Multi-cavity pressure-bearing block force sensor, testing device and method

Abstract

The invention discloses a multi-cavity pressure-bearing block force sensor, a testing device and a testing method. The force sensor comprises a multi-cavity pressure-bearing block and a strain sensor, the multi-cavity pressure-bearing block comprises an outer cylinder and a nesting plate, a first detection mounting part is arranged on the nesting plate, a second detection mounting part is arranged on the outer wall of the outer cylinder in the length direction of the nesting plate, and a third detection mounting part is arranged on the inner wall and the outer wall of the outer cylinder in the preset rotation angle direction of the nesting plate. The first detection installation part, the second detection installation part and the third detection installation part are all provided with strain sensors. According to the invention, the strain sensors are ingeniously designed on the outer cylinder and the nested plate, so that hardware support is provided for obtaining the pressure of the multi-cavity pressure-bearing block; based on the testing method of the multi-cavity pressure-bearing block force sensor and combined with simulation tests, the total pressure measurement of the multi-cavity pressure-bearing block force sensor is not influenced by the stress action position, the pressure borne by the support can be accurately measured, and good sensing stability is achieved; and the horizontal shearing force of the multi-cavity pressure-bearing shock insulation support can be further obtained.

Description

Technical Field

[0001] The invention relates to a multi-chamber pressure-bearing block force sensor, a testing device and a testing method, and belongs to the field of sensor circuit systems and detection technology. Background Art

[0002] The building structure foundation isolation technology can significantly reduce the seismic response of the structure by extending the natural vibration period of the structure and providing appropriate damping, effectively protecting the structural safety and improving the structural post-earthquake functional recovery ability. The seismic isolation bearing is the core component for realizing the seismic isolation function of the building. Effectively evaluating the status of the seismic isolation bearing is of great significance to ensuring the safety of the seismic isolation building.

[0003] When an earthquake occurs, the seismic isolation bearing consumes a lot of energy and is a key and weak point that is prone to damage. If the seismic isolation bearing has been damaged before the earthquake and is not discovered in time, it will affect its seismic isolation effect and even cause sudden failure of the entire structure. On the other hand, if the seismic isolation bearing is in an abnormal working state, such as excessive axial pressure or shear deformation, it will also have an adverse effect on its seismic isolation effect: when the axial pressure of the bearing is too large, the compressive stress on the effective overlapping area of ​​the bearing will exceed the allowable value under large deformation conditions, resulting in premature damage to the bearing and failure to fully exert its seismic isolation capacity; when the shear deformation of the bearing is too large, it will have an adverse effect on its ultimate deformation capacity, making the bearing capacity unable to meet the original design requirements, resulting in premature damage to the bearing or excessive displacement of the seismic isolation layer. Therefore, it is necessary to monitor the axial pressure, shear deformation and damage of the bearing, effectively evaluate the actual state of the seismic isolation bearing, and ensure the safety of the seismic isolation building.

[0004] During the long-term use of the bearings, even if they are qualified products and meet the construction and installation requirements, the bearings will inevitably have aging problems. This reflects the necessity and importance of monitoring the working status of the bearings. At present, the common evaluation method for seismic isolation bearings is to dismantle the bearings and evaluate them based on appearance inspections, load tests, etc. This method is time-consuming and labor-intensive, and it is impossible to accurately evaluate the status of the bearings in the structure. In addition, the bearings are relatively hidden, difficult to detect, and have certain dangers. If traditional manual methods are used for detection, the workload is huge, and the detection speed is difficult to meet modern management needs. Summary of the invention

[0005] The present invention provides a multi-chamber pressure-bearing block force sensor, a testing device and a method. By making a part of the multi-chamber pressure-bearing body seismic isolation support into a sensing element, the pressure of the multi-chamber pressure-bearing block can be obtained through the Wheatstone bridge principle, and the horizontal shear force of the multi-chamber pressure-bearing seismic isolation support can be further obtained.

[0006] The technical solution of the present invention is:

[0007] According to a first aspect of the present invention, there is provided a multi-chamber pressure block force sensor, comprising a multi-chamber pressure block 1 and a strain sensor 2; the multi-chamber pressure block 1 comprises an outer cylinder 6 and a nested plate 7, the outer cylinder 6 is a hollow cylinder, the nested plate 7 is extended from one end of the inner cavity of the hollow cylinder to the other end along the radial direction and is connected to the inner wall of the hollow cylinder to form a multi-chamber; a first detection mounting portion is provided on the nested plate 7, a second detection mounting portion is provided on the outer wall of the outer cylinder 6 along the length direction of the nested plate 7, and a third detection mounting portion is provided on the inner and outer walls of the outer cylinder 6 along the direction of a preset rotation angle of the nested plate 7, and the first detection mounting portion, the second detection mounting portion and the third detection mounting portion are all provided with strain sensors 2.

[0008] Furthermore, the first detection mounting portion, the second detection mounting portion, and the third detection mounting portion are all located at 1 / 2 of the height of the multi-chamber pressure-bearing block 1 .

[0009] Furthermore, the nested plate 7 adopts a cross-shaped nested plate, and a first detection mounting portion is distributed at the center of one side surface of each of the four branch plates of the cross-shaped nested plate. For any two adjacent branch plates, the side on which the first detection mounting portion is set is the side away from the two adjacent branch plates; each first detection mounting portion is fixed with a strain sensor along the longitudinal direction, and the four strain sensors are strain gauges 1 to strain gauges 4 respectively.

