CN117686310A - Pneumatic rod type tensile impact fatigue test device and method - Google Patents
Pneumatic rod type tensile impact fatigue test device and method Download PDFInfo
- Publication number
- CN117686310A CN117686310A CN202311629083.6A CN202311629083A CN117686310A CN 117686310 A CN117686310 A CN 117686310A CN 202311629083 A CN202311629083 A CN 202311629083A CN 117686310 A CN117686310 A CN 117686310A
- Authority
- CN
- China
- Prior art keywords
- rod
- sample
- loading
- gun barrel
- transmission rod
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000009661 fatigue test Methods 0.000 title claims abstract description 28
- 230000005540 biological transmission Effects 0.000 claims abstract description 139
- 238000006073 displacement reaction Methods 0.000 claims abstract description 27
- 239000000463 material Substances 0.000 claims abstract description 22
- 230000008569 process Effects 0.000 claims abstract description 17
- 230000009471 action Effects 0.000 claims abstract description 8
- 230000001960 triggered effect Effects 0.000 claims description 8
- 238000013461 design Methods 0.000 claims description 7
- 230000033001 locomotion Effects 0.000 claims description 7
- 230000004044 response Effects 0.000 claims description 7
- 238000007789 sealing Methods 0.000 claims description 7
- 239000003381 stabilizer Substances 0.000 claims description 7
- 230000002093 peripheral effect Effects 0.000 claims description 6
- 230000004323 axial length Effects 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 3
- 238000012360 testing method Methods 0.000 abstract description 26
- 238000002474 experimental method Methods 0.000 abstract description 2
- 238000010304 firing Methods 0.000 description 11
- 229910000831 Steel Inorganic materials 0.000 description 9
- 239000010959 steel Substances 0.000 description 9
- 230000006835 compression Effects 0.000 description 5
- 238000007906 compression Methods 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000003116 impacting effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012669 compression test Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- -1 polytetrafluoroethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
- G01N3/06—Special adaptations of indicating or recording means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
- G01N3/307—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight generated by a compressed or tensile-stressed spring; generated by pneumatic or hydraulic means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
- G01N3/36—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by pneumatic or hydraulic means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0042—Pneumatic or hydraulic means
- G01N2203/0044—Pneumatic means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/0202—Control of the test
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0682—Spatial dimension, e.g. length, area, angle
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention relates to a pneumatic rod type tensile impact fatigue test device and a method, belonging to the field of material tensile experiments; the system comprises a sample, a sample loading system, a resetting system, a data loading acquisition system and an automatic control system; limiting blocks are arranged at two ends of the sample and are in sliding connection with the sample loading system; the sample loading system comprises an incidence rod and a transmission rod which are connected to two ends of a sample in a sliding way, and limiting structures are arranged at the joints of the incidence rod, the transmission rod and the sample and used for limiting the axial sliding displacement of the sample; the resetting system is used for resetting the incidence rod and the transmission rod after single loading; the acquisition system is used for acquiring a strain signal in the loading process of the incident rod and the transmission rod; the automatic control system is respectively connected with the sample loading system and the resetting system and is used for controlling the action executing process of the automatic control system. The invention solves the problem that single loading control cannot be carried out in the existing tensile impact load test.
Description
Technical Field
The invention belongs to the field of material stretching experiments, and particularly relates to a pneumatic rod type stretching impact fatigue test device and method.
Background
In practice, a large number of structures or equipment are subjected to repeated impact loads, such as repeated tensile impact loads on the arresting hooks and the arresting ropes during the landing of the carrier. The mechanical properties of the material under impact fatigue are to be further studied, and therefore, the development of a tensile impact fatigue device with repeated impact loading is the basis for researching the impact fatigue problem of the material.
The invention discloses a repeated impact test device based on the Hopkinson rod principle and capable of carrying out automatic transformation, and the repeated dynamic compression test of a compressed sample can be carried out. Referring to fig. 1, the device consists of a striking rod 1, a limit handle 2, a limit device housing 3, an incident rod 4, a sample 5, a sample support 6, a transmission rod 7, a brake rod 8, a brake device housing 9, a brake and reload air chamber 10, an exhaust hole 11, a striking rod firing air source 12, a gun barrel 13, a striking rod return air source 14, a striking rod return air chamber 15, a strain gauge 16 and a reload air source 17. The test flow of the compression impact fatigue test of the equipment is that the impact rod 1 is at an initial position, namely the leftmost end, an impact rod emission air source 12 is deflated to drive the impact rod 1 to emit, the impact rod 1 moves rightwards in a gun barrel 13, compression stress waves are generated and transmitted to the incident rod 4 after impacting the limit handle 2, at the moment, a sample 5 is tightly contacted with the incident rod 4 and the transmission rod 7 through a bracket 6, after the compression stress waves pass through the sample 5, reflection stress waves and transmission stress waves are correspondingly generated on the incident rod 4 and the transmission rod 6, strain signals on the rod are acquired through a strain gauge 16, and the dynamic mechanical response of the sample 5 after impact loading each time can be calculated. The transmission rod 7 continues to move rightward, the stress wave on the transmission rod 7 is absorbed by the brake rod 8, the brake rod 8 moves rightward in the brake device 10, the gas in the brake chamber 10 is compressed, the speed is slowly reduced until the brake is stopped, the gas in the brake chamber 10 is slowly discharged through the exhaust hole 11, and the complete loading is finished. In order to carry out the second loading, the test device needs to be reset, firstly, the reloading air source 17 inflates the reloading air chamber 10, the brake rod 8 moves leftwards to push the transmission rod 7, the sample 5, the incidence rod 4 and the limit handle 2 to move leftwards to the initial position, the impact rod return air source 14 inflates the impact rod return air chamber 15 to drive the impact rod 1 to move leftwards to the initial position to prepare for the next impact, which is the test process of resetting after the impact loading, and the repeated impact loading of the sample 5 can be realized by cycling the above processes.
In the prior art, a drop hammer testing machine is adopted to repeatedly impact and load a round bar tensile test piece, so that the repeated impact fatigue performance of the material in a tensile state can be measured. Referring to fig. 2, the device mainly comprises a truss 18, a traction rope 19, a guide rail 20, a balancing weight 21, an impact head 22, a bottom fixer 23, a top support 24, a round bar sample 25, a supporting platform 26 and a base 27. The working principle of the device is that repeated stretching impact on the sample is realized by means of a drop hammer impact tester through designing a clamping mode of the sample. First, the upper end of the sample 25 is connected with the top support 24 through threads, the top support 24 is connected with the supporting platform 26, the lower end of the sample 25 is connected with the bottom fixer 23 through threads, and the bottom fixer 23 is spaced from the supporting platform 26 by a certain distance. When the weight 21 and the impact head 22 are released at the top end through the control system, the weight 21 falls down along the guide rail 20, the impact head 22 impacts the bottom holder 23, and the bottom holder 23 is connected with the lower end of the sample 25, which is equivalent to performing a tensile impact loading on the sample 25. Under the action of the traction rope 19, the weight 21 and the striking head 22 return to the top of the truss 18. The electromagnetic control system controls the falling and lifting of the balancing weight 21 and the impact head 22, repeated impact loading can be realized by cyclic reciprocation, and the tensile impact fatigue performance of the round bar sample 25 is measured.
