A device and method for controlling the impact test of a falling weight using a combination of magnetorheological fluid and metal sheet.

Abstract

This application relates to the technical field of structural dynamics testing equipment, and discloses a device and method for combined control of magnetorheological fluid and metal spring sheet for drop hammer impact testing. The device includes: a test bench comprising a rigid base, a vertical support column, and a horizontal fixed beam; a drop hammer system for lifting and releasing the drop hammer body; a combined control loading system for providing stiffness support; a uniformly distributed load transfer system for receiving the impact load and converting it into a line load for transfer to the beam / column component under test; a parameter monitoring system for data acquisition; and a control system for controlling the release of the drop hammer body and adjusting the current of the excitation coil. This invention, by employing the combination of magnetorheological fluid and metal spring sheet, and utilizing the synergistic effect of the continuously adjustable damping of the magnetorheological fluid and the stiffness support of the metal spring sheet, can achieve impact pulse trimming, thereby avoiding the shortcomings of traditional airbag and rubber loading methods, such as narrow control range and low precision.

Description

Technical Field

[0001] This invention relates to the field of structural dynamics testing equipment technology, specifically to a device and method for controlling the impact test of a falling hammer using a combination of magnetorheological fluid and metal sheet. Background Technology

[0002] In assessing the blast resistance of building structures, it is necessary to simulate the effects of explosive loads on key beam and column components through experiments to obtain the blast resistance capacity, deformation patterns, and failure modes of these components. Current mainstream explosive load simulation equipment suffers from the following core shortcomings:

[0003] Drop hammer impact airbag / rubber loading method: Some existing technologies attempt to apply uniformly distributed loads by impacting airbags or rubber components with a drop hammer. The principle is to use the elastic deformation of the airbag / rubber to disperse concentrated impacts. However, this method has inherent defects: First, the load control precision is low. The stiffness of the airbag depends on the inflation pressure, and the damping of the rubber depends on the material properties. Both are difficult to continuously adjust, making it impossible to accurately match the differentiated load requirements of TNT (high peak value, short duration) and gas explosion (low peak value, long duration). Second, the load stability is poor. The airbag is prone to load decay due to air pressure leakage, and the rubber is prone to fatigue deformation after long-term use, resulting in insufficient test repeatability. Third, the response speed is slow. The deformation of the airbag / rubber lags behind the drop hammer impact, which cannot meet the millisecond-level transient loading requirements of explosive loads and makes it difficult to reproduce the rise-edge characteristics of real explosive loads.

[0004] Specialized explosion simulation devices: TNT field explosion devices are highly dangerous, costly, and have poor repeatability; gas explosion canisters are bulky and only suitable for explosion simulation in enclosed spaces, and cannot be used with beam and column components; although hydraulic servo impact devices have adjustable loads, their response speed is slow (unable to meet the transient requirements of explosion loads) and their equipment cost is significantly higher than that of drop hammer devices.

[0005] Single control device: Existing single magnetorheological fluid control devices require high current drive to achieve high damping, which can easily lead to coil overheating and lack of stiffness support, resulting in poor load stability; single metal spring control devices have fixed stiffness and a narrow load adjustment range, making it impossible to take into account the simulation of dual explosion scenarios.

[0006] In summary, existing equipment and loading methods (including drop hammer impact airbag / rubber method) cannot simultaneously meet the testing requirements of precise and adjustable load characteristics, uniform load application, fast response speed, controllable cost, and high stability. There is an urgent need for a new type of composite adjustable drop hammer impact testing device. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a composite control device and method for falling hammer impact testing using magnetorheological fluid and metal pellets. This solves the problems of low load control accuracy and inability to accommodate the different scenarios of TNT and gas explosions in existing explosion simulation test equipment, as well as the lag in response and poor stability of uniformly distributed load application, high test costs, and low applicability.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a magnetorheological fluid and metal shrapnel composite controlled drop hammer impact testing device, comprising:

[0009] The test bench includes a rigid base, a vertical support column, and a horizontal fixing beam, wherein the horizontal fixing beam is used to fix the beam-column component to be tested;

[0010] A drop hammer system includes a drop hammer body, a guide mechanism disposed on the vertical support column, and a lifting and releasing mechanism, wherein the lifting and releasing mechanism is used to lift and release the drop hammer body;

[0011] A composite control loading system is installed at the bottom of the drop hammer body, and includes a magnetorheological fluid assembly and a metal spring assembly arranged coaxially; the magnetorheological fluid assembly includes an excitation coil for adjusting the damping force of the magnetorheological fluid when energized; the metal spring assembly is used to provide stiffness support.

