Long pulse shock acceleration load device and loading method

Abstract

This invention relates to the field of impact load testing technology, specifically to a long-pulse impact acceleration load generating device and loading method, comprising a support frame and a thin-walled conical shell. The support frame is used to mount the target test piece, and the thin-walled conical shell is mounted at the bottom of the support frame with its small end facing away from the support frame. After the device is lifted to a preset height, it is released and falls freely. The small end of the thin-walled conical shell impacts a rigid target surface. The plastic deformation of the thin-walled conical shell during the impact decelerates the device, applying a long-pulse impact acceleration load to the target test piece. This invention can apply millisecond-level long-pulse-width impact acceleration loads to target test pieces weighing hundreds of kilograms. The conical shell is replaceable, and the other components are reusable, making it suitable for long-duration impact dynamics research and structural impact resistance testing.

Description

Technical Field

[0001] This invention relates to the field of impact load testing technology, specifically to a long-pulse impact acceleration load generating device and loading method. Background Technology

[0002] During a fall, landing, or collision, the components mounted on the main structure are subjected to an acceleration environment transmitted by the abrupt change in the overall motion state. Reproducing this impact environment on the ground using a load generator is the primary testing method for obtaining the dynamic response behavior of components and assessing their impact resistance, while also avoiding the scale and cost of whole-machine testing.

[0003] Existing impact loading methods each have limitations. Drop hammer and pendulum devices apply load to a localized area of ​​the test specimen by impacting it, making them suitable for evaluating the response in the contact area, but difficult to apply a uniform acceleration boundary to large-mass test specimens simultaneously. Techniques such as fly-plate impact and split-bar compression can generate high load amplitudes, but the duration is typically in the microsecond to sub-millisecond range, which cannot cover the long pulse width requirements in the millisecond range. While explosive loading can balance amplitude and duration, it is difficult to organize, has many limitations, and carries high safety risks, making it difficult to promote as a routine assessment method.

[0004] In addition, most of the above methods are geared towards small-sized components, and the target test specimens they are adapted to have relatively simple structural forms. When the target test specimen weighs hundreds of kilograms and has complex internal components, existing devices are unable to apply an overall-level impact acceleration load with controllable amplitude and pulse width. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, the present invention provides a long pulse impact acceleration load generating device and loading method, which applies a long pulse impact acceleration load to the target test piece by the plastic deformation of the thin-walled conical shell during the drop impact, and controls the amplitude and pulse width of the load by the wall thickness of the thin-walled conical shell and the lifting height of the device, respectively.

[0006] This invention is achieved through the following technical solution:

[0007] A long-pulse impact acceleration load generating device includes a support frame and a thin-walled conical shell. The support frame is used to mount a target test piece. The thin-walled conical shell is mounted at the bottom of the support frame, with its small end facing away from the support frame. After being lifted to a preset height, the load generating device is released and falls freely. The small end of the thin-walled conical shell impacts a rigid target surface. The plastic deformation generated during the impact causes the load generating device to decelerate, thereby applying a long-pulse impact acceleration load to the target test piece.

[0008] Specifically, the thin-walled conical shell is a thin-walled truncated conical shell, the large end of the thin-walled truncated conical shell is detachably connected to the support frame, and the small end of the thin-walled truncated conical shell is a closed end or an open end.

[0009] More specifically, the thin-walled conical shell is made of a ductile metal material, and the wall thickness of the thin-walled conical shell is either constant or variable along its axial direction.

[0010] Preferably, the load generating device further includes a counterweight, which is installed on the side of the support frame away from the thin-walled conical shell, for adjusting the overall mass of the load generating device.

[0011] Furthermore, the load generating device also includes an aerodynamic tail fin assembly, which is installed on the side of the support frame away from the thin-walled conical shell, and is used to stabilize the attitude of the load generating device during free fall.

