CN110926937A - Device and method for measuring dynamic lateral strain of test piece through liquid volume - Google Patents
Device and method for measuring dynamic lateral strain of test piece through liquid volume Download PDFInfo
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- CN110926937A CN110926937A CN201911085119.2A CN201911085119A CN110926937A CN 110926937 A CN110926937 A CN 110926937A CN 201911085119 A CN201911085119 A CN 201911085119A CN 110926937 A CN110926937 A CN 110926937A
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- 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
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- 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
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- 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
- G01N2203/0001—Type of application of the stress
- G01N2203/001—Impulsive
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- 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
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Abstract
The invention discloses a device and a method for measuring dynamic lateral strain of a test piece through liquid volume. The invention converts the lateral strain of the test piece into the change of the volume of the measured liquid, further converts the change of the liquid elevation into the change of the liquid elevation, acquires the elevation signal received by the elevation signal sensor by the high-speed dynamic signal acquisition instrument, converts the elevation signal of the liquid into a digital signal and transmits the digital signal to the computer, forms a curve of the volume changing along with the time in the computer, and can obtain the curve of the lateral strain of the test piece changing along with the time under the dynamic load according to the specific size information of the test piece and the like. The invention has accurate measurement result of the dynamic lateral strain of the test piece and reasonable and reliable measurement method.
Description
Technical Field
The invention relates to the technical field of dynamic mechanical property testing of coal rock and other brittle materials by adopting an SHPB (split harmonic vibration) experimental system, in particular to a device and a method for measuring dynamic lateral strain of a test piece through liquid volume.
Background
In practical engineering application, materials such as coal rock and the like are often impacted by high-strength dynamic load, and the materials show mechanical characteristics which are completely different from static loading when impacted by high-strength dynamic load in a short time. Because the split Hopkinson pressure bar device has simple structure and novel design concept, the research on high strain rate (10)2～104) The most important experimental method for the mechanical properties of the materials is as follows. When the mechanical properties of brittle materials such as coal rocks and the like under the condition of dynamic load are measured, the axial strain and the axial stress of the test piece can be obtained by converting a strain signal on the waveguide rod. The dynamic lateral strain of the test piece is also an important parameter for researching the dynamic characteristics of the material. When an SHPB experiment platform is adopted to carry out loading tests on fragile materials such as coal rocks, the lateral strain of the materials is obtained by adopting a method of sticking a strain gauge on the side surface of a test piece. The method has certain limitations, firstly, under the impact of a dynamic load, the lateral strain of the test piece is often uneven, and the strain of a certain point on the side surface of the test piece can only be tested by adopting the method of sticking the strain gauge, so that the lateral strain of the whole test piece is represented to be inaccurate. Secondly, for dynamic load impact, the lateral strain of the test piece is increased rapidly in a short time, which easily causes the disconnection of the strain gauge, resulting in the inaccuracy of the lateral strain measurement. Thirdly, for brittle materials such as coal rocks, the surface of the brittle materials is a relatively rough cambered surface, so that the strain gauge is not easy to adhere, the surface of the test piece cannot be well attached, and the strain gauge is easy to fall off and shadow is easily caused under the action of dynamic loadAnd the integrity of the experimental data is influenced. Fourthly, the strain gauge is stuck on the surface of the test piece and is difficult to be reused.
Disclosure of Invention
In order to overcome the defect that the dynamic lateral strain of a test piece is obtained by sticking a strain gauge in the prior art, the invention provides a device and a method for measuring the dynamic lateral strain of the test piece through liquid volume.
