprises two transverse plates, directional sliding grooves are formed in the centers of the transverse plates, side plates are connected to the side walls of the two transverse plates, and steel columns are fixedly connected to the two transverse plates; a loading connection assembly, wherein the loading connection assembly is connected to the directional sliding groove; and the transverse adjusting assembly is connected to the side plate. The device is simple in design and convenient to load, can effectively carry out fatigue test of the FRP rib under complex stress, fills up the research and development blank of the device for testing the fatigue of the FRP rib under complex stress, solves the problem of fatigue test of the FRP rib under complex stress, and can also be used for testing the mechanical property of the FRP rib under the tension-bending coupling action.

Description

Technical Field

[0001] The invention relates to the technical field of FRP tendon mechanical testing, and in particular to a tensile fatigue testing device and method for FRP tendon under bending action. Background Art

[0002] At present, the development of marine resources in my country is developing from shallow sea to deep sea, and the demand for marine platforms has increased dramatically. Mooring cables are the core components of marine platforms. Traditional steel mooring cables are prone to corrosion, occupy a large area of ​​the seabed, and their heavy weight leads to insufficient buoyancy of floating marine structures, making them unsuitable for deep-water or ultra-deep-water mooring systems. The harsh and changeable environment of the deep-sea ocean has brought new challenges to the research and development, design and manufacturing of mooring cables, and has become one of the key technical bottlenecks that need to be urgently solved in my country's marine engineering construction. Fiber-reinforced resin composite (FRP) tendons have excellent properties such as light weight, high strength, fatigue resistance and corrosion resistance, and are expected to meet the service requirements of fatigue resistance and high durability of mooring cables for marine platforms.

[0003] During long-term service, mooring cables are in a complex stress state under the action of tension and bending loads. Under the action of complex environmental loads caused by waves, ocean currents and floating body movement, irreversible fatigue damage such as fiber breakage, matrix cracking and interface debonding inside the mooring cables is caused, which reduces their service performance. Studies have shown that the fatigue life and failure mechanism of FRP bars under single fatigue loads have been obtained, but mooring cables are subjected to tension and bending loads for a long time in the marine service environment. The influence of complex stress on the fatigue life and failure mechanism of FRP bars is still unclear, and it is urgent to carry out research on the fatigue performance of FRP bars under complex stress states.

[0004] It can be seen that FRP mooring cables have broad application prospects in offshore platform structures, but fatigue testing of FRP tendons under complex forces is still a key problem that needs to be solved. Therefore, in order to further promote the application of FRP mooring cables in offshore platform structures, a tensile fatigue testing device and method for FRP tendons under bending is urgently needed. Summary of the invention

[0005] The main purpose of the present invention is to provide a tensile fatigue testing device and method for FRP tendon bending to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A tensile fatigue testing device for FRP tendon under bending, comprising:

[0008] A steel frame, wherein the steel frame comprises two transverse plates, a directional slide groove is arranged at the center of the transverse plates, side walls of the two transverse plates are connected with side plates, and steel columns are fixedly connected to the two transverse plates;

[0009] A loading connection assembly, wherein the loading connection assembly is connected to the directional slideway;

[0010] A lateral adjustment component is connected to the side plate.

[0011] Furthermore, four steel columns are provided, and the four steel columns are respectively fixedly connected to the four corners of the transverse plate by nuts, and each of the steel columns passes through two of the transverse plates.

[0012] Furthermore, the loading connection assembly includes a loading head, an adapter and an anchor, each of the directional slide grooves is connected to a loading head, the adapter is connected to the end of the loading head, and the anchor is connected to the end of the adapter away from the loading head.

[0013] Furthermore, the loading head includes a columnar section and a first square block, the columnar section is connected to the directional slide slot, the first square block is connected to one end of the columnar section, the adapter is connected to the first square block through a pin, and the end of the columnar section that passes through the directional slide slot is connected to the chuck of the fatigue testing machine.

[0014] Furthermore, the diameter of the columnar segment is 35 mm, and the diameter of the pin connecting the adapter and the first square block is 10 mm.

[0015] Furthermore, the anchor is connected to the adapter via bolts.

[0016] Furthermore, the lateral adjustment assembly includes a connecting rod and a round stick, the connecting rod includes a round stick and a second square block, the round stick is fixedly connected to the side plate by a nut, the second square block is connected to the end of the round stick away from the side plate, the second square block is provided with a strip groove, the second square block is connected to the strip groove by a pin, the diameter of the pin is 6 mm, and the diameter of the round rod is 12 mm.

[0017] Furthermore, the hole direction of the directional slide groove is the same as the tensile direction of the FRP reinforcement, and the inner hole diameter of the directional slide groove is 35 mm.

[0018] Furthermore, the side plates are welded to the two transverse plates.