[0010] Furthermore, a total of 4 second detection mounting parts are distributed on the outer wall of the outer cylinder 6 along the length direction of the nested plate 7, and a strain sensor is fixed to each of the 4 second detection mounting parts along the longitudinal direction, and the 4 strain sensors are strain gauges 5, strain gauges 7, strain gauges 9, and strain gauges 11 respectively; wherein, the strain gauges 5 and strain gauges 9 are located on the outer wall of the outer cylinder 6 of the nested plate 7 along the first length direction, and the strain gauges 7 and strain gauges 11 are located on the outer wall of the outer cylinder 6 of the nested plate 7 along the second length direction; a total of 4 pairs of third detection mounting parts are distributed on the inner and outer walls of the outer cylinder 6 along the preset angle direction of the nested plate 7, and the 4 pairs of third detection mounting parts are arranged at equal intervals, and each third detection mounting part is fixed with a strain sensor along the longitudinal direction, namely, a first pair of strain gauges, a second pair of strain gauges, a third pair of strain gauges, and a fourth pair of strain gauges located on the inner and outer walls of the outer cylinder 6.

[0011] According to the second aspect of the present invention, a multi-chamber pressure block force sensor testing device is provided, and the multi-chamber pressure block force sensor testing device comprises the multi-chamber pressure block force sensor according to any one of claims 1 to 4 and a data processing module 5; the information collected by the strain sensor 2 in the multi-chamber pressure block force sensor is transmitted to the data processing module 5.

[0012] According to a third aspect of the present invention, a method for testing a multi-chamber pressure block force sensor is provided, comprising the following steps:

[0013] S1. Establish a finite element analysis model of a vertical pressure-bearing body to simulate the strain response of the vertical pressure-bearing body under a design load; wherein the vertical pressure-bearing body comprises a polytetrafluoroethylene pad 8, a cover plate 9, and the multi-chamber pressure-bearing block force sensor according to claim 4, the multi-chamber pressure-bearing block force sensor is buckled with a cover plate 9 with a slot on the upper and lower sides, and the two cover plates 9 are provided with a groove on the side away from the multi-chamber pressure-bearing block force sensor, and the polytetrafluoroethylene pad 8 is embedded in the groove;

[0014] S2. Based on the simulation results, extract the vertical strain values ​​of each detection installation part on the multi-chamber pressure-bearing block 1 to verify the plane section assumption;

[0015] S3. On the basis of the verification of the plane section assumption, the multi-chamber pressure-bearing block 1 is selected as the design area, and the design target is defined. The design target is set as: measuring the pressure on the multi-chamber pressure-bearing block 1 during the earthquake action;

[0016] S4. According to the design goal, a Wheatstone bridge is designed to solve the pressure values ​​on the outer cylinder 6 and the nesting plate 7 respectively through the strain value; and then the pressure of the multi-chamber pressure-bearing block 1 is obtained according to the pressure on the nesting plate 7 and the pressure of the outer cylinder 6.

[0017] Furthermore, the testing method further comprises:

[0018] S5. Calculate the horizontal shear force of the multi-chamber pressure-bearing seismic isolation bearing according to the pressure of the multi-chamber pressure-bearing block 1; wherein the multi-chamber pressure-bearing seismic isolation bearing includes a horizontal reset body and a vertical pressure-bearing body.

[0019] Furthermore, the S4 is specifically:

[0020] According to the Wheatstone bridge principle, strain gauges 1 to 4 are connected in series and then connected to the first branch of the Wheatstone bridge, four temperature compensation gauges are connected in series to the second branch adjacent to the first branch, and the other two branches are connected to a fixed resistor R, so as to obtain a first strain value based on the Wheatstone bridge; a first normal stress value is obtained according to the first strain value; the first normal stress value is multiplied by the first cross-sectional area to obtain the pressure on the nested plate 7; wherein the first cross-sectional area is the cross-sectional area of ​​the nested plate 7;

[0021] The strain gauge 5 and the strain gauge 9 are connected in series and connected to the first branch of the Wheatstone bridge, and two temperature compensation gauges are connected in series and connected to the second branch adjacent to the first branch. The other two branches are each connected to a fixed resistor R, so as to obtain a second strain value based on the Wheatstone bridge; and a second normal stress value is obtained according to the second strain value;

[0022] The strain gauge 7 and the strain gauge 11 are connected in series and connected to the first branch of the Wheatstone bridge, and two temperature compensation gauges are connected in series and connected to the second branch adjacent to the first branch. The other two branches are each connected to a fixed resistor R, so as to obtain a third strain value based on the Wheatstone bridge; and a third normal stress value is obtained according to the third strain value;

[0023] The first pair of strain gauges and the third pair of strain gauges are connected in series and connected to the first branch of the Wheatstone bridge, four temperature compensation gauges are connected in series and connected to the second branch adjacent to the first branch, and the other two branches are connected to a fixed resistor R, so as to obtain a fourth strain value based on the Wheatstone bridge; and a fourth normal stress value is obtained according to the fourth strain value;

[0024] The second pair of strain gauges and the fourth pair of strain gauges are connected in series and connected to the first branch of the Wheatstone bridge, and four temperature compensation gauges are connected in series and connected to the second branch adjacent to the first branch. The other two branches are connected to a fixed resistor R to obtain a fifth strain value based on the Wheatstone bridge; and the fifth normal stress value is obtained according to the fifth strain value;

[0025] An interpolation curve fitting is performed according to the second normal stress value, the third normal stress value, the fourth normal stress value, and the fifth normal stress value to obtain a normal stress curve function; the cylinder at the middle thickness of the outer cylinder 6 is flattened to calculate its length, and the flattened length is multiplied by the thickness of the outer cylinder 6 to obtain a second cross-sectional area; the normal stress curve function and the second cross-sectional area are multiplied and solved by a numerical integration method to obtain the pressure of the outer cylinder 6;

[0026] The pressure on the nesting plate 7 and the pressure on the outer cylinder 6 are added together to form the pressure of the multi-chamber pressure-bearing block 1 .