[0012] A uniformly distributed load transfer system is set below the composite control loading system to receive impact loads and convert them into line loads to transfer to the beam and column members to be tested.

[0013] The parameter monitoring system is used to collect data on impact loads, component displacement, and strain.

[0014] The control system is electrically connected to the lifting and releasing mechanism, the composite control loading system, and the parameter monitoring system, respectively, and is used to control the release of the drop hammer body and adjust the current of the excitation coil.

[0015] Preferably, the magnetorheological fluid assembly includes a sealed cylinder, a piston, and the excitation coil;

[0016] The top of the piston is fixedly connected to the bottom of the drop hammer body, the bottom end of the piston extends into the sealed cylinder, and the piston is provided with a damping hole.

[0017] The magnetorheological fluid is filled inside the sealed cylinder.

[0018] The excitation coil is wound around the inner wall of the sealed cylinder.

[0019] Preferably, the metal spring assembly includes multiple annular metal springs, which are coaxially sleeved on the outside of the piston extending out of the sealing cylinder; and the bottom of the metal spring assembly abuts against the top surface of the sealing cylinder.

[0020] Preferably, the uniformly distributed load transfer system includes a load distribution beam, a buffer layer, and a force transmission plate;

[0021] The top surface of the load distribution beam bears the impact of the composite control loading system;

[0022] The force transmission plate is located on the top surface of the beam-column member to be tested, and the length of the force transmission plate is the same as the length of the load distribution beam.

[0023] The buffer layer is located between the load distribution beam and the force transmission plate.

[0024] Preferably, the lifting and releasing mechanism includes a drive motor, a lifting assembly, and an electromagnetic release device. The drive motor adjusts the height of the drop hammer body through the lifting assembly, and the electromagnetic release device is used to hold or release the drop hammer body.

[0025] Preferably, the parameter monitoring system includes:

[0026] A force sensor is disposed between the drop hammer body and the composite control loading system;

[0027] A displacement sensor, mounted on the rigid base, is used to detect the vertical displacement of the beam-column member to be tested;

[0028] Strain gauges are attached to the surface of the beam-column member to be tested.

[0029] The force sensor, displacement sensor, and strain gauge are all connected to the control system via a data acquisition module.

[0030] Preferably, the control system includes a host computer, a main control chip, and a current regulation module; the host computer is used to set target explosion scene parameters, and the main control chip is used to control the current regulation module to output a changing current to the excitation coil according to the parameters.

[0031] A method for controlling the impact test of a falling weight using a combination of magnetorheological fluid and metal pellets includes the following steps:

[0032] Step S1: Fix the beam and column components to be tested onto the test bench, install the uniformly distributed load transfer system, and make the force transfer plate fit against the top surface of the component;

[0033] Step S2: Input the target explosion scene parameters into the host computer of the control system, and calculate the lifting height of the falling hammer body and the excitation current change law of the magnetorheological fluid component based on the target parameters;

[0034] Step S3: Control the lifting and release mechanism to raise the drop hammer system to the calculated set height;

[0035] Step S4: The control system sends a trigger command to lift the release mechanism to release the drop hammer body. At the same time, the control system adjusts the current of the excitation coil in the magnetorheological fluid assembly according to the excitation current change law. The drop hammer body impacts the composite control loading system. The metal spring assembly is compressed to provide stiffness, and the magnetorheological fluid assembly provides variable damping, which work together to control the impact load.

[0036] Step S5: The adjusted load is converted into a line load by the uniformly distributed load transfer system and applied to the beam and column members to be tested. The parameter monitoring system simultaneously collects test data and transmits it to the host computer.

[0037] Preferably, in step S2:

[0038] When simulating a TNT explosion scenario, the current regulation law is set to output a large current for a short period of time to simulate high peak value and short-term load.

