A large cable fatigue test equipment and test method with constant and dynamic load separation

Abstract

The present invention discloses a large-cable fatigue test equipment and a test method with separated constant and dynamic loads. The test equipment includes: a main support component, a load loading component, a power component and a control component; wherein the main support component is fixed on the working ground; the load loading component is fixed inside the main support component; the power component is fixed on the working ground around the main support component; the control component is communicatively connected with the power component via a communication line; the power output by the power component is regulated by the control component to control the load loading component to apply constant dynamic loads to cable specimens respectively, thereby performing fatigue loading tests on the cable specimens, so that the load level and energy consumption of the test equipment are significantly reduced in the process of carrying out cable fatigue performance loading tests in accordance with national and industry standards.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable performance testing, and more specifically, relates to a large-force cable fatigue testing device and a testing method with constant and dynamic load separation. Background Art

[0002] Cable systems play a crucial role in long-span bridge construction, not only transmitting loads but also supporting the entire bridge deck structure. This system includes the main cables and suspenders of suspension bridges and the stay cables of cable-stayed bridges. Cable components, such as the main cables of cable cars, are also considered cables. The loads borne by cables during operation are not constant but constantly changing. These changes can be caused by factors such as the bridge's own weight, wind loads, and traffic loads. Furthermore, repeated or cyclic stresses can cause metal fatigue in cables, and accumulated damage can eventually lead to material fracture. Therefore, metal fatigue has a significant impact on the long-term safety of cables. Metal fatigue is particularly prominent in cable components, as they bear constantly changing loads over long periods of time. Fatigue fracture in cables can cause serious damage to the bridge structure and even endanger life and property.

[0003] To ensure the reliability of cable products and the safety of cable components, fatigue loading tests are typically performed on sampled products before any process changes or the start of mass production. These tests adhere to national or industry standards to verify material performance, process stability, and production reliability. Fatigue testing can assess the durability of cable components and promptly identify potential defects, thereby safeguarding life and property in bridge projects. Chinese patent application number CN203758844U discloses a fatigue testing machine for cable-stayed bridges. This machine vertically mounts a cable specimen between a rigid crossbeam and a transverse rigid support of a frame. A through-hole pressure sensor is installed to measure the initial pretension of the cable specimen. A vibration motor applies vertical vibration (large vertical stress) to the cable specimen. A stress amplitude adjustment device applies a small vertical displacement adjustment to the cable specimen. Strain gauges installed on the cable specimen provide feedback on stress changes in the cable specimen. A regulating controller controls the stress amplitude applied by the stress amplitude adjustment device based on the numerical values ​​fed back by the through-hole pressure sensor and strain gauge. The fatigue testing machine for cable-stayed bridges described in Chinese patent application number CN203758844U can perform fatigue testing on cable specimens by selecting appropriate stress amplitudes and stress amplitude spectra based on different stress environments.

[0004] According to relevant standards, cable fatigue testing requires that the cable be tensioned to a certain level of constant load before a certain dynamic load is applied. For large-sized, high-strength cables used in bridges, the maximum load during loading may exceed 1,000 tons, and the standard loading cycle is 2 million times, which greatly challenges the loading equipment's capabilities. The stress magnitude provided by the Chinese patent application number CN203758844U is limited by the equipment and cannot meet the fatigue test requirements of high-force cables. Furthermore, directly using a loading actuator of 1,000 tons or more is not only expensive but also consumes extremely high energy during the test. Furthermore, when applying a constant load to the test cable using a tensioning cable no smaller than the tested cable and then applying a dynamic load via an actuator, the cable's stiffness is very high, and the cable force variation is non-negligible. This makes it impossible to apply the constant load ideally, and the efficiency of the dynamic load applied by the actuator on the test cable is less than 50%. Summary of the Invention

[0005] In response to the above defects or improvement needs of the prior art, the present invention provides a large-cable force cable fatigue testing equipment and testing method with separated constant dynamic loads, wherein the power output of the power component is regulated by the control component to control the load loading component to apply constant dynamic loads to the cable specimen fixed between the main support component and the load loading component, thereby performing a fatigue loading test on the cable specimen; through the precise regulation of the control component, the stability and consistency of the power output are ensured, so that the load level and energy consumption of the test equipment are significantly reduced in the process of conducting cable fatigue performance loading tests in accordance with national and industry standards, the average working efficiency of the test equipment is improved, and the initial investment cost and operating cost are reduced. In addition, the flexibility of the test equipment allows the test to adapt to different types of cable materials and structures, as well as different testing requirements, further reducing investment costs.

[0006] In order to achieve the above-mentioned object, the present invention provides a large cable fatigue test equipment with constant and dynamic load separation, comprising: a main support component, a load applying component, a power component and a control component; wherein:

[0007] The main support component is fixedly mounted on the working ground and comprises: a shock absorber base fixedly mounted on the working ground, and a reaction force frame fixedly mounted at the middle portion of the upper end of the shock absorber base; the reaction force frame comprises a first horizontal beam, a first longitudinal beam, a second horizontal beam, and a second longitudinal beam fixedly connected end to end at both ends.