The technical solution adopted by the invention is as follows:
a device for measuring dynamic lateral strain of a test piece through liquid volume comprises a conversion device, an acquisition device and a fixing device, wherein the conversion device is used for converting dynamic lateral strain information of the test piece to be tested into dynamic liquid elevation change information;
the conversion device comprises a cylinder body, a cover plate and a rubber leather sleeve, wherein the cylinder body is hollow and cylindrical and is horizontally arranged, two ends of the cylinder body are respectively in threaded connection with the cover plate, a round hole for a feed injection rod or a transmission rod to penetrate is formed in the center of the cover plate, and a rubber gasket for sealing the inner space of the cylinder body is arranged between the cylinder body and the cover plate; the test piece to be tested is cylindrical, the rubber leather sleeve is sleeved on the outer side of the test piece to be tested and tightly wraps the test piece to be tested, the test piece to be tested is arranged at the center of the interior of the cylinder body, and two ends of the test piece to be tested are respectively abutted against the end parts of the incident rod and the transmission rod; a liquid inlet hole and a first liquid outlet hole are formed in two sides of the bottom of the cylinder body, a second liquid outlet hole is formed in the top of the cylinder body, the liquid inlet hole and the first liquid outlet hole are connected with a liquid conveying pipeline, a measuring pipe is arranged above the cylinder body, the measuring pipe is a transparent glass pipe with two open ends and is vertically placed, and the bottom of the measuring pipe is communicated with the second liquid outlet hole;
the height signal sensor comprises a sensor shell, the sensor shell is sleeved outside the measuring tube, a vertically distributed light source is arranged on one side of the sensor shell, and vertically distributed photosensitive elements are arranged on the other side of the sensor shell; the elevation signal sensor is connected with a high-speed dynamic signal acquisition instrument through a lead, and the high-speed dynamic signal acquisition instrument is connected with a computer;
the fixing device comprises a base, a movable column and an arc supporting plate, the base is fixed on the SHPB test bed, the bottom end of the movable column is connected with the base, the top end of the movable column is connected with the arc supporting plate, the arc supporting plate is connected with the bottom of the cylinder body, and an adjusting bolt used for adjusting the lifting of the movable column is configured on the movable column.
Preferably, a communicating piece is arranged at the second liquid outlet hole, the communicating piece is of an inverted T-shaped structure, a through communicating hole is vertically formed in the communicating piece, the bottom of the communicating piece is connected with the top of the cylinder body, the upper portion of the communicating piece is inserted into the measuring pipe, and the communicating piece seals the bottom end opening of the measuring pipe.
Preferably, the outer surface of the cover plate is provided with a frosted surface.
Preferably, the liquid inlet hole and the first liquid outlet hole are connected with the transfusion pipeline by conical threads.
Preferably, the sensor housing is a light-tight black housing.
A method for measuring the dynamic lateral strain of a test piece by liquid volume, using the device as described above, comprising the steps of:
firstly, processing a to-be-tested piece into a cylindrical shape, and measuring and recording the radial radius and the axial length of the to-be-tested piece;
secondly, placing the conversion device at a position for clamping a test piece of the SHPB test bed, and adjusting a cylinder body of the conversion device to a proper height through a movable column of the fixing device; arranging a test piece in a rubber sleeve, arranging the test piece and the rubber sleeve in a cylinder body, and clamping the test piece through an incident rod and a transmission rod in an SHPB experimental device;
thirdly, installing an acquisition device, opening an elevation signal sensor and a high-speed dynamic signal acquisition instrument, opening a liquid inlet hole and a second liquid outlet hole, closing a first liquid outlet hole, and injecting liquid into the cylinder body from the liquid inlet hole until the elevation signal sensor starts to receive signals;
fourthly, closing the liquid inlet hole, starting an impact loading system of the SHPB experiment device, launching bullets to start a dynamic load experiment, converting elevation signals of liquid in the measuring tube into electric signals by an elevation signal sensor, and transmitting the electric signals to a high-speed dynamic signal acquisition instrument;
fifthly, storing data acquired by the high-speed dynamic signal acquisition instrument by a computer to form a curve of which the elevation changes along with time, and converting a curve of which the lateral strain of the test piece changes along with time in primary dynamic load impact by combining the inner radius of the measuring tube, the original radial radius and the axial length of the test piece;
and sixthly, opening the first liquid outlet hole, recovering liquid in the cylinder body, unscrewing the cover plates on the two sides, taking down the cylinder body, taking out the test piece from the rubber leather sheath, and cleaning the test bed.
