CN112630041A - Bidirectional compression mechanical test device and method for non-metallic material - Google Patents

Bidirectional compression mechanical test device and method for non-metallic material Download PDF

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Publication number
CN112630041A
CN112630041A CN202110014350.3A CN202110014350A CN112630041A CN 112630041 A CN112630041 A CN 112630041A CN 202110014350 A CN202110014350 A CN 202110014350A CN 112630041 A CN112630041 A CN 112630041A
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loading
loading arm
guide
arm
clamp body
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强洪夫
王哲君
王学仁
耿挺京
王广
张宇伦
王稼祥
代李菟
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Rocket Force University of Engineering of PLA
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Rocket Force University of Engineering of PLA
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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
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
    • G01N3/12—Pressure testing
    • 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
    • G01N3/04—Chucks

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Abstract

The invention belongs to the technical field of mechanical property test of materials, and particularly relates to a bidirectional compression mechanical test device and method for a non-metallic material, which can be used for testing the mechanical property of the non-metallic material under quasi-static and dynamic loading, wherein the device comprises an upper clamp and a lower clamp which are connected in a matching manner, the upper clamp comprises an upper clamp body and an upper loading platform arranged at the top of the upper clamp body, and a connector is fixedly connected to the upper loading platform; the lower clamp comprises a lower clamp body and a lower loading platform arranged at the lower end of the lower clamp body, and a bottom clamping end is fixedly connected to the lower loading platform; the upper clamp body and the lower clamp body are buckled with each other, and the area between the upper clamp body and the lower clamp body is a clamping area; the invention has simple structure, convenient use and low cost, and can be used for a high-speed tensile testing machine and a nonmetal material biaxial high-low speed compression mechanical test of a traditional universal material testing machine.

Description

Bidirectional compression mechanical test device and method for non-metallic material
Technical Field
The invention belongs to the technical field of mechanical property test of materials, and particularly relates to a bidirectional compression mechanical test device and method for a non-metallic material, which can be used for testing the mechanical property of the non-metallic material under quasi-static and dynamic loading.
Background
At present, the main test method for testing the mechanical properties of the materials is to adopt a traditional universal material testing machine to perform uniaxial tension and compression tests under a quasi-static condition. However, in actual conditions, stress states of many components are complex rather than one-dimensional, the same material may show completely different mechanical behaviors under different load modes, and the strength and reliability of the structure are analyzed and calculated only by using a uniaxial tension-compression test result, so that a certain deviation is generated, and the safety of the structure in actual use cannot be ensured. Therefore, in order to grasp the mechanical properties of the material more accurately, it is important to study the fracture characteristics in the biaxial stress state.
At present, biaxial loading implementations are generally divided into two main categories: (1) dual axis loading using two or more loading systems; (2) dual axis loading is achieved using a single axis loading system. The first type of device is independently realized by two or more loading systems, the test device can easily realize biaxial tension or compression tests in any proportion, but the test device has a complex structure and high cost, and has high requirements on a control system, so the application aspect is limited to a certain extent. In addition, the loading rate is limited, and the dynamic loading cannot be achieved due to the experimental strain rate. The second type of device mainly utilizes certain external mechanical structure or test fixture to realize the biax loading, based on using more ordinary unipolar material testing machine, comparatively easy realization biax mechanical properties test when reduce cost, even realize the biax mechanical test under the dynamic condition.
Furthermore, in order to study the mechanical behavior of materials under dynamic loading, researchers have conducted related studies based on split hopkinson Strut (SHPB) devices, but the SHPB devices introduce significant error due to the invalid data of the pre-stress balance test. Compared with the INSTRON160/100-20 high strain rate hydraulic servo testing machine produced by INSTRON corporation of America, the maximum compression speed can reach 20m/s, the mechanical property of the material under the dynamic loading condition can be tested, the precision is higher, and the measurable range is wider. However, the bi-directional compression test piece of the non-metallic material cannot be directly matched with the testing machine to realize the test of the biaxial compression mechanical property of the material, so that a new test fixture is needed to be matched with the testing machine for use in the research of the biaxial high-speed compression mechanical behavior of the non-metallic material.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings of the background technology and provides a bidirectional compression mechanical test device and method for a non-metallic material, which are suitable for testing the mechanical property of the non-metallic material under quasi-static and dynamic loading.