[0008] The load-applying component is fixedly arranged inside the main support component, and includes: a limiting device fixedly arranged at the middle of the first longitudinal beam and the second longitudinal beam at one end facing each other, a third crossbeam with two ends fixedly connected to the limiting devices by connecting bolts, a constant load actuator, and a dynamic load actuator; a plurality of the constant load actuators are fixedly arranged between the second crossbeam and the third crossbeam in a mirror-symmetrical manner with a cable specimen; a plurality of the dynamic load actuators are fixedly arranged between the first crossbeam and the third crossbeam in a mirror-symmetrical manner with the cable specimen;

[0009] The power component is fixedly arranged on the working ground around the main support component, and includes: a high-pressure gas cylinder accumulator group fixedly arranged on the working ground in front and rear sides of the shock absorber base with the center mirror image of the shock absorber base, a hydraulic oil source, a first hydraulic oil pipeline and a second hydraulic oil pipeline fixedly arranged on the working ground on the left side of the shock absorber base; the two ends of several first hydraulic oil pipelines are respectively fixedly connected to the hydraulic oil source and the several dynamic load actuators; the two ends of several second hydraulic oil pipelines are respectively fixedly connected to the hydraulic oil source and the several constant load actuators and the several high-pressure gas cylinder accumulator groups;

[0010] The control component is communicatively connected with the power component through a communication line, and includes a first electrically controlled valve fixedly arranged on the first hydraulic oil pipeline, a second electrically controlled valve fixedly arranged on the second hydraulic oil pipeline, and a controller communicatively connected with the first electrically controlled valve, the second electrically controlled valve and the hydraulic oil source; the power output by the power component is regulated by the control component to control the load loading component to apply a constant dynamic load to the cable specimen respectively, thereby significantly reducing the load level and energy consumption of the test equipment.

[0011] Furthermore, the limiting device includes a support seat, a guide rail and a sliding member; several of the support seats are symmetrically fixed at the middle of the opposite ends of the first longitudinal beam and the second longitudinal beam; the guide rail is fixed between the two support seats, and several of the guide rails are respectively away from the first longitudinal beam and the second longitudinal beam for a certain distance; the sliding member is adapted to the guide rail and is movably connected to the guide rail.

[0012] Furthermore, the first crossbeam, the first longitudinal beam, the second crossbeam, the second longitudinal beam and the third crossbeam are mainly composed of steel with a grade not lower than Q345 and are coated with anti-corrosion paint.

[0013] Furthermore, a plurality of the high-pressure gas cylinder accumulator groups are connected in series with a plurality of the adjacent constant load actuators through a plurality of the second hydraulic oil pipelines.

[0014] Another aspect of the present invention provides a high-force cable fatigue test method with constant and dynamic load separation, which is implemented using the test equipment described above and includes the following steps:

[0015] S1: Check the working status of the test equipment to ensure that it meets the fatigue test design requirements of the cable specimen to be tested;

[0016] S2: Open the first and second electrically controlled valves, use the constant load actuator as the active actuator and the dynamic load actuator as the passive actuator, and use the displacement loading mode to push the third beam to a position suitable for installing the cable specimen;

[0017] S3: After the cable specimen is installed, a number of the constant load actuators are used as active actuators, and a number of the dynamic load actuators are used as passive actuators. The cable specimen is slightly tensioned using a displacement loading mode to eliminate idle travel between various structures and mechanisms. At this time, the cable specimen is in a completely unloaded state.

[0018] S4: Maintaining the states of the first electrically controlled valve and the second electrically controlled valve unchanged, with the plurality of constant load actuators acting as masters and the plurality of dynamic load actuators acting as slaves, the pistons of the plurality of constant load actuators advance to push the third beam to tension the cable specimen to a balanced state. During the tensioning process, hydraulic oil enters the plurality of high-pressure gas cylinder accumulator groups, and the hydraulic pressure and the gas pressure are balanced with each other.

[0019] S5: After reaching a balanced state, the second electrically controlled valve is closed. At this time, the hydraulic oil in the second hydraulic oil pipeline flows in the pipeline between the plurality of constant load actuators and the plurality of high-pressure gas cylinder accumulator groups, and is not affected by the hydraulic oil source; the plurality of dynamic load actuators are active, the plurality of constant load actuators are driven, and the thrust of the plurality of constant load actuators is maintained by the air springs of the plurality of high-pressure gas cylinder accumulator groups, so as to push the third crossbeam to reciprocate on both sides of the balanced position in step S4, thereby applying a fatigue load to the cable specimen;

[0020] S6: During the fatigue loading phase in step S5, the control component periodically opens the second electrically controlled valve to compensate, through the hydraulic oil source, for energy loss caused by internal friction in the constant load operating system mainly composed of the plurality of constant load actuators and the plurality of high-pressure gas cylinder accumulator groups;

[0021] S7: After the standard loading cycle is met, step S2 is repeated, the cable specimen is removed, and after checking that the test equipment is in normal condition, subsequent fatigue tests of the cable specimen are performed.

[0022] Furthermore, in step S3, when the cable specimen is in a completely unloaded state, there is a pre-applied gas pressure in the plurality of high-pressure gas cylinder accumulator groups. p = p 0, the change in the volume of the internal high-pressure air ∆V are all 0, the loads of some of the constant load actuators Tis 0, the load of the dynamic actuator t is 0, the length change of the cable specimen ∆L is 0.

[0023] Furthermore, in step S4, when the cable specimen reaches a balanced state, the high-pressure air inside the plurality of high-pressure gas cylinder accumulator groups is further compressed by the hydraulic oil, and there is a negative volume change therein. ∆V =- ∆V 0, the air pressure increases p = p 0+ ∆p ; The load of several of the constant load actuators T = T 0, and T The value of 0 is equal to the value of the balanced load; the load t of the dynamic load actuator is 0; the cable specimen is stretched and the length change ∆L = ∆L 0, then the equilibrium relationship is:

[0024] k∆L 0= T 0= A ( p 0+ ∆p )

[0025] in, k is the tensile stiffness of the cable specimen, A is the total effective area of ​​the hydraulic oil in the constant load actuators.