[0039] When simulating a gas explosion scenario, the current regulation law is set to output a small current or control the current to decay slowly in order to simulate low peak value and long duration load.

[0040] Preferably, after step S5, the method further includes:

[0041] The host computer generates the impact load time-domain curve based on the collected force sensor data, and generates the component response curve based on the displacement sensor and strain gauge data. The simulation effect is verified by comparing the parameters of the target explosion scene.

[0042] This invention provides a device and method for controlling the impact test of a falling weight using a combination of magnetorheological fluid and a metal spring. It has the following beneficial effects:

[0043] 1. This invention uses a combination of magnetorheological fluid and metal spring sheet, and then utilizes the synergistic effect of the continuously adjustable damping of the magnetorheological fluid and the stiffness support of the metal spring sheet to achieve the adjustment of the impact pulse. This can cover two different scenarios: the high peak and short duration of TNT explosion and the low peak and long duration of gas explosion. This overcomes the shortcomings of traditional airbag and rubber loading methods, which have narrow control range and low precision.

[0044] 2. The present invention uses a load distribution beam, a buffer layer and a force transmission plate to form a transmission system that can convert the concentrated impact of the falling hammer into a line load acting on the surface of the component, thereby solving the problems of uneven force distribution and waveform transmission distortion in traditional soft medium loading, and thus can truly restore the stress state of beam and column components under explosion.

[0045] 3. This invention uses an excitation coil to control the magnetorheological fluid, and then combines it with the initial stiffness support of a metal spring sheet. This satisfies the rapid response of the transient rise edge of the explosive load, and avoids the overload or instability that is prone to occur in single fluid control. Therefore, it is superior to the airbag and rubber methods that have deformation hysteresis, thus ensuring high repeatability of the test and data reliability. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the structure of the present invention;

[0047] Figure 2 This is a cross-sectional schematic diagram of a portion of the uniformly distributed load transfer system of the present invention;

[0048] Figure 3 This is a front view of the composite control loading system of the present invention;

[0049] Figure 4 This is a cross-sectional view of the composite control loading system of the present invention;

[0050] Figure 5 This is a schematic diagram of the drop hammer system of the present invention;

[0051] Figure 6 This is a schematic diagram of the test bench of the present invention.

[0052] The components include: 1. Test bench; 101. Rigid base; 102. Vertical support column; 103. Horizontal fixed beam; 2. Drop hammer system; 201. Drop hammer body; 202. Guide mechanism; 203. Lifting and release mechanism; 3. Composite control loading system; 301. Magnetorheological fluid assembly; 3011. Sealed cylinder; 3012. Piston; 3013. Excitation coil; 3014. Magnetorheological fluid; 302. Metal spring assembly; 4. Uniformly distributed load transfer system; 401. Load distribution beam; 402. Buffer layer; 403. Force transmission plate; 5. Parameter monitoring system; 501. Force sensor; 502. Displacement sensor; 503. Strain gauge; 6. Control system; 7. Beam and column components to be tested. Detailed Implementation

[0053] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] To better understand the present invention, the above content will be described in detail below with reference to specific embodiments.

[0055] Example 1: Please refer to the appendix Figure 1 - Appendix Figure 6 The present invention provides a magnetorheological fluid and metal sheet composite controlled drop hammer impact test device, comprising:

[0056] The test bench 1 includes a rigid base 101, a vertical support column 102, and a horizontal fixing beam 103, the horizontal fixing beam 103 being used to fix the beam-column component 7 to be tested; the drop hammer system 2 includes a drop hammer body 201, a guide mechanism 202 mounted on the vertical support column 102, and a lifting and releasing mechanism 203, the lifting and releasing mechanism 203 being used to lift and release the drop hammer body 201; the composite control loading system 3 is installed at the bottom of the drop hammer body 201, and includes a magnetorheological fluid assembly 301 and a metal spring assembly 302 arranged coaxially; the magnetorheological fluid assembly 301 includes an excitation coil 301. 3, used to adjust the damping force of the magnetorheological fluid 3014 under energized conditions; metal spring assembly 302 is used to provide stiffness support; uniform load transfer system 4, located below the composite control loading system 3, is used to receive impact loads and convert them into line loads to be transferred to the beam-column member 7 under test; parameter monitoring system 5 is used to collect impact load, displacement and strain data of the beam-column member 7 under test; control system 6, electrically connected to the lifting and releasing mechanism 203, the composite control loading system 3 and the parameter monitoring system 5 respectively, is used to control the release of the drop hammer body 201 and adjust the current of the excitation coil 3013.