The two test devices have the defects that the test device shown in fig. 1 can realize repeated loading of a compressed sample, single loading of the sample cannot be realized, namely, after the stress wave on the rod is reflected back and forth, the sample cannot be separated from the loading rod in time, and the sample can be loaded for two times or even more times. The test sample is loaded repeatedly during each cycle, the repeated loading is uncontrollable, the amplitude and the times of the repeated loading cannot be accurately defined, the repeated loading causes difficulty in measuring the impact fatigue performance of the test sample, and in addition, the device cannot perform a tensile impact fatigue test. The test device shown in fig. 1 can realize repeated tensile loading of a round bar sample, but compared with a Hopkinson rod, the test device cannot measure actual loading of the sample and cannot control loading pulse width. The method has certain difficulty in loading the impact fatigue of the material and researching the impact fatigue performance and mechanism of the material, and the dynamic mechanical response of the material under repeated impact cannot be accurately quantified.
Disclosure of Invention
The technical problems to be solved are as follows:
in order to avoid the defects of the prior art, the invention provides the pneumatic rod type tensile impact fatigue test device, which realizes the loading control, the resetting control and the data acquisition of the whole device through an automatic control system, optimizes the connection modes of a sample, an incident rod and a transmission rod, and avoids the continuous loading of the sample after single loading. The invention solves the problem that single loading control cannot be carried out in the existing tensile impact load test.
The technical scheme of the invention is as follows: the pneumatic rod type tensile impact fatigue test device comprises a sample, a sample loading system for applying impact load to the sample, a resetting system for resetting the loading system, a loading data acquisition system and an automatic control system;
limiting blocks are arranged at two ends of the sample and are in sliding connection with the sample loading system;
the sample loading system comprises an incidence rod and a transmission rod which are connected to two ends of a sample in a sliding way, and limiting structures are arranged at the joints of the incidence rod, the transmission rod and the sample and used for limiting the axial sliding displacement of the sample; in the loading process, the displacement of the incident rod is controlled to be smaller than that of the transmission rod so as to ensure single loading of the sample;
the resetting system is respectively connected with the incident rod and the transmission rod and is used for resetting the incident rod and the transmission rod after single loading;
the acquisition system is respectively connected with the incident rod and the transmission rod and is used for acquiring a strain signal in the loading process;
the automatic control system is respectively connected with the sample loading system and the resetting system and is used for controlling the action executing process of the automatic control system.
The invention further adopts the technical scheme that: the sample loading system also comprises a power chamber sleeved on the incidence rod; the device comprises a power cavity, a through hole, an incidence rod, a gun barrel and a gun barrel, wherein the through holes are formed in two opposite sides of the power cavity, the incidence rod penetrates through the through hole, the gun barrel is coaxially sleeved at one end of the incidence rod, which is away from a sample, the bottom end of the gun barrel extends into the power cavity to be in contact with the emission piston, and the emission piston is in clearance fit with the power cavity and can move along the axial direction of the power cavity;
One end of the incidence rod is provided with a flange, and the other end of the incidence rod penetrates through the gun barrel, the launching piston and the power chamber to be connected with one end of the sample in a sliding manner; the impact rod is sleeved on the incidence rod between the flange and the power chamber, and the impact rod is in clearance fit with the gun barrel and the incidence rod, can slide along the incidence rod in the gun barrel, and applies axial load to the flange;
the flange is coaxially arranged in the flange support, and the flange support is arranged on the outer side of one end of the gun barrel, which is away from the power chamber, so that the part between the impact rod and the flange is communicated with the atmosphere.
The invention further adopts the technical scheme that: the gun barrel is in sealing connection with the power chamber, and an impact rod support is arranged between the gun barrel and the impact rod in the gun barrel; the striking rod support is of an annular structure and sleeved on the striking rod, the inner diameter of the striking rod support is consistent with that of the striking rod, and the outer diameter of the striking rod support is consistent with that of the gun barrel, so that the air tightness in the gun barrel is ensured.
The invention further adopts the technical scheme that: the method for controlling the displacement of the incident rod to be smaller than the displacement of the transmission rod in the loading process is to design the length of the incident rod to be longer than the length of the transmission rod or the elastic modulus of the material used for the incident rod to be longer than the elastic modulus of the material used for the transmission rod so as to improve the strain amplitude of the transmission wave of the transmission rod and ensure that stress wave loading can not be continuously generated after single loading.
The invention further adopts the technical scheme that: the cross-sectional areas of limiting blocks at two ends of the sample are larger than the cross-sectional areas of the stretching part in the middle, and the limiting blocks at two ends are respectively positioned in axial sliding grooves of the incident rod and the transmission rod and are in clearance fit, and the notch of the axial sliding groove is in clearance fit with the stretching part of the sample;
the dimensional relationship between the sample and the axial sliding groove is as follows: l (L) 1 ＜2L 2 Wherein L is 1 For the axial length of the sample L 2 Is the axial distance from the notch of the sliding groove to the groove bottom.
The invention further adopts the technical scheme that: the reset system comprises an incident rod reset assembly and a transmission rod reset assembly;
the incident rod resetting assembly comprises a first fastening clamp fixed on the peripheral surface of one end of the incident rod, which is close to the installation sample, and a spring connected between the first fastening clamp and the power chamber; after single loading, the first fastening clamp moves along the loading direction along with the incident rod, the spring is stressed and compressed, and the spring rebounds during resetting, and the incident rod is driven to reversely move and reset by the first fastening clamp;
the transmission rod resetting assembly comprises a second fastening clamp fixed on the peripheral surface of the transmission rod, a sliding sleeve sleeved on the transmission rod, a screw rod nut connected with the sliding sleeve, a screw rod, a servo motor for driving the screw rod and a position sensor; the servo motor drives the screw rod to rotate, the rotary motion of the screw rod is converted into linear motion through the screw rod nut, the sliding sleeve is driven to slide along the transmission rod, and the transmission rod is driven to axially move and reset through the second fastening clamp after the sliding sleeve slides to be contacted with the second fastening clamp; when the transmission rod is shifted to a state that the sample is in tension between the incidence rod and the transmission rod, the position sensor is triggered, and meanwhile, the servo motor is controlled to rotate reversely, so that the sliding sleeve moves to a safe position.
The invention further adopts the technical scheme that: the acquisition system includes strain gauges mounted on the incident and transmission rods.
