Non-contact dynamic cable horizontal tensile-bending combined test device and method

Abstract

The application discloses a kind of non-contact dynamic cable horizontal tensile bending combined test equipment and method, belong to dynamic cable test technical field, comprising: sample cable is slidably connected with two rectangular frames respectively by two fixed clamps, the both ends of connecting frame are connected with two fixed clamps respectively, connecting frame is connected with bending actuator;Two ends of sample cable are rotatably connected with hinged support, one end of tensile actuator is fixed on triangular support, the other end of tensile actuator is connected with sample cable through one of hinged support, and the other hinged support is connected with triangular support;Test adopts horizontal loading mode, avoids the influence of gravity on the bending behavior of sample cable. The two loading points in the test adopt point contact loading, this contact mode reduces the boundary influence of the area near the loading point, is closer to the requirement of loading point in four-point bending theoretical model, and the test adopts non-contact displacement measurement means, avoids the test error caused by contact displacement meter itself.

Description

Technical Field

[0001] This invention relates to the field of dynamic cable testing technology, specifically to a non-contact dynamic cable horizontal tension and bending combined testing equipment and method. Background Technology

[0002] Dynamic cables are crucial equipment in offshore wind farms and offshore oil and gas development, used to connect subsea production systems to surface buoys and serving as transmission channels for electrical energy and control signals. The top of the connection point between the dynamic cable and the floating platform is subjected to significant tensile loads due to its own weight, as well as repeated bending loads caused by harsh operating conditions and large-scale floating body movements, making it highly susceptible to fatigue failure. Because the dynamic cable has a multi-layered helical winding structure, the magnitude of the tensile force significantly affects the nonlinear bending behavior between components, making accurate prediction of fatigue stress difficult. Therefore, accurate and rapid analysis of the nonlinear mechanical response of the dynamic cable under combined tensile and bending loads is key to its fatigue life design.

[0003] In the fatigue design of dynamic cables, different constitutive models can cause significant differences in the internal stress of the elements, thus affecting the accuracy of fatigue life calculations. The bending behavior of dynamic cables can be divided into three stages: the viscous segment, the stick-slip segment, and the full-slip segment, with the bending internal forces exhibiting significant nonlinearity. While the nonlinear bending behavior of dynamic cables can be obtained through finite element analysis (FEM), some parameters are difficult to obtain, and the large number of layers and complex contact patterns of the spirally wound elements in dynamic cables lead to low computational efficiency and difficulty in verifying the accuracy of the calculation results. Therefore, it is necessary to conduct combined tension and bending simulation tests on dynamic cables using experimental methods to study the influence of tensile force on the nonlinear bending behavior of the dynamic cables.

[0004] In dynamic cable tension-bending combined experiments, various factors can lead to inaccuracies and errors. Current tension-bending combined testing devices suffer from excessive frictional resistance in the four-point bending truss and fail to account for the cable's own weight, resulting in overestimating force values. Furthermore, current contact measurement methods, such as strain gauges and pin-type displacement gauges, are susceptible to local defects in the cable, making it difficult to guarantee accurate results. Therefore, providing a device that avoids the influence of gravity on cable bending behavior and the testing errors introduced by contact displacement gauges is a pressing issue for those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a non-contact dynamic cable horizontal tension and bending combined test equipment and method, which can avoid the influence of gravity on the bending behavior of the sample cable and the test error caused by the contact displacement meter.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] On one hand, the present invention provides a non-contact dynamic cable horizontal tension and bending combined testing device, comprising:

[0008] A bending loading device includes a bending actuator, a connecting frame, a fixing clamp, and a rectangular frame. The sample cable is slidably connected to the two rectangular frames through two fixing clamps. The two ends of the connecting frame are connected to the two fixing clamps respectively. The connecting frame is connected to the bending actuator. Multiple non-contact laser displacement sensors are evenly distributed on the connecting frame.

[0009] A tensile loading device includes a triangular support, a tensile actuator, and a hinge support. Both ends of the sample cable are rotatably connected to the hinge support. One end of the tensile actuator is fixed to the triangular support, and the other end of the tensile actuator is connected to the sample cable through one of the hinge supports, while the other hinge support is connected to the triangular support.

[0010] The four loading points are the clamping positions of the two fixed clamps and the sample cable, and the connection positions of the two hinge supports and the sample cable.

[0011] Optionally, the connecting frame is a double-arm structure, with the top center of the connecting frame horizontally connected to the bending actuator, and the bottom two ends of the connecting frame collinear with the center of the fixing fixture, and this straight line is consistent with the output direction of the bending actuator.

[0012] Optionally, the rectangular frame is connected to a horizontal trench on the test surface by bolts, and the two rectangular frames are symmetrically distributed about the center position of the bending actuator.