[0057] In this embodiment, the test bench 1 serves as the basic support for the device and includes: a rigid base 101 made of high-strength steel with built-in impact-resistant counterweights to prevent displacement of the bench during testing; vertical support columns 102 consisting of multiple high-strength steel columns fixedly connected to the base to provide vertical support; and a transverse fixing beam 103 made of high-strength steel connected to the vertical support columns 102 via connectors to clamp and fix the beam-column component 7 to be tested.

[0058] The drop hammer system 2, serving as the impact power source, includes a drop hammer body 201, a guide mechanism 202 mounted on a vertical support column 102, and a lifting and release mechanism 203. The lifting and release mechanism 203 is used to lift the drop hammer body 201 to a preset height to accumulate potential energy and release it upon triggering. The composite control loading system 3 is a waveform shaping device installed at the bottom of the drop hammer body 201, including a magnetorheological fluid assembly 301 and a metal spring assembly 302 arranged coaxially. The magnetorheological fluid assembly 301 includes an excitation coil 3013, used to change the magnetic field under energized conditions to adjust the damping force of the magnetorheological fluid 3014 in real time. The metal spring assembly includes an excitation coil 3013, used to change the magnetic field under energized conditions to adjust the damping force of the magnetorheological fluid 3014 in real time. Component 302 utilizes elastic deformation to provide stiffness support, and the two work together to regulate the impact waveform; the uniformly distributed load transfer system 4 is located below the composite control loading system 3 and plays the role of load conversion, which is used to receive concentrated impact loads and convert them into line loads to be transferred to the beam-column member 7 to be tested; the parameter monitoring system 5 serves as a data feedback unit, which is used to collect impact load, member displacement and strain data; the control system 6 serves as a coordination hub, which is electrically connected to the lifting and releasing mechanism 203, the composite control loading system 3 and the parameter monitoring system 5 respectively, and is used to control the release of the drop hammer and adjust the current of the excitation coil 3013 according to a preset law.

[0059] The magnetorheological fluid assembly 301 includes a sealed cylinder 3011, a piston 3012, and an excitation coil 3013. The top of the piston 3012 is fixedly connected to the bottom of the drop hammer body 201, and the bottom end of the piston 3012 extends into the sealed cylinder 3011. The piston 3012 is provided with a damping hole. The magnetorheological fluid 3014 is filled inside the sealed cylinder 3011. The excitation coil 3013 is wound around the inner wall of the sealed cylinder 3011. The metal spring assembly 302 includes multiple annular metal springs, which are coaxially sleeved on the outer side of the portion of the piston 3012 that extends out of the sealed cylinder 3011. The bottom of the metal spring assembly 302 abuts against the top surface of the sealed cylinder 3011.

[0060] In this embodiment, the composite control loading system 3 of the present invention is connected below the drop hammer body 201 and is used to control the dynamic characteristics of the impact load. It includes: the magnetorheological fluid assembly 301 is composed of a sealed cylinder 3011, a piston 3012, an excitation coil 3013, and a magnetorheological fluid 3014; the sealed cylinder 3011 is made of corrosion-resistant material, with a connecting structure at the bottom (for docking with the uniformly distributed load transfer system 4), and a sealing structure on the inner wall (to prevent leakage of the magnetorheological fluid 3014); the piston 3012 is adapted to the cylinder, and its top end is rigidly connected to the bottom of the drop hammer body 201, and the piston 3012 is provided with damping holes (uniformly distributed); the excitation coil 3013 is wound on the outer wall of the cylinder and connected to the control system 6 through wires. The magnetic field strength can be changed by adjusting the current, thereby controlling the damping force of the magnetorheological fluid 3014 and realizing continuous and adjustable load; the magnetorheological fluid 3014 is made of a suitable smart material and is filled between the sealed cylinder 3011 and the piston 3012, and its working temperature covers the conventional test environment. The metal spring assembly 302 consists of multiple annular metal springs, which are coaxially sleeved on the outside of the piston 3012. The two ends abut against the bottom of the drop hammer body 201 and the top of the sealed cylinder 3011, respectively. The metal springs are made of elastic steel, and the stiffness can be adapted by adjusting the relevant parameters of the springs (such as thickness and quantity), providing stable stiffness support and avoiding the problem of uncontrollable stiffness in the drop hammer impact airbag / rubber method.

