Shiftless anchor chain out-of-plane bending fatigue experiment loading device and loading method thereof

Abstract

The invention discloses a gear-free anchor chain out-of-plane bending fatigue test loading device and a loading method thereof, the gear-free anchor chain out-of-plane bending fatigue test loading device comprises a group of loading devices, a series of gear-free anchor chains with different sizes and a series of testing devices, and the out-of-plane bending fatigue test of the gear-free anchor chains is completed through axial cyclic loading and radial cyclic loading of loading equipment. The test anchor chain is installed on the loading equipment, the out-of-plane bending fatigue test process of the test anchor chain is completed through axial cyclic loading and radial cyclic loading of the loading equipment, anchor chains of different sizes are tested through the loading equipment, and it is guaranteed that the anchor chain enters an unstable fracture state. The complete out-of-plane bending fatigue state of the anchor chain is obtained by measuring the strain, the inclination angle, the cycle index and the applied force of different anchor chains at the fatigue fracture moment in the out-of-plane bending loading state. The device supplements the uniaxial tension constant load to obtain the gap of the fatigue state of the anchor chain, and has the advantages of convenient operation, safe test, high efficiency, low cost and the like.

Description

Technical Field

[0001] The present invention relates to a method for testing the fatigue strength of an anchor chain, and more particularly to a loading device and a loading method for out-of-plane bending fatigue experiment of a studless anchor chain. Background Art

[0002] An anchor chain is a steel chain connecting a floating platform, mainly used to transmit the holding force generated by an anchor. The anchor chain is mostly eroded by seawater and wind and waves in the marine environment, so it is particularly important to detect the fatigue condition of the anchor chain.

[0003] The test of the fatigue strength of an anchor chain is usually carried out by applying a load at the end of the anchor chain. Generally, the anchor chain is installed on the hook of a test machine, and then a tensile test is carried out, so that the anchor chain deforms until it breaks under the action of the tensile force of the test machine, and the tensile force and strain data of the anchor chain are collected during the whole process. This method is a common method for measuring the fatigue state of an anchor chain, but since the tensile process is a simple unidirectional tension, it is mostly used to measure the fatigue state of the anchor chain under normal conditions.

[0004] For the fatigue state of the anchor chain under special stress conditions, many people directly use the conventional tensile method for testing. This method cannot accurately and completely simulate the fatigue condition of the anchor chain under special conditions, and thus cannot effectively find the fatigue points of the anchor chain under special stress, nor can it further prevent the fracture of the anchor chain. Summary of the Invention

[0005] Object of the Invention: Aiming at the above problems, the object of the present invention is to provide a loading device and a loading method for out-of-plane bending fatigue experiment of a studless anchor chain, which can be applicable to the detection of the fatigue state of the anchor chain under special stress conditions, optimize the test process and reduce the test cost.

[0006] Technical Solution: A loading device for out-of-plane bending fatigue experiment of a studless anchor chain includes a support frame, a tension assembly, a fixing frame, a hydraulic press, a lifting assembly and a sensing assembly. The tension assembly and the lifting assembly are respectively installed on the inner bottom surface of the support frame. The fixing frame is installed on the inner top surface of the support frame and is opposite to the tension assembly. The two ends of the studless anchor chain to be loaded are respectively connected with the tension assembly and the fixing frame. The tension assembly can apply a tensile force to the axial direction of the studless anchor chain. A sensing assembly is installed on the studless anchor chain. The hydraulic press is installed on the lifting assembly and is located on one side of the studless anchor chain and can apply a pressure to the radial direction of the studless anchor chain.

[0007] Further, the support frame includes support columns, a top plate and a bottom plate. The top plate is arranged parallel and at intervals above the bottom plate, and the two are connected by a plurality of support columns arranged at intervals. The fixing frame is connected with the top plate. The tension assembly and the lifting assembly are respectively installed on the bottom plate.

[0008] Preferably, the support column is provided with a hollow structure. The support column is designed as a hollow structure on the basis of ensuring the support requirements to reduce the mass of the overall equipment.

[0009] Further, the tension assembly includes a tension assembly support base, a hydraulic cylinder, a piston rod, a tension connecting rod, and a tension assembly baffle. The hydraulic cylinder is installed on the tension assembly support base. A plurality of tension assembly support columns are spaced on the tension assembly support base. The tension assembly baffle is installed on the plurality of tension assembly support columns and suspended above the hydraulic cylinder. The piston rod of the hydraulic cylinder passes through the tension assembly baffle and is connected to the tension connecting rod. The tension connecting rod is connected to the studless anchor chain.