The curve of the change of the elevation along with the time and the curve of the change of the lateral strain along with the time in the fifth step are converted by the following steps:
assuming that the dynamic elevation change acquired by the elevation signal sensor and acquired by the high-speed dynamic signal acquisition instrument is delta h (t), the lateral expansion volume generated by the dynamic load impact on the test piece is VSide wallVolume increase of liquid obtained in burette is VMeasurement ofThe original length of a cylindrical test piece is measured to be l, the original radius of the test piece is measured to be R, and the inner radius of a measuring tube is measured to be RPipeWhen stress wave is loaded to t moment, axial strain is epsilonShaft(t), lateral strain is εSide wall(t), then:
Vside wall＝π{[r(1+εSide wall(t))]2-r2}×l(1-εShaft(t))
VMeasurement of＝πRPipe 2×Δh(t)
Since the interior of the cylinder body is communicated with the measuring tube, and the measuring tube is communicated with the atmosphere, the volume of the test piece increased by the lateral strain caused by the impact of the dynamic load is equal to the volume of the liquid increased in the measuring tube, namely
VMeasurement of＝VSide wall
Through conversion, the following can be obtained:
namely the lateral strain of the test piece when the stress wave is loaded to the moment t.
The beneficial technical effects of the invention are as follows:
(1) the lateral strain of the coal rock and other brittle material test piece is not uniform when the test piece is impacted by dynamic load, the lateral strain information of the test piece is ingeniously converted into the volume change information of the measured liquid, and the lateral strain of the test piece is converted according to the volume change information of the liquid and the basic information of the test piece, so that the measurement method is reasonable, and the measurement result is accurate.
(2) The lateral strain rate of the coal rock test piece is high when the coal rock test piece is subjected to dynamic load, the strain gauge is easy to break and data loss is caused by the conventional method for sticking the strain gauge.
(3) When the coal rock test piece is measured, the surface of the coal rock test piece is a rough curved surface, and the method for manually pasting the strain gauge often cannot capture the real lateral strain of the test piece due to improper pasting angle or infirm pasting, so that the influence and manual error of the unsmooth curved surface of the coal rock test piece are avoided, and the measurement precision is obviously improved.
(4) The device has simple measurement principle, convenient operation and repeated use.
Drawings
The invention will be further described with reference to the following detailed description and drawings:
FIG. 1 is a schematic structural diagram of a device for measuring dynamic lateral strain of a test piece through liquid volume according to the present invention;
FIG. 2 is a general view of the assembly of the apparatus of the present invention in an SHPB testing system;
FIG. 3 is a schematic view of a fixing device of the present invention;
FIG. 4 is a schematic view of a conversion apparatus in the apparatus of the present invention;
FIG. 5 is a schematic view of the structure of the collecting device of the present invention;
FIG. 6 is a parameter labeling diagram of a test piece according to the present invention;
FIG. 7 is an experimental flow chart of the measurement method of the present invention.
In the figure: 1-base, 2-plunger, 3-arc supporting plate, 4-liquid inlet hole, 5-cylinder, 6-incident rod side cover plate, 7-rubber gasket, 8-incident rod, 9-tested piece, 10-elevation signal sensor, 11-transmission rod, 12-transmission rod side cover plate, 13-rubber leather sheath, 14-first liquid outlet hole, 15-burette, 16-conducting wire, 17-high-speed dynamic signal collector, 18-computer, 19-vertically distributed light source, 20-sensor shell, 21-vertically distributed photosensitive element, 22-conversion device, 23-fixing device, 24-dynamic load impact device, 25-SHPB experimental device base, 26-collection device, 27-second liquid outlet hole and 28-connecting piece.
Detailed Description
The separated Hopkinson pressure bar experiment system is used for researching high strain rate (10)2～104) The most important experimental method of the mechanical property of the material is an important composition in the experimental technology of explosion and impact dynamics. Aiming at the limitation that the conventional method for attaching a strain gauge to the side surface of a test piece obtains the lateral strain of the test piece, the invention provides a device and a method for measuring the dynamic lateral strain of the test piece through the volume of liquid. According to the invention, the expansion of the side volume of the test piece when the test piece is dynamically impacted is utilized, the change of the side volume of the test piece when the test piece is subjected to dynamic load is skillfully converted into the change of the liquid volume, and then the dynamic lateral strain parameter of the test piece in the process of the dynamic load is obtained. Compared with the traditional mode of manually pasting the strain gauge, the device has the advantages that the implementation principle is simple, the measurement precision is greatly improved, the device can be repeatedly used, and the device is economical on the whole.
The apparatus and method of the present invention will be described in more detail with reference to the accompanying drawings.