[0061] The uniformly distributed load transfer system 4 includes a load distribution beam 401, a buffer layer 402, and a force transmission plate 403; the top surface of the load distribution beam 401 receives the impact of the composite controlled loading system 3; the force transmission plate 403 is located on the top surface of the beam-column member 7 to be tested, and the length of the force transmission plate 403 is the same as the length of the load distribution beam 401; the buffer layer 402 is located between the load distribution beam 401 and the force transmission plate 403.

[0062] In this embodiment, the uniformly distributed load transfer system 4 is used to convert the concentrated impact load output by the composite controlled loading system 3 into a line load. Compared with the drop hammer impact airbag / rubber method, the load transfer is more stable and has less hysteresis. It includes: a load distribution beam 401: made of high-strength steel, with a length adapted to the beam-column member 7 to be tested; a buffer layer 402: made of elastic material, covering the lower surface of the load distribution beam 401 to avoid sudden load changes; and a force transmission plate 403: made of lightweight, high-strength material, with a width adapted to the cross-sectional width of the beam-column member, a length consistent with the load distribution beam 401, an upper surface attached to the buffer layer 402, and a lower surface attached to the top surface of the beam-column member 7 to be tested. The lifting and release mechanism 203 includes a drive motor, a lifting assembly, and an electromagnetic release device. The drive motor adjusts the height of the drop hammer body 201 through the lifting assembly, and the electromagnetic release device is used to hold or release the drop hammer body 201. Furthermore, in this embodiment, the positive functions of the load distribution beam 401 include:

[0063] 1. Mechanical conversion mechanism

[0064] The load distribution beam 401 is made of high-strength steel and has high bending stiffness. When the concentrated impact force output by the composite control loading system 3 is applied to the middle of the load distribution beam 401, it undergoes elastic bending deformation, converting the point load into a line load along the length of the beam, thereby ensuring that the load is transferred along the specimen and ultimately achieving the purpose of approximately uniform load distribution.

[0065] 2. Stiffness matching design

[0066] The length of the load distribution beam 401 is the same as that of the beam-column member to be tested, and its cross-sectional dimensions are determined by mechanical calculations to control its deformation under impact load within the elastic range. This ensures effective load distribution while avoiding load distribution distortion caused by excessive deformation of the load distribution beam 401.

[0067] Positive function of buffer layer 402

[0068] 1. Material properties and functions

[0069] The buffer layer 402 is preferably a high-density polyurethane (PU) elastomer sheet or a vulcanized rubber sheet with a Shore hardness of 60-80A. These materials have the following characteristics:

[0070] A moderate elastic modulus (typically between 10-100 MPa) allows for controlled compressive deformation during impact.

[0071] Excellent energy absorption and recovery performance, avoiding secondary impacts caused by load rebound;

[0072] The isotropic material properties ensure that the load is uniformly distributed in the plane.

[0073] 2. Load homogenization mechanism

[0074] The buffer layer 402 is located between the load distribution beam 401 and the force transmission plate 403, and serves as a mechanical leveling layer.

[0075] Micro-leveling: Filling the micro-unevenness between the lower surface of the load distribution beam 420 and the force transmission plate 403 to achieve full contact force transmission;

[0076] Stress diffusion: Through its own elastic deformation, the line load is further diffused into a surface load, avoiding stress concentration on the surface of the specimen;

[0077] Positive function of force transmission plate 403

[0078] 1. Interface optimization features

[0079] The force transmission plate 403 can be made of 7075 aluminum alloy thin plate (thickness 0.5-2mm), and its main function is:

[0080] Surface bonding guarantee: The aluminum alloy plate has a certain degree of flexibility and can be slightly deformed to fit the surface of the specimen, eliminating the tiny gaps between the buffer layer 402 and the specimen;

[0081] Anti-adhesion isolation: Prevents adhesion that may occur when the rubber buffer layer 402 comes into direct contact with the surface of the specimen, ensuring easy separation after the test;

[0082] Load transition interface: provides a flat and stable support surface for the buffer layer 402, ensuring uniform elastic deformation.