[0013] Optionally, the upper and lower crossbeams of the rectangular frame serve as limiting tracks, and the fixing clamp is connected to the limiting tracks via rollers.

[0014] Optionally, the fixing fixture includes multiple combined clamping plates, each clamping plate being provided with a rotating roller.

[0015] Optionally, the tension actuator is connected to the hinge support by bolts.

[0016] On the other hand, the present invention provides a non-contact dynamic cable horizontal tension-bending combined test method, specifically including:

[0017] S10: A constant tensile load T is applied to the sample cable using a force control method via a tension actuator, and the force is measured by a force sensor attached to the actuator.

[0018] S20: By using a bending actuator, a displacement control method is used to apply multiple reciprocating bending loads F to the sample cable. The force sensor on the bending actuator is used to measure the force, and the displacement sensor on the bending actuator is used to measure the reciprocating bending load distance H.

[0019] S30: Multiple non-contact laser displacement sensors with a fixed spacing Δl are continuously arranged on the connecting frame using glue to measure the distance h between the sample cable and the crossbeam in real time during the bending process. The distance l between the non-contact displacement sensors and the loading point can be arranged and measured according to the test device and site conditions. During the test, the distance H0 between the connecting frame and the fixed clamp, and the distances L1, L2, and L3 between the four loading points are also measured.

[0020] S40: By measuring key parameters during the test, the bending moment and curvature of the sample cable during the tension-bending combination process are calculated.

[0021] The horizontal tensile component of the sample cable is:

[0022]

[0023] The bending moment experienced by the sample cable at the non-contact laser displacement sensor is:

[0024]

[0025] The curvature of the sample cable can be determined by geometric relationships:

[0026]

[0027] in:

[0028] Optionally, the sample cable can be pre-stretched before the test to eliminate the influence of initial defects in the sample cable on the test results.

[0029] Optionally, the number of non-contact laser displacement sensors can be increased or image recognition-based measurement methods can be used to reduce experimental errors.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) The test system adopted a horizontal loading method to avoid the influence of gravity on the bending behavior of the sample cable.

[0032] (2) The two loading points in the middle of the test system adopted point contact loading. This contact method reduces the boundary influence of the area near the loading point and is closer to the requirements of the loading point in the four-point bending theoretical model.

[0033] (3) The test system adopts a non-contact displacement measurement method, which avoids the test error caused by the contact displacement gauge itself.

[0034] (4) The test system removes the rotation constraint of the test cable, which can ensure that the tension on the cable can continue to run along the axial direction of the cable.

[0035] (5) The test system restricts the spatial deformation of the sample cable through the slide rail, so that the sample cable only undergoes planar bending. Therefore, the deformation measured by the non-contact laser displacement sensor is the true deformation of the cross section.

[0036] (6) The testing system can be adapted to accommodate sample cables of different sizes by adjusting the spacing between adjacent clamps. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figure 1 A schematic diagram of a non-contact dynamic cable horizontal tension and bending combined test device;

[0039] Figure 2 This is a top view of a four-point bending loading device;

[0040] Figure 3 This is a schematic diagram of a fixed fixture.

[0041] Figure 4 This is a schematic diagram of the measurement parameters for a horizontal tension-bending combined test.

[0042] In the figure: 1. Triangular bracket; 2. Tension actuator; 3. Hinge support; 4. Sample cable; 5. Bending actuator; 6. Connecting frame; 7. Square plate; 8. Fixing clamp; 9. Rectangular frame; 10. Limiting track; 11. Track roller; 12. Non-contact laser displacement sensor. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] See appendix Figures 1-4 On the one hand, the present invention provides a non-contact dynamic cable horizontal tension and bending combined testing device, comprising:

[0045] The bending loading device includes a bending actuator 5, a connecting frame 6, a fixing clamp 8, and a rectangular frame 9. The sample cable 4 is slidably connected to the two rectangular frames 9 via two fixing clamps 8. Both ends of the connecting frame 6 are connected to the two fixing clamps 8, and the connecting frame 6 is connected to the bending actuator 5. Multiple non-contact laser displacement sensors 12 are evenly distributed on the connecting frame 6. Optionally, track rollers 11 are provided at the four inner corners of the fixing clamp 8. The track rollers 11 abut against the sample cable 4, and the axis of the track rollers 11 is perpendicular to the axis of the sample cable 4. This ensures that the stretching process of the sample cable 4 will not be seriously affected. Optionally, the vertex of the fixing clamp 8 coincides with the midpoint of the rectangular frame 9 along its length.