The invention further adopts the technical scheme that: the automatic control system comprises an electronic barometer, a vacuum pump, an air pipe, a programmable automatic controller, a vacuum electromagnetic valve, a high-pressure air chamber, an inflation electromagnetic valve, a voltage stabilizer, a transmitting electromagnetic valve and a high-pressure air source;
the electronic barometer, the high-pressure air chamber and the emission electromagnetic valve are respectively communicated with the power chamber, and a cavity between one side of the emission piston, which is away from the gun barrel, and the power chamber is communicated with the emission electromagnetic valve and is communicated with the high-pressure air source through the inflation electromagnetic valve and the pressure stabilizer; the electronic barometer and the high-pressure air chamber are communicated with one side of the power chamber where the gun barrel is arranged;
the vacuum pump is communicated with the inside of the gun barrel through a vacuum electromagnetic valve, the communication position is positioned between the striking rod and the power cavity, and the striking rod is reset through vacuumizing;
the programmable automatic controller is connected with the electronic barometer, the vacuum electromagnetic valve, the inflation electromagnetic valve, the emission electromagnetic valve and the servo motor, and the action control of the connected elements is realized through programming.
A method for carrying out tensile impact fatigue test by a pneumatic rod type tensile impact fatigue test device comprises the following specific steps:
The striking rod is set to zero position, namely, is positioned at the side of the inner part of the gun barrel, which is close to the power chamber;
opening the inflation electromagnetic valve through the programmable automatic controller, and introducing high-pressure gas into the power cavity by the gas source to push the emission piston to be tightly adhered to the gun barrel for sealing; meanwhile, high-pressure gas enters a high-pressure air chamber from a gap between the transmitting piston and the power chamber, after the air pressure measured by the electronic barometer reaches a set value, a signal is sent to a programmable automatic controller, and the programmable automatic controller controls the inflation electromagnetic valve to be closed;
opening a transmitting electromagnetic valve through a programmable automatic controller, instantly releasing high-pressure gas on the side, deviating from the gun barrel, of the transmitting piston, pushing the transmitting piston to move towards the side, deviating from the gun barrel, of the transmitting piston by pressure difference on two sides of the transmitting piston, namely separating the transmitting piston from the gun barrel, and enabling the high-pressure gas to enter the gun barrel to drive an impact rod to transmit;
the striking rod moves to the striking flange along the gun barrel, so that the incident rod generates tensile waves in the loading direction, when the tensile waves pass through the sample, reflected waves and transmitted waves are respectively generated on the incident rod and the transmission rod, and meanwhile, strain signals of the rod where the strain gauge is positioned are collected by the strain gauge, so that the mechanical response of the sample during one impact is obtained, and the single loading is completed;
resetting the incident rod and the transmission rod through a resetting system, and resetting the impact rod through a vacuum pump so as to prepare for the next loading;
Repeating the steps to finish repeated impact loading of the sample.
The invention further adopts the technical scheme that: the method for resetting the incidence rod, the transmission rod and the impact rod comprises the following steps:
the incident rod is reset through resilience force after being loaded;
after the impact rod is loaded, the emission electromagnetic valve is closed, the vacuum electromagnetic valve is opened, at the moment, pressure difference is formed at the two sides of the impact rod to suck the impact rod back to a zero position, and then the vacuum electromagnetic valve is closed;
after the transmission rod is loaded, a servo motor is controlled by a programmable automatic controller to drive a screw rod to rotate, a screw rod nut drives a sliding sleeve to slide on the transmission rod to the side deviating from a sample, the sliding sleeve slides to be in contact with a second fastening clamp, and the transmission rod is driven to axially move and reset by the second fastening clamp; when the transmission rod is shifted to a state that the sample is in tension between the incidence rod and the transmission rod, the position sensor is triggered, and meanwhile, the servo motor is controlled to rotate reversely, so that the sliding sleeve moves to a safe position, and resetting is completed.
Advantageous effects
The invention has the beneficial effects that: the invention provides a pneumatic rod type tensile impact fatigue test device, which is characterized in that a control system comprising a vacuum electromagnetic valve 45, an inflation electromagnetic valve 47, a transmitting electromagnetic valve 49, an electronic barometer 35, a servo motor 51 and a position sensor 52 is designed, and the automatic operation of the above mechanisms is controlled by a programmable automatic controller 44, so that the traditional manually-transmitted separated Hopkinson pull rod is improved into an automatic transmission and reset impact fatigue test device. The use of the hooked sample 38 then prevents compression waves in the rod from acting on the sample 38. Finally, a comparison is made by changing the length or material of the rod, as shown in fig. 5, 6 and 7. Fig. 5 shows the loading results of the incident rod and the transmission rod with the length of 1m, the material of the steel, fig. 6 shows the loading results of the incident rod 33 with the material of the steel, the transmission rod 39 with the material of the aluminum alloy with the length of 1m, fig. 7 shows the loading results of the incident rod 33 with the length of 2m, the transmission rod 39 with the length of 1m, and the material of the steel. The displacement of the end faces of the incident beam 33 and the transmission beam 39 near one end of the specimen 38, and the tensile stress to which the specimen 38 is subjected are shown in the three figures. As can be seen in fig. 5, the sample 38 is significantly loaded twice. When the transmission rod 39 is replaced with an aluminum rod, the displacement of the end face of the transmission rod 39 increases, and the magnitude of the second load applied to the specimen 38 decreases, as shown in fig. 6. When the length of the entrance beam 33 is increased to 2m, it can be seen from fig. 7 that the sample 38 is no longer subjected to the second loading. Thus, it was demonstrated that the proposed method of the present invention allows for a single loading of the sample 38.
Drawings
Fig. 1 is a schematic diagram of a repetitive impact loading device based on a Hopkinson plunger in the background art.
FIG. 2 is a schematic diagram of an apparatus for repeatedly impacting round bar tensile specimens using a drop hammer impact tester in the background art.
FIG. 3-1 is a schematic view of the apparatus of the present invention.
Fig. 3-2 is a schematic illustration of the hook-type sample 38 and the engagement of the incident rod 33 with the rod end of the transmission rod 39.
Fig. 4 is a schematic diagram of the propagation of stress waves in the incident beam 33 and the transmission beam 39 according to the invention.
Fig. 5 shows the incident rod 33 made of steel and the transmission rod 39 made of steel, which are 1m in length, loading the sample 33, and the resulting end surface displacement of the incident rod 33 and the transmission rod 39 near one end of the sample 33, and the tensile stress curve to which the sample 33 is subjected.
Fig. 6 shows the incident rod 33 made of steel and the transmission rod 39 made of aluminum alloy, which have a length of 1m, load the sample 33, and the end face displacement of the incident rod 33 and the transmission rod 39 near one end of the sample 33, and the tensile stress curve of the sample 33.
Fig. 7 shows the incident rod 33 made of steel and the transmission rod 39 made of steel, which are 2m in length, loading the sample 33, and the resulting end surface displacement of the incident rod 33 and the transmission rod 39 near one end of the sample 33, and the tensile stress curve to which the sample 33 is subjected.