[0026] Furthermore, in step S5, when the cable specimen is further loaded and stretched in a relatively balanced state, the pistons of the dynamic load actuators retreat, and the load is a tensile force. t = δt The cable specimen is stretched compared to the equilibrium state, and the length change ∆L = ∆L 0+ δL The pistons of the constant load actuators are passively advanced, and the negative pressure sucks the hydraulic oil out of the high-pressure gas cylinder accumulator group, and the hydraulic oil squeeze of the high-pressure air inside is reduced, and there is a relatively positive volume change. ∆V =-( ∆V 0- δV ), the air pressure has a negative increment, p = p 0+ ∆p - δp ; The load of several of the constant load actuators T Because the pressure changes of some of the high-pressure gas cylinder accumulator groups have negative increments, T = T 0- δT , at this time, the equilibrium relationship is:

[0027] k ( ∆L 0+ δL )= T 0- δT + δt = A ( p 0+ ∆p - δp )+ δt

[0028] in, k is the tensile stiffness of the cable specimen, A is the total effective area of ​​the hydraulic oil in the constant load actuators.

[0029] Furthermore, in step S5, when the cable specimen is further loaded and shortened in a relatively balanced state, the pistons of the dynamic load actuators advance, and the load is a tensile force. t =- δt The cable specimen is shortened compared to the equilibrium state, and the length change ∆L = ∆L 0- δL The pistons of the constant load actuators passively retreat, and the hydraulic oil is pressed from the second hydraulic oil pipelines into the high-pressure gas cylinder accumulator group. The high-pressure air inside is squeezed by the hydraulic oil and increases, and there is a relatively negative volume change. ∆V =-( ∆V 0+ δV ), the air pressure has a positive increment, p = p 0+ ∆p + δp ; The load of several of the constant load actuators T Since the pressure change of some of the high-pressure gas cylinder accumulator groups has a positive increment, T = T 0+ δT , at this time, the equilibrium relationship is:

[0030] k ( ∆L 0- δL )= T 0+ δT - δt = A ( p 0+ ∆p + δp )- δt

[0031] in, k is the tensile stiffness of the cable specimen,A is the total effective area of ​​the hydraulic oil in the constant load actuators.

[0032] Furthermore, in the step S6, the load of the dynamic load actuator in a single fatigue loading cycle is obtained from the balance relationship between the loading stretch and the loading shortening. δt ,and:

[0033] 2 δt =2 kδL +2 Aδp

[0034] in, k is the tensile stiffness of the cable specimen, A is the total effective area of ​​the hydraulic oil in the constant load actuators, 2 kδL is the fatigue load amplitude required by the test scheme within a single fatigue loading cycle, 2 Aδp Compensation for fluctuations in the constant load operating system within a single fatigue loading cycle.

[0035] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0036] 1. The test equipment of the present invention regulates the power output by the power component through the control component, so as to control the load-loading component to apply a constant dynamic load to the cable specimen fixed between the main support component and the load-loading component, thereby performing a fatigue loading test on the cable specimen; through the precise regulation of the control component, the stability and consistency of the power output are ensured, so that the load level and energy consumption of the test equipment are significantly reduced in the process of conducting cable fatigue performance loading tests in accordance with national and industry standards, the average working efficiency of the test equipment is improved, and the initial investment cost and operating cost are reduced. In addition, the flexibility of the test equipment allows the test to adapt to different types of cable materials and structures, as well as different testing requirements, further reducing investment costs.

[0037] 2. The test equipment of the present invention regulates the first electrically controlled valve, the second electrically controlled valve and the hydraulic oil source through the controller, and at the same time, separates the constant load actuator and the dynamic load actuator through the third crossbeam, the first hydraulic oil pipeline and the second hydraulic oil pipeline, so that several of the constant load actuators and several of the dynamic load actuators respectively adopt a force loading mode or a displacement loading mode to apply load to the cable specimen, and the smaller dynamic load part is borne by the several dynamic load actuators, and the larger constant load part is borne by the low-energy actuation system composed of the several constant load actuators and the high-pressure gas cylinder accumulator group and the second accumulator group, thereby improving the working efficiency of the entire test equipment, significantly reducing the load level and energy consumption of the fatigue loading equipment, and reducing the initial investment cost and operating cost.

[0038] 3. The test equipment of the present invention improves the wear resistance of the contact surface, increases the service life of the limit device, and ensures the safety of the test by processing the contact surface between the guide rail and the sliding part through processing methods such as heat treatment, surface hardening or coating treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic structural diagram of a test device according to an embodiment of the present invention;

[0040] Figure 2 This is a structural diagram of the hydraulic oil circuit connection according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the steps of the test method according to an embodiment of the present invention;

[0042] Figure 4 Schematic diagram of force analysis of a cable specimen and a test device when the cable specimen is in a completely unloaded state according to an embodiment of the present invention;

[0043] Figure 5 Schematic diagram of force analysis of a cable specimen and a test device when the cable specimen is in equilibrium according to an embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of force analysis of a cable specimen and a test device when the cable specimen is loaded and stretched according to an embodiment of the present invention;

[0045] Figure 7 Schematic diagram of force analysis of a cable specimen and a test device when the cable specimen is loaded and shortened according to an embodiment of the present invention.