The invention relates to a bidirectional compression mechanical test device for a non-metallic material, which comprises an upper clamp and a lower clamp which are connected in a matching manner, wherein the upper clamp comprises an upper clamp body and an upper loading table arranged at the top of the upper clamp body, and a connector is fixedly connected to the upper loading table;
the lower clamp comprises a lower clamp body and a lower loading platform arranged at the lower end of the lower clamp body, and a bottom clamping end is fixedly connected to the lower loading platform;
the clamping device comprises an upper clamp body, a lower clamp body, a clamping area and a clamping mechanism, wherein the upper clamp body and the lower clamp body are buckled with each other, the area between the upper clamp body and the lower clamp body is a clamping area, the clamping area is cuboid, and one plane of the planes of diagonals of the clamping area is parallel to a vertical plane;
and a guide device is also arranged between the upper clamp body and the lower clamp body.
Preferably, the upper clamp body comprises a first loading arm and a second loading arm which are fixedly connected, the first loading arm and the second loading arm are both plate-shaped, one end of the first loading arm is fixedly connected with one end of the second loading arm, and the first loading arm and the second loading arm are arranged vertically to each other;
the lower clamp body comprises a third loading arm and a fourth loading arm which are fixedly connected, the third loading arm and the fourth loading arm are both plate-shaped, one end of the third loading arm is fixedly connected with one end of the fourth loading arm, and the third loading arm and the fourth loading arm are arranged vertically to each other;
a cross through groove is formed in the middle of each of the second loading arm and the third loading arm, loading plates are arranged in the middle of each of the first loading arm and the fourth loading arm, the loading plates on the first loading arm and the cross through grooves on the third loading arm are matched and crossed to be connected, and the cross through grooves on the second loading arm and the loading plates on the fourth loading arm are matched and crossed to be connected;
the first loading arm, the third loading arm, the second loading arm and the fourth loading arm are further connected through auxiliary guide structures respectively.
Preferably, the auxiliary guide structure comprises a strip-shaped through hole chute, the first loading arm, the second loading arm, the third loading arm and the fourth loading arm are all provided with through hole chutes, the through hole chutes on the first loading arm and the fourth loading arm are arranged at two sides of the loading plate on the loading arm, and the through hole chutes on the second loading arm and the third loading arm are arranged at two sides of the loading arm which is crossed and penetrated through the hole;
the through hole chutes on the same loading arm extend out along one end of the loading arm far away from the clamping area, and the loading arm positioned on one side of the through hole chute far away from the crossed through hole or the loading plate is a loading branch arm; the loading sub-arms cross and penetrate through corresponding through-hole chutes on the connected loading arms;
the number of the through hole chutes on the same side of the first loading arm, the second loading arm, the third loading arm and the fourth loading arm is two.
Preferably, the first loading arm and the second loading arm are fixedly connected and then are fixedly connected with the upper loading platform;
the third loading arm and the fourth loading arm are fixedly connected and then are fixedly connected with the lower loading platform;
the upper loading platform and the lower loading platform are arranged in parallel.
Preferably, the guide device comprises guide holes arranged at two ends of the upper loading platform and guide rods fixedly arranged at two ends of the lower loading platform, one end of each guide rod is fixedly connected with the lower loading platform, and the other end of each guide rod extends towards the upper loading platform and penetrates through the guide holes arranged on the upper loading platform and corresponding to the guide rods.
Preferably, the guide device comprises a guide frame and two guide rods, guide holes for the guide rods to pass through are correspondingly formed in the two ends of the upper loading platform and the lower loading platform respectively, and the guide rods respectively pass through the corresponding guide holes in the upper loading platform and the lower loading platform;
the two guide rods are arranged in parallel, one end of each guide rod is fixedly connected with one side edge of the guide frame, the side edge is the bottom edge of the guide frame, the other end of each guide rod is fixedly connected with the other side edge corresponding to the bottom edge of the guide frame, the side edge is the top edge of the guide frame, and the bottom edge of the guide frame is fixedly connected with the lower loading platform;
and a channel for the upper loading platform to move up and down is arranged at the top edge of the guide frame between the two guide rods, and the upper loading platform is arranged in the channel.
Or preferably, the device also comprises two loading guide plates, wherein each loading guide plate comprises a short plate and a long plate, the short plates are fixedly connected with the long plates, and the planes of the short plates and the long plates are perpendicular;
after the two loading guide plates are buckled with each other, one end of the long plate of one loading guide plate, which is far away from the short plate, extends out of the first guide hole, one end of the long plate of the other loading guide plate, which is far away from the short plate, extends out of the second guide plate, and the long plate and the guide hole which penetrates through the long plate are in sliding connection;
the short plates of the two loading guide plates are respectively abutted to the first loading plate and the loading plate on the fourth loading arm, and the clamping area is located in a cuboid-shaped area formed by buckling the two loading plates.