[0010] Further, the lifting assembly includes a lifting assembly base, a lead screw, a guide rail, a slider, a connecting rod, a lifting assembly top plate, a connecting shaft, a coupling, and a motor. The lifting assembly base is installed on the support frame. The lifting assembly top plate is arranged above the lifting assembly base and is connected to the lifting assembly base through two relatively spaced X-shaped connecting rods. The lead screw and the guide rail are installed in parallel and spaced on the lifting assembly base. The sliders are respectively connected to the lead screw and the guide rail. The motor is installed on the lifting assembly base and is connected to the lead screw through a coupling. The two connecting rods are connected through a connecting rod nut. One ends of the lower parts of the two connecting rods are respectively connected to the slider, and the other ends of the lower parts are respectively hinged to the lifting assembly base through a first bolt. The connecting shaft passes through the lifting assembly top plate and can slide in the chute thereon. One ends of the upper parts of the two connecting rods are respectively connected to the connecting shaft, and the other ends of the upper parts are respectively hinged to the lifting assembly top plate through a second bolt. The hydraulic press is installed on the lifting assembly top plate.

[0011] Further, the sensing assembly includes at least one strain gauge and an inclinometer, which are respectively installed on the studless anchor chain.

[0012] Preferably, the number of strain gauges is 4 to 6, which are installed at intervals along the circumferential direction on one side surface of the studless anchor chain. The included angle α formed by two adjacent strain gauges and the center of the studless anchor chain is 30° to 60°; the number of inclinometers is 2 to 4, which are installed at intervals along the circumferential direction on the inner ring of the studless anchor chain.

[0013] A loading method for the above-mentioned out-of-plane bending fatigue test loading device of a studless anchor chain includes the following steps:

[0014] Step 1: Install the sensing assembly on the studless anchor chain according to the axisymmetric principle;

[0015] Step 2: Connect the studless anchor chains in series in sequence, connect one end of the serially connected studless anchor chains to the fixed frame through a pin, and connect the other end to the tension assembly through a pull ring to complete the installation of the test piece;

[0016] Step 3: The tension assembly performs a retracting action to generate an outward tension F a, to keep the entire studless anchor chain in a taut state;

[0017] Step Four: Adjust the position of the lifting component up and down to ensure that the hydraulic press is located in the middle of the studless anchor chain, and the pressure contact block of the hydraulic press is in close contact with the link of the studless anchor chain and is exactly in the middle of the contacted studless anchor chain;

[0018] Step Five: Measure the strain and inclination angle of the studless anchor chain in the initial state, measure the length of the studless anchor chain with a ruler, clear the number of cycles of the cycle counter, and ensure that the studless anchor chain does not shift forward and backward during the fatigue test;

[0019] Step Six: The tension component applies a cyclic tension F a to the studless anchor chain, and at the same time the hydraulic press applies a cyclic pressure F b to make the studless anchor chain deflect obliquely, where F b = F a tanθ, and the included angle θ is 45 - 60°, so that the tested studless anchor chain reaches the state of fracture instability under the cyclic load. Record the number of cycles at this time through the cycle counter to complete the out-of-plane bending fatigue test;

[0020] Step Seven: Record the tension, number of cycles, inclination angle, and strain of the studless anchor chain under the cyclic loading of the tension component and the hydraulic press;

[0021] Step Eight: Summarize and obtain the out-of-plane bending fatigue state of the studless anchor chain.

[0022] Preferably, in Step Six, the maximum value of F a1 is less than or equal to the breaking load of the studless anchor chain, and the minimum value of F a1 is greater than or equal to 70% of the breaking load of the studless anchor chain.

[0023] Preferably, in Step Six, F a2 = 1 / 6F a1 , F a3 = 2F a2 .

[0024] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows: The present invention provides a method for obtaining the out-of-plane bending fatigue state of studless anchor chains of different sizes, aiming to make up for the gap in obtaining a complete fatigue state by conventional tension; this method can be applied to the out-of-plane bending fatigue experiments of studless anchor chains of different sizes due to the setting of the lifting component. Since the studless anchor chain is vertically installed, there is no need to overcome the self-weight of the studless anchor chain during the test, reducing the requirements for the tension component, thus having the advantages of simple operation, safe test, high efficiency, and low cost. Description of the Drawings

[0025] Figure 1 is a three-dimensional structural schematic diagram of the present invention;

[0026] Figure 2 is a schematic structural diagram of the tension assembly;

[0027] Figure 3 is a schematic structural diagram of the lifting assembly;

[0028] Figure 4 is a schematic distribution diagram of strain gauges and inclinometers on the studless anchor chain;

[0029] Figure 5 is a schematic force diagram of the studless anchor chain;

[0030] Figure 6 is the load application frequency diagram of the present invention. Specific embodiments

[0031] The present invention will be further clarified below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0032] A studless anchor chain out-of-plane bending fatigue test loading device, as Figures 1 to 4 shown, includes a support frame, a tension assembly 2, a fixing frame 5, a hydraulic press 8, a lifting assembly 9, and a sensing assembly. The sensing assembly includes a strain gauge 29 and an inclinometer 30.