[0046] In all the drawings, the same figure marks represent the same technical features, specifically: 1-cable specimen, 2-shock absorber base, 31-first crossbeam, 32-first longitudinal beam, 33-second crossbeam, 34-second longitudinal beam, 4-limiting device, 41-support seat, 42-guide rail, 43-sliding member, 5-third crossbeam, 6-constant load actuator, 7-dynamic load actuator, 8-high-pressure gas cylinder accumulator group, 9-hydraulic oil source, 10-first hydraulic oil pipeline, 11-second hydraulic oil pipeline. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0048] Example 1

[0049] like Figure 1 and Figure 2 As shown, Example 1 of the present application provides a large cable fatigue test equipment with constant and dynamic load separation, including: a main support component, a load loading component, a power component and a control component; wherein, the main support component is fixed on the working ground; the load loading component is fixed inside the main support component; the power component is fixed on the working ground around the main support component; the control component is communicatively connected to the power component via a communication line; during the actual test process, the power output of the power component is regulated by the control component to control the load loading component to apply a constant dynamic load to the cable specimen 1 fixed between the main support component and the load loading component, thereby performing a fatigue loading test on the cable specimen 1; through the precise regulation of the control component, the stability and consistency of the power output are ensured, so that the load level and energy consumption of the test equipment are significantly reduced in the process of carrying out cable fatigue performance loading tests in accordance with national and industry standards, the average working efficiency of the test equipment is improved, and the initial investment cost and operating cost are reduced. In addition, the flexibility of the test equipment allows the test to adapt to different types of cable materials and structures, as well as different testing requirements, further reducing investment costs.

[0050] Specifically, if Figure 1 and Figure 2 As shown, the main support component is fixed on the working ground to support other components, which includes: a shock absorber base 2 and a reaction frame;

[0051] The shock-absorbing base 2 is fixed on the working ground to stably support other components and ensure the stability of the entire test equipment during the test;

[0052] Preferably, the shock absorber base 2 is stably and fixedly connected to the working ground through a force transmission embedded part;

[0053] In an optional embodiment, the upper surface of the shock absorber base 2 is fixed with a plurality of evenly parallel grooves for stably fixing the reaction frame;

[0054] The reaction frame is fixedly arranged at the middle of the upper end of the shock absorber base 2 and is used to stably support other components. It includes: a first cross beam 31, a first longitudinal beam 32, a second cross beam 33 and a second longitudinal beam 34;

[0055] The first crossbeam 31 is fixedly arranged on the left side of the middle portion of the upper end of the shock absorber base 2;

[0056] The first longitudinal beam 32 is fixedly arranged at the rear side of the middle portion of the upper end of the shock absorber base 2;

[0057] The second crossbeam 33 is fixedly arranged on the right side of the middle portion of the upper end of the shock absorber base 2, and a through hole adapted to the cable specimen 1 is fixedly provided in the middle portion thereof;

[0058] The second longitudinal beam 34 is fixedly arranged on the front side of the middle portion of the upper end of the shock absorber base 2;

[0059] Preferably, the first cross beam 31, the first longitudinal beam 32, the second cross beam 33 and the second longitudinal beam 34 are fixedly connected end to end in sequence;

[0060] Preferably, the first cross beam 31, the first longitudinal beam 32, the second cross beam 33 and the second longitudinal beam 34 are mainly composed of steel with a grade not lower than Q345 and are coated with anti-corrosion paint. The color of the anti-corrosion paint can be customized according to user requirements.

[0061] Specifically, if Figure 1 and Figure 2 As shown, the load-applying component is fixedly arranged inside the main supporting component and is used to apply a constant and dynamic load to the cable specimen 1. The load-applying component includes a limit device 4, a third beam 5, a constant load actuator 6, and a dynamic load actuator 7.

[0062] The plurality of limiting devices 4 are respectively fixedly arranged at the middle portion of the first longitudinal beam 32 and the second longitudinal beam 34 at one end facing each other, and include a support seat 41, a guide rail 42 and a sliding member 43;

[0063] The plurality of support seats 41 are symmetrically fixed at the middle portions of the first longitudinal beam 32 and the second longitudinal beam 34 at opposite ends.

[0064] Preferably, the support seat 41 includes a support seat such as a triangular support seat or a circular support seat;

[0065] The guide rail 42 is fixed between the two support seats 41;

[0066] Preferably, the guide rails 42 are each spaced a distance away from the first longitudinal beam 32 and the second longitudinal beam 34 ;

[0067] The sliding member 43 is adapted to the guide rail 42 and is movably connected to the guide rail 42;

[0068] Preferably, the contact surface between the guide rail 42 and the sliding member 43 is processed by a processing method including heat treatment, surface hardening or coating treatment, so as to improve the wear resistance of the contact surface, increase the service life of the limit device 4, and ensure the safety of the test;

[0069] Both ends of the third crossbeam 5 are fixedly connected to the plurality of sliding members 43 in the plurality of limiting devices 4 via connecting bolts;

[0070] Preferably, the third crossbeam 5 is mainly composed of steel with a grade not lower than Q345 and is coated with anti-corrosion paint;

[0071] Preferably, a through hole adapted to the cable specimen 1 is fixedly provided in the middle of the third crossbeam 5;

[0072] Preferably, both ends of the cable specimen 1 pass through the middle through-holes of the second crossbeam 33 and the third crossbeam 5, respectively, and are stably fixed inside the test equipment by anchor heads and reinforcing washers fixedly sleeved on the outer sides of both ends of the cable specimen 1.