Fig. 8 is a graph showing voltage signals continuously collected by the strain gauge 40 attached to the incidence rod 33 when the sample 33 is continuously impacted.
Reference numerals illustrate: 1-strike bar, 2-stop lever, 3-stop device housing, 4-strike bar, 5-sample, 6-sample holder, 7-transmission bar, 8-brake bar, 9-brake device housing, 10-brake and reload air chamber, 11-vent, 12-strike bar firing air source, 13-barrel, 14-strike bar return air source, 15-strike bar return air chamber, 16-strain gauge, 17-reload air source, 18-truss, 19-pull cord, 20-rail, 21-counterweight, 22-strike head, 23-bottom anchor, 24-top mount, 25-round bar sample, 26-support platform, 27-mount, 28-flange, 29-flange mount, 30-strike bar, 31-strike bar holder, 32-barrel, 33-strike bar, 34-firing piston, 35-electronic barometer, 36-spring, 37-first fastening clip, 38-sample, 39-transmission bar, 40-strain gauge, 41-slide sleeve, 42-vacuum pump, 43-air tube, 44-programmable automatic controller, 45-46-solenoid valve, high pressure sensor, 48-solenoid valve, pressure sensor, 52-magnet valve, pressure sensor, pressure transducer, 52-magnet, pressure transducer, pressure sensor, servo-46-magnet, pressure transducer, pressure sensor, magnet, pressure sensor, 52-magnet valve, pressure transducer, pressure sensor, 54-magnet, pressure sensor, and servo-52-actuator.
Detailed Description
The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
Based on the problems that the impact fatigue test device in the prior art can only realize repeated loading of a compressed sample, single loading of the sample cannot be realized, namely, after stress waves on a rod are reflected back and forth, the sample cannot be separated from a loading rod in time, and the sample can be subjected to secondary or even repeated loading and the like, the invention provides a pneumatic rod type tensile impact fatigue test device, which comprises the sample, a sample loading system for applying impact load to the sample, a reset system for resetting the loading system, a loading data acquisition system and an automatic control system, wherein the pneumatic rod type tensile impact fatigue test device comprises a sample, a load receiving system for receiving load data, and a load receiving system for receiving the load data from the load receiving system; limiting blocks are arranged at two ends of the sample and are in sliding connection with the sample loading system; the sample loading system comprises an incidence rod and a transmission rod which are connected to two ends of a sample in a sliding way, and limiting structures are arranged at the joints of the incidence rod, the transmission rod and the sample and used for limiting the axial sliding displacement of the sample; in the loading process, the displacement of the incident rod is controlled to be smaller than that of the transmission rod so as to ensure single loading of the sample; the resetting system is respectively connected with the incident rod and the transmission rod and is used for resetting the incident rod and the transmission rod after single loading; the acquisition system is respectively connected with the incident rod and the transmission rod and is used for acquiring a strain signal in the loading process; the automatic control system is respectively connected with the sample loading system and the resetting system and is used for controlling the action executing process of the automatic control system.
Specifically, the sample loading system further comprises a power chamber sleeved on the incidence rod; the device comprises a power cavity, a through hole, an incidence rod, a gun barrel and a gun barrel, wherein the through holes are formed in two opposite sides of the power cavity, the incidence rod penetrates through the through hole, the gun barrel is coaxially sleeved at one end of the incidence rod, which is away from a sample, the bottom end of the gun barrel extends into the power cavity to be in contact with the emission piston, and the emission piston is in clearance fit with the power cavity and can move along the axial direction of the power cavity; one end of the incidence rod is provided with a flange, and the other end of the incidence rod penetrates through the gun barrel, the launching piston and the power chamber to be connected with one end of the sample in a sliding manner; the impact rod is sleeved on the incidence rod between the flange and the power chamber, and the impact rod is in clearance fit with the gun barrel and the incidence rod, can slide along the incidence rod in the gun barrel, and applies axial load to the flange; the flange is coaxially arranged in the flange support, and the flange support is arranged on the outer side of one end of the gun barrel, which is away from the power chamber, so that the part between the impact rod and the flange is communicated with the atmosphere.
Specifically, the gun barrel is in sealing connection with the power chamber, and an impact rod support is arranged between the gun barrel and the impact rod in the gun barrel; the striking rod support is of an annular structure and sleeved on the striking rod, the inner diameter of the striking rod support is consistent with that of the striking rod, and the outer diameter of the striking rod support is consistent with that of the gun barrel, so that the air tightness in the gun barrel is ensured.
Specifically, the method for controlling the displacement of the incident rod to be smaller than the displacement of the transmission rod in the loading process is to design the length of the incident rod to be longer than the length of the transmission rod or design the elastic modulus of the material used for the incident rod to be longer than the elastic modulus of the material used for the transmission rod so as to improve the transmission wave strain amplitude of the transmission rod and ensure that stress wave loading can not be continuously generated after single loading.
Specifically, the cross-sectional areas of limiting blocks at two ends of the sample are larger than the cross-sectional area of a stretching part in the middle, and the limiting blocks at two ends are respectively positioned in axial sliding grooves of an incident rod and a transmission rod and are in clearance fit, and the notch of the axial sliding groove is in clearance fit with the stretching part of the sample; the dimensional relationship between the sample and the axial sliding groove is as follows: l (L) 1 ＜2L 2 Wherein L is 1 For the axial length of the sample L 2 Is the axial distance from the notch of the sliding groove to the groove bottom.
Specifically, the reset system comprises an incident rod reset assembly and a transmission rod reset assembly;
the incident rod resetting assembly comprises a first fastening clamp fixed on the peripheral surface of one end of the incident rod, which is close to the installation sample, and a spring connected between the first fastening clamp and the power chamber; after single loading, the first fastening clamp moves along the loading direction along with the incident rod, the spring is stressed and compressed, and the spring rebounds during resetting, and the incident rod is driven to reversely move and reset by the first fastening clamp;
The transmission rod resetting assembly comprises a second fastening clamp fixed on the peripheral surface of the transmission rod, a sliding sleeve sleeved on the transmission rod, a screw rod nut connected with the sliding sleeve, a screw rod, a servo motor for driving the screw rod and a position sensor; the servo motor drives the screw rod to rotate, the rotary motion of the screw rod is converted into linear motion through the screw rod nut, the sliding sleeve is driven to slide along the transmission rod, and the transmission rod is driven to axially move and reset through the second fastening clamp after the sliding sleeve slides to be contacted with the second fastening clamp; when the transmission rod is shifted to a state that the sample is in tension between the incidence rod and the transmission rod, the position sensor is triggered, and meanwhile, the servo motor is controlled to rotate reversely, so that the sliding sleeve moves to a safe position.
Specifically, the acquisition system includes strain gauges mounted on the incident and transmission rods.