[0033] The support frame includes support columns 1, a top plate 10, and a bottom plate 11. The top plate 10 is arranged parallel and spaced above the top plate 10, and the two are connected by a plurality of spaced support columns 1. The fixing frame 5 is connected to the top plate 10. The tension assembly 2 and the lifting assembly 9 are respectively installed on the bottom plate 11, and the fixing frame 5 is arranged opposite to the tension assembly 2.

[0034] Both ends of the studless anchor chain 4 to be loaded are respectively connected to the tension assembly 2 and the fixing frame 5. The tension assembly 2 can apply a tensile force to the axial direction of the studless anchor chain 4. The tension assembly 2 includes a tension assembly support seat 12, a hydraulic cylinder 13, a piston rod 14, a tension connecting rod 15, and a tension assembly baffle 16. The hydraulic cylinder 13 is installed on the tension assembly support seat 12. A plurality of tension assembly support columns are spaced on the tension assembly support seat 12. The tension assembly baffle 16 is installed on the plurality of tension assembly support columns and is suspended above the hydraulic cylinder 13. The piston rod 14 of the hydraulic cylinder 13 passes through the tension assembly baffle 16 and is connected to the tension connecting rod 15. The tension connecting rod 15 is connected to the studless anchor chain 4.

[0035] The hydraulic press 8 is installed on the lifting assembly 9, located on one side of the studless anchor chain 4, and can apply pressure to the radial direction of the studless anchor chain 4. The lifting assembly 9 includes a lifting assembly base 17, a lead screw 18, a guide rail 19, a slider 20, a connecting rod 21, a lifting assembly top plate 22, a connecting shaft 23, a coupling 24, and a motor 26. The lifting assembly base 17 is installed on the support frame. The lifting assembly top plate 22 is arranged above the lifting assembly base 17 and is connected to the lifting assembly base 17 through two relatively spaced X-shaped connecting rods 21. The lead screw 18 and the guide rail 19 are installed in parallel and spaced on the lifting assembly base 17. The sliders 20 are respectively connected to the lead screw 18 and the guide rail 19. The motor 26 is installed on the lifting assembly base 17 and is connected to the lead screw 18 through the coupling 24. The two connecting rods 21 are connected through a connecting rod nut 25. One end of the lower part of the two connecting rods 21 is respectively connected to the slider 20, and the other end of the lower part is respectively hinged to the lifting assembly base 17 through a first bolt 27. The connecting shaft 23 passes through the lifting assembly top plate 22 and can slide in the chute thereon. One end of the upper part of the two connecting rods 21 is respectively connected to the connecting shaft 23, and the other end of the upper part is respectively hinged to the lifting assembly top plate 22 through a second bolt 28. The hydraulic press 8 is installed on the lifting assembly top plate 22.

[0036] In the lifting assembly 9, the lead screw 18 and the motor 26 are connected through the coupling 24 and fixed on the lifting assembly base 17 by the first bolt 27 to ensure that the lead screw 18 and the motor 26 can achieve good transmission. The guide rail 19 is fastened to the lifting assembly base 17 by the first bolt 27 to ensure that there is no looseness between the guide rail 19 and the lifting base 17. The slider 20 is placed on the guide rail 19 to ensure smooth sliding between the two without jamming. By adjusting the tightness of the first bolt 27, bolt 25, and second bolt 28, ensure that the lifting assembly top plate 22 is always in a horizontal state. Install the hydraulic press 8 on the lifting assembly top plate 22 to ensure that the hydraulic press is in a horizontal state.

[0037] A sensing assembly is installed on the studless anchor chain 4. The number of strain gauges 29 is 4 to 6, which are installed at intervals along the circumferential direction on one side surface of the studless anchor chain 4. The included angle α formed by two adjacent strain gauges 29 and the center of the studless anchor chain 4 is 30° to 60°. The number of inclinometers 30 is 2 to 4, which are installed at intervals along the circumferential direction on the inner ring of the studless anchor chain 4.