[0083] 2. Lightweight and interference-free design

[0084] 7075 aluminum alloy has low density and high strength. Its own mass has a negligible impact on impact response, which can ensure the fit function without introducing additional stiffness and ensure the transparency of the load transfer path.

[0085] In this embodiment, the drop hammer system 2 is used to provide impact energy, including:

[0086] Drop hammer body 201: Made of high-strength steel, the mass can be adjusted according to test requirements, and a guide mechanism 202 is provided on the outer surface;

[0087] Guide mechanism 202: Multiple parallel guide components (with wear-resistant surface treatment) are adapted to the drop hammer guide structure to ensure vertical impact of the drop hammer;

[0088] The lifting and release mechanism 203 includes a release device, a drive motor, and a lifting assembly, which can precisely control the lifting height of the drop hammer and synchronize its release. Specifically, the motor drives the lifting assembly to lift the drop hammer body 201, which is held by the electromagnetic release device, to a predetermined height. When release is required, the electromagnetic release device is de-energized and demagnetized, releasing the attraction on the drop hammer body 201 and thus releasing it.

[0089] The parameter monitoring system 5 includes: a force sensor 501, positioned between the drop hammer body 201 and the composite control loading system 3; a displacement sensor 502, mounted on the rigid base 101, used to detect the vertical displacement of the beam-column component 7 under test; and a strain gauge 503, attached to the surface of the beam-column component 7 under test. The force sensor 501, displacement sensor 502, and strain gauge 503 are all connected to the control system 6 via a data acquisition module. The control system 6 includes a host computer, a main control chip, and a current regulation module. The host computer is used to set the parameters of the target explosion scenario, and the main control chip is used to control the current regulation module to output varying current to the excitation coil 3013 according to the parameters.

[0090] In this embodiment, the parameter monitoring system 5 is used to collect test data, including: a force sensor 501: located between the drop hammer body 201 and the piston 3012, used to collect the time-domain curve of the impact load; a displacement sensor 502: fixed to the vertical support column 102, with the detection end aligned with the force transmission plate 403, used to monitor the vertical displacement of the component; a strain gauge 503: attached to the key section of the beam-column component (beam end, mid-span, or column center), using an appropriate wiring method, used to collect the strain distribution; and a data acquisition module: supporting multi-channel synchronous acquisition (force, displacement, strain) to realize test data storage. The control system 6 is used for coordinated control of the device, including: a main control chip that supports multi-protocol communication to achieve linkage control of various modules; a current regulation module that controls the current of the excitation coil 3013 to ensure regulation accuracy and response speed, solving the problem of slow response of the drop hammer impact airbag rubber method; a drop hammer control module that controls the start and stop of the drive motor (to achieve drop hammer lifting height adjustment) and the on / off of the release device (to achieve synchronous release of the drop hammer); and a host computer that installs dedicated control software, supports preset TNT / gas explosion standard load curves (with customizable key load characteristics), displays test data and curves in real time, and supports data export.

[0091] Working principle:

[0092] When using:

[0093] First, the beam-column component 7 to be tested is placed and fixed on the rigid base 101 of the test bench 1. Then, the beam-column component 7 is fixed by the transverse fixing beam 103. A force transmission plate 403, a buffer layer 402, and a load distribution beam 401 are then installed sequentially from bottom to top on the top surface of the beam-column component 7, ensuring that the force transmission plate 403 is in close contact with the beam-column component 7. Subsequently, by inputting the target explosion scenario parameters into the host computer of the control system 6, the system automatically calculates the lifting height of the drop hammer body 201 and the change law of the excitation current. If simulating a TNT explosion, the system sets a pulsed high current and a relatively high drop hammer height; if simulating a gas explosion, it sets a smaller or attenuated current and a lower drop hammer height.