Preferably, the connector is a plate-shaped connector or a circular truncated cone-shaped connector; the bottom clamping end is fixedly connected with a reversing plate, the bottom clamping end is plate-shaped, and the plane of the reversing plate is perpendicular to the plane of the bottom clamping end.
A bidirectional compression mechanical test method for non-metallic materials is used for quasi-static mechanical property tests and specifically comprises the following steps:
step 1, connecting a bidirectional compression mechanical test device for non-metallic materials with a universal material testing machine through a plate-shaped connector and a bottom clamping end;
step 2, the two loading guide plates respectively penetrate through a first loading guide hole and a second loading guide hole, bolts penetrate through the short plates and the corresponding through hole sliding grooves and then are connected with nuts to realize fixation, and the bolts and the nuts are adjusted to be pre-tightened to proper positions;
step 3, enabling the guide rod to penetrate through the guide hole, and ensuring that the upper clamp body and the lower clamp body are aligned with each other;
step 4, uniformly coating friction-reducing agents on the first loading arm, the second loading arm, the third loading arm, the fourth loading arm, and the loading arms, the through hole chutes, the upper loading table and the lower loading table on the loading arms, starting the universal material testing machine, running in a no-load mode, and judging whether the force is output or not;
step 5, when the output force is smaller than 10N, resetting the universal material testing machine, placing the prepared test piece into a clamping area, and placing the test piece in the middle;
step 6, operating the universal material testing machine, adjusting the distance between the upper clamp body and the lower clamp body to a proper position, and ensuring that the gravity does not directly act on the test piece;
and 7, setting loading rates according to different test conditions, carrying out biaxial compression test under a quasi-static condition, and measuring strain or deformation by using a sensor or a digital image correlation method to output a force-displacement curve.
A bidirectional compression mechanical test method for non-metallic materials is used for dynamic mechanical property tests and specifically comprises the following steps:
step 1, connecting a bidirectional compression mechanical test device for non-metallic materials with a high strain rate hydraulic servo test machine through a bottom clamping end;
step 2, realizing the matched installation of the upper clamp body, the lower clamp body and the loading guide plate on the basis of installing the connecting head in the shape of a circular truncated cone of the upper clamp body and ensuring the parallelism of the connecting head and a chuck contact surface of the high-strain-rate hydraulic servo testing machine;
step 3, the guide rod penetrates through the guide hole, the upper clamp body and the lower clamp body are guaranteed to be mutually centered, two ends of the upper clamp body are respectively connected with the top end of the guide rod at the corresponding end through a thin rope, and the influence of the gravity of the lower clamp body on materials is reduced;
step 4, uniformly coating friction-reducing drag reducers on the first loading arm, the second loading arm, the third loading arm, the fourth loading arm, and the loading arms, the through hole chutes, the upper loading table and the lower loading table on the loading arms;
step 5, starting the high-strain-rate hydraulic servo testing machine, reserving a section of acceleration displacement, and enabling the high-strain-rate hydraulic servo testing machine to reach a specified loading rate to realize constant strain rate loading before applying load to the test piece;
and 6, setting loading rates according to different test conditions, carrying out a biaxial compression test under a high strain rate condition, and measuring strain or deformation by a sensor or a digital image correlation method to output a force-displacement curve.
The clamp has the advantages of simple structure, convenient use and low cost, and can be used for a high-speed tensile testing machine and a clamp for a nonmetal material biaxial high-low speed compression mechanical test of a traditional universal material testing machine;
the clamp is designed to be matched with the configuration of a test piece, the test piece is placed in a square area formed by the clamp and is fixed and compressed through the clamp transmission structure, so that the direct operation on the test piece is avoided, and the prestress and damage caused by fixing the test piece are reduced;
the testing device is simple in structure, convenient to process and capable of conveniently completing testing tasks.
The test device provided by the invention is easy to process the shape of the sample, does not need a special processing shape, and has low requirements on the sample.
The test device can realize a biaxial compression loading test with a loading ratio of 1:1 on an INSTRON160/100-20 high strain rate hydraulic servo test machine, and has low test cost.
The test device has uniform load distribution and enough bidirectional compression loading precision.
According to the test device, the guide rod on the lower fixture body is correspondingly connected with the guide hole on the upper fixture body, so that the upper fixture body and the lower fixture body are mutually centered, and the upper fixture body and the lower fixture body are coaxial.
Drawings
FIG. 1 is a schematic view of the structure of the present invention.
Fig. 2 is a left side view of one of the guides of fig. 1.
Fig. 3 is a top view of the upper clamp body of fig. 1.