[0038] The loading method of the above-mentioned loading device for the out-of-plane bending fatigue experiment of the studless anchor chain is as Figure 5 、 6 shown, including the following steps:

[0039] Step 1: Install strain gauges 29 on the outer surface of the studless anchor chain 4 and inclinometers 30 on the inner side of the studless anchor chain 4 according to the principle of axial symmetry, ensuring that the strain gauges 29 and inclinometers 30 will not fall off during the test;

[0040] Step 2: Connect the studless anchor chains 4 in series in sequence, connect one end of the serially connected studless anchor chains 4 to the fixed frame 5 through a pin 6, and connect the other end to the tensile assembly 2 through a pull ring 3 to complete the installation of the test piece;

[0041] Step 3: Retract the piston rod 14 of the tensile assembly 2 to generate an outward pulling force F a , keeping the entire studless anchor chain 4 in a taut state;

[0042] Step 4: Adjust the position of the lifting assembly 9 up and down to ensure that the hydraulic press 8 is located at the middle position of the studless anchor chain 4 where the strain gauges 29 and inclinometers 30 are installed. The hydraulic press 8 applies a lateral pressure, and the pressure contact block 7 of the hydraulic press 8 is in close contact with the link of the studless anchor chain 4 and is located exactly in the middle of the contacted studless anchor chain 4. There will be no vertical displacement between the pressure contact block 7 and the studless anchor chain 4 during the test;

[0043] Step 5: Measure the strain and inclination angle of the studless anchor chain 4 in the initial state, measure the length of the studless anchor chain 4 using a meter stick, clear the number of cycles of the cycle counter, and ensure that the studless anchor chain 4 does not shift forward and backward during the fatigue test;

[0044] Step 6: Apply a cyclic tensile force F to the studless anchor chain 4 through the tensile assembly 2 a and a cyclic pressure F to the studless anchor chain 4 through the hydraulic press 8 b to make the studless anchor chain 4 form an included angle θ of 45 - 60°. The relationship between F a and F b is F b = F a tanθ, so that the test piece reaches the state of fracture instability under the cyclic load with the cyclic law as shown in Figure 6 . Record the number of cycles to complete the out-of-plane bending fatigue test. In one embodiment, the experimental parameters are shown in Table 1.

[0045] Step 7: Record the tensile force, number of cycles, inclination angle, and strain of the studless anchor chain 4 under the cyclic loading of the tensile assembly 2 and the hydraulic press 8;

[0046] Step 8: Summarize and obtain the out-of-plane bending fatigue state of the studless anchor chain 4.

[0047] Table 1

[0048]

[0049]

[0050]

Claims

1. An out-of-plane bending fatigue test loading device for studless anchor chain, characterized in that: Comprising a support frame, a tension assembly (2), a fixing frame (5), a hydraulic press (8), a lifting assembly (9), and a sensing assembly. The tension assembly (2) and the lifting assembly (9) are respectively installed on the inner bottom surface of the support frame. The fixing frame (5) is installed on the inner top surface of the support frame and is opposite to the tension assembly (2). The two ends of the studless anchor chain (4) to be loaded are respectively connected to the tension assembly (2) and the fixing frame (5). The tension assembly (2) can apply a tensile force to the axial direction of the studless anchor chain (4). A sensing assembly is installed on the studless anchor chain (4). The hydraulic press (8) is installed on the lifting assembly (9) and is located on one side of the studless anchor chain (4) and can apply a pressure to the radial direction of the studless anchor chain (4).

2. The out-of-plane bending fatigue test loading device for studless anchor chain according to claim 1, wherein: The support frame includes support columns (1), a top plate (10), and a bottom plate (11). The top plate (10) is arranged parallel and spaced above the top plate (10), and the two are connected by a plurality of support columns (1) arranged at intervals. The fixing frame (5) is connected to the top plate (10). The tension assembly (2) and the lifting assembly (9) are respectively installed on the bottom plate (11).

3. The out-of-plane bending fatigue test loading device for studless anchor chain according to claim 2, wherein: The support column (1) is provided with a hollow structure.

4. A loading device for out-of-plane bending fatigue experiment of studless anchor chain according to claim 1, wherein: The tension assembly (2) includes a tension assembly support base (12), a hydraulic cylinder (13), a piston rod (14), a tension connecting rod (15), and a tension assembly baffle (16). The hydraulic cylinder (13) is installed on the tension assembly support base (12). A plurality of tension assembly support columns are arranged at intervals on the tension assembly support base (12). The tension assembly baffle (16) is installed on the plurality of tension assembly support columns and is suspended above the hydraulic cylinder (13). The piston rod (14) of the hydraulic cylinder (13) passes through the tension assembly baffle (16) and is connected to the tension connecting rod (15). The tension connecting rod (15) is connected to the studless anchor chain (4).