Specifically, the automatic control system comprises an electronic barometer, a vacuum pump, an air pipe, a programmable automatic controller, a vacuum electromagnetic valve, a high-pressure air chamber, an inflation electromagnetic valve, a voltage stabilizer, a transmitting electromagnetic valve and a high-pressure air source; the electronic barometer, the high-pressure air chamber and the emission electromagnetic valve are respectively communicated with the power chamber, and a cavity between one side of the emission piston, which is away from the gun barrel, and the power chamber is communicated with the high-pressure air source and the emission electromagnetic valve through the inflation electromagnetic valve and the voltage stabilizer; the electronic barometer and the high-pressure air chamber are communicated with one side of the power chamber where the gun barrel is arranged; the vacuum pump is communicated with the inside of the gun barrel through a vacuum electromagnetic valve, the communication position is positioned between the striking rod and the power cavity, and the striking rod is reset through vacuumizing; the programmable automatic controller is connected with the electronic barometer, the vacuum electromagnetic valve, the inflation electromagnetic valve, the emission electromagnetic valve and the servo motor, and the action control of the connected elements is realized through programming.
The method for carrying out the tensile impact fatigue test by the pneumatic rod type tensile impact fatigue test device comprises the following specific steps:
the striking rod is set to zero position, namely, is positioned at the side of the inner part of the gun barrel, which is close to the power chamber;
opening the inflation electromagnetic valve through the programmable automatic controller, and introducing high-pressure gas into the power cavity by the gas source to push the emission piston to be tightly adhered to the gun barrel for sealing; meanwhile, high-pressure gas enters a high-pressure air chamber from a gap between the transmitting piston and the power chamber, after the air pressure measured by the electronic barometer reaches a set value, a signal is sent to a programmable automatic controller, and the programmable automatic controller controls the inflation electromagnetic valve to be closed;
opening a transmitting electromagnetic valve through a programmable automatic controller, instantly releasing high-pressure gas on the side, deviating from the gun barrel, of the transmitting piston, pushing the transmitting piston to move towards the side, deviating from the gun barrel, of the transmitting piston by pressure difference on two sides of the transmitting piston, namely separating the transmitting piston from the gun barrel, and enabling the high-pressure gas to enter the gun barrel to drive an impact rod to transmit;
the striking rod moves to the striking flange along the gun barrel, so that the incident rod generates tensile waves in the loading direction, when the tensile waves pass through the sample, reflected waves and transmitted waves are respectively generated on the incident rod and the transmission rod, and meanwhile, strain signals of the rod where the strain gauge is positioned are collected by the strain gauge, so that the mechanical response of the sample during one impact is obtained, and the single loading is completed;
Resetting the incident rod and the transmission rod through a resetting system, and resetting the impact rod through a vacuum pump so as to prepare for the next loading;
repeating the steps to finish repeated impact loading of the sample.
The method for resetting the incidence rod, the transmission rod and the impact rod comprises the following steps:
the incident rod is reset through resilience force after being loaded;
after the impact rod is loaded, the emission electromagnetic valve is closed, the vacuum electromagnetic valve is opened, at the moment, pressure difference is formed at the two sides of the impact rod to suck the impact rod back to a zero position, and then the vacuum electromagnetic valve is closed;
after the transmission rod is loaded, a servo motor is controlled by a programmable automatic controller to drive a screw rod to rotate, a screw rod nut drives a sliding sleeve to slide on the transmission rod to the side deviating from a sample, the sliding sleeve slides to be in contact with a second fastening clamp, and the transmission rod is driven to axially move and reset by the second fastening clamp; when the transmission rod is shifted to a state that the sample is in tension between the incidence rod and the transmission rod, the position sensor is triggered, and meanwhile, the servo motor is controlled to rotate reversely, so that the sliding sleeve moves to a safe position, and resetting is completed.
The invention can avoid continuous loading after single loading.
The technical scheme is further described below with reference to the accompanying drawings:
Referring to fig. 3-1, a test apparatus for repeated impact on a hooked tensile specimen according to this embodiment is divided into a device resetting system, an automatic control system, a specimen loading section, and a data acquisition system. The main components of the test device are a flange 28, a flange support 29, an impact rod 30, an impact rod support 31, a gun barrel 32, an incident rod 33, an emission piston 34, an electronic barometer 35, a spring 36, a fastening clamp 37, a sample 38, a transmission rod 39, a strain gauge 40, a sliding sleeve 41, a vacuum pump 42, an air pipe 43, a programmable automatic controller 44, a vacuum electromagnetic valve 45, a high-pressure air chamber 46, an inflation electromagnetic valve 47, a pressure stabilizer 48, an emission electromagnetic valve 49, a high-pressure air source 50, a servo motor 51, a position sensor 52, a lead screw nut and support 53 and a lead screw 54.
The test flow of the test apparatus is as follows, and first, the programmable automatic controller 44 is connected to the electronic barometer 35, the vacuum solenoid valve 45, the inflation solenoid valve 47, the emission solenoid valve 49, and the servo motor 51, and the operations of these mechanisms are controlled by programming. At the beginning of the test, the striking rod 30 is positioned at the bottom of the right side of the gun barrel 32, the controller 44 controls the inflation electromagnetic valve 47 to open, the high-pressure gas in the gas source 50 firstly pushes the piston 34 to move leftwards, the firing piston 34 and the gun barrel 32 form sealing contact, meanwhile, the high-pressure gas enters the high-pressure gas chamber 46 from the gap of the firing piston 34, the electronic barometer 35 measures the gas pressure in the high-pressure gas chamber 46, and after the specified gas pressure is reached, the controller 44 receives a signal to control the inflation electromagnetic valve 47 to close. The firing solenoid valve 49 is then controlled to open, and the high pressure gas on the right side of the firing piston 34 is momentarily released, causing the firing piston 34 to move to the right, the high pressure gas entering the barrel 32, driving the firing rod 30 to fire. The striking rod 30 moves leftwards to strike the flange 28, a right-going tensile wave is generated in the incident rod 33, when the tensile wave passes through the sample 38, a reflected wave and a transmitted wave are correspondingly generated on the incident rod 33 and the transmission rod 39, and a strain signal on the rod is acquired through the strain gauge 40, so that the mechanical response of the sample during one impact can be obtained. The incident rod 33 is displaced to the left by the propagation of the stress wave, and the spring 36 restricts the displacement of the incident rod 33 by the power chamber 55 where the transmitting piston 34 is located and the fastening clip 37 on the rod, and returns the incident rod 33 to the original position by the resilience force, so that the transmission rod 39 is also displaced to the left by the tensile wave. After the whole test system is loaded once, the test system needs to be reset, firstly, the emission electromagnetic valve 49 is closed, the vacuum electromagnetic valve 45 is opened, at the moment, the pressure difference is formed at the two sides of the impact rod 30 to suck the impact rod back to the original position, and then the vacuum electromagnetic valve 45 is closed. The controller 44 then controls the servo motor 51 to rotate the screw rod 54, drives the screw rod nut 53 on the screw rod 54 to move rightwards, the screw rod nut 53 is connected with the sliding sleeve 41 on the rod, the sliding sleeve 41 contacts the fastening clamp 37 on the rod after moving a certain distance, the transmission rod 39 is driven to move backwards, the screw rod nut 53 moves to a specified position, the position sensor 52 is triggered, the sample 38 is in a tensioning state between the incident rod 33 and the transmission rod 39, then the servo motor 51 is driven to rotate reversely, the position sensor 52 is triggered to stop after the screw rod nut 53 is retracted to a safe position, and the resetting process is finished until the next inflation loading can be prepared.
