CN101769838B - Dynamic impact loading test bed and test system thereof - Google Patents

Abstract

The invention discloses a dynamic impact loading test bench and a test system thereof. The dynamic impact loading test bench includes an impact unit carried on a fixed frame, a lifting unit and a test piece carrying platform, the impact unit is connected with a tension spring unit, and the tension spring unit can exert elastic recovery force on the impact unit. The dynamic impact loading test system includes the dynamic impact loading test bench, which is connected to a computer to test the mechanical properties of the test piece. The dynamic impact loading test bench and test system of the present invention use the extension spring unit to apply an additional downward elastic recovery force to the impact unit, and on the premise of realizing the miniaturization of the device, it still obtains a high impact loading speed and has an energy conversion rate High performance, low noise pollution, stable emission, easy speed adjustment, easy to repeat the test and other functions and characteristics.

Description

Dynamic impact loading test bench and its test system

technical field

The invention relates to test equipment in the technical field of structural deformation and mechanical experiments, in particular to a dynamic impact loading test bench and a test system thereof.

Background technique

In engineering practice, many engineering materials and structures are subjected to impact loads, and the materials subjected to these loads deform at high strain rates. A large number of experimental results show that under different strain rates, the mechanical properties of materials are often different. Therefore, the dynamic mechanical properties of materials are of great significance to the safety and reliability design of engineering structures.

At present, the testing equipment often used in the study of the mechanical properties of materials under high strain rates is the drop weight testing machine. The basic principle is: a heavy hammer is released from a high place, and the heavy hammer falls freely to hit the test piece to be tested. This type of equipment is simple in structure and easy to operate. However, in order to provide a higher impact rate, the test equipment needs to meet a certain height. The height of the common drop weight testing machine is 3 to 5 meters, and the equipment is bulky, which is limited to a certain extent by the working environment of the testing machine. In addition, split Hopkinson pressure bar (SHPB for short) is also one of the more widely used techniques when measuring the mechanical properties of specimen materials under high strain rates. However, SHPB equipment is mostly based on pneumatic launching devices or light gas cannon launching devices. Such devices are relatively expensive, and the energy conversion rate during the experiment is low, the emission noise pollution is large, and the experiment cost is high.

At present, most of the existing domestic and foreign equipment for impact loading of test pieces are drop-weight test devices. Such as the patent application number: CN01205945.5 discloses that the oil casing protection ring drop hammer impact tester is designed for the drop weight guide problem; problem has been improved. However, in the above designs, the heavy hammers for loading all fall in a form close to free fall, which fails to solve the problem of bulky equipment. Therefore, how to provide an impact testing machine with a smaller volume without sacrificing the impact rate is an urgent problem to be solved.

Contents of the invention

The purpose of the present invention is to provide a dynamic impact loading test stand with a smaller volume and still provide a larger impact rate, which has the following technical solutions:

A dynamic impact loading test bench, comprising an impact unit carried on a fixed frame, a lifting unit and a specimen carrying platform, wherein the impact unit is connected to a tension spring unit, and the tension spring unit can apply an elastic recovery force to the impact unit.

Preferably, the extension spring unit includes a pull rope, a first pulley and an extension spring assembly; wherein, the extension spring assembly is fixed on the upper part of the fixing frame; the first pulley is positioned on the front of the extension spring assembly Below, it is installed between the upper part and the lower part of the fixed frame; the stay rope goes around the first pulley, one end is connected with the impact unit, and the other end is connected with the tensile end of the extension spring assembly .

Preferably, there are two pull cords, each of which is connected to one of the extension spring assemblies, and is arranged symmetrically on both sides of the impact unit through the respective first pulleys.

The extension spring assembly may include a plurality of extension springs and a connection plate, the connection plate is provided with extension spring connection holes, and the extension springs are arranged in parallel.

Preferably, each set of extension spring assemblies is equipped with 5 extension springs at full load, and the maximum stroke of the extension springs is 1.2 meters. The number and stroke of the extension springs can be selected according to requirements, so as to facilitate the adjustment of the impact rate.

The impact unit may be a T-shaped hammer, which includes a hammer body and a hammer head perpendicular to the hammer body, and ends on both sides of the hammer body are connected to the pull cords of the extension spring unit.

