Large-span adjustable stiffness counterforce device

Abstract

The application discloses a large-span adjustable rigidity counterforce device, according to the force value collected by a load sensor, the deformation of a pull rod is calculated, according to the ratio of the rigidity of a cross beam and the rigidity of the pull rod, the stroke required by an actuator to retract is calculated, the problem of accumulated rigidity due to partial specimen limit test is solved, the cost is greatly saved, and problems such as large-area shielding of test observation are solved, and the device has certain use value and popularization value.

Description

TECHNICAL FIELD

[0001] The present application relates to the mechanical field, especially to a large-span adjustable stiffness counterforce device. BACKGROUND

[0002] At present, the structural seismic test methods in the laboratory are mainly pseudo-static test and pseudo-dynamic test. High stiffness counterforce device is usually needed to provide counterforce to simulate the role of vertical load during the test.

[0003] Since it is difficult to obtain complete and reliable data of the overall structure performance by using standard samples or small size models, in order to solve such problems, more and more research institutions need to carry out tests close to actual structures or full size tests. However, the problem that follows is that as the size of the test piece becomes larger, the span of the counterforce device also increases, resulting in a sharp decrease in the stiffness of the counterforce device, so that the reliability of the test data obtained is insufficient.

[0004] At present, the methods to solve the stiffness problem of the counterforce device mainly include: increasing the stiffness of individual parts, improving the overall stiffness of the frame, and applying prestress.

[0005] Although the above schemes can solve the stiffness problem, there are still several deficiencies: the weight increase of the parts leads to exponential growth of the cost and is not conducive to the installation of the equipment and the test piece; the three-dimensional volume becomes larger, the transportation of the equipment is difficult, and the test observation area is largely blocked, etc.

[0006] In summary, a large-span adjustable stiffness counterforce device is needed to solve the deficiencies in the prior art. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a large-span adjustable stiffness counterforce device, which aims to solve the above problems.

[0008] To achieve the above purpose, the present application provides the following technical scheme: a large-span adjustable stiffness counterforce device, comprising a base and a cross beam, a stand column is arranged between the base and the cross beam, the stand column is detachably connected with the base and the cross beam, a servo adjusting mechanism is arranged on the cross beam, the upper end of the servo adjusting mechanism is connected with the cross beam, the lower end of the servo adjusting mechanism is connected with the base, the servo adjusting mechanism comprises a pull rod, a servo actuator, a displacement sensor and a load sensor are arranged on the pull rod, the servo actuator is arranged on the upper surface of the cross beam, the displacement sensor is arranged above the servo actuator, and the load sensor is arranged to be attached to the lower surface of the cross beam.

[0009] When the vertical load is applied, the beam will gradually deform with the increase of the load, the pull rod on the servo adjusting mechanism will also deform with the beam, and the load sensor will measure the force value due to the force of the pull rod. When the deformation exceeds the allowable range, the deformation of the pull rod is calculated according to the force value collected by the load sensor, and the stroke required for the actuator to retract is calculated according to the ratio of the stiffness of the beam to the stiffness of the pull rod, thereby solving the problem of accumulated stiffness due to partial specimen limit test, greatly saving the cost, and solving the problem of large area shielding in test observation.

[0010] Optionally, the calculation step of the adjustment displacement of the servo adjusting mechanism is as follows:

[0011] Step A1: installing the device and calculating the stiffness k1 of the frame;

[0012] Step A2: calculating the stiffness k2 of the pull rod of the servo adjusting mechanism according to the stiffness of the frame;

[0013] Step A3: measuring the force value F of the servo adjusting mechanism, calculating the stress σ of the pull rod, and calculating the deformation of the pull rod;

[0014] Step A4: calculating the adjustment displacement s of the servo adjusting mechanism, and adjusting the displacement by the servo actuator according to the adjustment displacement s, and ending the adjustment.

[0015] Firstly, the stiffness of the frame is directly measured after the installation and debugging of the equipment are completed. Since the stiffness of the frame is close to linear, it only needs to be measured once, that is, the stiffness k1 of the frame is linear. After the stiffness of the frame and the stiffness of the pull rod are determined, the force value of the servo adjusting mechanism can be measured in real time during the loading process, the stress σ of the pull rod can be calculated, and then the deformation of the pull rod can be calculated according to the stress. Since the stiffness of the frame and the stiffness of the pull rod are inconsistent, the displacement of the servo actuator retracted and the deformation of the adjustment are proportional to the ratio of the stiffness, the displacement of the servo adjusting mechanism retracted is calculated, and the adjustment is completed. After the force value of the servo adjusting mechanism is cleared, the adjustment can be performed once.

[0016] Optionally, the formula for calculating the stiffness of the frame in step A1 is:

[0017]

[0018] Wherein, k1 is the stiffness of the frame, F1 is the vertical applied force value, and s1 is the deformation of the frame.

[0019] Optionally, the stiffness k2 of the pull rod of the servo adjusting mechanism in step A2 is:

[0020] According to the derivation formula of the stress:

[0021]

[0022] The stiffness k2 of the pull rod is:

[0023]

[0024] Wherein F2 is the force of the pull rod, S2 is the deformation of the pull rod, k2 is the stiffness of the pull rod, R is the radius of the pull rod, E is the elastic modulus of the pull rod, and l is the length of the pull rod.

