Stretching / compression integrated test fixture

Abstract

The application discloses a tensile / compressive integrated test clamp. The clamp comprises a cross-shaped rod, a pressure head and a clamp. The cross-shaped rod comprises cross-shaped threaded rods arranged on the same plane and clamping rods fixedly and perpendicularly connected with the centers of the cross-shaped threaded rods for applying force. The ends of the cross-shaped threaded rods are detachably connected with the clamp, and the other end of the clamp is provided with a clamping part. When tension is applied, the upper and lower cross-shaped rods are both assembled with two clamps. The upper clamp is used for clamping the upper part of a tensile member, and the lower clamp is used for clamping the lower part of the tensile member. When compression is applied, the upper and lower cross-shaped rods are both assembled with four clamps, and the upper and lower clamps are staggered. A lower pressure head is arranged between the clamping parts of the clamps of the upper cross-shaped rod, and an upper pressure head is arranged between the clamping parts of the clamps of the lower cross-shaped rod. A compression test piece is arranged between the upper pressure head and the lower pressure head. The application avoids the problems of eccentricity of a traditional clamp, such as compression test piece compression deviation or test piece extrusion from a test table, and is simple to install and use.

Description

Technical Field

[0001] This invention belongs to the field of materials testing, and specifically relates to an integrated tensile / compression testing fixture. Background Technology

[0002] Currently, mechanical testing techniques for solid propellant / explosive materials under conventional conditions are quite mature. However, research on the mechanical properties of solid propellant / explosive materials under confined pressure is still incomplete. This is mainly because there are no standard experimental methods for these materials, and testing must be conducted independently through the design and development of confined pressure testing systems and related test fixtures. A major problem exists in the design of such testing systems: to achieve high confined pressure conditions, the internal structural components of the confined pressure system must be sufficiently compact to reduce volume. In small material testing machines within confined pressure systems, servo motors or stepper motors typically drive a lead screw, which in turn moves the specimen to complete the test. However, because the lead screw is located in the center of the testing system, the specimen can only be placed to the side of the lead screw. The loading direction of the lead screw and the tensile direction of the specimen are not in the same vertical line, resulting in an eccentric state. For tensile tests, this eccentricity has a relatively small impact, but for compression tests, this eccentricity can lead to uneven stress on the compressed specimen, resulting in compression bias or specimen extrusion, thus affecting the test results. Summary of the Invention

[0003] The purpose of this invention is to provide an integrated tensile / compression testing fixture for solid propellant / explosive materials.

[0004] The technical solution to achieve the purpose of this invention is: a tensile / compression integrated test fixture, comprising a cross-shaped threaded rod, an indenter, and a clamp;

[0005] The cross member includes a cross-shaped threaded rod disposed on the same plane, and a clamping rod fixedly and perpendicularly connected to the center of the cross-shaped threaded rod, the clamping rod being used to apply force;

[0006] The four ends of the cross-shaped threaded rod are detachably connected to the clamp, and the other end of the clamp is provided with a clamping part for clamping dumbbell-shaped stretching parts or for fixing the pressure head;

[0007] When the testing device is used for tension, the upper and lower cross-shaped rods are each equipped with two clamps at 180°. The upper clamp is used to clamp the upper part of the tensile member, and the lower clamp is used to clamp the lower part of the tensile member. Tension is achieved by applying tension to the clamping rod of the upper cross-shaped rod.

[0008] When the test apparatus is used for compression, both the upper and lower cross-shaped rods are equipped with four clamps, which are arranged alternately. The clamping parts of the upper cross-shaped rod are provided with a lower pressure head, and the clamping parts of the lower cross-shaped rod are provided with an upper pressure head. The compression specimen is placed between the upper and lower pressure heads, and compression is achieved by applying tension to the clamping rods of the upper cross-shaped rod.

[0009] Furthermore, each threaded rod connected to the fixture is equipped with a nut, which allows the position of the fixture on the threaded rod to be adjusted, thus enabling the fixture to be used for specimens of different sizes.

[0010] Furthermore, the fixture is shaped like a "[", and the upper surface of the clamping part at the bottom of the fixture is wedge-shaped with an arc-shaped upper surface. The tensile specimen / indenter is clamped by the arc-shaped wedge.

[0011] Furthermore, the clamping rod is assembled with a small material testing machine or a universal material testing machine or confining pressure system.

[0012] Furthermore, the upper and lower pressure heads are cylindrical in shape.

[0013] One application of the above-mentioned test fixture is for solid propellant or explosive materials.

[0014] Compared with the prior art, the significant advantages of this invention are:

[0015] (1) The tensile specimen clamp of the present invention can perform contour clamping on dumbbell-shaped specimens, that is, the width of the clamp can be changed according to the width of the specimen. This can avoid the specimen slipping off due to loose assembly between the specimen and the clamp, thus causing the test data curve to slip.

[0016] (2) Compared with traditional compression fixtures, the present invention can achieve compression test by tensile loading, which can avoid the phenomenon of uneven deformation of specimen caused by eccentricity in traditional compression test. At the same time, the surrounding fixtures can also prevent the compression specimen from being squeezed out.

[0017] (3) The present invention can realize tensile and compression tests using an integrated fixture, saving the time of fixture replacement and installation, which is extremely convenient. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the tensile assembly of the integrated test fixture of the present invention.