With reference to the attached drawings, the device for measuring dynamic lateral strain of the test piece through the liquid volume comprises a conversion device 22, an acquisition device 26 and a fixing device 23, wherein the conversion device is used for converting dynamic lateral strain information of the test piece to be tested into dynamic liquid elevation change information, and particularly converts expansion of the side volume of the test piece when the test piece is dynamically impacted into change of liquid elevation in a measuring tube through a closed cylinder body and other components. The acquisition device 26 is used for acquiring dynamic liquid elevation change information in real time, specifically acquiring dynamic liquid elevation change information in the measuring tube through an elevation signal sensor, and finally acquiring real-time dynamic lateral strain of the test piece through computer processing. Fixing device 23 is used for fixing conversion equipment on the SHPB laboratory bench, guarantees that conversion equipment can not take place to remove when carrying out the dynamic load experiment and cause experimental error, and the vertical height of the adjustable conversion equipment of fixing device makes the cylinder body be in suitable height moreover.
The conversion device 22 comprises a cylinder body 5, an incident rod side cover plate 6, a transmission rod side cover plate 12 and a rubber leather sheath 13, wherein the cylinder body 5 is hollow and cylindrical and is horizontally arranged, two ends of the cylinder body are respectively in threaded connection with the incident rod side cover plate 6 and the transmission rod side cover plate 12, the two side cover plates are circular, and a round hole slightly larger than the diameter of the incident rod 8 or the transmission rod 11 is formed in the middle of the cylinder body so that the incident rod or the transmission rod can conveniently penetrate through and move. A rubber gasket 7 used for sealing the inner space of the cylinder body is further arranged between the cylinder body 5 and the cover plate, the rubber gasket 7 is specifically a circular rubber gasket and is fixed between the end face of the cylinder body 5 and the inner side face of the cover plate, the inner ring of the rubber gasket is in close contact with the penetrating incident rod or the penetrating transmission rod to play a role in sealing, and the cover plates on the two sides and the cylinder body 5 are guaranteed to form a closed liquid storage space.
The test piece 9 to be tested is processed into a cylinder shape, and the diameter of the cylinder is equal to that of the incident rod 8 or the transmission rod 11. The rubber leather sheath 13 is sleeved on the outer side of the piece to be tested and tightly wraps the piece to be tested. The piece to be tested is arranged at the center of the interior of the cylinder body, and two ends of the piece to be tested are respectively abutted against the end parts of the incident rod and the transmission rod. The purpose of the test piece side parcel rubber leather sheath that awaits measuring is isolated with the liquid of filling in test piece and cylinder body, eliminates the influence of liquid to test piece side direction strain. Wrap up the side of test piece through the rubber leather sheath like this, cover the both ends of test piece through incidence pole and transmission pole, can make the test piece completely isolated with the liquid in the cylinder body, need not consider in the experimentation whether the test piece material can take place to adsorb the scheduling problem with the liquid in the cylinder body, guaranteed the accuracy of experimental result.
A liquid inlet hole 4 and a first liquid outlet hole 14 are formed in two sides of the bottom of the cylinder body, a second liquid outlet hole 27 is formed in the top of the cylinder body, and the liquid inlet hole 4 and the first liquid outlet hole 14 are connected with a liquid conveying pipeline. A measuring tube 15 is arranged above the cylinder body, the measuring tube 15 is a transparent glass tube with two open ends and is vertically arranged, and the bottom of the measuring tube 15 is communicated with a second liquid outlet hole 27.
The acquisition device 26 comprises an elevation signal sensor 10 and a high-speed dynamic signal acquisition instrument 17, the elevation signal sensor 10 comprises a sensor shell 20, the sensor shell 20 is sleeved outside the measuring tube 15, a vertically-distributed light source 19 is arranged on one side of the sensor shell, and a vertically-distributed photosensitive element 21 is arranged on the other side of the sensor shell. The elevation signal sensor 10 is connected with a high-speed dynamic signal acquisition instrument 17 through a lead 16, and the high-speed dynamic signal acquisition instrument 17 is connected with a computer 18 through a lead.
The sensor housing 20 is a light-tight black housing, which can block the interference of external light to the photosensitive element. The liquid in the cylinder body can be selected from opaque black liquid and the like. The light emitted by the vertical distribution light source 19 passes through the transparent burette 15 and is received by the vertical distribution photosensitive element 21, so that the elevation signal of the liquid in the burette can be converted into an electric signal, the electric signal is transmitted to the high-speed dynamic signal acquisition instrument through the data wire, and finally the electric signal is transmitted to the computer to form a curve of the elevation changing along with time, and the curve of the lateral strain of the test piece changing along with time is obtained after processing.