[0094] Next, the drop hammer system 2 is raised to a set height by controlling the lifting and release mechanism 203 (specifically, the lifting assembly is driven by a motor to pull the drop hammer body 201, which is held by the electromagnetic release device, to a predetermined height; when release is needed, the electromagnetic release device is de-energized and demagnetized, releasing the drop hammer body 201). During the trigger test, the control system 6 releases the drop hammer body 201 and energizes the excitation coil 3013 according to a preset pattern. At this time, the drop hammer body 201 falls freely and impacts the composite control loading system 3. At this time, the metal spring assembly 302 is compressed to provide elastic stiffness support; at the same time, the piston 3012, under the impact force, makes an axial downward intrusion movement relative to the sealed cylinder 3011, forcing the magnetorheological fluid 3014 to flow through the damping hole on the piston 3012. The magnetic field generated by the excitation coil 3013 changes the fluid viscosity of the magnetorheological fluid 3014, thereby generating a variable damping force, which in turn shapes the impact kinetic energy into the target load carrier shape.

[0095] Finally, as the drop hammer body 201 falls, the generated load can be distributed through the load distribution beam 401 and the buffer layer 402, and then transferred to the beam and column member 7 to be tested in the form of an approximately uniformly distributed load. At this time, the parameter monitoring system 5 simultaneously collects force, displacement and strain data to complete the explosion load simulation.

[0096] Example 2: This embodiment of the invention provides a method for controlling the impact test of a falling weight using a combination of magnetorheological fluid and metal sheet, comprising the following steps:

[0097] Step S1: Fix the beam and column components to be tested onto the test bench, install the uniformly distributed load transfer system, and make the force transfer plate fit against the top surface of the component;

[0098] Step S2: Input the target explosion scene parameters into the host computer of the control system, and calculate the lifting height of the falling hammer body and the excitation current change law of the magnetorheological fluid component based on the target parameters;

[0099] Step S3: Control the lifting and release mechanism to raise the drop hammer system to the calculated set height;

[0100] Step S4: The control system sends a trigger command to lift the release mechanism to release the drop hammer body. At the same time, the control system adjusts the current of the excitation coil in the magnetorheological fluid component according to the excitation current change law. The drop hammer body impacts the composite control loading system. The metal spring assembly is compressed to provide stiffness, and the magnetorheological fluid component provides variable damping, which work together to control the impact load.

[0101] Step S5: The adjusted load is converted into a line load by the uniformly distributed load transfer system and applied to the beam and column members to be tested. The parameter monitoring system simultaneously collects test data and transmits it to the host computer.

[0102] In step S2:

[0103] When simulating a TNT explosion scenario, the current regulation law is set to output a large current for a short period of time to simulate high peak value and short-term load.

[0104] When simulating a gas explosion scenario, the current regulation law is set to output a small current or control the current to decay slowly in order to simulate low peak value and long duration load.

[0105] Step S5 is followed by:

[0106] The host computer generates the impact load time-domain curve based on the collected force sensor data, and generates the component response curve based on the displacement sensor and strain gauge data. The simulation effect is verified by comparing the parameters of the target explosion scene.