[0025] Optionally, the calculation formula of the stress σ of the pull rod in step A3 is:

[0026]

[0027]

[0028] Wherein S2 is the deformation of the pull rod, R is the radius of the pull rod, E is the elastic modulus of the pull rod, and l is the length of the pull rod.

[0029] Optionally, the calculation formula of the adjustment displacement s of the servo adjustment mechanism in step A4 is:

[0030]

[0031] Wherein k1 is the stiffness of the frame, and k2 is the stiffness of the pull rod.

[0032] Optionally, a connecting disc is further arranged on the pull rod, and the connecting disc is detachably connected with the pull rod. The connecting disc facilitates the connection of the servo adjustment mechanism and the cross beam.

[0033] Optionally, a connecting nut is arranged at the lower end of the pull rod, a mounting groove is arranged on the base, and the connecting nut is arranged in the mounting groove. The mounting groove facilitates the counter-sinking processing of the connecting nut on the pull rod, and improves the appearance of the device.

[0034] The beneficial effects of the present application are:

[0035] 1. In the present application, when the deformation exceeds the allowable range, the deformation of the pull rod is calculated according to the force value collected by the load sensor, and the stroke required for the actuator to retract is calculated according to the ratio of the stiffness of the cross beam to the stiffness of the pull rod, thereby solving the problem of accumulated stiffness due to partial specimen limit testing, greatly saving the cost, and solving the problem of large-area shielding of test observation.

[0036] 2. In the present application, the displacement of the servo actuator retraction and the deformation of the adjustment are proportional to the stiffness ratio, the displacement of the servo adjustment mechanism retraction is calculated, and after the adjustment is completed, the force value of the servo adjustment mechanism is zero, and then one adjustment can be performed.

[0037] 3. In the present application, the connecting disc facilitates the connection of the servo adjustment mechanism and the cross beam, the mounting groove facilitates the counter-sinking processing of the connecting nut on the pull rod, improves the appearance of the device, and has certain use value and popularization value. Attached Figure Description

[0038] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0039] Figure 2 This is a schematic diagram of a servo adjustment mechanism.

[0040] In the diagram: 1. Base; 2. Column; 3. Servo adjustment mechanism; 4. Crossbeam; 5. Displacement sensor; 6. Servo actuator; 7. Load sensor; 8. Connecting plate; 9. Tie rod. Detailed Implementation

[0041] like Figure 1 , 2 As shown, a large-span adjustable stiffness reaction device includes a base 1 and a crossbeam 4. A column 2 is provided between the base 1 and the crossbeam 4. The column 2 is detachably connected to both the base 1 and the crossbeam 4. A servo adjustment mechanism 3 is provided on the crossbeam 4. The upper end of the servo adjustment mechanism 3 is connected to the crossbeam 4, and the lower end of the servo adjustment mechanism 3 is connected to the base 1. The servo adjustment mechanism 3 includes a pull rod 9. A servo actuator 6, a displacement sensor 5, and a load sensor 7 are provided on the pull rod 9. The servo actuator 6 is located on the upper surface of the crossbeam 4, the displacement sensor 5 is located above the servo actuator 6, and the load sensor 7 is located in contact with the lower surface of the crossbeam 4. A connecting plate 8 is also provided on the pull rod 9. The connecting plate 8 is detachably connected to the pull rod 9. A connecting nut 10 is provided at the lower end of the pull rod 9. An installation groove 11 is provided on the base 1, and the connecting nut 10 is located in the installation groove 11.

[0042] When a vertical load is applied, the crossbeam gradually deforms as the load increases, and the tie rod on the servo adjustment mechanism also deforms along with the crossbeam. The load sensor measures the force value due to the force on the tie rod. When the deformation exceeds the allowable range, the deformation of the tie rod is calculated based on the force value collected by the load sensor. Based on the ratio of the crossbeam stiffness to the tie rod stiffness, the required retraction stroke of the actuator is calculated. This solves the problem of accumulating stiffness due to extreme testing of some specimens, greatly saving costs and solving the problem of large-area obstruction of test observation. The connecting plate facilitates the connection between the servo adjustment mechanism and the crossbeam, and the mounting groove facilitates the countersunk treatment of the connecting nut on the tie rod, improving the aesthetics of the device.

[0043] The calculation steps for the adjustment displacement of the servo adjustment mechanism are as follows:

[0044] Step A1: Install the device and calculate the frame stiffness k1. The formula for calculating the frame stiffness is:

[0045]

[0046] Where k1 is the frame stiffness, F1 is the vertically applied force, and s1 is the deformation of the frame.

[0047] Step A2: According to the stiffness of the frame, the pull rod stiffness k2 of the servo adjusting mechanism is calculated, and the specific calculation formula of the pull rod stiffness is:

[0048]

[0049] The pull rod stiffness k2 is:

[0050]

[0051] Wherein F2 is the force of the pull rod, S2 is the deformation of the pull rod, k2 is the stiffness of the pull rod, R is the radius of the pull rod, E is the elastic modulus of the pull rod, and l is the length of the pull rod;

[0052] Step A3: Measure the force value F of the servo adjusting mechanism, calculate the pull rod stress σ, and calculate the deformation of the pull rod. The calculation formula of the pull rod stress σ is:

[0053]

[0054]

[0055] Wherein S2 is the deformation of the pull rod, R is the radius of the pull rod, E is the elastic modulus of the pull rod, and l is the length of the pull rod;

[0056] Step A4: Calculate the adjusting displacement s of the servo adjusting mechanism,

[0057] The calculation formula of the adjusting displacement s of the servo adjusting mechanism is:

[0058]

[0059] Wherein k1 is the stiffness of the frame, and k2 is the stiffness of the pull rod;

[0060] According to the adjusting displacement s, the displacement adjustment is carried out through the servo actuator, and the adjustment is completed.

[0061] Firstly, after the equipment installation and commissioning is completed, the stiffness of the frame is directly measured. Since the stiffness of the frame is close to linear, it only needs to be measured once, that is, the stiffness of the frame k1 is linear. After the stiffness of the frame and the stiffness of the pull rod are determined, the force value of the servo adjusting mechanism can be measured in real time during the loading process, the pull rod stress σ can be calculated, and then the deformation of the pull rod can be calculated according to the stress. Since the stiffness of the frame and the stiffness of the pull rod are inconsistent, the displacement of the servo actuator retracted and the deformation of the adjustment are proportional to the stiffness ratio. The displacement of the servo adjusting mechanism retracted is calculated, and after the adjustment is completed, the force value of the servo adjusting mechanism is zero, that is, one adjustment is completed.

[0062] The application has simple design, convenient installation and transportation and high automation degree, solves the problem of the limit large size test of the partial test piece, greatly saves the cost, and solves the problem that the tested piece is observed by a large area shielding in the test process, Figure 1 The observation surface is installed with a servo adjusting device, the shielding area is only the projection area of the pull rod, the change in the test piece loading process can be fully observed through the double cameras, and the servo actuator can reduce the deformation amount of the cross beam through displacement control through servo control.

[0063] The above only describes the preferred embodiments of the application and is not used to limit the application, and any modification, equivalent replacement or improvement within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A large span adjustable stiffness reaction device, characterized in that, The application relates to a servo adjusting mechanism, which comprises a base and a crossbeam, a stand column is arranged between the base and the crossbeam, the stand column is detachably connected with the base and the crossbeam, a servo adjusting mechanism is arranged on the crossbeam, the upper end of the servo adjusting mechanism is connected with the crossbeam, the lower end of the servo adjusting mechanism is connected with the base, the servo adjusting mechanism comprises a pull rod, a servo actuator, a displacement sensor and a load sensor are arranged on the pull rod, the servo actuator is arranged on the upper surface of the crossbeam, the displacement sensor is arranged above the servo actuator, the load sensor is arranged to be attached to the lower surface of the crossbeam, and the adjusting displacement of the servo adjusting mechanism is calculated according to the following steps. Step A1: installing the device and calculating the rigidity k1 of the frame; Step A2: calculating the rigidity k2 of the pull rod of the servo adjusting mechanism according to the rigidity of the frame; Step A3: measuring the force value F of the servo adjusting mechanism, calculating the stress sigma of the pull rod, and calculating the deformation amount of the pull rod; Step A4: calculating the adjusting displacement s of the servo adjusting mechanism, and adjusting the displacement through the servo actuator according to the adjusting displacement s, and ending the adjustment.

2. The large span adjustable stiffness reaction device according to claim 1, characterized in that, The formula for calculating the rigidity of the frame in the step A1 is as follows: k1=F1 / s1. ， According to the derivation formula of the stress:

3. The large span adjustable stiffness reaction device according to claim 1, characterized in that, The step A2 in the servo adjusting mechanism of the pull rod stiffness : The rigidity k2 of the pull rod is as follows: F2 / s2=k2, wherein F2 is the force borne by the pull rod, s2 is the deformation amount of the pull rod, k2 is the rigidity of the pull rod, R is the radius of the pull rod, E is the elastic modulus of the pull rod, and l is the length of the pull rod. ， The calculation formula of the stress sigma of the pull rod in the step A3 is as follows: sigma=s2 / R / E / l. ， The calculation formula of the adjusting displacement s of the servo adjusting mechanism in the step A4 is as follows: s=k1 / k2.

4. The large span adjustable stiffness reaction device according to claim 1, wherein, A connecting disc is further arranged on the pull rod, and the connecting disc is detachably connected with the pull rod. ， ， A connecting nut is arranged at the lower end of the pull rod, an installation groove is arranged on the base, and the connecting nut is arranged in the installation groove.

5. The large span adjustable stiffness reaction device according to claim 3, wherein, ​ ， ​ 6. The large span adjustable stiffness reaction device according to claim 1, wherein, ​ 7. The large span adjustable stiffness reaction device according to any one of claims 1-6, characterized in that, ​

Images