Fig. 4 is a schematic diagram of a loading guide plate structure.
Fig. 5 is a left side view of fig. 4.
Fig. 6 is a top view of fig. 4.
Fig. 7 is a schematic view of a truncated cone-shaped connecting head.
Fig. 8 is a schematic view of a plate-shaped connecting head.
FIG. 9 is a force-displacement curve recorded by a universal material tester.
FIG. 10 is a stress-strain curve under bi-directional loading for a test piece calculated using equation (1).
Reference numerals: the method comprises the following steps of 1-connecting head, 2-upper loading platform, 3-guide rod, 4-fourth loading arm, 5-second loading arm, 6-lower loading platform, 7-loading guide plate, 8-first loading arm, 9-third loading arm, 10-through hole chute, 11-clamping area, 12-bottom clamping end, 13-reversing plate and 14-guide frame.
Detailed Description
The invention relates to a bidirectional compression mechanical test device for a non-metallic material, which comprises an upper clamp and a lower clamp which are connected in a matching way, wherein the upper clamp comprises an upper clamp body and an upper loading table 2 arranged at the top of the upper clamp body, the upper loading table 2 is fixedly connected with a connector 1, and when the bidirectional compression mechanical test device is used, the upper loading table 2 and the connector 1 can be connected in a threaded connection way;
the lower clamp comprises a lower clamp body and a lower loading table 6 arranged at the lower end of the lower clamp body, and a bottom clamping end 12 is fixedly connected to the lower loading table 6;
the upper clamp body and the lower clamp body are buckled with each other, the area between the upper clamp body and the lower clamp body is a clamping area 11, the clamping area 11 is cuboid, and one of the planes of the diagonal lines of the clamping area 11 is parallel to the vertical plane; and a guide device is also arranged between the upper clamp body and the lower clamp body.
The upper clamp body comprises a first loading arm 8 and a second loading arm 5 which are fixedly connected, the first loading arm 8 and the second loading arm 5 are both plate-shaped, one end of the first loading arm 8 is fixedly connected with one end of the second loading arm 5, and the first loading arm 8 and the second loading arm 5 are arranged vertically to each other;
the lower clamp body comprises a third loading arm 9 and a fourth loading arm 4 which are fixedly connected, the third loading arm 9 and the fourth loading arm 4 are both plate-shaped, one end of the third loading arm 9 is fixedly connected with one end of the fourth loading arm 4, and the third loading arm 9 and the fourth loading arm 4 are arranged vertically to each other;
a cross through groove is formed in the middle of each of the second loading arm 5 and the third loading arm 9, loading plates are arranged in the middle of each of the first loading arm 8 and the fourth loading arm 4, the loading plates on the first loading arm 8 and the cross through groove on the third loading arm 9 are in matched cross connection, and the cross through groove on the second loading arm 5 and the loading plate on the fourth loading arm 4 are in matched cross connection; when the upper clamp body and the lower clamp body are mutually buckled, the loading plate on the first loading arm 8 passes through the crossed through groove on the third loading arm 9, and the recording arm on the fourth loading arm 4 passes through the crossed through groove on the second loading arm 5;
the first loading arm 8 and the third loading arm 9, and the second loading arm 5 and the fourth loading arm 4 are further connected through auxiliary guide structures respectively.
The auxiliary guide structure comprises a strip-shaped through hole chute 10, the first loading arm 8, the second loading arm 5, the third loading arm 9 and the fourth loading arm 4 are all provided with the through hole chutes 10, the through hole chutes 10 on the first loading arm 8 and the fourth loading arm 4 are arranged on two sides of a loading plate on the loading arm, and the through hole chutes 10 on the second loading arm 5 and the third loading arm 9 are arranged on two sides of a crossed hole on the loading arm;
through hole chutes 10 on the same loading arm extend out along one end of the loading arm far away from the clamping area 11, and the loading arm positioned on one side of the through hole chute 10 far away from the crossed through hole or the loading plate is a loading branch arm; the loading sub-arms cross through the corresponding through-hole chutes 10 on the connected loading arms.
The number of the through-hole chutes 10 on the same side of the first loading arm 8, the second loading arm 5, the third loading arm 9, and the fourth loading arm 4 is two.
The first loading arm 8 and the second loading arm 5 are fixedly connected and then are fixedly connected with the upper loading platform 2;
the third loading arm 9 and the fourth loading arm 4 are fixedly connected and then are fixedly connected with the lower loading platform 6;
the upper loading table 2 and the lower loading table 6 are arranged in parallel.