Claims

1. A magnetorheological fluid and metal pellet composite controlled drop hammer impact test device, characterized in that, include: The test bench (1) includes a rigid base (101), a vertical support column (102) and a transverse fixing beam (103), wherein the transverse fixing beam (103) is used to fix the beam-column component (7) to be tested. The drop hammer system (2) includes a drop hammer body (201), a guide mechanism (202) disposed on the vertical support column (102), and a lifting and releasing mechanism (203), wherein the lifting and releasing mechanism (203) is used to lift and release the drop hammer body (201). A composite control loading system (3) is installed at the bottom of the drop hammer body (201), which includes a magnetorheological fluid assembly (301) and a metal spring assembly (302) arranged coaxially; the magnetorheological fluid assembly (301) includes an excitation coil (3013) for adjusting the damping force of the magnetorheological fluid (3014) when energized; the metal spring assembly (302) is used to provide stiffness support; The uniformly distributed load transfer system (4) is located below the composite control loading system (3) and is used to receive impact loads and convert them into uniformly distributed loads to be transferred to the beam and column members (7) to be tested. The parameter monitoring system (5) is used to collect impact load, component displacement and strain data; The control system (6) is electrically connected to the lifting and releasing mechanism (203), the composite control loading system (3) and the parameter monitoring system (5) respectively, and is used to control the release of the drop hammer body (201) and adjust the current of the excitation coil (3013); The magnetorheological fluid assembly (301) includes a sealed cylinder (3011), a piston (3012), and an excitation coil (3013). The top of the piston (3012) is fixedly connected to the bottom of the drop hammer body (201), the bottom end of the piston (3012) extends into the sealed cylinder (3011), and the piston (3012) is provided with a damping hole. The magnetorheological fluid (3014) is filled inside the sealed cylinder (3011); The excitation coil (3013) is wound around the inner wall of the sealed cylinder (3011); The metal spring assembly (302) includes multiple annular metal springs, which are coaxially sleeved on the outside of the portion of the piston (3012) that extends out of the sealing cylinder (3011); and the bottom of the metal spring assembly (302) abuts against the top surface of the sealing cylinder (3011). The uniformly distributed load transfer system (4) includes a load distribution beam (401), a buffer layer (402), and a force transmission plate (403). The top surface of the load distribution beam (401) bears the impact of the composite control loading system (3); The force transmission plate (403) is located on the top surface of the beam-column member (7) to be tested, and the length of the force transmission plate (403) is the same as the length of the load distribution beam (401). The buffer layer (402) is located between the load distribution beam (401) and the force transmission plate (403); The parameter monitoring system (5) includes: A force sensor (501) is disposed between the drop hammer body (201) and the composite control loading system (3); A displacement sensor (502) is mounted on the rigid base (101) to detect the vertical displacement of the beam-column member (7) to be tested; Strain gauges (503) are attached to the surface of the beam-column member (7) to be tested; The force sensor (501), displacement sensor (502) and strain gauge (503) are all connected to the control system (6) through the data acquisition module; The control system (6) includes a host computer, a main control chip and a current regulation module; the host computer is used to set the target explosion scene parameters, and the main control chip is used to control the current regulation module to output a changing current to the excitation coil (3013) according to the parameters.

2. The magnetorheological fluid and metal pellet composite controlled drop hammer impact test device according to claim 1, characterized in that, The lifting and releasing mechanism (203) includes a drive motor, a lifting component and an electromagnetic release device. The drive motor adjusts the height of the drop hammer body (201) through the lifting component, and the electromagnetic release device is used to hold or release the drop hammer body (201).

3. A method for controlling the impact of a falling weight using a magnetorheological fluid and a metal spring, comprising the magnetorheological fluid and metal spring composite controlled falling weight impact testing apparatus as described in any one of claims 1-2, characterized in that, Includes the following steps: Step S1: Fix the beam-column member (7) to be tested to the test bench (1), install the uniformly distributed load transfer system (4), and make the force transfer plate (403) fit against the top surface of the member; Step S2: Input the target explosion scene parameters into the host computer of the control system (6), and calculate the lifting height of the drop hammer body (201) and the excitation current change law of the magnetorheological fluid component (301) according to the target parameters; Step S3: Control the lifting and releasing mechanism (203) to lift the drop hammer system (2) to the calculated set height; Step S4: The control system (6) sends a trigger command to lift the release mechanism (203) to release the drop hammer body (201). At the same time, the control system (6) adjusts the current of the excitation coil (3013) in the magnetorheological fluid assembly (301) according to the excitation current change law. The drop hammer body (201) impacts the composite control loading system (3). The metal spring assembly (302) is compressed to provide stiffness, and the magnetorheological fluid assembly (301) provides variable damping, which works together to control the impact load. Step S5: The adjusted load is converted into a uniformly distributed load by the uniformly distributed load transfer system (4) and applied to the beam and column members to be tested (7). The parameter monitoring system (5) simultaneously collects the test data and transmits it to the host computer.

4. The impact testing method according to claim 3, characterized in that, In step S2: When simulating a TNT explosion scenario, the current regulation law is set to output a large current for a short period of time to simulate high peak value and short-term load. When simulating a gas explosion scenario, the current regulation law is set to output a small current or control the current to decay slowly in order to simulate low peak value and long duration load.

5. The impact testing method according to claim 3, characterized in that, Following step S5, the following is also included: The host computer generates the impact load time domain curve based on the collected force sensor (501) data, and generates the component response curve based on the displacement sensor (502) and strain gauge (503) data. The simulation effect is verified by comparing the target explosion scene parameters.

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