[0027] Furthermore, the S5 is specifically:

[0028] According to the pressure of the multi-chamber pressure-bearing block 1, the friction force of the multi-chamber pressure-bearing seismic isolation bearing is calculated;

[0029] According to the horizontal displacement of the multi-chamber pressure-bearing seismic isolation bearing and the rubber 14 parameters, the yield force of the multi-chamber pressure-bearing seismic isolation bearing is obtained;

[0030] The sum of the friction force of the multi-chamber pressure-bearing seismic isolation bearing and the yield force of the multi-chamber pressure-bearing seismic isolation bearing is taken as the horizontal shear force of the multi-chamber pressure-bearing seismic isolation bearing.

[0031] The beneficial effects of the present invention are as follows: the present invention cleverly designs strain sensors on the outer cylinder and nested plates of the multi-chamber pressure-bearing block, thereby providing hardware support for obtaining the pressure of the multi-chamber pressure-bearing block; based on the testing method of the multi-chamber pressure-bearing block force sensor and combined with simulation experiments, it can be seen that the total pressure measured by the multi-chamber pressure-bearing block force sensor is not affected by the force application position, and can more accurately measure the pressure on the bearing, and has good sensing stability; and further, the horizontal shear force of the multi-chamber pressure-bearing seismic isolation bearing can be obtained; compared with the manual measurement method, the testing process greatly reduces the workload and improves the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of a multi-chamber pressure block force sensor testing device;

[0033] Figure 2 It is a cross-sectional view of a multi-chamber pressure-bearing block;

[0034] Figure 3 It is a top view of the cross-shaped pressure block patch;

[0035] Figure 4 This is the structural diagram of the overall seismic isolation bearing;

[0036] Figure 5 It is the finite element model diagram of the vertical pressure-bearing body;

[0037] Figure 6 This is a schematic diagram of the detection points of the multi-chamber pressure block detection installation part;

[0038] Figure 7 This is the finite element simulation strain result diagram;

[0039] Figure 8 This is the bridge diagram of four strain gauges in series connected in a cross-type pressure-bearing block Wheatstone bridge;

[0040] Fig. 9 This is the bridge diagram of two strain gauges in series connected in a cross-type pressure-bearing block Wheatstone bridge;

[0041] Fig.10 A loading device for testing the accuracy of force sensors of multi-chamber pressure-bearing body supports;

[0042] Fig.11 It is the μ-N correlation fitting curve when the loading frequency is 0.01Hz;

[0043] Fig.12 It is the μ-N correlation fitting curve when the loading frequency is 0.05Hz;

[0044] Figure 1 , Figure 2 , Figure 4The numbers are: 1. Multi-chamber pressure block; 2. Strain sensor; 3. Acquisition module; 4. Transmission module; 5. Data processing module; 6. Outer cylinder; 7. Nesting plate; 8. Polytetrafluoroethylene pad; 9. Cover plate; 10. Sliding friction surface; 11. Upper connecting plate; 12. Lower connecting plate; 13. Rubber connecting plate; 14. Rubber; 15. Middle connecting plate. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0046] Example 1: Figure 1-4 As shown, according to the first aspect of an embodiment of the present invention, a multi-chamber pressure block force sensor is provided, comprising a multi-chamber pressure block 1 and a strain sensor 2; the multi-chamber pressure block 1 comprises an outer cylinder 6 and a nested plate 7, the outer cylinder 6 is a hollow cylinder, the nested plate 7 is extended from one end of the inner cavity of the hollow cylinder to the other end along the radial direction and is connected to the inner wall of the hollow cylinder to form a multi-cavity; a first detection mounting portion is provided on the nested plate 7, a second detection mounting portion is provided on the outer wall of the outer cylinder 6 along the length direction of the nested plate 7, and a third detection mounting portion is provided on the inner and outer walls of the outer cylinder 6 along the direction of a preset rotation angle of the nested plate 7, and the first detection mounting portion, the second detection mounting portion and the third detection mounting portion are all provided with strain sensors 2.

[0047] For example, Figure 4As shown, the multi-chamber pressure-bearing block force sensor is used for a multi-chamber pressure-bearing seismic isolation bearing, and the multi-chamber pressure-bearing seismic isolation bearing includes a horizontal reset body and a vertical pressure-bearing body. The vertical pressure-bearing body includes a polytetrafluoroethylene pad 8, a cover plate 9, and a multi-chamber pressure-bearing block force sensor. The horizontal reset body includes a sliding friction surface 10, an upper connecting plate 11, a lower connecting plate 12, a rubber connecting plate 13, rubber 14, and a middle connecting plate 15; wherein the sliding friction surface 10 of the horizontal reset body is symmetrically welded and fixed to the inner sides of the upper connecting plate 11 and the lower connecting plate 12 to form double-sided friction, and the sulfur The rubber 14 on the rubber connecting plate 13 is connected to the upper connecting plate 11, the middle connecting plate 15 and the four corners of the middle connecting plate 15 and the lower connecting plate 12 arranged in parallel through the rubber connecting plate 13 by high-strength bolts; the central opening of the middle connecting plate 15 allows the multi-chamber pressure-bearing block force sensor to pass through; the multi-chamber pressure-bearing block force sensor is buckled with a cover plate 9 with a slot on the upper and lower sides, and the two cover plates 9 are provided with a groove on the side away from the multi-chamber pressure-bearing block force sensor, and the polytetrafluoroethylene pad 8 is embedded in the groove, and the polytetrafluoroethylene pad 8 is slidably matched with the sliding friction surface 10. The vertical pressure-bearing body and the horizontal reset body are bidirectionally decoupled, the vertical pressure-bearing body provides support force for the upper structure, and the horizontal reset body only provides reset force.