The design advantages of this embodiment are described as follows:
first, the design of the flange mount 29 and the strike bar mount 31. In order to ensure smooth movement of the striking rod 30 within the barrel 32 and to ensure good air tightness within the barrel 32, rapid firing and resetting of the striking rod 30 may be achieved. The annular bullet holds in the palm 31 through polytetrafluoroethylene material, and bullet holds in the palm 31 internal diameter and the striking pole 30 external diameter the same, and bullet holds in the palm 31 external diameter and barrel 32 internal diameter the same, has reduced frictional force like this, has guaranteed the gas tightness simultaneously. The flange support 29 is separated from the barrel 32 to ensure that one end of the striking rod 30 is connected to the atmosphere, since a pressure differential is created across the striking rod 30.
Second, the design of the hook-type sample 38. The sample 38 is first designed as shown in fig. 3-2 (left), and the ends of the incident rod 33 and the transmission rod 39 connected to the sample 38 are machined into mating grooves, as shown in fig. 3-2 (right), so as to avoid loading the sample 38 with subsequent compression stress waves in the rod by fixedly connecting the sample 38 to the incident rod 33 and the transmission rod 39. It should be noted that in order to prevent excessive displacement of the transmission rod 39, a compressive load is applied to the sample 38, so that the length (L1) of the sample 38 should be less than 2 times (2L) 2 )。
Third, a single load. According to one-dimensional stress wave theory, a stress wave can generate corresponding strain when transmitted to any section of the rod, and the displacement of the section can be obtained by multiplying the strain by the wave speed after time integration. In order to achieve a single loading of the sample, when the displacement of the incident beam 33 to the left near the end face of the sample is smaller than the displacement of the transmission beam 39 near the end face of the sample 38, the sample 38 can be separated from the two beam end faces near the sample 38, and subsequent stress wave loading is avoided. On the other hand, the displacement of the end face can be determined by the strain in the rod, and under the same load, the transmission rod is made of a low-modulus material, so that the strain amplitude of the transmission wave can be improved, for example, the incident rod 33 is made of a steel rod (the elastic modulus is about 210 GPa), the transmission rod 39 is made of an aluminum rod (the elastic modulus is about 70 GPa), and the strain amplitude in the transmission rod can be improved by 3 times. On the other hand, the stress wave is reflected back and forth in the rod to reach the end face for multiple times, so that the end face generates multiple displacements, for example, the wave speed is about 5000m/s for the incident rod 33 and the transmission rod 39 of aluminum, so that the length of the incident rod 33 is 2 times that of the transmission rod 39, and then the stress wave in the transmission rod 39 can be propagated back and forth twice within the time of the stress wave propagating back and forth in the incident rod 33, as shown in fig. 4, the end face of the transmission rod 39 close to one end of the sample 38 is overlapped by multiple displacements, the displacement of the end face of the transmission rod 39 is further ensured to be larger than that of the incident rod 33, and the separation of the sample and the end face of the rod is realized. The realization of single loading has great significance for accurately representing the impact fatigue performance of the material, and is an important part of the invention.
The working procedure of this embodiment is:
before the device is tested, firstly, the test device is ensured to be in an initial state, the automatic controller 44 firstly executes a return program, the vacuum pump 42 works, the vacuum pump electromagnetic valve 45 is started, negative pressure is generated in the gun barrel 32, and the vacuum electromagnetic valve 45 is closed after the impact rod 30 returns to the bottom of the gun barrel 32. Then, the servo motor 51 starts to operate, and the lead screw nut 53 and the slide sleeve 41 are driven to move rightward by rotating the lead screw 54. After the sliding sleeve 41 contacts the fastening clamp 37, the transmission rod 39 is pulled to move rightward to a designated position, the position sensor 52 sends a signal to the controller 44, the controller 44 controls the servo motor 51 to rotate reversely, the screw nut 53 is retracted to the safe position, the position sensor 52 sends a signal to the controller 44, the servo motor 51 stops rotating, and the test device returns to the end.
The test was started, the inflation solenoid valve 47 was opened, and the high-pressure air source 50 inflated the high-pressure air chamber 46. When the air pressure reaches the preset air pressure value, the electronic air pressure gauge 35 feeds back a signal to the controller 44, the controller 44 sends a closing signal to the inflation electromagnetic valve 47 at the moment to stop inflation, after a preset time delay, the computer control acquisition system 44 sends an opening signal to the emission electromagnetic valve 49, and the high-pressure air pushes the impact rod 30 to emit. The striking rod 30 strikes the flange 28, a tensile stress wave is generated on the incident rod 33 to propagate rightward, a reflected wave and a transmitted wave are generated on the incident rod 33 and the transmission rod 39 respectively through the sample 38, signals are acquired through the on-rod strain gauge 40, and the mechanical response of the sample 38 can be obtained subsequently. The firing solenoid valve 49 is closed, the vacuum solenoid valve 45 is opened, the striking rod 30 is sucked back to the bottom of the barrel 32, the servo motor 51 is rotated, the transmission rod 39 is pulled to a designated position, and the motor 51 is reversed and returned to a safe position, which is consistent with the return procedure described above. After all parts return to the initial position, the system is re-inflated, deflated, fired, returned and cycled back and forth to achieve repeated impact loading of the test specimen 38.
The testing steps are as follows:
the first step: the test device is turned on, an emission air pressure threshold is set in the electronic air pressure gauge 35, the position sensor 52 is adjusted to a proper position, and whether the equipment is connected normally or not is detected.
And a second step of: the automatic controller 44 is operated, the automatic controller 44 operates a return program, a signal is sent to operate the vacuum pump 42, the vacuum solenoid valve 45 is opened, the striking rod 30 is returned to the bottom of the gun barrel 32 by negative pressure, and then the vacuum solenoid valve 45 is closed. Simultaneously, the controller 44 sends a signal to enable the servo motor 51 to start to operate, the screw rod 54 is rotated, the screw rod nut 53 drives the sliding sleeve 41 to move rightwards, after the screw rod nut 53 contacts the fastening clamp 37 on the transmission rod 39, the transmission rod 39 is pulled to move backwards, when the transmission rod 39 moves to a designated position, the sample 38 is in a tensioning state, the position sensor 52 sends a signal to the controller 44, the controller 44 sends a command to enable the servo motor 51 to rotate reversely, the sliding sleeve 41 moves leftwards to a safe position, the sensor 52 sends a signal to the controller 44, the controller 44 sends a command to enable the servo motor 51 to stop rotating, and the return procedure is finished.