Fixing device 23 includes base 1, post 2 and arc layer board 3 that lives, and base 1 is the long slab type, and both sides are opened there are two holes, can pass through the bolt fastening on SHPB experimental apparatus base 25. The bottom and the base of post 2 are connected alive, and the top and the arc layer board 3 of post 2 are connected alive, and arc layer board 3 is connected with the bottom of cylinder body. An adjusting bolt is arranged on the plunger and used for adjusting the lifting of the plunger so as to ensure that the tested piece and the SHPB wave guide rod (the incident rod and the transmission rod) meet the same height.
As a further design of the invention, a communicating piece 28 is arranged at the second liquid outlet hole, the communicating piece 28 is in an inverted T-shaped structure, a through communicating hole is vertically arranged in the communicating piece, the bottom of the communicating piece is connected with the top of the cylinder body, the upper part of the communicating piece is inserted into the measuring pipe 15, and the communicating piece seals the bottom end opening of the measuring pipe. The liquid in the cylinder 5 enters the burette 15 through the communication piece 28. The arrangement of the communicating piece 28 not only facilitates the communication between the cylinder body and the burette, but also facilitates the installation and fixation of the burette.
Furthermore, the outer surfaces of the incident rod side cover plate 6 and the transmission rod side cover plate 12 are both provided with frosted surfaces, so that the installation and the disassembly are convenient.
Furthermore, two ends of the rubber leather sheath are provided with outwards protruding circular rings, and the extending direction of the rubber leather sheath is perpendicular to the plane where the circular rings are located. When carrying out threaded connection between apron and the cylinder body like this, the ring and the rubber packing ring of rubber leather sheath are arranged in the lump between apron inboard and cylinder body terminal surface, are compressed tightly by apron and cylinder body, can further play the inside sealed effect of cylinder body.
Furthermore, the liquid inlet hole 4 and the first liquid outlet hole 14 are respectively connected with a liquid inlet pipe and a liquid outlet pipe of the infusion pipeline through tapered threads, and the tapered threads can realize interference fit and guarantee sealing performance.
The invention also provides a method for measuring the dynamic lateral strain of the test piece through the liquid volume. The method skillfully transfers the lateral strain of the test piece to the change of the volume of the measured liquid, and then converts the dynamic change of the volume of the liquid to obtain the dynamic lateral strain of the test piece.
A method for measuring the dynamic lateral strain of a test piece by liquid volume, using the device as described above, comprising the steps of:
in the first step, the test piece 9 to be tested is processed into a cylindrical shape, and the radial radius and the axial length of the test piece to be tested are measured and recorded.
Secondly, the conversion device 22 is placed on the base of the SHPB experimental device and is placed at the position for clamping the test piece, and the cylinder body 5 of the conversion device is adjusted to a proper height through the plunger 2 of the fixing device. The test piece to be tested 9 is arranged in the rubber leather sheath 13, the test piece and the rubber leather sheath are arranged in the cylinder body 5, and the test piece is clamped by the incident rod 8 and the transmission rod 11 in the SHPB experimental device.
And thirdly, installing the acquisition device 26, opening the elevation signal sensor 10 and the high-speed dynamic signal acquisition instrument 17, opening the liquid inlet hole 4 and the second liquid outlet hole 27, closing the first liquid outlet hole 14, and injecting black liquid into the cylinder body from the liquid inlet hole until the elevation signal sensor 10 starts to receive signals.
And fourthly, closing the liquid inlet hole 4, starting an impact loading system (comprising a dynamic load impact device 24) of the SHPB experimental device, launching a bullet to start a dynamic load experiment, converting an elevation signal of liquid in the burette into an electric signal by the elevation signal sensor 10, and transmitting the electric signal to the high-speed dynamic signal acquisition instrument 17.
And fifthly, storing the data acquired by the high-speed dynamic signal acquisition instrument by a computer to form a curve of elevation changing along with time, and converting a curve of the lateral strain of the test piece changing along with time in primary dynamic load impact by combining the inner radius of the measuring tube, the original radial radius and the axial length of the test piece.
And sixthly, opening the first liquid outlet hole 14, recovering liquid in the cylinder body, then unscrewing the cover plates on the two sides, namely the incident rod side cover plate 6 and the transmission rod side cover plate 12, taking down the cylinder body 5, taking out the test piece from the rubber leather sheath, and cleaning the test bed.