[0048] refer to Figure 1 The height of the outer cylinder 6 is the same as that of the nesting plate 7, and the height direction is the axial direction of the hollow cylinder; the length direction of the nesting plate 7 is the same as the radial direction of the hollow cylinder.

[0049] Furthermore, the first detection mounting portion, the second detection mounting portion, and the third detection mounting portion are all located at 1 / 2 of the height of the multi-chamber pressure-bearing block 1 .

[0050] like Figure 1-Figure 3 As shown, the nesting plate 7 adopts a cross-shaped nesting plate, and a first detection installation portion is distributed at the center of one side surface of each of the four branch plates of the cross-shaped nesting plate. For any two adjacent branch plates, the side where the first detection installation portion is set is the side away from the two adjacent branch plates; Figure 3 There are a total of 4 first detection mounting parts, each of which is fixed with a strain sensor along the longitudinal direction. The 4 strain sensors are strain gauges 1 to 4. For example, strain gauges 2 and 3 are mounted on one side of two adjacent branch plates, and the side of the branch plate where strain gauge 2 is mounted is far away from the side of the branch plate where strain gauge 3 is mounted.

[0051] like Figure 1 , Figure 3As shown, the outer wall of the outer cylinder 6 is distributed with 4 second detection mounting parts along the length direction of the nesting plate 7, and each of the 4 second detection mounting parts is fixed with a strain sensor along the longitudinal direction, and the 4 strain sensors are strain gauges 5, 7, 9, and 11; wherein, the strain gauges 5 and 9 are located along the first length direction of the nesting plate 7, and the strain gauges 7 and 11 are located along the second length direction of the nesting plate 7; the inner and outer walls of the outer cylinder 6 are distributed with 4 pairs of third detection mounting parts (i.e., 8) along the direction of the nesting plate 7 rotating at a preset angle, and the 4 pairs of third detection mounting parts are respectively fixed with a strain sensor 5, 7, 9, and 11; wherein, the strain gauges 5 and 9 are located along the first length direction of the nesting plate 7, and the strain gauges 7 and 11 are located along the second length direction of the nesting plate 7; Arranged at equal intervals, each third detection installation part is fixed with a strain sensor in the longitudinal direction, namely, a first pair of strain gauges (strain gauge 8, strain gauge 14), a second pair of strain gauges (strain gauge 6, strain gauge 13), a third pair of strain gauges (strain gauge 12, strain gauge 16), and a fourth pair of strain gauges (strain gauge 10, strain gauge 15) located on the inner and outer walls of the outer cylinder 6; wherein the first pair of strain gauges and the third pair of strain gauges are located in the direction of the preset angle rotated along the first length of the nesting plate 7, and the second pair of strain gauges and the fourth pair of strain gauges are located in the direction of the preset angle rotated along the second length of the nesting plate 7. Exemplarily, the preset angle is 45 degrees.

[0052] According to the second aspect of an embodiment of the present invention, a multi-chamber pressure block force sensor testing device is provided, and the multi-chamber pressure block force sensor testing device includes a multi-chamber pressure block force sensor and a data processing module 5; the information collected by the strain sensor 2 in the multi-chamber pressure block force sensor is transmitted to the data processing module 5 through the acquisition module 3 / transmission module 4 for obtaining pressure and horizontal shear force according to the multi-chamber pressure block force sensor testing method.

[0053] Specifically, the data processing module 5 is a host computer. If the acquisition module 3 is used, the communication with the host computer is carried out by wire; if the transmission module 4 is used, the information is transmitted to the host computer by wireless communication. Exemplarily, the acquisition module 3 is a strain tester; the transmission module 4 is a wifi module / bluetooth module, etc., and the wifi module is used for explanation. The wifi module is placed in the cavity, and the lead-out port is connected to each strain sensor. At the same time, the lead-out port from the outer cylinder 6 is used to connect the battery, so that the battery can be replaced from the outside of the cavity.

[0054] like Figure 1-Figure 12 As shown, according to a third aspect of an embodiment of the present invention, a method for testing a multi-chamber pressure block force sensor is provided, comprising the following steps:

[0055] S1. Establish a finite element analysis model of a vertical pressure-bearing body to simulate the strain response of the vertical pressure-bearing body under a design load; wherein the vertical pressure-bearing body includes a polytetrafluoroethylene pad 8, a cover plate 9, and a multi-chamber pressure-bearing block force sensor, and the multi-chamber pressure-bearing block force sensor is buckled with a cover plate 9 with a slot on the upper and lower sides, and the two cover plates 9 are provided with a groove on the side away from the multi-chamber pressure-bearing block force sensor, and the polytetrafluoroethylene pad 8 is embedded in the groove; it should be noted that when establishing the finite element analysis model, the influence of the polytetrafluoroethylene pad 8 and the cover plate 9 on the interaction of the multi-chamber pressure-bearing block force sensor is considered, so the finite element analysis model established for the vertical pressure-bearing body in the present invention is more in line with the actual stress state than directly establishing a finite element analysis model for the multi-chamber pressure-bearing block force sensor;

[0056] S2. Based on the simulation results, extract the vertical strain values ​​of each detection installation part on the multi-chamber pressure-bearing block 1 to verify the plane section assumption;

[0057] S3. On the basis of the verification of the plane section assumption, the multi-chamber pressure-bearing block 1 is selected as the design area, and the design target is defined. The design target is set as: measuring the pressure and horizontal shear force on the multi-chamber pressure-bearing block 1 during the earthquake action;

[0058] S4. According to the design goal, a Wheatstone bridge is designed to solve the pressure values ​​on the outer cylinder 6 and the nesting plate 7 respectively through the strain value; and then the pressure of the multi-chamber pressure-bearing block 1 is obtained according to the pressure on the nesting plate 7 and the pressure of the outer cylinder 6.

[0059] Furthermore, it also includes:

[0060] S5. Calculate the horizontal shear force of the multi-chamber pressure-bearing isolation bearing according to the pressure of the multi-chamber pressure-bearing block 1.

[0061] Furthermore, the S4 is specifically:

[0062] According to the Wheatstone bridge principle, strain gauges 1 to 4 are connected in series and then connected to the first branch (such as AB branch) of the Wheatstone bridge, and four temperature compensation gauges are connected in series to the second branch (such as BC branch) adjacent to the first branch, and the other two branches are connected to a fixed resistor R, so as to obtain a first strain value based on the Wheatstone bridge; a first normal stress value is obtained according to the first strain value; the first normal stress value is multiplied by the first cross-sectional area to obtain the pressure on the nested plate 7; wherein the first cross-sectional area is the cross-sectional area of ​​the nested plate 7 (i.e., the length of the nested plate 7*the thickness, the length is the length in the first length direction / the length in the second length direction, and the length in the first length direction is equal to the length in the second length direction);

[0063] The strain gauge 5 and the strain gauge 9 are connected in series and connected to the first branch (such as the AB branch) of the Wheatstone bridge, and the two temperature compensation gauges are connected in series and connected to the second branch (such as the BC branch) adjacent to the first branch. The other two branches are connected to a fixed resistor R to obtain a second strain value based on the Wheatstone bridge; and the second normal stress value is obtained according to the second strain value;

[0064] The strain gauge 7 and the strain gauge 11 are connected in series and connected to the first branch (such as the AB branch) of the Wheatstone bridge, and the two temperature compensation gauges are connected in series and connected to the second branch (such as the BC branch) adjacent to the first branch. The other two branches are connected to a fixed resistor R, so as to obtain a third strain value based on the Wheatstone bridge; and the third normal stress value is obtained according to the third strain value;

[0065] Strain gauges 8, 14, 12 and 16 are connected in series and connected to a first branch (such as AB branch) of a Wheatstone bridge, four temperature compensation gauges are connected in series and connected to a second branch (such as BC branch) adjacent to the first branch, and the other two branches are connected to a fixed resistor R, so as to obtain a fourth strain value based on the Wheatstone bridge; and a fourth normal stress value is obtained according to the fourth strain value;

[0066] Strain gauges 6, 13, 10 and 15 are connected in series and connected to the first branch (such as AB branch) of the Wheatstone bridge, four temperature compensation gauges are connected in series and connected to the second branch (such as BC branch) adjacent to the first branch, and the other two branches are connected to a fixed resistor R, so as to obtain a fifth strain value based on the Wheatstone bridge; and a fifth normal stress value is obtained according to the fifth strain value;

[0067] An interpolation curve is fitted according to the second normal stress value, the third normal stress value, the fourth normal stress value, and the fifth normal stress value to obtain a normal stress curve function; the cylinder at the middle thickness of the outer cylinder 6 is flattened to calculate its length (the length is the circumference of the cylinder at the middle thickness), and the flattened length is multiplied by the thickness of the outer cylinder 6 to obtain a second cross-sectional area; the normal stress curve function and the second cross-sectional area are multiplied and solved by a numerical integration method to obtain the pressure of the outer cylinder 6; in the above, the interpolation curve fitting specifically adopts cubic spline interpolation; the numerical integration method specifically adopts Gaussian integration.

[0068] The pressure on the nesting plate 7 and the pressure on the outer cylinder 6 are added together to form the pressure of the multi-chamber pressure-bearing block 1 .

[0069] The general expression for solving the normal stress value for the strain value is: σ=Eε; where σ is the normal stress on the cross section, E is the elastic modulus, and ε is the strain value.

[0070] Furthermore, the S5 is specifically:

[0071] Considering that the horizontal shear force of the seismic isolation bearing is the sum of the yield force and the frictional resistance, the horizontal shear force of the multi-chamber pressure-bearing seismic isolation bearing is calculated based on the pressure of the multi-chamber pressure-bearing block 1, specifically:

[0072] According to the pressure of the multi-chamber pressure-bearing block 1, the friction force of the multi-chamber pressure-bearing seismic isolation bearing is calculated;

[0073] According to the horizontal displacement of the multi-chamber pressure-bearing seismic isolation bearing and the rubber 14 parameters, the yield force of the multi-chamber pressure-bearing seismic isolation bearing is obtained;

[0074] The sum of the friction force of the multi-chamber pressure-bearing seismic isolation bearing and the yield force of the multi-chamber pressure-bearing seismic isolation bearing is taken as the horizontal shear force of the multi-chamber pressure-bearing seismic isolation bearing.

[0075] Specifically:

[0076] In the above, when only the compressive stress correlation is considered, the dynamic friction coefficient μ is only related to the pressure N, and the expression for the friction force F is: F = μ(N)·N; wherein N is the pressure of the multi-chamber pressure block 1, μ is the dynamic friction coefficient, and the correlation curve between the dynamic friction coefficient μ and the pressure N can be obtained based on the compression shear test.

[0077] The expression for solving the yield force f for the multi-chamber pressure isolation bearing mentioned above is: Where G is the shear modulus of the rubber in the multi-chamber pressure-bearing isolation bearing, A is the cross-sectional area of ​​the rubber 14 in the multi-chamber pressure-bearing bearing, T r is the total height of the two layers of rubber arranged up and down in the multi-chamber pressure-bearing seismic isolation bearing (i.e., the height of the two rubbers 14), and x is the horizontal displacement of the multi-chamber pressure-bearing seismic isolation bearing. The rubber volume is determined according to the actual design requirements, thereby determining the yield force of the multi-chamber pressure-bearing seismic isolation bearing.

[0078] The test method is further explained below in combination with the test and finite element simulation:

[0079] 1. Verification of the plane section assumption

[0080] In order to better illustrate the performance of the present invention, ABAQUS software is used to perform numerical simulation on the vertical pressure-bearing body used for the multi-chamber pressure-bearing seismic isolation bearing. The model parameters are as follows: the outer diameter of the multi-chamber pressure-bearing block 1 is 230mm; the thickness of the outer cylinder 6 and the nested plate 7 is 25mm; the pressure-bearing block is 62mm high; the diameter of the cover plate 9 is 240mm, the thickness is 25mm, the upper groove depth of the cover plate is 7mm, and the lower groove depth is 5mm; the elastic modulus of the steel material is defined as 210000MPa, the Poisson's ratio is 0.3, the yield strength is 235MPa, and the plastic strain is 0; the diameter of the polytetrafluoroethylene pad 8 is 210mm, the thickness is 7mm, and it is defined as an elastic material with an elastic modulus of 280MPa and a Poisson's ratio of 0.42; and the C3D8R unit is used for simulation; the normal stresses applied to the vertical pressure-bearing body are 25, 30, and 50MPa, respectively, and the bottom of the vertical pressure-bearing body is completely fixed.

[0081] By establishing the vertical pressure-bearing body Figure 5 The finite element analysis model shown in FIG. 1 is used to extract the multi-chamber pressure block 1. Figure 6 The vertical strain values ​​at the locations of the various detection installation parts are shown as follows: Figure 7 As shown; from the finite element simulation results, it can be seen that when the compressive stress is the same, the displacement value of the first detection mounting portion on the nested plate 7 is basically the same, the displacement values ​​of the second detection mounting portion on the outer wall of the outer cylinder 6 and the third detection mounting portion on the inner and outer walls of the outer cylinder 6 are basically consistent, but the displacement values ​​of the nested plate 7 and the outer cylinder 6 are different. It is believed that the nested plate 7 and the outer cylinder 6 approximately meet the plane section assumption.

[0082] 2. Obtaining pressure value

[0083] like Figure 8 As shown, strain gauges 1 to 4 are connected in series and then connected to the AB branch of the Wheatstone bridge, four temperature compensation gauges are connected in series and connected to the adjacent BC branch, and the other two branches are each connected to a fixed resistor R, so as to obtain a first strain value based on the Wheatstone bridge; a first normal stress value is obtained based on the first strain value; the first normal stress value is multiplied by the first cross-sectional area to obtain the pressure on the nested plate 7; wherein the first cross-sectional area is the cross-sectional area of ​​the nested plate 7.

[0084] like Fig. 9 As shown, the strain gauge 5 and the strain gauge 9 are connected in series and then connected to the AB branch of the Wheatstone bridge, and the two temperature compensation gauges are connected in series and connected to the adjacent BC branch. The other two branches are connected to a fixed resistor R, so as to obtain the second strain value based on the Wheatstone bridge; the second normal stress value is obtained according to the second strain value; the connection method of the strain gauge 7 and the strain gauge 11 is the same as the connection method of the strain gauge 5 and the strain gauge 9, and finally the third normal stress value is obtained;

[0085] like Figure 8 As shown, strain gauges 8, 14, 12 and 16 are connected in series and then connected to the AB branch of the Wheatstone bridge; four temperature compensation gauges are connected in series and connected to the BC branch; the other two branches are connected to a fixed resistor R, so as to obtain a fourth strain value based on the Wheatstone bridge; the fourth normal stress value is obtained according to the fourth strain value; the connection method of strain gauges 6, 13, 10 and 15 is the same as the connection method of "strain gauges 8, 14, 12 and 16", and finally the fifth normal stress value is obtained.

[0086] An interpolation curve fitting is performed according to the second normal stress value, the third normal stress value, the fourth normal stress value, and the fifth normal stress value to obtain a positive stress curve function; the cylinder at the middle thickness of the outer cylinder 6 is flattened to calculate its length (the length is the circumference of the cylinder at the middle thickness), and the flattened length is multiplied by the thickness of the outer cylinder 6 to obtain a second cross-sectional area; the positive stress curve function and the second cross-sectional area are multiplied and solved by a numerical integration method to obtain the pressure of the outer cylinder 6; the pressure on the nesting plate 7 and the pressure of the outer cylinder 6 are added as the pressure of the multi-chamber pressure block 1.

[0087] In the above, the calculation process of each bridge group is as follows (assuming that the direction of strain gauges No. 5 and No. 9 is the x direction, the direction of strain gauges No. 7 and No. 11 is the y direction, the strain in the compression area is positive, the strain in the tension area is negative, and the bending moments Mx and My are both counterclockwise):

[0088] for Figure 8 The four strain gauges shown are connected in series in one bridge arm, and the strain measured by each strain gauge is (taking strain gauges 1-4 as an example, the same applies to the others):

[0089] ε1=ε P -ε Mx -ε My +ε t

[0090] ε2=ε P +ε Mx -ε My +ε t

[0091] ε3=ε P +ε Mx +ε My +ε t

[0092] ε4=ε P -ε Mx +ε My +ε t

[0093] Then the strain value of 4 strain gauges connected in series under one bridge arm is:

[0094] ε=ε AB -ε BC +ε CD -ε AD =(ε1+ε2+ε3+ε4)-4×ε t =4×ε P

[0095] For Fig. 9 The two strain gauges shown are connected in series in one bridge arm, and the strain measured by each strain gauge is (taking strain gauges 5 and 9 measuring the X direction as an example, the same applies to measuring the Y direction):

[0096] ε5=ε P -ε Mx +ε t

[0097] ε9=ε P +ε Mx +ε t

[0098] Then the strain value of two strain gauges connected in series under one bridge arm is:

[0099] ε=ε AB -ε BC +ε CD -ε AD =(ε5+ε9)-2×ε t =2×ε P

[0100] In order to study the sensing stability of the multi-chamber pressure-bearing block force sensor, a vertical pressure-bearing body specimen was made and a pad was placed on it to carry out pure pressure and bias pressure tests. The multi-chamber pressure-bearing block 1 has an outer diameter of 230mm; the outer cylinder 6 and the nesting plate 7 are both 25mm thick; the pressure block is 62mm high; the cover plate 9 has a diameter of 240mm and a thickness of 25mm, the upper groove of the cover plate is 7mm deep, and the lower groove is 5mm deep; the polytetrafluoroethylene pad 8 has a diameter of 210mm and a thickness of 7mm. A 10000kN microcomputer-controlled electro-hydraulic servo pressure testing machine was used to test the vertical pressure-bearing body. The loading device is as follows: Fig.10 As shown. This test adopts continuous loading mode, and the loading speed is 1kN / s. The pressure control system of the electro-hydraulic servo pressure testing machine is controlled by a microcomputer to record the load time history data; the strain data is recorded by the strain tester. The test conditions are shown in Table 1 (CY represents pure pressure test, 1 / 4D-0°, 1 / 3D-0°, 1 / 3D-0°, 1 / 3D-45° represent bias pressure test; PTFE pad is polytetrafluoroethylene pad). The instruments and equipment used in the test are shown in Table 2.

[0101] Table 1

[0102]

[0103] Table 2

[0104]

[0105] Taking the elastic modulus of steel E=210GPa, the total pressure N on the cross section of the multi-chamber pressure block 1 under each working condition is calculated by the test method of the multi-chamber pressure block force sensor of the present invention, and the relative error between it and the actual load is calculated ((calculated total pressure N-actual load) / actual load), and the results are shown in Table 3. Comparing the test conditions of pure pressure and bias pressure, the same deflection angle and different eccentricity (working conditions 1 / 4D-0° and 1 / 3D-0°) and the same eccentricity and different deflection angle (working conditions 1 / 3D-0° and 1 / 3D-45°), the maximum relative error between the calculated total pressure N and the actual load is 2.26%, indicating that the multi-chamber pressure block force sensor is not affected by the force position when measuring the total pressure, can more accurately measure the pressure on the seismic isolation bearing, and has good sensing stability.

[0106] Table 3

[0107] Condition Name Actual load / kN Calculate the total pressure N / kN Relative error CY 1815 1781.46 1.85％ 1 / 4D-0° 930 909.02 2.26％ 1 / 3D-0° 930 910.60 2.09％ 1 / 3D-45° 930 917.15 1.38％

[0108] 3. Obtaining horizontal shear force

[0109] The fitting curves of dynamic friction coefficient under different pressures are as follows: Fig.11 (Loading frequency 0.01Hz), Fig.12 (Loading frequency 0.05Hz). It can be seen that when the loading frequency is the same, the dynamic friction coefficient μ is basically linearly related to the pressure. The dynamic friction coefficient μ corresponding to different pressures can be obtained according to the μ-N fitting curve, and the friction force can be calculated according to F=μ(N)·N; then the rubber parameters are determined according to the actual design requirements, so as to determine the yield force and then calculate the horizontal shear force.

[0110] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A multi-chamber pressure block force sensor, characterized in that: The invention comprises a multi-chamber pressure-bearing block (1) and a strain sensor (2); the multi-chamber pressure-bearing block (1) comprises an outer cylinder (6) and a nesting plate (7); the outer cylinder (6) is a hollow cylinder; the nesting plate (7) is extended from one end of the inner cavity of the hollow cylinder to the other end along the radial direction and is connected to the inner wall of the hollow cylinder to form a multi-chamber; a first detection mounting portion is provided on the nesting plate (7); a second detection mounting portion is provided on the outer wall of the outer cylinder (6) along the length direction of the nesting plate (7); a third detection mounting portion is provided on the inner and outer walls of the outer cylinder (6) along the direction of a preset rotation angle of the nesting plate (7); the first detection mounting portion, the second detection mounting portion, and the third detection mounting portion are all provided with strain sensors (2).

2. The multi-chamber pressure block force sensor according to claim 1, characterized in that: The first detection mounting part, the second detection mounting part and the third detection mounting part are all located at 1 / 2 of the height of the multi-chamber pressure-bearing block (1).

3. The multi-chamber pressure block force sensor according to claim 1, characterized in that: The nesting plate (7) adopts a cross-shaped nesting plate, and a first detection installation part is distributed at the center of one side surface of each of the four branch plates of the cross-shaped nesting plate. For any two adjacent branch plates, the side where the first detection installation part is set is the side away from the two adjacent branch plates; each first detection installation part is fixed with a strain sensor in the longitudinal direction, and the four strain sensors are strain gauges 1 to 4 respectively.

4. The multi-chamber pressure block force sensor according to claim 3, characterized in that: The outer wall of the outer cylinder (6) is provided with four second detection mounting parts along the length direction of the nesting plate (7), and one strain sensor is fixed to each of the four second detection mounting parts along the longitudinal direction. The four strain sensors are strain gauges 5, 7, 9 and 11 respectively; wherein the strain gauges 5 and 9 are located on the outer wall of the outer cylinder (6) along the first length direction of the nesting plate (7), and the strain gauges 7 and 11 are located on the outer wall of the outer cylinder (6) along the second length direction of the nesting plate (7); and four pairs of third detection mounting parts are distributed on the inner and outer walls of the outer cylinder (6) along the direction of the preset rotation angle of the nesting plate (7), and the four pairs of third detection mounting parts are arranged at equal intervals, and each third detection mounting part is fixed with one strain sensor along the longitudinal direction, namely, a first pair of strain gauges, a second pair of strain gauges, a third pair of strain gauges and a fourth pair of strain gauges located on the inner and outer walls of the outer cylinder (6).