[0073] Preferably, the cable specimen 1 comprises a parallel steel cable or a steel strand cable such as a main cable strand of a suspension bridge, a suspender cable of a suspension bridge, a stay cable of a cable-stayed bridge, a suspender rod of a cable-arch bridge, or a cable car cable;

[0074] The plurality of constant load actuators 6 are fixedly arranged between the second crossbeam 33 and the third crossbeam 5 in a mirror-symmetrical manner with the cable specimen 1, and are fixedly connected to the second crossbeam 33 and the third crossbeam 5 respectively by connecting bolts;

[0075] The plurality of dynamic load actuators 7 are fixedly arranged between the first crossbeam 31 and the third crossbeam 5 in a mirror-symmetrical manner with the cable specimen 1, and are fixedly connected to the first crossbeam 31 and the third crossbeam 5 respectively by connecting bolts;

[0076] Specifically, if Figure 1 and Figure 2As shown, the power component is fixedly arranged on the working ground around the main support component, and is used to provide the load-applying component with power to apply the load to the cable specimen 1, and includes: a high-pressure gas cylinder accumulator group 8, a hydraulic oil source 9, a first hydraulic oil pipeline 10 and a second hydraulic oil pipeline 11;

[0077] The plurality of high-pressure gas cylinder accumulator groups 8 are respectively fixed on the front and rear working surfaces of the shock absorber base 2 in a mirror image of the center of the shock absorber base 2, and are mainly composed of a plurality of high-pressure gas cylinder accumulators connected in parallel;

[0078] The hydraulic oil source 9 is fixedly installed on the working ground on the left side of the shock absorber base 2, and a plurality of hydraulic oil pumps and hydraulic oil tanks are fixedly installed inside the hydraulic oil source 9 to provide power for the load-applying component to apply the load to the cable specimen 1;

[0079] Both ends of the plurality of first hydraulic oil pipelines 10 are fixedly connected to the hydraulic oil source 9 and the plurality of dynamic load actuators 7 respectively;

[0080] Both ends of the plurality of second hydraulic oil pipelines 11 are respectively fixedly connected to the hydraulic oil source 9 and the plurality of constant load actuators 6 and the plurality of high-pressure gas cylinder accumulator groups 8;

[0081] Preferably, the plurality of high-pressure gas cylinder accumulator groups 8 are connected in series with the plurality of adjacent constant load actuators 6 through the plurality of second hydraulic oil pipelines 11, and form a constant load operation system;

[0082] Preferably, the middle section of the second hydraulic oil pipeline 11 is fixed to the working ground in front of the shock absorber base 2 through a bracket;

[0083] Specifically, if Figure 1 and Figure 2 As shown, the control component is fixedly arranged on one side of the main support component and is connected to the power component via a communication line for regulating the test process, and includes: a first electrically controlled valve, a second electrically controlled valve and a controller;

[0084] The first electrically controlled valve is fixedly mounted on the first hydraulic oil pipeline 10 and is located on the left side of the shock absorber base 2. It can open or cut off the oil supply pipeline to the plurality of dynamic load actuators 7 according to different working conditions.

[0085] The second electrically controlled valve is fixedly mounted on the second hydraulic oil pipeline 11 and is located on the left side of the shock absorber base 2. It can open or cut off the oil supply pipelines to the plurality of constant load actuators 6 and the plurality of high-pressure gas cylinder accumulator groups 8 according to different working conditions.

[0086] The controller is in communication with the first electrically controlled valve, the second electrically controlled valve and the hydraulic oil source 9 for regulating the test process;

[0087] During the fatigue test, the first electrically controlled valve, the second electrically controlled valve and the hydraulic oil source 9 are regulated by the controller. At the same time, the constant load actuator 6 and the dynamic load actuator 7 are separated by the third crossbeam 5, the first hydraulic oil pipeline 10 and the second hydraulic oil pipeline 11, so that the plurality of constant load actuators 6 and the plurality of dynamic load actuators 7 respectively apply loads to the cable specimen 1 using a force loading mode or a displacement loading mode, and the plurality of dynamic load actuators 7 bear a smaller dynamic load portion, while the constant load actuation system composed of the plurality of constant load actuators 6 and the plurality of high-pressure gas cylinder accumulator groups 8 bears a larger constant load portion, thereby improving the working efficiency of the entire test equipment, significantly reducing the load level and energy consumption of the fatigue loading equipment, and reducing the initial investment cost and operating cost;

[0088] Preferably, the main energy consumption of the constant load operating system composed of the plurality of constant load actuators 6 and the high-pressure gas cylinder accumulator group 8 is to compensate for the energy consumption generated by friction in the system;

[0089] Example 2

[0090] like Figure 1 to Figure 7 As shown, based on the above-mentioned embodiment 1, embodiment 2 of the present application provides a large cable fatigue test method with constant and dynamic load separation, including the following steps:

[0091] S1: Check the working status of the test equipment to ensure that it meets the fatigue test design requirements of the cable specimen 1 to be tested;

[0092] S2: Open the first and second electrically controlled valves, use the constant load actuators 6 as the active actuators and the dynamic load actuators 7 as the passive actuators, and use the displacement loading mode to push the third beam 5 to a position suitable for installing the cable test piece 1;

[0093] S3: After the cable specimen 1 is installed, the cable specimen 1 is slightly tensioned using a displacement loading mode with the plurality of constant load actuators 6 acting as active actuators and the plurality of dynamic load actuators 7 acting as passive actuators, thereby eliminating idle travel between various structures and mechanisms. At this point, the cable specimen 1 is in a completely unloaded state.