The guide device comprises guide holes formed in two ends of an upper loading platform 2 and guide rods 3 fixedly arranged at two ends of a lower loading platform 6, one end of each guide rod 3 is fixedly connected with the lower loading platform 6, the other end of each guide rod extends out of the upper loading platform 2 and penetrates through the guide holes formed in the upper loading platform 2 corresponding to the guide rods 3, when the guide device is used, one end of each guide rod 3 is provided with an external thread and is used for being in threaded connection with the lower loading platform 6, and the guide device is more suitable for quasi-static experiments.
The guide means may also be arranged as follows: the guide device comprises a guide frame 14 and two guide rods 3, guide holes for the guide rods to pass through are correspondingly formed in the two ends of the upper loading platform 2 and the lower loading platform 6 respectively, and the guide rods 3 respectively pass through the corresponding guide holes in the upper loading platform 2 and the lower loading platform 6;
the two guide rods 3 are arranged in parallel, one end of each guide rod 3 is fixedly connected with one side edge of the guide frame 14, the side edge is the bottom edge of the guide frame, the other end of each guide rod 3 is fixedly connected with the other side edge corresponding to the bottom edge of the guide frame, the side edge is the top edge of the guide frame, and the bottom edge of the guide frame is fixedly connected with the lower loading platform 6;
a channel for the upper loading platform 2 to move up and down is arranged at the top edge of the guide frame between the two guide rods 3, and the upper loading platform 2 is arranged in the channel; the guide device is more suitable for dynamic loading experiments with larger stress.
The loading guide plate 7 comprises a short plate and a long plate, the short plate is fixedly connected with the long plate, and the plane of the short plate is perpendicular to the plane of the long plate;
a first loading guide hole is formed at the joint of the first loading arm 8 and the upper loading platform 2, one side surface of the first loading guide hole is coplanar with the lower surface of the second loading arm 5, a second loading guide hole is formed at the joint of the fourth loading arm 4 and the lower loading platform 6, and one side surface of the second loading guide hole is coplanar with the lower surface of the third loading arm 9; after the two loading guide plates 7 are buckled with each other, one end, far away from the short plate, of the long plate of one loading guide plate 7 extends out of the first guide hole, one end, far away from the short plate, of the long plate of the other loading guide plate 7 extends out of the second guide plate, and the long plate is connected with the guide hole through which the long plate passes in a sliding mode;
the short plates of the two loading guide plates 7 are respectively abutted to the first loading plate and the loading plate on the fourth loading arm 4, and the clamping area 11 is located in a cuboid-shaped area formed by buckling the two loading plates.
The connector 1 is a plate-shaped connector 1 or a circular truncated cone-shaped connector 1; the bottom clamping end 12 is fixedly connected with a reversing plate 13, the bottom clamping end 12 is plate-shaped, and the plane of the reversing plate 13 is perpendicular to the plane of the bottom clamping end 12.
A bidirectional compression mechanical test method for non-metallic materials is used for quasi-static mechanical property tests and specifically comprises the following steps:
step 1, connecting a bidirectional compression mechanical test device for non-metallic materials with a universal material tester through a plate-shaped connector 1 and a bottom clamping end 12;
step 2, respectively enabling the two loading guide plates 7 to penetrate through a first loading guide hole and a second loading guide hole, enabling bolts to penetrate through the short plates and the corresponding through hole sliding grooves 10 and then connecting nuts to realize fixation, and adjusting the pre-tightening of the bolts and the nuts to proper positions;
step 3, enabling the guide rod 3 to penetrate through the guide hole, and ensuring that the upper clamp body and the lower clamp body are aligned with each other;
step 4, uniformly coating friction-reducing drag reducers on the first loading arm 8, the second loading arm 5, the third loading arm 9, the fourth loading arm 4, loading arms on the loading arms, the through hole chutes 10, the upper loading table 2 and the lower loading table 6, starting the universal material testing machine, running in a no-load mode, and judging whether the universal material testing machine is outputting powerfully;
step 5, when the output force is smaller than 10N, resetting the universal material testing machine, placing the prepared test piece into the clamping area 11, and placing the test piece in the middle;
step 6, operating the universal material testing machine, adjusting the distance between the upper clamp body and the lower clamp body to a proper position, and ensuring that the gravity does not directly act on the test piece;
and 7, setting loading rates according to different test conditions, carrying out biaxial compression test under a quasi-static condition, and measuring strain or deformation by using a sensor or a digital image correlation method to output a force-displacement curve.