[0019] A method for testing the tensile fatigue of FRP tendons under bending, using a tensile fatigue testing device for testing the tensile fatigue of FRP tendons under bending, comprising the following steps:

[0020] S1: Connect the anchors to both ends of the FRP bars;

[0021] S2: Connect a pair of adapters to two anchors;

[0022] S3: inserting the columnar section of the loading head into the directional chute;

[0023] S4: Connect a pair of adapters to the loading head through pins;

[0024] S5: Fix the round bar at one end of the connecting rod to the side plate through a pair of nuts;

[0025] S6: Place the round stick close to the surface of the FRP bar and connect the round stick and the connecting rod with a pin;

[0026] S7: Change the position of the connecting rod by adjusting the nut to set the transverse bending deflection of the FRP reinforcement;

[0027] S8: Clamp the chuck of the fatigue testing machine to the columnar section of the loading head, set the fatigue loading program, and perform the tensile fatigue test of the FRP tendon under bending.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention fills the gap in the research and development of fatigue testing devices for FRP bars under complex stress.

[0030] 2. The present invention solves the problem of fatigue testing of FRP bars under complex stresses, provides lateral bending deflection to the FRP bars and tests the mechanical properties of the FRP bars under tension-bending coupling.

[0031] 3. The present invention and the testing method have simple principles and are easy to operate, and can accurately simulate the complex stress state of FRP bars in marine mooring cables. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The figure is a schematic diagram of the overall structure of a tensile fatigue testing device for FRP tendon bending in the present invention.

[0033] Figure 2 It is a schematic diagram of the structure of the loading head in the present invention.

[0034] Figure 3 It is a schematic diagram of the structure of the transfer joint in the present invention.

[0035] Among them, 1-steel frame; 101-steel column; 102-cross plate; 103-nut; 104-side plate; 2-loading head; 3-directional slide; 4-adapter; 5-pin; 6-anchor; 7-connecting rod; 8-round stick; 9-FRP reinforcement. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0037] Example 1

[0038] Combination Figure 1-3 The present invention provides a tensile fatigue testing device for FRP tendon bending, comprising a steel frame 1, a loading connection assembly and a lateral adjustment assembly, wherein the steel frame 1 comprises two transverse plates 102, a directional slide groove 3 is arranged at the center of the transverse plate 102, side walls of the two transverse plates 102 are connected with side plates 104, steel columns 101 are fixedly connected to the two transverse plates 102, the loading connection assembly is connected to the directional slide groove 3, and the lateral adjustment assembly is connected to the side plate 104.

[0039] The hole direction of the directional slide groove 3 is the same as the tensile direction of the FRP reinforcement, which is convenient for tensile fatigue testing of the FRP reinforcement. The inner hole diameter of the directional slide groove 3 is 35 mm; the side plate 104 is welded to the two horizontal plates 102.

[0040] There are four steel columns 101, and the steel columns are of a rectangular structure. The four steel columns 101 are fixedly connected to the four corners of the cross plate 102 by nuts 103, and each of the steel columns 101 passes through two cross plates 102. Two nuts 103 are set at the corresponding parts of the steel columns 101 and the cross plates 102. The position of the cross plate 102 can be adjusted by adjusting the positions of the two corresponding nuts 103.

[0041] The loading connection assembly includes a loading head 2, an adapter 4 and an anchor 6. Each of the directional slide grooves 3 is connected to a loading head 2. The adapter 4 is connected to the end of the loading head 2. The anchor 6 is connected to the end of the adapter 4 away from the loading head 2. The anchor 6 is connected to the adapter 4 via bolts.

[0042] The loading head 2 includes a columnar section and a first square block, the columnar section is connected to the directional slide groove 3, the first square block is connected to one end of the columnar section, the adapter 4 is connected to the first square block through a pin 5, and the end of the columnar section that passes through the directional slide groove 3 is connected to the chuck of the fatigue testing machine.

[0043] The diameter of the columnar section is 35 mm, and the diameter of the pin 5 connecting the adapter 4 and the first square block is 10 mm.

[0044] The lateral adjustment assembly includes a connecting rod 7 and a round stick 8. The connecting rod 7 includes a round stick and a second square block. The round stick is fixedly connected to the side plate 104 by a nut. The second square block is connected to the end of the round stick away from the side plate 104. The second square block is provided with a strip groove. The second square block is connected to the strip groove by a pin. The diameter of the pin is 6 mm. The diameter of the round stick is 12 mm.

[0045] The present invention has a simple design and is convenient to load, and can effectively carry out fatigue testing of FRP bars under complex stresses, filling the research and development gap of fatigue testing devices for FRP bars under complex stresses, and solving the problem of fatigue testing of FRP bars under complex stresses. At the same time, it can also be used to test the mechanical properties of FRP bars under tension-bending coupling. The device and the testing method are simple in principle and convenient to operate, and can accurately simulate the complex stress state of FRP bars in marine mooring cables.