[0094] S4: Maintaining the states of the first electrically controlled valve and the second electrically controlled valve unchanged, with the plurality of constant load actuators 6 acting as masters and the plurality of dynamic load actuators 7 acting as slaves, the pistons of the plurality of constant load actuators 6 move forward, pushing the third crossbeam 5 to tension the cable specimen 1 to a balanced state. During the tensioning process, hydraulic oil enters the plurality of high-pressure gas cylinder accumulator groups 8, and the hydraulic pressure and the gas pressure are balanced with each other.

[0095] S5: After reaching a balanced state, the second electrically controlled valve is closed. At this time, the hydraulic oil in the second hydraulic oil pipeline 11 flows in the pipeline between the plurality of constant load actuators 6 and the plurality of high-pressure gas cylinder accumulator groups 8, and is not affected by the hydraulic oil source 9. The plurality of dynamic load actuators 7 are active, the plurality of constant load actuators 6 are driven, and the thrust of the plurality of constant load actuators 6 is maintained by the air springs of the plurality of high-pressure gas cylinder accumulator groups 8, so as to push the third crossbeam 5 to reciprocate on both sides of the balanced position in step S4, thereby applying a fatigue load to the cable specimen 1.

[0096] S6: During the fatigue loading phase in step S5, the control component periodically opens the second electrically controlled valve to compensate for the energy loss caused by internal friction of the constant load operating system mainly composed of the plurality of constant load actuators 6 and the plurality of high-pressure gas cylinder accumulator groups 8 through the hydraulic oil source 9;

[0097] S7: After the standard loading cycle is met, step S2 is repeated, the cable specimen 1 is removed, and after checking that the test equipment is in normal condition, subsequent fatigue tests of the cable specimen 1 are performed.

[0098] Preferably, in step S3, when the cable specimen 1 is in a completely unloaded state, the force analysis of the cable specimen 1 and the test equipment is as follows: Figure 4 As shown, there is a pre-applied gas pressure in the plurality of high pressure gas cylinder accumulator groups 8. p = p 0, the change in the volume of the internal high-pressure air ∆V are all 0, the load of the constant load actuator 6 T is 0, the load of the dynamic load actuator 7 t is 0, the length change of the cable specimen 1 ∆L is 0;

[0099] Preferably, the balance load is calculated according to the upper and lower limits of fatigue load determined by relevant national standards, industry standards or negotiation, and the balance load value is (upper limit of load + lower limit of load) / 2;

[0100] Preferably, in step S4, when the cable specimen 1 reaches a balanced state, the force analysis of the cable specimen 1 and the test equipment is as follows: Figure 5 As shown, the high-pressure air inside the high-pressure gas cylinder accumulator group 8 is further compressed by the hydraulic oil, and there is a negative volume change therein. ∆V =- ∆V 0, the air pressure increases p = p 0+ ∆p ; The load of the constant load actuator 6 T = T 0, andT The value of 0 is equal to the value of the balanced load; the load t of the dynamic load actuator 7 is 0; the cable specimen 1 is stretched and the length change ∆L = ∆L 0, then the equilibrium relationship is:

[0101] k∆L 0= T 0= A ( p 0+ ∆p )

[0102] in, k is the tensile stiffness of the cable specimen 1, A is the total effective area of ​​the hydraulic oil in the constant load actuators 6;

[0103] Preferably, in step S5, when the cable specimen 1 is further loaded and stretched in a relatively balanced state, the force analysis of the cable specimen 1 and the test equipment is as follows: Figure 6 As shown; the piston of several dynamic load actuators 7 retreats, and the load is tensile t = δt The cable specimen 1 is stretched compared to the equilibrium state, and the length change ∆L = ∆L 0+ δL Several of the constant load actuator piston 6 passively move forward, the negative pressure of the hydraulic oil are sucked out from the several high-pressure cylinder accumulator group 8, the internal high-pressure air by the hydraulic oil squeeze is reduced, there is a relatively positive volume change, ∆V =-( ∆V 0- δV ), the air pressure has a negative increment, p = p 0+ ∆p - δp ; The load of the constant load actuator 6 T Because the pressure changes of some of the high-pressure gas cylinder accumulator groups 8 have negative increments, T = T 0- δT , at this time, the equilibrium relationship is:

[0104] k ( ∆L 0+ δL )= T 0- δT + δt = A ( p 0+ ∆p - δp )+ δt

[0105] in,k is the tensile stiffness of the cable specimen 1, A is the total effective area of ​​the hydraulic oil in the constant load actuators 6;

[0106] Preferably, in step S5, when the cable specimen 1 is further loaded and shortened in a relatively balanced state, the force analysis of the cable specimen 1 and the test equipment is as follows: Figure 7 As shown; the piston of the dynamic load actuator 7 moves forward, and the load is a tensile force t =- δt The cable specimen 1 is shortened compared to the equilibrium state, and the length change ∆L = ∆L 0- δL The piston of the constant load actuator 6 is passively retreated, and the hydraulic oil is pressed from the second hydraulic oil pipeline 11 into the high-pressure gas cylinder accumulator group 8, and the high-pressure air inside is squeezed by the hydraulic oil to increase, and there is a relatively negative volume change. ∆V =-( ∆V 0+ δV ), the air pressure has a positive increment, p = p 0+ ∆p + δp ; The load of the constant load actuator 6 T Since the pressure changes of some of the high-pressure gas cylinder accumulator groups 8 have positive increments, T = T 0+ δT , at this time, the equilibrium relationship is:

[0107] k ( ∆L 0- δL )= T 0+ δT - δt = A ( p 0+ ∆p + δp )- δt

[0108] in, k is the tensile stiffness of the cable specimen 1, A is the total effective area of ​​the hydraulic oil in the constant load actuators 6;