A bidirectional compression mechanical test method for non-metallic materials is used for dynamic mechanical property tests and specifically comprises the following steps:
step 1, connecting a bidirectional compression mechanical test device for non-metallic materials with a high strain rate hydraulic servo test machine through a bottom clamping end 12;
step 2, realizing the matched installation of the upper clamp body, the lower clamp body and the loading guide plate 7 on the basis of installing the connecting head 1 in the shape of a circular truncated cone of the upper clamp body and ensuring the parallelism of the connecting head 1 and a chuck contact surface of the high-strain-rate hydraulic servo testing machine;
step 3, the guide rod 3 penetrates through the guide hole, the upper clamp body and the lower clamp body are guaranteed to be in mutual centering, two ends of the upper clamp body are respectively connected with the top end of the guide rod 3 at the corresponding end through a thin rope, the influence of the gravity of the lower clamp body on materials is reduced, and specifically, two ends of the upper loading platform 2 are respectively connected with the top ends of the corresponding guide rods 3;
step 4, uniformly coating friction-reducing drag reducers on the first loading arm 8, the second loading arm 5, the third loading arm 9, the fourth loading arm 4, loading arms on the loading arms, the through hole chutes 10, the upper loading table 2 and the lower loading table 6;
step 5, starting the high-strain-rate hydraulic servo testing machine, reserving a section of acceleration displacement, and enabling the high-strain-rate hydraulic servo testing machine to reach a specified loading rate to realize constant strain rate loading before applying load to the test piece;
and 6, setting loading rates according to different test conditions, carrying out a biaxial compression test under a high strain rate condition, and measuring strain or deformation by a sensor or a digital image correlation method to output a force-displacement curve.
The guide rod 3 on the lower clamp body is correspondingly connected with the guide hole on the upper clamp body, and the purpose is two, firstly, a pre-experiment is carried out before the testing device is matched with the testing machine, so that the upper clamp body and the lower clamp body are well matched, the testing machine is further ensured to provide a load direction which is concentric with the central symmetry line of the clamp, and the expected load condition is achieved; and secondly, the support function is realized by matching with the string so as to reduce the influence of the self weight of the clamp on the material before the test. The bottom clamping end 12 and the reversing plate 13 are in cross fit through mutually perpendicular notches, the fixing direction of the lower testing device is changed, and the adaptability of different testing machines can be improved.
The loading guide plate 7 comprises four bolts and nuts for fixing, and two long plates and two short plates which are H0 thick and form L-shaped flat plates; the short plates are connected with the bolts after penetrating through the corresponding through hole chutes 10 through the bolts, so that the long plates extend out along the penetrating loading guide holes only when the upper clamp body and the lower clamp body are buckled; wherein the two long plates are respectively tightly attached to the two loading plates, and the thickness of each loading plate is larger than that of the corresponding loading arm.
Wherein the material of the test piece is HTPB composite solid propellant.
According to the technical scheme of the invention, corresponding connectors 1 are selected according to test requirements and are connected and matched with corresponding single-axis testing machines, so that the test equipment is convenient to useThe biaxial compression mechanical behavior test of the non-metallic material under the wide range of strain rate can be realized. The stress-strain curve in the stress state can be obtained from the force-displacement curve output by the testing machine by the formula (1), and as shown in fig. 10, the strain rate of the test piece obtained by the formula (1) is 0.4min-1Stress-strain curve under bidirectional loading, equation (1) is as follows:
Figure BDA0002886361370000091
Figure BDA0002886361370000092
wherein F is the loading force acting on the clamp; σ is the nominal stress, ε is the nominal strain; u is the displacement of the clamp in the vertical direction; l is0And W0The original length and width of the test piece, respectively.

Claims (10)

1. A bidirectional compression mechanical test device for non-metallic materials comprises an upper clamp and a lower clamp which are connected in a matching manner, and is characterized in that the upper clamp comprises an upper clamp body and an upper loading table (2) arranged at the top of the upper clamp body, and a connector (1) is fixedly connected to the upper loading table (2);
the lower clamp comprises a lower clamp body and a lower loading table (6) arranged at the lower end of the lower clamp body, and a bottom clamping end (12) is fixedly connected to the lower loading table (6); the upper loading platform (2) and the lower loading platform (6) are arranged in parallel, and the axes of the upper loading platform and the lower loading platform are positioned in the same vertical plane;
the upper clamp body and the lower clamp body are buckled with each other, a clamping area (11) is arranged between the upper clamp body and the lower clamp body, the clamping area (11) is cuboid, and one plane of planes of diagonals of the clamping area (11) is parallel to a vertical plane;
and a guide device is also arranged between the upper clamp body and the lower clamp body.