[0012] Specifically, the aerodynamic tail fin assembly includes multiple axial connecting rods, a circumferential connector, and an aerodynamic stabilizing surface; the multiple axial connecting rods are arranged circumferentially at intervals along the support frame, and one end of the multiple axial connecting rods is connected to the support frame; the aerodynamic stabilizing surface is fixed to the end of the multiple axial connecting rods away from the support frame; the circumferential connector is connected to the multiple axial connecting rods and is used to constrain the relative positions between the multiple axial connecting rods.

[0013] More specifically, the aerodynamic stabilizing surface is a thin-walled cylindrical shell structure, and the circumferential connector is a ring structure.

[0014] In some embodiments, the load generating device further includes a measurement system, which includes an acceleration sensor, a lead wire, and a signal processing instrument; the acceleration sensor is used to be mounted on the target test piece, the signal processing instrument is placed on the ground, the acceleration sensor is connected to the signal processing instrument through the lead wire, and the length of the lead wire is not less than the preset height.

[0015] The present invention also provides a method for applying a long-pulse impact acceleration load, which is implemented using any of the above-mentioned long-pulse impact acceleration load generating devices, and includes the following steps:

[0016] S1. Determine the wall thickness of the thin-walled conical shell according to the preset acceleration amplitude, install the thin-walled conical shell with the wall thickness at the bottom of the support frame, and install the target test piece on the support frame;

[0017] S2. Determine the lifting height of the load generating device according to the preset acceleration pulse width, and lift the load generating device to the lifting height;

[0018] S3. Release the load generating device, allowing it to fall freely and impact the rigid target surface with the small end of the thin-walled conical shell. The thin-walled conical shell undergoes plastic deformation, applying a long-pulse impact acceleration load to the target test piece.

[0019] Furthermore, in step S1, an acceleration sensor is also installed on the target test piece, and the acceleration sensor is connected to a signal processing instrument placed on the ground via a lead wire.

[0020] In step S3, the lead wire falls together with the load generating device, and the signal processing instrument collects the acceleration data of the target test piece during the process of the load generating device impacting the rigid target surface.

[0021] This invention achieves long-pulse impact acceleration loading on large-mass target test pieces by utilizing the energy dissipation of plastic deformation during the impact of a thin-walled conical shell onto a rigid target surface, the separation and control of wall thickness and lifting height, and the attitude stabilization of the aerodynamic tail fin assembly. Compared with existing technologies, it has the following advantages:

[0022] The load generating device is allowed to fall freely and impacts a rigid target surface with a thin-walled conical shell. During the crushing deformation, the conical shell continuously absorbs kinetic energy, causing the target test piece mounted on the support frame to decelerate along with the entire device, resulting in a millisecond-level long-pulse impact acceleration load. This loading method balances the requirements of large-mass targets, long action times, and load controllability.

[0023] The load amplitude is pre-designed and determined by the wall thickness and material parameters of the thin-walled conical shell, and the pulse width is adjusted by the lifting height, i.e. the initial velocity of the target. The two controls are independent of each other, and the target load conditions can be matched as needed before the test.

[0024] The aerodynamic tail fin assembly generates an aerodynamic torque pointing in the attitude recovery direction during the device's descent, which suppresses device tilting, improves the consistency of positive target contact, and enhances the repeatability of multiple test results.

[0025] The accelerometer falls with the device, while the signal processing instrument remains stationary on the ground. The acceleration response during the target impact process is collected online via a lead wire, avoiding damage to the instrument as it falls with the device. This solves the problem of difficulty in obtaining real-time response information of large-mass targets in free-fall impact tests.

[0026] Except for the thin-walled conical shell undergoing plastic deformation during the test, the support frame, counterweight, and aerodynamic tail fin assembly can all be reused. A series of tests can be carried out by replacing the thin-walled conical shell with different wall thicknesses, thus reducing the cost of testing. Attached Figure Description

[0027] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0028] Figure 1 This is a schematic diagram of the overall structure of the long pulse impact acceleration load generating device provided in an embodiment of the present invention;

[0029] Figure 2 This is a cross-sectional view of a thin-walled conical shell provided in an embodiment of the present invention;

[0030] Figure 3 The diagram shows the structure of the support frame provided in the embodiment of the present invention, wherein (a) is a front view and (b) is a bottom view;

[0031] Figure 4 This is a schematic diagram of the structure of the aerodynamic tail fin assembly provided in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the test setup for the long-pulse impact acceleration load loading method provided in an embodiment of the present invention.

[0033] Reference numerals: 1-Support frame; 2-Thin-walled conical shell; 3-Counterweight; 4-Aerodynamic tail fin assembly; 41-Axial connecting rod; 42-Circumferential connector; 43-Aerodynamic stabilizing surface; 51-Acceleration sensor; 52-Lead wire; 53-Signal processing instrument; 6-Lifting connecting rope; 7-Target test piece; 8-Rigid target surface; 9-Lifting equipment; 10-High-speed camera equipment. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0035] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0036] Where there is no conflict, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Example 1

[0038] This embodiment provides the basic structure of a long-pulse impact acceleration load generator. For example... Figure 1 As shown, the load generating device includes a support frame 1 and a thin-walled conical shell 2.

[0039] Support frame 1 is used to mount the target test piece 7. Thin-walled conical shell 2 is mounted at the bottom of support frame 1, with the small end of thin-walled conical shell 2 facing away from support frame 1. The common axis of symmetry between thin-walled conical shell 2 and support frame 1 is defined as the axis of the load generating device.

[0040] Support frame 1 is the connecting base of the entire device. It has a certain mass and high rigidity, and will not undergo plastic deformation during drop impact, thus ensuring that all installed components receive a consistent acceleration trajectory during the impact deceleration process. For example... Figure 3 As shown, the support frame 1 can adopt a flange structure with a central through hole, and multiple rings of mounting holes are opened on the plate surface, which are used to connect the thin-walled conical shell 2, the counterweight 3 and other components.

[0041] The thin-walled conical shell 2 is the plastic energy dissipation element in the device. After the load generating device is lifted to a preset height, it is released and falls freely, having an initial velocity corresponding to the lifting height upon impact with the target. The small end of the thin-walled conical shell 2 impacts the rigid target surface 8 first, and the conical shell undergoes gradual large plastic deformation from the small end to the large end. The crushing reaction force decelerates the entire load generating device, and the target test piece 7 mounted on the support frame 1 decelerates accordingly, thus being subjected to a long-pulse impact acceleration load. The plastic crushing of the conical shell is a continuous stroke process, and the load application time is much longer than that of a rigid body collision, thus generating millisecond-level long-pulse acceleration.

[0042] The control mechanism for load amplitude and pulse width is as follows: During the impact, the deceleration of the device depends on the ratio of the crushing reaction force of the conical shell to the overall mass of the device. The crushing reaction force is determined by the wall thickness, material strength, and cone angle of the thin-walled conical shell 2. Therefore, once the overall mass of the device is determined, the acceleration amplitude can be controlled by designing the wall thickness. The load application time is related to the initial velocity and deceleration upon impact with the target. The initial velocity upon impact with the target is determined by the lifting height. Therefore, adjusting the lifting height can control the pulse width. The two control pathways are independent of each other and can be used to match the amplitude and pulse width of the target load separately.

[0043] The load generating device of this embodiment is suitable for target test pieces 7 with a mass in the range of several hundred kilograms, such as 200kg, 300kg, and 500kg; the achievable acceleration amplitude range is from 10g to 3000g, such as 50g, 500g, and 2000g; and the achievable pulse width range is from 1ms to 20ms, such as 2ms, 10ms, and 20ms.

[0044] Example 2

[0045] This embodiment further illustrates the specific form of the thin-walled conical shell 2 based on Embodiment 1.

[0046] like Figure 2As shown, the thin-walled conical shell 2 is a thin-walled truncated cone shell with a connecting edge at its large end. A ring of bolt holes is opened on the connecting edge, and it is detachably connected to the support frame 1 by screws. The two can be detachably fixed by tooling. The detachable connection allows the cone shell to be quickly replaced after a single test crushing, and the support frame 1 and other components can be reused. The small end of the thin-walled truncated cone shell is either a closed end or an open end: when the small end is closed, the initial contact area with the target smoothly transitions from small to large; when the small end is open, the initial crushing force can be adjusted according to the load waveform design requirements.

[0047] The thin-walled conical shell 2 is made of a ductile metallic material, which continuously dissipates energy through plastic deformation during the compression stroke without brittle fracture. Suitable materials include low-carbon steel, aluminum alloys, and copper, all of which have good ductility. The wall thickness of the conical shell can be set to constant or variable along its axial direction: a conical shell with constant wall thickness exhibits an approximately stable increase in crush reaction force with the deformation stroke, suitable for reproducing near-trapezoidal or semi-sine acceleration waveforms; a conical shell with variable wall thickness can have its crush reaction force varied according to a predetermined pattern through axial wall thickness distribution design, thereby reproducing acceleration histograms with specific rise times or multi-step characteristics. The specific wall thickness value is determined based on the expected acceleration amplitude, the overall mass of the device, the strength of the conical shell material, and the cone angle design, and can be corrected through numerical simulation or calibration tests.

[0048] Example 3

[0049] This embodiment further describes the aerodynamic tail wing assembly 4 based on the aforementioned embodiments.

[0050] When the load generating device is in free fall in the field, it is affected by disturbances such as crosswinds. If the axis deviates from the vertical direction upon impact with the target, the conical shell will be crushed eccentrically, and the acceleration waveform will deviate from the expected value. To address this, the load generating device also includes an aerodynamic tail fin assembly 4, which is installed on the side of the support frame 1 away from the thin-walled conical shell 2 to stabilize the attitude of the load generating device during free fall.

[0051] like Figure 4 As shown, the aerodynamic tail fin assembly 4 includes multiple axial connecting rods 41, circumferential connectors 42, and aerodynamic stabilizing surfaces 43. The multiple axial connecting rods 41 are arranged circumferentially around the support frame 1, with one end screwed into a pre-drilled countersunk hole on the support frame 1 via a rod end thread, or connected via tooling. The aerodynamic stabilizing surface 43 is fixed to the end of the multiple axial connecting rods 41 furthest from the support frame 1, i.e., located at the tail end of the device. The circumferential connectors 42 are located in the middle and tail end of the aerodynamic tail fin assembly 4, connecting to the multiple axial connecting rods 41, constraining the relative positions between the rods, and preventing lateral and longitudinal relative movement of the rods during lifting and lowering of the device.

[0052] If the device tilts during descent, the oncoming airflow generates an aerodynamic torque on the aerodynamic stabilization surface 43, pointing in the attitude recovery direction. This restores the device to a near-vertical descent attitude, improving the consistency of forward target contact. The aerodynamic stabilization surface 43 is a thin-walled cylindrical shell structure, and the circumferential connector 42 is a ring structure. Figure 4 As shown, the aerodynamic stabilizing surface 43 can be configured as two concentric rings, inner and outer, to increase the aerodynamic area within a limited component height. The aerodynamic tail fin assembly 4 is made entirely of lightweight materials, and its height is minimized while still satisfying the aerodynamic area requirements, thereby reducing the lateral wind load area. In other embodiments, the aerodynamic stabilizing surface 43 can also be other surface structures capable of generating attitude restoring moments, such as an annular wingplate or a multi-bladed tail fin.

[0053] Example 4

[0054] This embodiment further describes the counterweight 3, the measuring system, and the lifting connection rope 6 based on the aforementioned embodiments.

[0055] like Figure 1 As shown, the load generating device also includes a counterweight 3, which is installed on the side of the support frame 1 away from the thin-walled conical shell 2. The counterweight 3 is directly or fixedly connected to the support frame 1 via tooling and is used to adjust the overall mass of the load generating device. The overall mass of the device is one of the parameters determining the acceleration amplitude. Under the condition of a constant crushing reaction force of the conical shell, the amplitude can be finely adjusted by adding or removing the counterweight. Simultaneously, the center of mass of the counterweight 3 and the target test piece 7 should be adjusted to be on the axis of the device to reduce the deflection torque upon contact with the target. The counterweight 3 does not undergo plastic deformation during the drop and can be reused.

[0056] The load generating device also includes a measurement system, which comprises an acceleration sensor 51, a lead wire 52, and a signal processing instrument 53. The acceleration sensor 51 is mounted on the target test piece 7, and can also be mounted simultaneously on the upper surface of the counterweight 3 to obtain the overall acceleration history of the device. The signal processing instrument 53 is stationary on the ground, and the acceleration sensor 51 is connected to the signal processing instrument 53 via the lead wire 52. The length of the lead wire 52 is not less than the preset lifting height of the device, and a certain margin is reserved to prevent the lead wire 52 from being taut or pulled during the entire descent.

[0057] One end of the lifting connection rope 6 is connected to the bottom surface of the pneumatic tail fin assembly 4, and the other end is connected to the lifting equipment 9, which can be a crane, drop test tower, etc. When the pneumatic tail fin assembly 4 is not used in the test, the lifting connection rope 6 is connected to the counterweight 3 through tooling.

[0058] Example 5

[0059] This embodiment provides a long-pulse impact acceleration load loading method, implemented using the load generating device of any of the aforementioned embodiments. Combined with... Figure 5The method includes the following steps:

[0060] S1. Determine the wall thickness of the thin-walled conical shell 2 according to the preset acceleration amplitude, install the thin-walled conical shell 2 with the wall thickness at the bottom of the support frame 1, and install the target test piece 7 on the upper surface of the support frame 1.

[0061] The counterweight 3 and the aerodynamic tail fin assembly 4 are installed or fixed together on the support frame 1;

[0062] An acceleration sensor 51 is installed on the target test piece 7. The acceleration sensor 51 is connected to a signal processing instrument 53 placed on the ground via a lead wire 52.

[0063] S2. Determine the lifting height of the load generating device according to the preset acceleration pulse width, fix one end of the lifting connection rope 6 to the aerodynamic tail fin assembly 4, and connect the other end to the lifting equipment 9, and lift the load generating device to the lifting height through the lifting equipment 9.

[0064] When the pneumatic tail fin assembly 4 is not used, one end of the lifting connection rope 6 is fixed to the counterweight 3 by means of tooling;

[0065] S3. Cut or release the lifting connection rope 6 to allow the load generating device to fall freely under the action of gravity and obtain the preset initial velocity when it hits the target.

[0066] The lead wire 52 falls together with the load generating device, while the signal processing instrument 53 remains stationary on the ground.

[0067] The load generating device impacts the rigid target surface 8 with the small end of the thin-walled conical shell 2, causing the thin-walled conical shell 2 to undergo plastic deformation, thus applying a long pulse impact acceleration load to the target test piece 7; the signal processing instrument 53 collects the acceleration data of the target test piece 7 during the impact process;

[0068] S4. After the load generating device stops moving, read the data collected by the signal processing instrument 53 and compare the measured acceleration history with the preset load conditions.

[0069] The test site can also be equipped with a high-speed camera 10 to record the device's contact posture with the target and the crushing process of the cone shell, which can be used to verify the consistency of posture and deformation mode.

[0070] When a series of tests are required, only the thin-walled conical shell 2 needs to be replaced and the wall thickness and lifting height need to be re-determined according to the target load conditions, and the remaining parts can be reused.

[0071] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0072] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A long-pulse impact acceleration load generating device, characterized in that, It includes a support frame (1) and a thin-walled conical shell (2); the support frame (1) is used to install the target test piece (7); the thin-walled conical shell (2) is installed at the bottom of the support frame (1), and the small end of the thin-walled conical shell (2) is away from the support frame (1). The load generating device is lifted to a preset height and then released and falls freely. The small end of the thin-walled conical shell (2) impacts the rigid target surface (8). The thin-walled conical shell (2) decelerates the load generating device through plastic deformation generated during the impact, and applies a long pulse impact acceleration load to the target test piece (7).

2. The long-pulse impact acceleration load generating device according to claim 1, characterized in that, The thin-walled conical shell (2) is a thin-walled truncated conical shell. The large end of the thin-walled truncated conical shell is detachably connected to the support frame (1). The small end of the thin-walled truncated conical shell is a closed end or an open end.

3. The long-pulse impact acceleration load generating device according to claim 2, characterized in that, The thin-walled conical shell (2) is made of a ductile metal material, and the wall thickness of the thin-walled conical shell (2) is set to be constant or variable along its axial direction.

4. The long-pulse impact acceleration load generating device according to claim 1, characterized in that, The load generating device further includes a counterweight (3), which is installed on the side of the support frame (1) away from the thin-walled conical shell (2).

5. The long-pulse impact acceleration load generating device according to claim 1, characterized in that, The load generating device also includes an aerodynamic tail fin assembly (4), which is mounted on the side of the support frame (1) away from the thin-walled conical shell (2).

6. The long-pulse impact acceleration load generating device according to claim 5, characterized in that, The aerodynamic tail fin assembly (4) includes multiple axial connecting rods (41), circumferential connecting parts (42), and aerodynamic stabilizing surfaces (43). Multiple axial connecting rods (41) are arranged circumferentially around the support frame (1), and one end of the multiple axial connecting rods (41) is connected to the support frame (1); the aerodynamic stabilizing surface (43) is fixed to the end of the multiple axial connecting rods (41) away from the support frame (1); the circumferential connector (42) is connected to the multiple axial connecting rods (41) and constrains the relative position between the multiple axial connecting rods (41).

7. The long-pulse impact acceleration load generating device according to claim 6, characterized in that, The aerodynamic stabilizing surface (43) is a thin-walled cylindrical shell structure, and the circumferential connector (42) is a ring structure.

8. The long-pulse impact acceleration load generating device according to claim 1, characterized in that, The load generating device also includes a measurement system, which includes an acceleration sensor (51), a lead wire (52), and a signal processing instrument (53). The acceleration sensor (51) is used to be installed on the target test piece (7), the signal processing instrument (53) is placed on the ground, the acceleration sensor (51) is connected to the signal processing instrument (53) through the lead wire (52), and the length of the lead wire (52) is not less than the preset height.

9. A method for applying a long-pulse impact acceleration load, implemented using the long-pulse impact acceleration load generating device as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Determine the wall thickness of the thin-walled conical shell (2) according to the preset acceleration amplitude, install the thin-walled conical shell (2) with the wall thickness on the bottom of the support frame (1), and install the target test piece (7) on the support frame (1); S2. Determine the lifting height of the load generating device according to the preset acceleration pulse width, and lift the load generating device to the lifting height; S3. Release the load generating device, allowing it to fall freely and impact the rigid target surface (8) with the small end of the thin-walled conical shell (2). The thin-walled conical shell (2) undergoes plastic deformation, applying a long pulse impact acceleration load to the target test piece (7).

10. The long-pulse impact acceleration load loading method according to claim 9, characterized in that, In step S1, an acceleration sensor (51) is also installed on the target test piece (7), and the acceleration sensor (51) is connected to a signal processing instrument (53) placed on the ground via a lead wire (52). In step S3, the lead wire (52) falls together with the load generating device, and the signal processing instrument (53) collects the acceleration data of the target test piece (7) during the process of the load generating device hitting the rigid target surface (8).

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