5. A multi-chamber pressure block force sensor testing device, characterized in that: The multi-chamber pressure block force sensor testing device comprises the multi-chamber pressure block force sensor described in any one of claims 1 to 4 and a data processing module (5); the information collected by the strain sensor (2) in the multi-chamber pressure block force sensor is transmitted to the data processing module (5).

6. A method for testing a multi-chamber pressure block force sensor, characterized in that: The steps include: S1. Establish a finite element analysis model of a vertical pressure-bearing body to simulate the strain response of the vertical pressure-bearing body under a design load; wherein the vertical pressure-bearing body comprises a polytetrafluoroethylene pad (8), a cover plate (9), and the multi-chamber pressure-bearing block force sensor according to claim 4, the multi-chamber pressure-bearing block force sensor is buckled with a cover plate (9) with a slot on the upper and lower sides, and the two cover plates (9) are provided with a groove on the side away from the multi-chamber pressure-bearing block force sensor, and the polytetrafluoroethylene pad (8) is embedded in the groove; S2. Based on the simulation results, extract the vertical strain values ​​at the locations of the detection installation parts on the multi-chamber pressure-bearing block (1) to verify the plane section assumption; S3. On the basis of the verification of the plane section assumption, the multi-chamber pressure-bearing block (1) is selected as the design area, and a design target is defined. The design target is set as: measuring the pressure on the multi-chamber pressure-bearing block (1) during the earthquake action; S4. According to the design objectives, a Wheatstone bridge is designed to solve the pressure values ​​on the outer cylinder (6) and the nesting plate (7) respectively through the strain value; and then the pressure of the multi-chamber pressure-bearing block (1) is obtained according to the pressure on the nesting plate (7) and the pressure of the outer cylinder (6).

7. The method for testing a multi-chamber pressure block force sensor according to claim 6, characterized in that: Also includes: S5. Calculate the horizontal shear force of the multi-chamber pressure-bearing seismic isolation bearing according to the pressure of the multi-chamber pressure-bearing block (1); wherein the multi-chamber pressure-bearing seismic isolation bearing comprises a horizontal reset body and a vertical pressure-bearing body.

8. The method for testing a multi-chamber pressure block force sensor according to claim 6, characterized in that: The S4 is specifically: According to the Wheatstone bridge principle, strain gauges 1 to 4 are connected in series and then connected to the first branch of the Wheatstone bridge, four temperature compensation gauges are connected in series to the second branch adjacent to the first branch, and the other two branches are connected to a fixed resistor R, so as to obtain a first strain value based on the Wheatstone bridge; and a first normal stress value is obtained according to the first strain value; Multiplying the first normal stress value by the first cross-sectional area to obtain the pressure on the nested plate (7); wherein the first cross-sectional area is the cross-sectional area of ​​the nested plate (7); The strain gauge 5 and the strain gauge 9 are connected in series and connected to the first branch of the Wheatstone bridge, and two temperature compensation gauges are connected in series and connected to the second branch adjacent to the first branch. The other two branches are each connected to a fixed resistor R, so as to obtain a second strain value based on the Wheatstone bridge; and a second normal stress value is obtained according to the second strain value; The strain gauge 7 and the strain gauge 11 are connected in series and connected to the first branch of the Wheatstone bridge, and two temperature compensation gauges are connected in series and connected to the second branch adjacent to the first branch. The other two branches are each connected to a fixed resistor R, so as to obtain a third strain value based on the Wheatstone bridge; and a third normal stress value is obtained according to the third strain value; The first pair of strain gauges and the third pair of strain gauges are connected in series and connected to the first branch of the Wheatstone bridge, four temperature compensation gauges are connected in series and connected to the second branch adjacent to the first branch, and the other two branches are connected to a fixed resistor R, so as to obtain a fourth strain value based on the Wheatstone bridge; and a fourth normal stress value is obtained according to the fourth strain value; The second pair of strain gauges and the fourth pair of strain gauges are connected in series and connected to the first branch of the Wheatstone bridge, and four temperature compensation gauges are connected in series and connected to the second branch adjacent to the first branch. The other two branches are connected to a fixed resistor R to obtain a fifth strain value based on the Wheatstone bridge; and the fifth normal stress value is obtained according to the fifth strain value; Performing interpolation curve fitting according to the second normal stress value, the third normal stress value, the fourth normal stress value, and the fifth normal stress value to obtain a normal stress curve function; flattening the cylinder at the middle thickness of the outer cylinder (6) to calculate its length, and multiplying the flattened length by the thickness of the outer cylinder (6) to obtain a second cross-sectional area; multiplying the normal stress curve function and the second cross-sectional area to obtain a solution using a numerical integration method to obtain a pressure of the outer cylinder (6); The pressure on the nesting plate (7) and the pressure on the outer cylinder (6) are added together to form the pressure of the multi-chamber pressure-bearing block (1).

9. The method for testing a multi-chamber pressure block force sensor according to claim 7, characterized in that: The S5 is specifically: Calculating the friction force of the multi-chamber pressure-bearing seismic isolation bearing according to the pressure of the multi-chamber pressure-bearing block (1); According to the horizontal displacement of the multi-chamber pressure-bearing seismic isolation bearing and the parameters of the rubber (14), the yield force of the multi-chamber pressure-bearing seismic isolation bearing is calculated; The sum of the friction force of the multi-chamber pressure-bearing seismic isolation bearing and the yield force of the multi-chamber pressure-bearing seismic isolation bearing is taken as the horizontal shear force of the multi-chamber pressure-bearing seismic isolation bearing.

Images