2. The bi-directional compression mechanical test device for the non-metallic material according to claim 1, wherein the upper clamp body comprises a first loading arm (8) and a second loading arm (5) which are fixedly connected, the first loading arm (8) and the second loading arm (5) are both plate-shaped, one end of the first loading arm (8) is fixedly connected with one end of the second loading arm (5), and the first loading arm (8) and the second loading arm (5) are arranged vertically to each other;
the lower clamp body comprises a third loading arm (9) and a fourth loading arm (4) which are fixedly connected, the third loading arm (9) and the fourth loading arm (4) are both plate-shaped, one end of the third loading arm (9) is fixedly connected with one end of the fourth loading arm (4), and the third loading arm (9) and the fourth loading arm (4) are arranged vertically to each other;
a cross through groove is formed in the middle of each of the second loading arm (5) and the third loading arm (9), loading plates are arranged in the middle of each of the first loading arm (8) and the fourth loading arm (4), the loading plates on the first loading arm (8) are matched and crossed with the cross through grooves on the third loading arm (9) to be connected, and the cross through grooves on the second loading arm (5) are matched and crossed with the loading plates on the fourth loading arm (4) to be connected;
the first loading arm (8) and the third loading arm (9), and the second loading arm (5) and the fourth loading arm (4) are further connected through auxiliary guide structures respectively.
3. The device for bidirectional compression mechanical test of non-metallic materials of claim 2, wherein the auxiliary guide structure comprises an elongated through-hole chute (10), the through-hole chutes (10) are disposed on the first loading arm (8), the second loading arm (5), the third loading arm (9) and the fourth loading arm (4), the through-hole chutes (10) on the first loading arm (8) and the fourth loading arm (4) are disposed on both sides of the loading plate on the loading arm, and the through-hole chutes (10) on the second loading arm (5) and the third loading arm (9) are disposed on both sides of the crossed through hole on the loading arm;
through hole chutes (10) on the same loading arm extend out along one end of the loading arm far away from the clamping area (11), and the loading arm positioned on one side of the through hole chute (10) far away from the crossed through hole or the loading plate is a loading branch arm; the loading sub-arms cross and penetrate through corresponding through hole sliding grooves (10) on the connected loading arms;
the number of the through hole sliding grooves (10) on the same side of the first loading arm (8), the second loading arm (5), the third loading arm (9) and the fourth loading arm (4) is two.
4. The bi-directional compression mechanical test device for the non-metallic materials according to claim 3, wherein the first loading arm (8) and the second loading arm (5) are fixedly connected and then are fixedly connected with the upper loading platform (2);
the third loading arm (9) and the fourth loading arm (4) are fixedly connected and then are fixedly connected with the lower loading platform (6);
the upper loading platform (2) and the lower loading platform (6) are arranged in parallel, and the lengths of the upper loading platform and the lower loading platform in the length direction of the clamping area (11) are equal.
5. The bi-directional compression mechanical test device for the non-metallic materials according to claim 4, wherein the guide means comprises guide holes provided at both ends of the upper loading platform (2) and guide rods (3) fixedly provided at both ends of the lower loading platform (6), one end of the guide rod (3) is fixedly connected with the lower loading platform (6), and the other end thereof extends toward the upper loading platform (2) and passes through the guide holes provided on the upper loading platform (2) corresponding to the guide rods (3).
6. The bi-directional compression mechanical test device for the non-metallic materials according to claim 4, wherein the guiding device comprises a guiding frame (14) and two guiding rods (3), guiding holes for the guiding rods to pass through are respectively and correspondingly arranged at two ends of the upper loading platform (2) and the lower loading platform (6), and the guiding rods (3) respectively pass through the corresponding guiding holes on the upper loading platform (2) and the lower loading platform (6);
the two guide rods (3) are arranged in parallel, one end of each guide rod (3) is fixedly connected with one side edge of the guide frame (14), the side edge is the bottom edge of the guide frame, the other end of each guide rod is fixedly connected with the other side edge corresponding to the bottom edge of the guide frame, the side edge is the top edge of the guide frame, and the bottom edge of the guide frame is fixedly connected with the lower loading platform (6);
a channel for the upper loading platform (2) to move up and down is arranged on the top edge of the guide frame between the two guide rods (3), and the upper loading platform (2) is arranged in the channel.