5. The out-of-plane bending fatigue test loading device for studless anchor chain according to claim 1, characterized in that: The lifting assembly (9) includes a lifting assembly base (17), a lead screw (18), a guide rail (19), a slider (20), a connecting rod (21), a lifting assembly top plate (22), a connecting shaft (23), a coupling (24), and a motor (26). The lifting assembly base (17) is installed on the support frame. The lifting assembly top plate (22) is arranged above the lifting assembly base (17) and is connected to the lifting assembly base (17) through two X-shaped connecting rods (21) arranged at intervals opposite to each other. The lead screw (18) and the guide rail (19) are installed on the lifting assembly base (17) in parallel at intervals. The sliders (20) are respectively connected to the lead screw (18) and the guide rail (19). The motor (26) is installed on the lifting assembly base (17) and is connected to the lead screw (18) through the coupling (24). The two connecting rods (21) are connected through a connecting rod nut (25). One end of the lower part of the two connecting rods (21) is respectively connected to the slider (20), and the other end of the lower part is respectively hinged to the lifting assembly base (17) through a first bolt (27). The connecting shaft (23) passes through the lifting assembly top plate (22) and can slide in the chute thereon. One end of the upper part of the two connecting rods (21) is respectively connected to the connecting shaft (23), and the other end of the upper part is respectively hinged to the lifting assembly top plate (22) through a second bolt (28). The hydraulic press (8) is installed on the lifting assembly top plate (22).

6. The out-of-plane bending fatigue test loading device for studless anchor chain according to claim 1, wherein: The sensing assembly includes at least two strain gauges (29) and an inclinometer (30), which are respectively installed on the studless anchor chain (4).

7. An out-of-plane bending fatigue test loading device for studless anchor chain according to claim 5, characterized in that: The number of strain gauges (29) is 4 to 6, and they are installed at intervals along the circumferential direction on one side surface of the studless anchor chain (4). The included angle α formed by two adjacent strain gauges (29) and the center of the studless anchor chain (4) is 30° to 60°. The number of inclinometers (30) is 2 to 4, and they are installed at intervals along the circumferential direction on the inner ring of the studless anchor chain (4).

8. A loading method for the out-of-plane bending fatigue experiment loading device of a studless anchor chain as described in any one of claims 1 to 7, characterized in that It includes the following steps: Step 1: Install the sensing assembly on the studless anchor chain (4) according to the axisymmetric principle; Step 2: Connect the studless anchor chains (4) in series in turn. One end of the series-connected studless anchor chain (4) is connected to the fixed frame (5) through a pin (6), and the other end is connected to the tension assembly (2) through a pull ring (3) to complete the installation of the test piece; Step 3: The pulling component (2) performs a retracting action, generating an outward pulling force F a , keeping the entire studless anchor chain (4) in a taut state; Step 4: Adjust the position of the lifting assembly (9) up and down to ensure that the hydraulic press (8) is located at the middle position of the studless anchor chain (4). The pressure contact block (7) of the hydraulic press (8) is in close contact with the link of the studless anchor chain (4) and is located exactly in the middle of the contacted studless anchor chain (4); Step 5: Measure the strain and inclination angle of the studless anchor chain (4) in the initial state, measure the length of the studless anchor chain (4) with a ruler, clear the number of cycles of the cycle counter, and keep the studless anchor chain (4) from moving forward and backward during the fatigue test; Step 6: The tension assembly (2) applies a cyclic tension force F to the studless anchor chain (4). a Meanwhile, the hydraulic press (8) applies a cyclic pressure force F to the studless anchor chain (4). b This causes the studless anchor chain (4) to deflect obliquely, where F b = F a tanθ, and the included angle θ is 45 - 60°, such that the tested studless anchor chain (4) reaches a state of rupture and instability under the cyclic load. Record the number of cycles at this time through the cycle counter to complete the out-of-plane bending fatigue test. Step 7: Record the tension, number of cycles, inclination angle, and strain of the studless anchor chain (4) under the cyclic loading of the tension assembly (2) and the hydraulic press (8); Step 8: Summarize to obtain the out-of-plane bending fatigue state of the studless anchor chain (4).

9. The loading method of a loading device for out-of-plane bending fatigue experiment of a studless anchor chain according to claim 8, characterized in that: In step six, the maximum value of F a1 is less than or equal to the breaking load of the studless anchor chain (4), and the minimum value of F a1 is greater than or equal to 70% of the breaking load of the studless anchor chain (4).

10. The loading method of a loading device for out-of-plane bending fatigue experiment of a studless anchor chain according to claim 8 or 9, characterized in that: In step six, F a2 = 1 / 6F a1 , F a3 = 2F a2 .

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