[0046] The tensile loading device includes a triangular support 1, a tensile actuator 2, and a hinge support 3. Both ends of the sample cable 4 are rotatably connected to the hinge support 3. One end of the tensile actuator 2 is fixed to the triangular support 1, and the other end of the tensile actuator 2 is connected to the sample cable 4 through one of the hinge supports 3. The other hinge support 3 is connected to the triangular support 1. The centers of both ends of the sample cable 4 are aligned with the hinge support 3, and the hinge support 3 can rotate freely.

[0047] The four loading points are the clamping positions of the two fixed clamps 8 and the sample cable 4, and the connection positions of the two hinge supports 3 and the sample cable 4.

[0048] In this embodiment, specifically, the connecting frame 6 is a double-arm structure. The top center of the connecting frame 6 is horizontally connected to the bending actuator 5, and the bottom two ends of the connecting frame 6 are on the same straight line as the center of the fixing clamp 8, and the straight line is consistent with the output direction of the bending actuator 5. Optionally, the top and bottom of the connecting frame 6 are connected to the bending actuator 5 and the fixing clamp 8 respectively through square plates 7.

[0049] In this embodiment, the rectangular frame 9 is specifically connected to a horizontal trench on the test surface by bolts, and the two rectangular frames 9 are symmetrically distributed about the center of the bending actuator 5. The symmetrical distribution of the two rectangular frames 9 ensures that the sample cable 4 is subjected to uniform force on both sides, thereby improving the accuracy of the experiment.

[0050] In this embodiment, specifically, the upper and lower crossbeams of the rectangular frame 9 are the limiting rails 10, and the fixing clamp 8 is connected to the limiting rails 10 through rollers, which reduces the mechanical resistance when the connecting frame 6 reciprocates, limits the spatial deformation of the sample cable 4, and makes the sample cable 4 only bend in the horizontal plane.

[0051] In this embodiment, specifically, the fixing clamp 8 includes multiple combined clamping plates, each clamping plate is provided with a rotating roller, which can be rotated in a plane to ensure that the tension on the sample cable 4 can be continuously along the axial direction of the sample cable 4. Each clamping plate is provided with a rotating roller, and the surface of the rotating roller is tangent to the same circle to better clamp the sample cable 4.

[0052] In this embodiment, specifically, the tension actuator 2 is connected to the hinge support 3 by bolts, thereby enabling planar rotation to ensure that the tension on the sample cable 4 can be continuously along the axial direction of the sample cable 4.

[0053] This testing device is multifunctional and detachable, and can perform pure bending tests and axial tensile tests separately without affecting each other, making it a versatile device.

[0054] On the other hand, the present invention provides a non-contact dynamic cable horizontal tension-bending combined test method, specifically including:

[0055] S10: By using the tension actuator 2, a constant tensile load T is applied to the sample cable 4 using the force control method, and the force is measured by the force sensor attached to the actuator; When conducting the dynamic cable horizontal tension-bending combined test, a constant tensile load T is first applied to the sample cable 4 by using the tension actuator 2 along the axial direction of the sample cable 4 using the force control method, and the force is measured by the force sensor attached to the tension actuator 2.

[0056] S20: Using the bending actuator 5, multiple reciprocating bending loads F are applied to the sample cable 4 using a displacement control method. The force sensor attached to the bending actuator 5 is used to measure the load, and the displacement sensor attached to the bending actuator 5 is used to measure the reciprocating bending distance H. Using the bending actuator 5 connected to the center of the top of the connecting frame 6 in the horizontal direction, multiple reciprocating bending loads F are applied to the sample cable 4 using a displacement control method. The force sensor attached to the bending actuator 5 is used to measure the load, and the displacement sensor attached to the bending actuator 5 is used to measure the reciprocating bending distance H.

[0057] S30: Multiple non-contact laser displacement sensors 12 with fixed spacing Δl are continuously arranged on the connecting frame 6 using adhesive to measure the distance h between the sample cable 4 and the crossbeam during bending in real time. The distance l between the non-contact displacement sensors and the loading points can be arranged and measured according to the test equipment and site conditions. During the test, the distance H0 between the connecting frame 6 and the fixing clamp 8, and the distances L1, L2, and L3 between the four loading points are measured. Three non-contact laser displacement sensors 12 are continuously arranged on the crossbeam of the connecting frame 6 to measure the distance h between the sample cable 4 and the crossbeam of the connecting frame 6, the spacing Δl between the non-contact laser displacement sensors 12, the distance H0 between the crossbeam of the connecting frame 6 and the fixing clamp 8, and the distances L1, L2, and L3 between the four loading points are measured. The distance l between the non-contact laser displacement sensors 12 and the loading points needs to be arranged and measured according to the test equipment and site conditions.