7. The bi-directional compression mechanical test device for the non-metallic materials according to any one of claims 1 to 6, further comprising two loading guide plates (7), wherein the loading guide plates (7) comprise a short plate and a long plate, the short plate is fixedly connected with the long plate, and the plane of the short plate is perpendicular to the plane of the long plate;
a first loading guide hole is formed in the joint of the first loading arm (8) and the upper loading platform (2), a second loading guide hole is formed in the joint of the fourth loading arm (4) and the lower loading platform (6), after the two loading guide plates (7) are buckled with each other, one end, far away from the short plate, of the long plate of one loading guide plate (7) extends out of the first guide hole, one end, far away from the short plate, of the long plate of the other loading guide plate (7) extends out of the second guide plate, and the long plate is connected with the guide hole through which the long plate penetrates in a sliding mode;
the short plates of the two loading guide plates (7) are respectively abutted to the first loading plate and the loading plate on the fourth loading arm (4), and the clamping area (11) is positioned in a cuboid-shaped area formed by buckling the two loading plates.
8. The bi-directional compression mechanical test device for the non-metallic materials according to claim 7, wherein the connector (1) is a plate-shaped connector (1) or a truncated cone-shaped connector (1); the bottom clamping end (12) is fixedly connected with a reversing plate (13), the bottom clamping end (12) is plate-shaped, and the plane of the reversing plate (13) is perpendicular to the plane of the bottom clamping end (12).
9. A bidirectional compression mechanical test method for non-metallic materials is used for quasi-static mechanical property tests and is characterized by comprising the following steps:
step 1, connecting the bidirectional compression mechanical test device for the non-metallic material according to claim 7 with a universal material testing machine through a plate-shaped connector (1) and a bottom clamping end (12);
step 2, the two loading guide plates (7) respectively penetrate through a first loading guide hole and a second loading guide hole, bolts penetrate through the short plates and the corresponding through hole sliding grooves (10) and then are connected with nuts to realize fixation, and the bolts and the nuts are adjusted to be pre-tightened to proper positions;
step 3, enabling the guide rod (3) to penetrate through the guide hole, and ensuring that the upper clamp body and the lower clamp body are aligned with each other;
step 4, uniformly coating friction-reducing agents on the first loading arm (8), the second loading arm (5), the third loading arm (9), the fourth loading arm (4), loading arms on the loading arms, a through hole chute (10), an upper loading platform (2) and a lower loading platform (6), starting a universal material testing machine, running in a no-load mode, and judging whether powerful output is available;
step 5, when the output force is smaller than 10N, resetting the universal material testing machine, placing the prepared test piece into the clamping area (11), and placing the test piece in the middle;
step 6, operating the universal material testing machine, adjusting the distance between the upper clamp body and the lower clamp body to a proper position, and ensuring that the gravity does not directly act on the test piece;
and 7, setting loading rates according to different test conditions, carrying out biaxial compression test under a quasi-static condition, and measuring strain or deformation by using a sensor or a digital image correlation method to output a force-displacement curve.
10. A bidirectional compression mechanical test method for non-metallic materials is used for dynamic mechanical property tests and is characterized by comprising the following steps:
step 1, connecting the bidirectional compression mechanical test device for the non-metallic material according to claim 7 with a high strain rate hydraulic servo test machine through a bottom clamping end (12);
step 2, realizing the matched installation of the upper clamp body, the lower clamp body and the loading guide plate (7) on the basis of installing the connecting head (1) of the upper clamp body in a circular truncated cone shape and ensuring the parallelism of the connecting head (1) and a chuck contact surface of the high-strain-rate hydraulic servo testing machine;
step 3, the guide rod (3) penetrates through the guide hole, the upper clamp body and the lower clamp body are guaranteed to be aligned with each other, two ends of the upper clamp body are respectively connected with the top end of the guide rod at the corresponding end through a thin rope, and the influence of the gravity of the lower clamp body on materials is reduced;
step 4, uniformly coating friction-reducing drag reducers on the first loading arm (8), the second loading arm (5), the third loading arm (9), the fourth loading arm (4) and loading arms on the loading arms, the through hole chutes (10), the upper loading table (2) and the lower loading table (6);
step 5, starting the high-strain-rate hydraulic servo testing machine, reserving a section of acceleration displacement, and enabling the high-strain-rate hydraulic servo testing machine to reach a specified loading rate to realize constant strain rate loading before applying load to the test piece;
and 6, setting loading rates according to different test conditions, carrying out a biaxial compression test under a high strain rate condition, and measuring strain or deformation by a sensor or a digital image correlation method to output a force-displacement curve.
CN202110014350.3A 2021-01-06 2021-01-06 Bidirectional compression mechanical test device and method for non-metallic material Pending CN112630041A (en)

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Application Number Priority Date Filing Date Title
CN202110014350.3A CN112630041A (en) 2021-01-06 2021-01-06 Bidirectional compression mechanical test device and method for non-metallic material

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