[0019] Figure 2 This is a schematic diagram of the integrated test fixture compression assembly of the present invention.

[0020] Explanation of reference numerals in the attached figures:

[0021] 1-Upper cross-shaped threaded rod, 2-Nut, 3-Indenter I, 4-Upper clamp, 5-Compression specimen, 6-Indenter II, 7-Lower clamp, 8-Lower cross-shaped threaded rod, 9-Tension specimen. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings.

[0023] Reference Figure 1 and Figure 2 A tensile / compression integrated testing fixture for solid propellant / explosive materials comprises a cross-shaped rod and a specimen clamp to perform tensile and compression tests. The tensile testing fixture is characterized by: a cross-shaped rod 1, and a clamp 4 assembled with the cross-shaped rod 1 to form a dumbbell-shaped specimen clamp for testing tensile specimens 9. The cross-shaped rod 1 can be fixed to a material tensile testing machine, and the clamp 4 can be pre-tightened by adjusting its position using a nut 2. The compression testing fixture is characterized by: a cross-shaped rod 1 and a clamp 4 forming a tensile dumbbell-shaped specimen clamp, and a pressure head 6 paired with the tensile dumbbell-shaped clamp to form a single compression clamp. The upper and lower pairs of compression clamps are placed crosswise, with the compression specimen placed in the middle. Tensile loading drives the pressure head 6 upwards to achieve the compression test. The cross-shaped rod 1 can be fixed to a general-purpose universal tensile testing machine or a self-made confining pressure system small material testing machine.

[0024] Compared with other devices, the biggest feature of the tensile / compression integrated testing fixture device of the present invention is that, compared with traditional compression fixtures, it can achieve compression testing through tensile loading, which can avoid the uneven deformation of the specimen caused by eccentricity in traditional compression testing. On this basis, the tensile specimen fixture of this device can also perform contour clamping on dumbbell-shaped specimens, that is, the width of the fixture can be changed according to the width of the specimen. Tensile and compression tests can be carried out with a single fixture, which is extremely simple.

[0025] Example

[0026] Before starting the tensile test, the dumbbell-shaped specimen must be placed into the fixture, such as... Figure 1 First, assemble the two clamps 4 with the two support rods of the cross-shaped frame 1, then assemble the nuts 2 to initially form a tensile test clamp. Then, place the tensile dumbbell-shaped specimen into the clamp 4. Adjust the position of the clamp 4 to make the specimen centered and in close contact with the clamp. Finally, pre-tighten the nuts 2 to lock the position of the clamp.

[0027] Before the compression test begins, the tensile dumbbell-shaped specimen must be placed into the fixture, such as... Figure 2First, assemble the four clamps 4 with the cross-shaped frame 1, then assemble the nuts 2 to initially form the compression test fixture. Place the upper and lower pairs of compression clamps crosswise, place the compression specimen 5 in the middle part, and finally place the pressure head 3 at the upper and lower ends of the specimen. Assemble the upper clamping part of the cross bar with the material testing machine. Adjust the distance between the two cross compression test fixtures by adjusting the material testing machine up and down to pre-tighten the compression specimen.

[0028] After the specimen is installed, the material testing machine can be started to perform tensile and compression tests on the material.

Claims

1. A tensile / compression integrated testing fixture, characterized in that, Includes crossbars, pressure heads, and clamps; The cross member includes a cross-shaped threaded rod disposed on the same plane, and a clamping rod fixedly and perpendicularly connected to the center of the cross-shaped threaded rod, the clamping rod being used to apply force; The four ends of the cross-shaped threaded rod are detachably connected to the clamp, and the other end of the clamp is provided with a clamping part for clamping dumbbell-shaped stretching parts or for fixing the pressure head; When the testing device is used for tension, the upper and lower cross-shaped rods are each equipped with two clamps at 180°. The upper clamp is used to clamp the upper part of the tensile member, and the lower clamp is used to clamp the lower part of the tensile member. Tension is achieved by applying tension to the clamping rod of the upper cross-shaped rod. When the test device is used for compression, both the upper and lower cross-shaped rods are equipped with four clamps, and the upper and lower clamps are arranged alternately. The clamping parts of the upper cross-shaped rod are provided with a lower pressure head, and the clamping parts of the lower cross-shaped rod are provided with an upper pressure head. The compression specimen is placed between the upper pressure head and the lower pressure head. Compression is achieved by applying tension to the clamping rod of the upper cross-shaped threaded rod. The fixture is shaped like a "[". The upper surface of the clamping part at the bottom of the fixture is wedge-shaped, and the upper surface of the wedge is arc-shaped. The tensile specimen / indenter is clamped by the arc-shaped wedge.

2. The test fixture according to claim 1, characterized in that, Each threaded rod connected to the fixture is equipped with a nut. The position of the fixture on the threaded rod is adjusted by the nut, so that the fixture can be used for specimens of different sizes.

3. The test fixture according to claim 2, characterized in that, Assembly of clamping rods and universal testing machines or confining pressure systems for small material testing machines.

4. The test fixture according to claim 3, characterized in that, The upper and lower pressure heads are cylindrical in shape.

5. The use of the test fixture according to any one of claims 1-4, characterized in that, Used in solid propellants or explosives.

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