The curve of the change of the elevation along with the time and the curve of the change of the lateral strain along with the time in the fifth step are converted by the following steps:
assuming that the dynamic elevation change acquired by the elevation signal sensor and acquired by the high-speed dynamic signal acquisition instrument is delta h (t), the lateral expansion volume generated by the dynamic load impact on the test piece is VSide wallVolume increase of liquid obtained in burette is VMeasurement ofThe original length of a cylindrical test piece is measured to be l, the original radius of the test piece is measured to be R, and the inner radius of a measuring tube is measured to be RPipeWhen stress wave is loaded to t moment, axial strain is epsilonShaft(t), lateral strain is εSide wall(t), then:
Vside wall＝π{[r(1+εSide wall(t))]2-r2}×l(1-εShaft(t))
VMeasurement of＝πRPipe 2×Δh(t)
Since the interior of the cylinder body is communicated with the measuring tube, and the measuring tube is communicated with the atmosphere, the volume of the test piece increased by the lateral strain caused by the impact of the dynamic load is equal to the volume of the liquid increased in the measuring tube, namely
VMeasurement of＝VSide wall
Through conversion, the following can be obtained:
namely the lateral strain of the test piece when the stress wave is loaded to the moment t.
Parts not described in the above modes can be realized by adopting or referring to the prior art.
It is intended that any equivalents, or obvious modifications, which may be made by those skilled in the art in light of the teachings herein, be within the scope of the present invention.
Claims (7)
1. The utility model provides a device through liquid volume measurement test piece developments side direction is met an emergency which characterized in that: the device comprises a conversion device for converting dynamic lateral strain information of a piece to be tested into dynamic liquid elevation change information, an acquisition device for acquiring the dynamic liquid elevation change information in real time, and a fixing device for fixing the conversion device on an SHPB experiment table and adjusting the vertical height of the conversion device;
the conversion device comprises a cylinder body, a cover plate and a rubber leather sleeve, wherein the cylinder body is hollow and cylindrical and is horizontally arranged, two ends of the cylinder body are respectively in threaded connection with the cover plate, a round hole for a feed injection rod or a transmission rod to penetrate is formed in the center of the cover plate, and a rubber gasket for sealing the inner space of the cylinder body is arranged between the cylinder body and the cover plate; the test piece to be tested is cylindrical, the rubber leather sleeve is sleeved on the outer side of the test piece to be tested and tightly wraps the test piece to be tested, the test piece to be tested is arranged at the center of the interior of the cylinder body, and two ends of the test piece to be tested are respectively abutted against the end parts of the incident rod and the transmission rod; a liquid inlet hole and a first liquid outlet hole are formed in two sides of the bottom of the cylinder body, a second liquid outlet hole is formed in the top of the cylinder body, the liquid inlet hole and the first liquid outlet hole are connected with a liquid conveying pipeline, a measuring pipe is arranged above the cylinder body, the measuring pipe is a transparent glass pipe with two open ends and is vertically placed, and the bottom of the measuring pipe is communicated with the second liquid outlet hole;
the height signal sensor comprises a sensor shell, the sensor shell is sleeved outside the measuring tube, a vertically distributed light source is arranged on one side of the sensor shell, and vertically distributed photosensitive elements are arranged on the other side of the sensor shell; the elevation signal sensor is connected with a high-speed dynamic signal acquisition instrument through a lead, and the high-speed dynamic signal acquisition instrument is connected with a computer;
the fixing device comprises a base, a movable column and an arc supporting plate, the base is fixed on the SHPB test bed, the bottom end of the movable column is connected with the base, the top end of the movable column is connected with the arc supporting plate, the arc supporting plate is connected with the bottom of the cylinder body, and an adjusting bolt used for adjusting the lifting of the movable column is configured on the movable column.
2. The device for measuring the dynamic lateral strain of the test piece through the liquid volume according to claim 1, is characterized in that: the communicating piece is arranged at the second liquid outlet hole and is of an inverted T-shaped structure, the communicating hole which is communicated with the communicating piece is vertically arranged in the communicating piece, the bottom of the communicating piece is connected with the top of the cylinder body, the upper portion of the communicating piece is inserted into the measuring pipe, and the communicating piece seals the bottom end opening of the measuring pipe.