And a third step of: after the previous step is ready, the test is formally started. The controller 44 controls to open the inflation electromagnetic valve 47, inflates the high-pressure air chamber 46, after the inflation reaches the preset air pressure threshold value, the electronic air pressure meter 35 feeds back a signal to the controller 44, the controller 44 controls the inflation electromagnetic valve 47 to be closed, the emission electromagnetic valve 49 is opened, the impact rod 30 is pushed to emit, and stress waves are generated to load the sample.
Fourth step: the incident lever 33 compresses the spring 36, and the spring 36 generates a rebound force to pull the incident lever 33 back to the original position. The controller 44 repeats the second step of the return procedure and the striking rod 30 returns to the bottom of the barrel 32 and the transmission rod 39 pulls the sample 38 back.
And (3) circulating the third step to the fourth step to realize automatic repeated impact loading. As shown in fig. 8, the voltage signal curve acquired by the strain gauge 40 on the incident beam 33 after four consecutive impact loads, the magnitude and interval time of which are substantially constant, demonstrates the reliability of the automated procedure.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations may be made in the above embodiments by those skilled in the art without departing from the spirit and principles of the invention.
Claims (10)
1. A pneumatic rod type tensile impact fatigue test device is characterized in that: the system comprises a sample, a sample loading system for applying impact load to the sample, a resetting system for resetting the loading system, a data acquisition system and an automatic control system;
Limiting blocks are arranged at two ends of the sample and are in sliding connection with the sample loading system;
the sample loading system comprises an incidence rod and a transmission rod which are connected to two ends of a sample in a sliding way, and limiting structures are arranged at the joints of the incidence rod, the transmission rod and the sample and used for limiting the axial sliding displacement of the sample; in the loading process, the displacement of the incident rod is controlled to be smaller than that of the transmission rod so as to ensure single loading of the sample;
the resetting system is respectively connected with the incident rod and the transmission rod and is used for resetting the incident rod and the transmission rod after single loading;
the acquisition system is respectively connected with the incident rod and the transmission rod and is used for acquiring a strain signal in the loading process;
the automatic control system is respectively connected with the sample loading system and the resetting system and is used for controlling the action executing process of the automatic control system.
2. The pneumatic rod type tensile impact fatigue test device according to claim 1, wherein: the sample loading system also comprises a power chamber sleeved on the incidence rod; the device comprises a power cavity, a through hole, an incidence rod, a gun barrel and a gun barrel, wherein the through holes are formed in two opposite sides of the power cavity, the incidence rod penetrates through the through hole, the gun barrel is coaxially sleeved at one end of the incidence rod, which is away from a sample, the bottom end of the gun barrel extends into the power cavity to be in contact with the emission piston, and the emission piston is in clearance fit with the power cavity and can move along the axial direction of the power cavity;
One end of the incidence rod is provided with a flange, and the other end of the incidence rod penetrates through the gun barrel, the launching piston and the power chamber to be connected with one end of the sample in a sliding manner; the impact rod is sleeved on the incidence rod between the flange and the power chamber, and the impact rod is in clearance fit with the gun barrel and the incidence rod, can slide along the incidence rod in the gun barrel, and applies axial load to the flange;
the flange is coaxially arranged in the flange support, and the flange support is arranged on the outer side of one end of the gun barrel, which is away from the power chamber, so that the part between the impact rod and the flange is communicated with the atmosphere.
3. The pneumatic rod type tensile impact fatigue test device according to claim 2, wherein: the gun barrel is in sealing connection with the power chamber, and an impact rod support is arranged between the gun barrel and the impact rod in the gun barrel; the striking rod support is of an annular structure and sleeved on the striking rod, the inner diameter of the striking rod support is consistent with that of the striking rod, and the outer diameter of the striking rod support is consistent with that of the gun barrel, so that the air tightness in the gun barrel is ensured.
4. A pneumatic rod type tensile impact fatigue test device according to claim 3, wherein: the method for controlling the displacement of the incident rod to be smaller than the displacement of the transmission rod in the loading process is to design the length of the incident rod to be longer than the length of the transmission rod or the elastic modulus of the material used for the incident rod to be longer than the elastic modulus of the material used for the transmission rod so as to improve the strain amplitude of the transmission wave of the transmission rod and ensure that stress wave loading can not be continuously generated after single loading.
5. The pneumatic rod type tensile impact fatigue test device according to claim 4, wherein: the cross-sectional areas of limiting blocks at two ends of the sample are larger than the cross-sectional areas of the stretching part in the middle, and the limiting blocks at two ends are respectively positioned in axial sliding grooves of the incident rod and the transmission rod and are in clearance fit, and the notch of the axial sliding groove is in clearance fit with the stretching part of the sample;
the dimensional relationship between the sample and the axial sliding groove is as follows: l (L) 1 ＜2L 2 Wherein L is 1 For the axial length of the sample L 2 Is the axial distance from the notch of the sliding groove to the groove bottom.
6. The pneumatic rod type tensile impact fatigue test device according to claim 5, wherein: the reset system comprises an incident rod reset assembly and a transmission rod reset assembly;
the incident rod resetting assembly comprises a first fastening clamp fixed on the peripheral surface of one end of the incident rod, which is close to the installation sample, and a spring connected between the first fastening clamp and the power chamber; after single loading, the first fastening clamp moves along the loading direction along with the incident rod, the spring is stressed and compressed, and the spring rebounds during resetting, and the incident rod is driven to reversely move and reset by the first fastening clamp;
the transmission rod resetting assembly comprises a second fastening clamp fixed on the peripheral surface of the transmission rod, a sliding sleeve sleeved on the transmission rod, a screw rod nut connected with the sliding sleeve, a screw rod, a servo motor for driving the screw rod and a position sensor; the servo motor drives the screw rod to rotate, the rotary motion of the screw rod is converted into linear motion through the screw rod nut, the sliding sleeve is driven to slide along the transmission rod, and the transmission rod is driven to axially move and reset through the second fastening clamp after the sliding sleeve slides to be contacted with the second fastening clamp; when the transmission rod is shifted to a state that the sample is in tension between the incidence rod and the transmission rod, the position sensor is triggered, and meanwhile, the servo motor is controlled to rotate reversely, so that the sliding sleeve moves to a safe position.
7. The pneumatic rod type tensile impact fatigue test device according to claim 6, wherein: the acquisition system includes strain gauges mounted on the incident and transmission rods.