[0109] Preferably, in step S6, the load of the dynamic load actuator 7 in a single fatigue loading cycle is obtained from the balance relationship between the loading stretch and the loading shortening. δt ,and:

[0110] 2 δt =2 kδL +2 Aδp

[0111] Preferably, during the fatigue loading process of the cable specimen 1, the total load 2 borne by the plurality of dynamic load actuators 7 is δt Equal to the fatigue load amplitude required by the test plan2 kδL In addition, the compensation for the fluctuation of the constant load operation system mainly composed of several constant load actuators 6 and several high-pressure gas cylinder accumulator groups 8 is 2 Aδp , and since the air compression modulus is extremely small, it can be considered that the constant load fluctuation is caused by the change in the volume of high-pressure air. Aδp ≈0, thereby improving the average working efficiency of the test equipment, reducing energy consumption and reducing test costs.

[0112] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0113] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0114] In this patent, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Those skilled in the art will readily understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fatigue test method for a large cable with constant and dynamic load separation, implemented using a large cable with constant and dynamic load separation fatigue test equipment, characterized in that: The test equipment includes: a main body support component, a load loading component, a power component and a control component; wherein: The main support component is fixedly mounted on the working ground and comprises: a shock absorber base (2) fixedly mounted on the working ground, and a reaction force frame fixedly mounted on the middle portion of the upper end of the shock absorber base (2); the reaction force frame comprises a first crossbeam (31), a first longitudinal beam (32), a second crossbeam (33), and a second longitudinal beam (34) fixedly connected end to end at both ends. The load-applying component is fixedly arranged inside the main support component, and comprises: a limiting device (4) fixedly arranged at the middle of the first longitudinal beam (32) and the second longitudinal beam (34) at one end thereof, a third crossbeam (5) fixedly connected to the limiting devices (4) at both ends by connecting bolts, a constant load actuator (6) and a dynamic load actuator (7); the constant load actuators (6) are fixedly arranged between the second crossbeam (33) and the third crossbeam (5) with a mirror image of the cable specimen (1); the dynamic load actuators (7) are fixedly arranged between the first crossbeam (31) and the third crossbeam (5) with a mirror image of the cable specimen (1); The power component is fixed on the working ground around the main support component, and comprises: a high-pressure gas cylinder accumulator group (8) fixed on the working ground in front and rear of the shock absorber base (2) in a mirror image of the center of the shock absorber base (2), a hydraulic oil source (9), a first hydraulic oil pipeline (10) and a second hydraulic oil pipeline (11) fixed on the working ground on the left side of the shock absorber base (2); the two ends of a plurality of the first hydraulic oil pipelines (10) are respectively fixedly connected to the hydraulic oil source (9) and the plurality of the dynamic load actuators (7); the two ends of a plurality of the second hydraulic oil pipelines (11) are respectively fixedly connected to the hydraulic oil source (9), the plurality of the constant load actuators (6) and the plurality of the high-pressure gas cylinder accumulator groups (8); The control component is connected to the power component via a communication line, and comprises a first electrically controlled valve fixedly arranged on the first hydraulic oil pipeline (10), a second electrically controlled valve fixedly arranged on the second hydraulic oil pipeline (11), and a controller connected to the first electrically controlled valve, the second electrically controlled valve and the hydraulic oil source (9); the control component regulates the power output by the power component to control the load-applying component to apply a constant dynamic load to the cable specimen (1), thereby significantly reducing the load level and energy consumption of the test equipment; The test method comprises the following steps: S1: Check the working status of the test equipment to ensure that it meets the fatigue test design requirements of the cable specimen to be tested (1); S2: Open the first electrically controlled valve and the second electrically controlled valve, use the constant load actuator (6) as the active actuator and the dynamic load actuator (7) as the passive actuator, and use the displacement loading mode to push the third beam (5) to a position suitable for installing the cable test piece (1); S3: After the cable specimen (1) is installed, the cable specimen (1) is slightly tensioned using a displacement loading mode with a plurality of the constant load actuators (6) as active and a plurality of the dynamic load actuators (7) as passive, thereby eliminating idle travel between various structures and mechanisms. At this time, the cable specimen (1) is in a completely unloaded state; S4: Maintaining the states of the first electrically controlled valve and the second electrically controlled valve unchanged, with the plurality of constant load actuators (6) acting as the active actuators and the plurality of dynamic load actuators (7) acting as the passive actuators, the pistons of the plurality of constant load actuators (6) moving forward, pushing the third beam (5) to tension the cable specimen (1) to a balanced state, and during the tensioning process, hydraulic oil respectively enters the plurality of high-pressure gas cylinder accumulator groups (8), and the hydraulic pressure and the gas pressure are balanced with each other; S5: After reaching the equilibrium state, the second electrically controlled valve is closed, and at this time, the hydraulic oil in the second hydraulic oil pipeline (11) flows in the pipeline between the plurality of constant load actuators (6) and the plurality of high-pressure gas cylinder accumulator groups (8), and is not affected by the hydraulic oil source (9); the plurality of dynamic load actuators (7) are active, the plurality of constant load actuators (6) are driven, and the thrust of the plurality of constant load actuators (6) is maintained by the air springs of the plurality of high-pressure gas cylinder accumulator groups (8), so as to push the third crossbeam (5) to reciprocate on both sides of the equilibrium position in step S4, and load the fatigue load on the cable specimen (1); S6: During the fatigue loading phase in step S5, the control component periodically opens the second electrically controlled valve to compensate for the energy loss caused by internal friction of the constant load operating system mainly composed of the plurality of constant load actuators (6) and the plurality of high-pressure gas cylinder accumulator groups (8) through the hydraulic oil source (9); S7: After the standard loading cycle is satisfied, step S2 is repeated, the cable specimen (1) is removed, and after checking that the test equipment is in normal condition, a subsequent fatigue test of the cable specimen (1) is performed.