[0046] Example 2

[0047] A method for testing the tensile fatigue of FRP tendons under bending, using a tensile fatigue testing device for testing the tensile fatigue of FRP tendons under bending, comprising the following steps:

[0048] S1: Connect the anchors to both ends of the FRP bars;

[0049] S2: Connect a pair of adapters to two anchors;

[0050] S3: inserting the columnar section of the loading head into the directional chute;

[0051] S4: Connect a pair of adapters to the loading head through pins;

[0052] S5: Fix the round bar at one end of the connecting rod to the side plate through a pair of nuts;

[0053] S6: Place the round stick close to the surface of the FRP bar and connect the round stick and the connecting rod with a pin;

[0054] S7: Change the position of the connecting rod by adjusting the nut to set the transverse bending deflection of the FRP reinforcement;

[0055] S8: Clamp the chuck of the fatigue testing machine to the columnar section of the loading head, set the fatigue loading program, and perform the tensile fatigue test of the FRP tendon under bending.

[0056] The tensile fatigue testing method for FRP tendons under bending in this embodiment has simple and convenient operation steps, thereby improving the fatigue testing efficiency of FRP tendons.

[0057] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A tensile fatigue testing device for FRP tendon under bending, characterized in that: include: A steel frame, wherein the steel frame comprises two transverse plates, a directional slide groove is arranged at the center of the transverse plates, side walls of the two transverse plates are connected with side plates, and steel columns are fixedly connected to the two transverse plates; A loading connection assembly, wherein the loading connection assembly is connected to the directional slideway; A lateral adjustment component is connected to the side plate.

2. The tensile fatigue testing device for FRP tendon under bending as claimed in claim 1, characterized in that: There are four steel columns, which are respectively fixedly connected to the four corners of the transverse plate by nuts, and each of the steel columns passes through two transverse plates.

3. The tensile fatigue testing device for FRP tendon under bending as claimed in claim 1, characterized in that: The loading connection assembly includes a loading head, an adapter and an anchor. Each of the directional slide slots is connected to a loading head. The adapter is connected to the end of the loading head, and the anchor is connected to the end of the adapter away from the loading head.

4. The tensile fatigue testing device for FRP tendon under bending as claimed in claim 3, characterized in that: The loading head includes a columnar section and a first square block, the columnar section is connected through the directional slide slot, the first square block is connected to one end of the columnar section, the adapter is connected to the first square block through a pin, and the end of the columnar section that passes through the directional slide slot is connected to the chuck of the fatigue testing machine.

5. The tensile fatigue testing device for FRP tendon under bending as claimed in claim 4, characterized in that: The diameter of the columnar section is 35 mm, and the diameter of the pin connecting the adapter and the first square block is 10 mm.

6. The tensile fatigue testing device for FRP tendon under bending as claimed in claim 3, characterized in that: The anchor is connected to the adapter via bolts.

7. The tensile fatigue testing device for FRP tendon under bending as claimed in claim 1, characterized in that: The lateral adjustment assembly includes a connecting rod and a round stick, the connecting rod includes a round stick and a second square block, the round stick is fixedly connected to the side plate by a nut, the second square block is connected to the end of the round stick away from the side plate, the second square block is provided with a strip groove, the second square block is connected to the strip groove by a pin, the diameter of the pin is 6 mm, and the diameter of the round rod is 12 mm.

8. The tensile fatigue testing device for FRP tendon under bending as claimed in claim 1, characterized in that: The hole direction of the directional slide groove is the same as the tensile direction of the FRP reinforcement, and the inner hole diameter of the directional slide groove is 35 mm.

9. The tensile fatigue testing device for FRP tendon under bending as claimed in claim 1, characterized in that: The side plates are welded to the two transverse plates.

10. A method for testing the tensile fatigue of FRP bars under bending, using the tensile fatigue testing device for FRP bars under bending as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Connect the anchors to both ends of the FRP bars; S2: Connect a pair of adapters to two anchors; S3: inserting the columnar section of the loading head into the directional chute; S4: Connect a pair of adapters to the loading head through pins; S5: Fix the round bar at one end of the connecting rod to the side plate through a pair of nuts; S6: Place the round stick close to the surface of the FRP bar and connect the round stick and the connecting rod with a pin; S7: Change the position of the connecting rod by adjusting the nut to set the transverse bending deflection of the FRP reinforcement; S8: Clamp the chuck of the fatigue testing machine to the columnar section of the loading head, set the fatigue loading program, and perform the tensile fatigue test of the FRP tendon under bending.

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