3. The device for measuring the dynamic lateral strain of the test piece through the liquid volume according to claim 1, is characterized in that: the outer surface of the cover plate is set to be a frosted surface.
4. The device for measuring the dynamic lateral strain of the test piece through the liquid volume according to claim 1, is characterized in that: the liquid inlet hole and the first liquid outlet hole are connected with the transfusion pipeline by adopting tapered threads.
5. The device for measuring the dynamic lateral strain of the test piece through the liquid volume according to claim 1, is characterized in that: the sensor housing is an opaque black housing.
6. A method for measuring the dynamic lateral strain of a test piece by means of a liquid volume, using a device according to any one of claims 1 to 5, characterized in that it comprises the following steps:
firstly, processing a to-be-tested piece into a cylindrical shape, and measuring and recording the radial radius and the axial length of the to-be-tested piece;
secondly, placing the conversion device at a position for clamping a test piece of the SHPB test bed, and adjusting a cylinder body of the conversion device to a proper height through a movable column of the fixing device; arranging a test piece in a rubber sleeve, arranging the test piece and the rubber sleeve in a cylinder body, and clamping the test piece through an incident rod and a transmission rod in an SHPB experimental device;
thirdly, installing an acquisition device, opening an elevation signal sensor and a high-speed dynamic signal acquisition instrument, opening a liquid inlet hole and a second liquid outlet hole, closing a first liquid outlet hole, and injecting liquid into the cylinder body from the liquid inlet hole until the elevation signal sensor starts to receive signals;
fourthly, closing the liquid inlet hole, starting an impact loading system of the SHPB experiment device, launching bullets to start a dynamic load experiment, converting elevation signals of liquid in the measuring tube into electric signals by an elevation signal sensor, and transmitting the electric signals to a high-speed dynamic signal acquisition instrument;
fifthly, storing data acquired by the high-speed dynamic signal acquisition instrument by a computer to form a curve of which the elevation changes along with time, and converting a curve of which the lateral strain of the test piece changes along with time in primary dynamic load impact by combining the inner radius of the measuring tube, the original radial radius and the axial length of the test piece;
and sixthly, opening the first liquid outlet hole, recovering liquid in the cylinder body, unscrewing the cover plates on the two sides, taking down the cylinder body, taking out the test piece from the rubber leather sheath, and cleaning the test bed.
7. The method for measuring the dynamic lateral strain of the test piece through the liquid volume as claimed in claim 6, wherein the curve of the change of the elevation with the time and the curve of the change of the lateral strain with the time in the fifth step are converted by the following steps:
assuming that the dynamic elevation change acquired by the elevation signal sensor and acquired by the high-speed dynamic signal acquisition instrument is delta h (t), the lateral expansion volume generated by the dynamic load impact on the test piece is VSide wallVolume increase of liquid obtained in burette is VMeasurement ofThe original length of a cylindrical test piece is measured to be l, the original radius of the test piece is measured to be R, and the inner radius of a measuring tube is measured to be RPipeWhen stress wave is loaded to t moment, axial strain is epsilonShaft(t), lateral strain is εSide wall(t), then:
Vside wall＝π{[r(1+εSide wall(t))]2-r2}×l(1-εShaft(t))
VMeasurement of＝πRPipe 2×Δh(t)
Since the interior of the cylinder body is communicated with the measuring tube, and the measuring tube is communicated with the atmosphere, the volume of the test piece increased by the lateral strain caused by the impact of the dynamic load is equal to the volume of the liquid increased in the measuring tube, namely
VMeasurement of＝VSide wall
Through conversion, the following can be obtained:
namely the lateral strain of the test piece when the stress wave is loaded to the moment t.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911085119.2A CN110926937B (en) | 2019-11-08 | 2019-11-08 | Device and method for measuring dynamic lateral strain of test piece through liquid volume |
| PCT/CN2019/129987 WO2021088239A1 (en) | 2019-11-08 | 2019-12-30 | Device and method for measuring dynamic lateral strain of test piece by means of liquid volume |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN112539992A (en) * | 2020-12-02 | 2021-03-23 | 山东科技大学 | Hopkinson pressure bar experiment multistage pulse loading device and experiment method thereof |
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| CN110926937B (en) | 2020-09-08 |
| WO2021088239A1 (en) | 2021-05-14 |
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