The hammer body can be coated with a nylon sleeve, and the nylon sleeve is used to reduce friction and play a position-limiting role when the weight falls.

Preferably, the lifting unit may include a locking piece, a lifting rope and a lifting assembly, the locking piece is connected to the impact unit in a releasable and locking manner; two ends of the lifting rope are respectively connected to the The locking piece is connected with the lifting assembly, and the locking piece is provided with a release switch capable of disengaging the impact unit from the locking piece.

Preferably, the release switch cooperates with the pin on the top of the hammer body to form a releasable snap connection.

The lifting assembly may include a ratchet and a second pulley fixed on the fixed frame; one end of the lifting rope is wound on the ratchet, and the other end is connected to the lock through the second pulley to change direction. Firmware; The ratchet can also be provided with a rocker that drives the ratchet to wind the lifting rope, so as to facilitate repeated tests.

Preferably, the lifting assembly further includes a safety pin, which is configured to keep the ratchet moving forward when the impact unit is lifted, and the ratchet can run backwards when the safety pin is pressed. to rewind.

Preferably, the fixed frame is provided with a horizontal plate that can be adjusted up and down between the upper plate at its upper part and the test piece bearing platform at its lower part, and the horizontal plate is provided with a limit vertical rod, and the limit vertical The upper end of the rod passes through the upper plate, and the lower end is fixed on the horizontal plate; the body of the impact unit is sleeved on the limit vertical bar, and can be interposed between the upper plate and the horizontal plate vertical movement, the horizontal plate is also provided with an opening through which the striking part of the impact unit passes; the first pulley is arranged on the horizontal plate, and the tension spring assembly is fixed on the upper plate On the lower surface, the pull rope is wound around the first pulley, and one end of the pull rope is connected to the lower surface of the body of the impact unit, and the other end is connected to the tension end of the extension spring assembly; the first pulley There are two pulleys, respectively arranged in the middle of the upper plate and near the end of the ratchet; one end of the lifting rope is wound on the ratchet, and the other end is connected to the ratchet through the second pulley. the lock.

The horizontal plate may be provided with a buffer directly under the body of the impact unit.

The pull cord and the handle cord may be nylon cords.

The present invention also proposes a dynamic impact loading test system, which tests the mechanical properties of the piece to be tested by connecting to a computer, including a dynamic impact loading test bench adopting the above-mentioned technical solution, an impact load signal acquisition device and a A force sensor located directly under the entire impact unit in the test piece loading platform, the force sensor is connected to the computer through the impact load signal acquisition device.

The dynamic impact loading test bench and test system of the present invention apply an additional downward elastic recovery force to the impact unit by using the extension spring unit, so that a relatively high impact loading speed can be obtained on the premise of realizing the miniaturization of the device, and at the same time, the energy conversion rate is high. High performance, low noise pollution, stable emission, easy speed adjustment, easy to repeat the test and other functions and characteristics.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of a dynamic impact loading test bench according to a specific embodiment of the present invention.

FIG. 2A is a schematic diagram of a transverse plate in the dynamic impact loading test bench shown in FIG. 1 .

FIG. 2B is a schematic diagram of the locking member in the dynamic impact loading test bench shown in FIG. 1 .

FIG. 3 is a schematic diagram of a specimen bearing platform in the dynamic impact loading test platform shown in FIG. 1 .

Detailed ways

The specific embodiment of the present invention will be further described in detail below in conjunction with the accompanying drawings. For those skilled in the art, the above objects, features and advantages of the present invention will be apparent from the detailed description of the present invention.

Referring to FIG. 1 , it is a schematic diagram of the overall structure of a dynamic impact loading test bench according to a specific embodiment of the present invention. As shown in the figure, the dynamic impact loading test bench 100 includes an impact unit, a tension spring unit, a lifting unit and a specimen carrying platform carried on a fixed frame.

In FIG. 1 , the impact unit is a T-shaped heavy hammer, which includes a hammer body 5 forming a body and a hammer head 14 forming a striking part. The hammer body 5 is coated with a nylon sleeve, which is used to reduce the friction with the "I"-shaped adjustment horizontal plate 6 mentioned below and play a position-limiting role when the weight falls.