2. The test method according to claim 1, characterized in that The limiting device (4) includes a support seat (41), a guide rail (42) and a sliding member (43); a plurality of the support seats (41) are symmetrically fixed at the middle of the first longitudinal beam (32) and the second longitudinal beam (34) at one end facing each other; the guide rail (42) is fixed between the two support seats (41), and a plurality of the guide rails (42) are respectively away from the first longitudinal beam (32) and the second longitudinal beam (34) by a certain distance; the sliding member (43) is adapted to the guide rail (42) and is movably connected to the guide rail (42).

3. The test method according to claim 1, characterized in that The first crossbeam (31), the first longitudinal beam (32), the second crossbeam (33), the second longitudinal beam (34) and the third crossbeam (5) are mainly composed of steel with a grade not lower than Q345 and are coated with anti-corrosion paint.

4. The test method according to any one of claims 1 to 3, characterized in that The plurality of high-pressure gas cylinder accumulator groups (8) are respectively connected in series with the plurality of adjacent constant load actuators (6) via the plurality of second hydraulic oil pipelines (11).

5. The test method according to claim 1, wherein In step S3, when the cable test piece (1) is in a completely unloaded state, a plurality of the high-pressure gas cylinder accumulator groups (8) have a pre-applied gas pressure. p = p 0, the change in the volume of the internal high-pressure air ∆V are all 0, the loads of the constant load actuators (6) T is 0, the load of the dynamic load actuator (7) t is 0, the length change of the cable specimen (1) ∆L is 0.

6. The test method according to claim 1, wherein In step S4, when the cable specimen (1) reaches a balanced state, the high-pressure air inside the plurality of high-pressure gas cylinder accumulator groups (8) is further compressed by the hydraulic oil, and a negative volume change occurs therein. ∆V =- ∆V 0, the air pressure increases p = p 0+ ∆p ; The load of the constant load actuator (6) T = T 0, and T The value of 0 is equal to the value of the equilibrium load; the load t of the dynamic load actuator (7) is 0; the cable specimen (1) is stretched and the length change ∆L = ∆L 0, then the equilibrium relationship is: k∆L 0= T 0＝ A ( p 0＋ ∆p ) in, k is the tensile stiffness of the cable specimen (1), A is the total effective area of ​​the hydraulic oil in the plurality of constant load actuators (6).

7. The test method according to claim 1, wherein In the step S5, when the cable specimen (1) is further loaded and stretched in a relatively balanced state, the pistons of the dynamic load actuators (7) retreat, and the load is a tensile force. t = δt The cable specimen (1) is stretched compared to the equilibrium state, and the length change is ∆L = ∆L 0+ δL The pistons of the constant load actuators (6) are passively advanced, and the negative pressure sucks the hydraulic oil out of the high-pressure gas cylinder accumulator groups (8) respectively, and the hydraulic oil extrusion of the high-pressure air inside is reduced, and there is a relatively positive volume change. ∆V =-( ∆V 0- δV ), the air pressure has a negative increment, p = p 0+ ∆p - δp ; The load of the constant load actuator (6) T Since the pressure changes of some of the high pressure gas cylinder accumulator groups (8) have negative increments, T = T 0- δT , at this time, the equilibrium relationship is: k ( ∆L 0+ δL )= T 0- δT + δt = A ( p 0+ ∆p - δp )+ δt in, k is the tensile stiffness of the cable specimen (1), A is the total effective area of ​​the hydraulic oil in the plurality of constant load actuators (6).

8. The test method according to claim 7, characterized in that In step S5, when the cable specimen (1) is further loaded and shortened in a relatively balanced state, the pistons of the dynamic load actuators (7) advance, and the load is a tensile force. t =- δt The cable specimen (1) is shortened compared to the equilibrium state, and the length change is ∆L = ∆L 0- δL The pistons of the constant load actuators (6) passively retreat, and the hydraulic oil is pressed from the second hydraulic oil pipelines (11) into the high-pressure gas cylinder accumulator groups (8). The high-pressure air inside is squeezed by the hydraulic oil more, and there is a relatively negative volume change. ∆V =-( ∆V 0+ δV ), the air pressure has a positive increment, p = p 0+ ∆p+δp ; The load of the constant load actuator (6) T Since the pressure changes of some of the high pressure gas cylinder accumulator groups (8) have positive increments, T = T 0+ δT , at this time, the equilibrium relationship is: k ( ∆L 0- δL )= T 0+ δT - δt = A ( p 0+ ∆p+δp )- δt in, k is the tensile stiffness of the cable specimen (1), A is the total effective area of ​​the hydraulic oil in the plurality of constant load actuators (6).

9. The test method according to claim 8, characterized in that In the step S6, the load of the dynamic load actuator (7) in a single fatigue loading cycle is obtained from the balance relationship between the loading stretch and the loading shortening. δ t ,and: 2 δt =2 kδL +2 Aδp in, k is the tensile stiffness of the cable specimen (1), A is the total effective area of ​​the hydraulic oil in the constant load actuators (6), 2 kδL is the fatigue load amplitude required by the test scheme within a single fatigue loading cycle, 2 Aδp Compensation for fluctuations in the constant load operating system within a single fatigue loading cycle.

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