[0058] S40: By measuring key parameters during the test, the bending moment and curvature of sample cable 4 during the tension-bending combination process are calculated.

[0059] In the figure, the horizontal tensile force component of sample cable 4 is:

[0060]

[0061] In the figure, the bending moment experienced by sample cable 4 at the non-contact laser displacement sensor 12 is:

[0062]

[0063] In the figure, the curvature of sample cable 4 can be determined by geometric relationships:

[0064]

[0065] in:

[0066] The dynamic cable bending behavior curve can be obtained by calculating the bending moment and curvature results.

[0067] In this embodiment, specifically, the sample cable 4 is pre-stretched before the test to eliminate the influence of the initial defects of the sample cable 4 on the test results.

[0068] In this embodiment, specifically, in order to reduce the impact of deformation measurement on the bending test of the sample cable 4, the number of non-contact laser displacement sensors 12 can be appropriately increased, or a more advanced image recognition-based measurement method can be used to reduce test errors.

[0069] To reduce the impact of the test on loading control, a reasonable reciprocating bending loading rate can be set by monitoring the tensile value of sample cable 4 to ensure the accuracy of the test results.

[0070] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to the embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A non-contact dynamic cable horizontal tension-bending combined test method, based on a non-contact dynamic cable horizontal tension-bending combined test device, characterized in that, The device includes: A bending loading device includes a bending actuator, a connecting frame, a fixing clamp, and a rectangular frame. The sample cable is slidably connected to the two rectangular frames through two fixing clamps. The two ends of the connecting frame are connected to the two fixing clamps respectively. The connecting frame is connected to the bending actuator. Multiple non-contact laser displacement sensors are evenly distributed on the connecting frame. A tensile loading device includes a triangular support, a tensile actuator, and a hinge support. Both ends of the sample cable are rotatably connected to the hinge support. One end of the tensile actuator is fixed to the triangular support, and the other end of the tensile actuator is connected to the sample cable through one of the hinge supports, while the other hinge support is connected to the triangular support. The four loading points are the clamping positions of the two fixed clamps and the sample cable, and the connection positions of the two hinge supports and the sample cable, respectively. The upper and lower crossbeams of the rectangular frame serve as limiting tracks, and the fixing clamp is connected to the limiting tracks via rollers; The experimental method specifically includes: S10: Apply a constant tensile load to the sample cable using a force control method via a tension actuator. T And the force is measured by the force sensor attached to the actuator; S20: Apply multiple reciprocating bending loads to the sample cable using a bending actuator and displacement control method. F The bending load reciprocating distance H is measured by the force sensor attached to the bending actuator and the displacement sensor attached to the bending actuator. S30: Multiple fixed-spacing connections are continuously arranged on the connector using adhesive. Δl A non-contact laser displacement sensor measures the distance between the sample cable and the crossbeam in real time during bending. h The distance between the non-contact displacement sensor and the loading point l The distance between the connecting frame and the fixed clamp during the test can be arranged and measured according to the test setup and site conditions. H 0 Distance between the four loading points L 1 , L 2 , L 3 ; S40: By measuring key parameters during the test, the bending moment and curvature of the sample cable during the tension-bending combination process are calculated. The horizontal tensile component of the sample cable is: The bending moment experienced by the sample cable at the non-contact laser displacement sensor is: The curvature of the sample cable can be determined by geometric relationships: in: .

2. The non-contact dynamic cable horizontal tension-bending combined test method according to claim 1, characterized in that, Before the test, the sample cable was pre-stretched to eliminate the influence of initial defects on the test results.

3. The non-contact dynamic cable horizontal tension-bending combined test method according to claim 1, characterized in that, Increase the number of non-contact laser displacement sensors or use image recognition-based measurement methods to reduce experimental errors.

4. The non-contact dynamic cable horizontal tension-bending combined test method according to claim 1, characterized in that, The connecting frame has a double-arm structure. The top center of the connecting frame is horizontally connected to the bending actuator. The bottom two ends of the connecting frame are on the same straight line as the center of the fixing fixture, and this straight line is consistent with the output direction of the bending actuator.

5. The non-contact dynamic cable horizontal tension-bending combined test method according to claim 1, characterized in that, The rectangular frame is connected to a horizontal trench on the test ground by bolts, and the two rectangular frames are symmetrically distributed with the center position of the bending actuator as the axis.

6. The non-contact dynamic cable horizontal tension-bending combined test method according to claim 1, characterized in that, The fixing fixture includes multiple combined clamping plates, each of which is equipped with a rotating roller.

7. The non-contact dynamic cable horizontal tension-bending combined test method according to claim 1, characterized in that, The tension actuator is connected to the hinge support by bolts.

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