The fixed frame provides support and support for the entire dynamic impact loading test bench 100, which is the guarantee of the safety of the test bench 100. flat bolt 19. The upper board 1 and the horizontal board 6 here are respectively an "I"-shaped upper board and an "I"-shaped horizontal board. However, it should be understood that the upper board 1 and the horizontal board 6 are not limited to "I"-shaped boards, as long as they are boards that can provide support and support. The base 18 plays the role of stabilizing the entire test bench 100, which is connected with the "I"-shaped upper plate 1 through two outer columns 8; the leveling bolt 19 here plays a leveling role, and can be leveled with a level.

The fixed frame is installed between the "I"-shaped upper plate 1 and the test piece bearing platform located at the lower part of the "I"-shaped adjustable horizontal plate 6, which can be adjusted up and down, and the two ends of the "I"-shaped adjustable horizontal plate 6 They are detachably installed on two outer columns 8 respectively; vertically parallel limit vertical rods 12 are also arranged on the "I"-shaped adjustment horizontal plate 6, and the upper ends of the limit vertical rods 12 pass through the "I" character. Type upper plate 1, the lower end is fixed on the "I"-shaped adjustment horizontal plate 6; the "I"-shaped adjustment horizontal plate 6 can drive the limit vertical bar 12 to adjust up and down to adapt to test pieces of different heights; the hammer body 5 The ends on both sides are sleeved on the limit vertical bar 12, and can move vertically along the limit vertical bar 12 between the "I"-shaped upper plate 1 and the "I"-shaped adjustment horizontal plate 6. The "I" shaped adjustment horizontal plate 6 is also provided with an opening through which the hammer head 14 hits the test piece when it moves and falls. Reinforcement screw 15 is located at the outer side of outer column 8, and connects this " I " font adjustment horizontal plate 6 and base 18 so as to play a reinforcing role.

Continuing to refer to Fig. 1, the extension spring unit includes two nylon stay ropes 11, two first pulleys 7, two extension spring connecting plates 10 and two sets of extension spring groups 9, forming two mutually symmetrical tension spring unit.

The first pulley 7 is arranged on the "I"-shaped adjustment horizontal plate 6, and the extension spring group 9 is fixed on the lower surface of the "I"-shaped upper plate 1, and the extension spring group 9 is connected with the extension spring connecting plate 10. Group extension spring group 9 comprises 5 extension springs, and described 5 extension springs are arranged in parallel, avoid contact or winding between extension springs, extension spring connection plate 10 is provided with extension spring connection holes corresponding to the extension spring quantity, can according to actual Requirements, remove the tension end of the tension spring from the tension spring connection hole to reduce the number of tension springs acting on the weight, or hook the tension end of the tension spring that has been removed in the tension spring connection hole to increase The number of extension springs acting on the weight; the stay cord 11 is wound around the first pulley 7, and one end of the stay cord 11 is connected to the lower surface of the ends on both sides of the hammer body 5, and the other end is connected to the extension spring connecting plate 10.

The lifting unit includes a locking member 4, a nylon lifting rope 13, a ratchet 3 constituting a pulling assembly, two second pulleys 7', and a rocker 2 arranged on the ratchet 3 to drive the ratchet 3 to wind the lifting rope 13. 2 provides power for ratchet 3 operation. The locking member 4 is connected with the hammer body 5 in a releasable and locked manner; the two ends of the lifting rope 13 are connected with the locking member 4 and the ratchet 3 respectively, and the locking member 4 is provided with a latch that can make the hammer body 5 break away from the locking member 4. The release switch 40, wherein, the connection mode between the locking member 4 and the hammer body 5 can be any connection method adopted by those skilled in the art, as long as it can realize that the locking member 4 can be connected with the hammer body 5 in a locked manner. connection, when the release switch 40 is operated, the hammer body 5 can be disengaged from the locking member 4; Lifting unit in the invention.

The ratchet 3 is fixed on one of the outer columns 8, and the two second pulleys 7' are respectively arranged in the middle of the "I"-shaped upper plate 1 and the end near the ratchet 3; one end of the lifting rope 13 is wound around the ratchet 3 , and the other end is connected to the locking member 4 through two second pulleys 7' to change direction.

Also can be provided with safety pin (not shown) on ratchet 3, safety pin here is any element and structure that those skilled in the art can think of, as long as described safety pin can guarantee that ratchet 3 is lifted when weight is lifted. During the process, keep running in the forward direction, and the ratchet 3 can be reversed and reversed after pressing the safety pin.

Referring to FIG. 2A , it is a schematic diagram of a horizontal plate in the dynamic impact loading test bench shown in FIG. 1 . On the "I"-shaped adjustment horizontal plate 6, between the two first pulleys 7 and directly below the hammer body 5, four rubber uprights 60 for buffering are installed to buffer the weight when the weight falls. Adjust the impact of the "I"-shaped horizontal plate 6 to improve the stability of the test bench 100. In Fig. 2A, since the locking element 4 is disengaged from the weight 5, it can be seen that a connecting pin 51 is provided at the middle position on the upper surface of the hammer body 5, combined with the bottom of the locking element 4 shown in Fig. 2B. Some jacks 41, the connecting pin 51 and the socket 41 cooperate to form a releasable snap connection, so as to lock and release the weight. When the release switch 40 on the locking member 4 is pressed, the weight is released .

Referring to FIG. 3 , it is a schematic diagram of a specimen bearing platform in the dynamic impact loading test platform shown in FIG. 1 . The specimen carrying table includes a three-point bending lower clamp 16 and a clamp support plate 17 . The three-point bending lower fixture 16 contains a scale, and the distance between the two supporting ends can be adjusted according to requirements; the fixture support plate 17 is used to support the three-point bending lower fixture 16, which is a circular platform with concentric circular through holes. Of course, the dynamic impact loading test bench of the present invention is not limited to the specimen bearing platform composed of the above-mentioned three-point bending lower clamp 16 and the clamp support plate 17, as an alternative, any device that can carry and clamp the specimen can be selected Or components as a specimen carrier.

The following describes how to use the dynamic impact loading test bench in conjunction with Figure 1-3:

1. First, place the test piece on the three-point bending lower fixture 16;

2. According to the height of the test piece, adjust the "I" shape up and down to adjust the height of the horizontal plate 6;

3. Select the hammer head 14 with suitable quality according to the size and type of the test piece (the hammer body and the hammer head are detachable), select the extension spring group 9 with a suitable stroke, and adjust it to the appropriate number of extension springs (dismount or increase), according to the above-mentioned dynamic impact loading test bench connection relationship of each component to carry out the assembly of the test bench;

4. Shake the rocker arm 2, the hammer body 5 and the hammer head 14 are lifted by the ratchet 3 through the nylon rope 13. At this time, the extension spring group 9 fixed on the "I"-shaped upper plate 1 is moved to the Stretch down, when the hammer body 5 and the hammer head 14 reach the required height, press the release switch 40 on the locking member 4, the hammer body 5 and the hammer head 14 will be under the pressure of their own gravity and the elastic recovery force given by the extension spring. Under the action, the hammer head 14 falls rapidly along the limit vertical bar 12 at the same time, and the hammer head 14 impacts the test piece placed on the three-point bending lower fixture 16 through the opening on the "I" shaped adjustment horizontal plate 6; the hammer body 5 passes through the four A rubber column 60 buffers and limits.

5. Repeat step 4 if necessary.

The dynamic impact loading test bench adopts the technique of applying impact loading to the test piece by pulling the impact unit with the tension spring unit. It has a compact structure and has the characteristics of miniaturization. The height of the whole device is about 1.5 meters, and the width is about 60 centimeters. The processing is simple and convenient. , low cost, and easy to move, thereby greatly expanding the impact rate in a limited space, and avoiding the current situation that the existing drop weight test device has a large volume. The device has high stability, and the falling speed of the weight can reach up to 10m/s, which is easy to realize and meet the requirements of different impact loading speed adjustments; the device has low requirements for the experimental site, which reduces the cost of the experiment; It will not fall or deviate when falling behind, and has high safety.

At the same time, in the actual impact load of the test material, the impact test system can also be constructed based on the above-mentioned dynamic impact loading test bench, only need to pass: a force sensor is arranged in the fixture support plate containing the concentric circular through hole , the force sensor is connected to the computer through the impact load signal acquisition device. The above-mentioned force sensor can be a commercially available S-type cylindrical force sensor, and the above-mentioned impact load signal acquisition device includes a dynamic strain gauge and a strain gauge pasted on the above-mentioned S-type cylindrical force sensor, and the above-mentioned strain gauge will generate the strain caused by the impact load. converted into electrical signals; the acquisition end of the above-mentioned dynamic strain gauge is connected with the electric bridge of the strain gauge, and its output end is connected with the computer. The force measurement system formed by the above settings can be stored in a large amount. Based on the dynamic strain measurement technology, it can be used for real-time test load data, thus providing a complete real-time impact load signal measurement and analysis platform. The system can measure the impact load quickly, accurately and in real time, and can test the dynamic mechanical properties of brittle specimens.

It is worth noting that the above description is only a preferred embodiment of the present invention, and does not limit the scope of patent protection of the present invention. The present invention can also improve the materials and structures of the above-mentioned various components, or use Replacement with technical equivalents, such as: changing the shape and structure of the tension spring unit, changing the shape and structure of the lifting unit, changing the number of tension springs and pulleys, etc. Therefore, all equivalent structural changes made by using the description and illustrations of the present invention, or directly or indirectly applied to other related technical fields are also included in the scope of the present invention.

Claims (6)

1. A dynamic impact loading test bench, comprising an impact unit, a lifting unit and a test piece carrying platform carried on a fixed mount, is characterized in that, the impact unit is connected with an extension spring unit, and the extension spring unit can apply elasticity The restoring force is on the impact unit, which includes a pull cord, a first pulley and a tension spring assembly, wherein: The tension spring assembly is fixed on the upper part of the fixing frame; The first pulley is positioned directly below the tension spring assembly; The pull rope goes around the first pulley, one end is connected with the impact unit, and the other end is connected with the tension end of the extension spring assembly. 2. The dynamic impact loading test bench according to claim 1, wherein the extension spring unit comprises 2 stay ropes, 2 first pulleys and 2 sets of extension spring assemblies; on both sides of the impact unit symmetrical arrangement; The extension spring assembly is fixed on the upper part of the fixed frame; the extension spring assembly includes a plurality of extension springs and a connection plate, and the connection plate is provided with extension spring connection holes corresponding to the number of extension springs. spring parallel setting; The first pulley is positioned directly below the tension spring assembly; The pull cord goes around the first pulley, one end is connected with the impact unit, and the other end is connected with the extension spring through the connecting plate. 3. dynamic impact loading test stand according to claim 2, is characterized in that, The lifting unit includes a locking piece, a lifting rope and a lifting assembly, and the locking piece is connected to the impact unit in a releasable and locking manner; Both ends of the lifting rope are respectively connected to the locking member and the lifting assembly; The locking piece is provided with a release switch capable of disengaging the impact unit from the locking piece; The lifting assembly includes a ratchet wheel and a second pulley fixed on the fixed frame; one end of the lifting rope is wound around the ratchet wheel, and the other end is connected to the locking member through the direction change of the second pulley ; The ratchet is also provided with a rocker that drives the ratchet to wind the lifting rope. 4. dynamic impact loading test stand according to claim 3, is characterized in that, The fixed frame is equipped with a horizontal plate that can be adjusted up and down between the upper plate at its upper part and the test piece bearing platform at its lower part, The horizontal plate is provided with a limit vertical bar, the upper end of the limit vertical bar passes through the upper plate, and the lower end is fixed on the horizontal plate; The body of the impact unit is sleeved on the limit vertical bar, and can move vertically between the upper plate and the horizontal plate, and the horizontal plate is also provided with a strike for the impact unit. the opening through which the part passes; The first pulley is arranged on the horizontal plate, and the tension spring assembly is fixed on the lower surface of the upper plate; There are two second pulleys, which are respectively arranged in the middle of the upper plate and at the end close to the ratchet. 5 . The dynamic impact loading test bench according to claim 4 , characterized in that, the transverse plate is provided with a cushioning member right below the impact unit. 6 . 6. A dynamic impact loading test system, which tests the mechanical properties of the test piece by connecting it to a computer, it is characterized in that the test system comprises the dynamic impact loading test bench described in any one of claims 1-5, impact A load signal acquisition device and a force sensor arranged in the specimen carrying platform and directly below the entire impact unit, the force sensor is connected to the computer via the impact load signal acquisition device.

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