8. The pneumatic rod type tensile impact fatigue test device according to claim 7, wherein: the automatic control system comprises an electronic barometer, a vacuum pump, an air pipe, a programmable automatic controller, a vacuum electromagnetic valve, a high-pressure air chamber, an inflation electromagnetic valve, a voltage stabilizer, a transmitting electromagnetic valve and a high-pressure air source;
the electronic barometer, the high-pressure air chamber and the emission electromagnetic valve are respectively communicated with the power chamber, and a cavity between one side of the emission piston, which is away from the gun barrel, and the power chamber is communicated with the emission electromagnetic valve and is communicated with the high-pressure air source through the inflation electromagnetic valve and the pressure stabilizer; the electronic barometer and the high-pressure air chamber are communicated with one side of the power chamber where the gun barrel is arranged;
the vacuum pump is communicated with the inside of the gun barrel through a vacuum electromagnetic valve, the communication position is positioned between the striking rod and the power cavity, and the striking rod is reset through vacuumizing;
the programmable automatic controller is connected with the electronic barometer, the vacuum electromagnetic valve, the inflation electromagnetic valve, the emission electromagnetic valve and the servo motor, and the action control of the connected elements is realized through programming.
9. A method for performing a tensile impact fatigue test by the pneumatic rod type tensile impact fatigue test device according to claim 8, which is characterized by comprising the following specific steps:
the striking rod is set to zero position, namely, is positioned at the side of the inner part of the gun barrel, which is close to the power chamber;
opening the inflation electromagnetic valve through the programmable automatic controller, and introducing high-pressure gas into the power cavity by the gas source to push the emission piston to be tightly adhered to the gun barrel for sealing; meanwhile, high-pressure gas enters a high-pressure air chamber from a gap between the transmitting piston and the power chamber, after the air pressure measured by the electronic barometer reaches a set value, a signal is sent to a programmable automatic controller, and the programmable automatic controller controls the inflation electromagnetic valve to be closed;
opening a transmitting electromagnetic valve through a programmable automatic controller, instantly releasing high-pressure gas on the side, deviating from the gun barrel, of the transmitting piston, pushing the transmitting piston to move towards the side, deviating from the gun barrel, of the transmitting piston by pressure difference on two sides of the transmitting piston, namely separating the transmitting piston from the gun barrel, and enabling the high-pressure gas to enter the gun barrel to drive an impact rod to transmit;
the striking rod moves to the striking flange along the gun barrel, so that the incident rod generates tensile waves in the loading direction, when the tensile waves pass through the sample, reflected waves and transmitted waves are respectively generated on the incident rod and the transmission rod, and meanwhile, strain signals of the rod where the strain gauge is positioned are collected by the strain gauge, so that the mechanical response of the sample during one impact is obtained, and the single loading is completed;
Resetting the incident rod and the transmission rod through a resetting system, and resetting the impact rod through a vacuum pump so as to prepare for the next loading;
repeating the steps to finish repeated impact loading of the sample.
10. The method of tensile impact fatigue testing according to claim 9, wherein: the method for resetting the incidence rod, the transmission rod and the impact rod comprises the following steps:
the incident rod is reset through resilience force after being loaded;
after the impact rod is loaded, the emission electromagnetic valve is closed, the vacuum electromagnetic valve is opened, at the moment, pressure difference is formed at the two sides of the impact rod to suck the impact rod back to a zero position, and then the vacuum electromagnetic valve is closed;
after the transmission rod is loaded, a servo motor is controlled by a programmable automatic controller to drive a screw rod to rotate, a screw rod nut drives a sliding sleeve to slide on the transmission rod to the side deviating from a sample, the sliding sleeve slides to be in contact with a second fastening clamp, and the transmission rod is driven to axially move and reset by the second fastening clamp; when the transmission rod is shifted to a state that the sample is in tension between the incidence rod and the transmission rod, the position sensor is triggered, and meanwhile, the servo motor is controlled to rotate reversely, so that the sliding sleeve moves to a safe position, and resetting is completed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311629083.6A CN117686310A (en) | 2023-11-30 | 2023-11-30 | Pneumatic rod type tensile impact fatigue test device and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311629083.6A CN117686310A (en) | 2023-11-30 | 2023-11-30 | Pneumatic rod type tensile impact fatigue test device and method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117686310A true CN117686310A (en) | 2024-03-12 |
Family
ID=90134461
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311629083.6A Pending CN117686310A (en) | 2023-11-30 | 2023-11-30 | Pneumatic rod type tensile impact fatigue test device and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117686310A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118655005A (en) * | 2024-08-21 | 2024-09-17 | 大连华升精密铸件制造有限公司 | Mould shell intensity detection equipment |
-
2023
- 2023-11-30 CN CN202311629083.6A patent/CN117686310A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118655005A (en) * | 2024-08-21 | 2024-09-17 | 大连华升精密铸件制造有限公司 | Mould shell intensity detection equipment |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113049420B (en) | Device and method for realizing pull/press impact fatigue test based on Hopkinson pull rod | |
| CN117686310A (en) | Pneumatic rod type tensile impact fatigue test device and method | |
| CN102879261B (en) | Reluctance-type miniature Hopkinson tension and pressure integrated bar device | |
| CN110057696B (en) | Take energy-absorbing device can simulate normal position stress environment's disconnect-type hopkinson depression bar | |
| CN106525577A (en) | Device and method for testing dynamic mechanical properties of materials under tensile/shear combined loading | |
| CN110082203B (en) | Device and method for testing tensile/compressive high-strain-rate mechanical property of material | |
| JP6860256B1 (en) | Equipment for testing the impact resistance of beam column structural members | |
| CN202770702U (en) | Miniature reluctance type integrated pulling-pressing Hopkinson bar device | |
| CN115585960B (en) | Hydraulic cylinder leakproofness testing arrangement | |
| CN112129659B (en) | Portable dynamic indentation testing device and testing method thereof | |
| CN104747234A (en) | Seismal wave excitation method for earthquake CT detection and seismal wave excitation device arranged in roadway | |
| CN114112741A (en) | Anchoring body dynamic load impact resistance in-situ measurement device and testing method | |
| CN113640118B (en) | Material in-situ dynamic tensile loading test device | |
| CN111896396B (en) | Rock dynamic mechanical property experimental device and experimental method thereof | |
| CN116698626B (en) | Single-pulse high strain rate tensile test device based on Hopkinson pressure bar | |
| KR102013393B1 (en) | Multi-purpose high strain rate material testing machine | |
| CN116337661A (en) | Loading control device and method for Hopkinson bar impact test | |
| CN111504822A (en) | Simple pneumatic lifting and quick releasing vertical automatic impact cylinder | |
| CN117606905A (en) | Pneumatic reciprocating rod type oscillography impact fatigue test device and method | |
| CN111044373B (en) | Dynamic mechanical test system | |
| CN108845278B (en) | Measuring device and method for giant magnetostrictive material | |
| CN116678720B (en) | Large-tonnage rock transmitting device for simulating falling rock impact and application method | |
| CN108195462B (en) | Calibration device of vibration sensor | |
| CN216051184U (en) | Two-dimensional bidirectional impact stretching experimental device | |
| CN118168962B (en) | Single-pulse experimental device and experimental method based on Hopkinson pressure bar |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |