1. The device for testing the pure shear creep performance of the energetic material comprises a test fixture kit (13), and is characterized in that the test fixture kit (13) comprises an upper fixture and a lower fixture which are connected in a matching manner, and a region enclosed by the upper fixture and the lower fixture is a test piece clamping region;

the upper clamp comprises an upper clamp body (1) and an upper clamping part (2) fixedly connected with the support frame, one end, far away from the support frame, of the upper clamping part (2) is fixedly connected with the upper clamp body (1), an upper accommodating opening used for fixing one end of a test piece is formed in the upper clamp body (1), and a test piece fixing device is arranged in the upper accommodating opening;

the lower clamp comprises a lower clamp body (3) and a lower clamping part (4), the lower clamp body (3) is connected with the upper clamp body (1) through a test piece arranged in a test piece clamping area, a lower accommodating opening used for fixing the other end of the test piece is arranged on the lower clamp body (3), the upper accommodating opening and the lower accommodating opening are positioned on the same vertical height, the upper accommodating opening and the lower accommodating opening are oppositely arranged, and a test piece fixing device is also arranged in the lower accommodating opening;

go up clamping part (2), test piece clamping area and lower clamping part (4) along vertical direction from last to corresponding setting down.

2. The device for testing the pure shear creep property of the energetic material according to claim 1, wherein the upper clamp body (1) and the lower clamp body (3) respectively comprise a connecting long arm and a connecting short arm which are horizontally arranged, and one ends of the connecting short arms are fixedly connected through a vertically arranged middle connecting arm;

the connecting long arm of the upper clamp body (1) is arranged above the connecting short arm on the upper clamp body (1), and the connecting long arm of the lower clamp body (3) is arranged below the connecting short arm of the lower clamp body (3);

the area surrounded by the long connecting arm, the short connecting arm and the middle connecting arm on the upper clamp body (1) is an upper accommodating opening, and the area surrounded by the long connecting arm, the short connecting arm and the middle connecting arm on the lower clamp body (3) is a lower accommodating opening;

the length of the long connecting arm on the upper clamp body (1) is equal to that of the long connecting arm on the lower clamp body (3), the length of the short connecting arm on the upper clamp body (1) is equal to that of the short connecting arm on the lower clamp body (3), and the length of the short connecting arm is smaller than half of that of the long connecting arm.

3. The device for testing the pure shear creep performance of the energetic material according to claim 2, wherein the length of the middle connecting arm on the upper clamp body (1) is equal to that of the middle connecting arm on the lower clamp body (3);

when one end of the test piece is fixedly arranged in the upper accommodating opening and the other end of the test piece is fixedly arranged in the lower accommodating opening, the connecting short arm of the upper clamp body (1) is abutted against the connecting long arm of the lower clamp body (3), and the connecting short arm of the lower clamp body (3) is abutted against the connecting long arm of the upper clamp body (1).

4. The device for testing the pure shear creep property of an energetic material according to claim 2, wherein the test piece fixing device comprises a jacking bolt, the jacking bolt connected with the upper clamp body (1) is an upper jacking bolt (5), and the jacking bolt connected with the lower clamp body (3) is a lower jacking bolt (6);

go up tight bolt (5) and pass behind the connection long arm of last anchor clamps body (1) and stretch into and hold the opening in and offset with the test piece, down tight bolt (6) passes behind the connection long arm of lower anchor clamps body (3) and stretch into down hold the opening in and offset with the test piece, go up tight bolt (5) and the connection long arm screw thread of last anchor clamps body (1) link to each other, down tight bolt (6) and the connection long arm screw thread of lower anchor clamps body (3) link to each other.

5. The device for testing the pure shear creep performance of an energetic material according to claim 4, wherein the test piece fixing device further comprises an adjusting clamp block, the adjusting clamp block arranged in the upper accommodating opening is an upper adjusting clamp block (7), and the adjusting clamp block arranged in the lower accommodating opening is a lower adjusting clamp block (8);

the upper adjusting clamping block (7) is arranged between the upper puller bolt (5) and the test piece, and the lower adjusting clamping block (8) is arranged between the lower puller bolt (6) and the test piece.

6. The device for testing the pure shear creep property of the energetic material according to claim 4, further comprising a positioning plate (9), wherein the connecting long arm of the lower clamp body (3) is provided with a V-shaped groove, the positioning plate (9) is vertically arranged, and the vertically downward end of the positioning plate (9) is clamped in the V-shaped groove on the connecting long arm of the lower clamp body (3);

the test piece is a plate-shaped test piece (101) and comprises a left clamping part (19) and a right clamping part, the left clamping part (19) and the right clamping part are respectively connected with a gauge length part (21) through a trapezoidal deformation part (20), the width of the gauge length part (21) is smaller than that of the left clamping part (19) or the right clamping part, and the two trapezoidal deformation parts (20) and the gauge length part (21) form V-shaped grooves on two side faces of the test piece;

when left clamping part (19) set up in last holding opening, right clamping part sets up when holding opening down, V-arrangement recess on the connection long arm of lower anchor clamps body (3) is corresponding with the V-arrangement recess position on the test piece, the vertical decurrent one end block of locating plate (9) is in the V-arrangement recess on the connection long arm of lower anchor clamps body (3), the other end block is in the V-arrangement recess on the test piece orientation connection long arm of lower anchor clamps body (3), and a terminal surface of locating plate (9) offsets with the terminal surface of the connection short arm on the last anchor clamps body (1).

7. The device for testing the pure shear creep performance of the energetic material according to claim 2, wherein the connecting long arm of the lower clamp body (3) is provided with a loading device;

the loading device is a weight (10), a hook is arranged on the upper end face of the weight (10), and the weight (10) is connected with the lower clamp body (3) through the hook and a lifting ring (11) arranged on a connecting long arm of the lower clamp body (3);

a pin hole is formed in the middle of the connecting long arm of the lower clamp body (3), the hanging ring (11) is connected with the connecting long arm of the lower clamp body (3) through a pin shaft matched with the pin hole, and the symmetrical center plane of the V-shaped groove and the vertical plane of the central axis of the pin shaft are located in the same plane;

still including the laser range finder who is used for measuring the deformation volume, fixedly connected with transmitting head (12) on the laser range finder, transmitting head (12) are connected with the laser range finder electricity, and the laser range finder is fixed to be set up in weight (10) bottom, and transmitting head (12) are stretched out towards the direction of keeping away from weight (10) in vertical direction.

8. The device for testing the pure shear creep property of the energetic material according to claim 6, wherein the upper clamping part (2) is an upper clamping plate, the lower clamping part (4) is a lower clamping plate, the upper clamping plate is integrally formed with the connecting long arm on the upper clamp body (1), and the lower clamping plate is fixedly connected with the connecting long arm on the lower clamp body (3) through a bolt.

9. The device for testing the pure shear creep property of the energetic material according to claim 7, further comprising a support frame, wherein a plurality of test fixture kits (13) are arranged on the support frame, the support frame comprises a horizontally arranged fixture hoisting crossbeam (14), two ends of the fixture hoisting crossbeam (14) are fixedly connected with mounting sleeves (15), internal threads are arranged in the mounting sleeves (15), the mounting sleeves (15) are connected with tripod bases (17) through telescopic support rods (16), and the telescopic support rods (16) are in threaded connection with the mounting sleeves (15);

the upper clamping part (2) on the test fixture suite (13) is connected with the fixture hoisting beam (14) through a connecting pin (18).

10. A method for testing the pure shear creep property of an energetic material is characterized by comprising a shear strength test method of the energetic material under quasi-static pure shear loading and a creep deformation and accumulated damage test method of the energetic material under pure shear loading;

the shear strength test method of the energetic material under the quasi-static pure shear loading comprises the following steps:

step (1): processing a plate-shaped test piece (101) suitable for a mechanical performance test under pure shear loading of an energetic material;

step (2): arranging one end of a plate-shaped test piece (101) in an upper accommodating opening of the device for testing the pure shear creep property of the energetic material according to claim 1, arranging the other end of the plate-shaped test piece in a lower accommodating opening, and fixing the plate-shaped test piece (101) by using a test piece fixing device;

and (3): an upper clamping part (2) of an upper clamp and a lower clamping part (4) of a lower clamp are respectively connected with an upper clamping end (102) and a lower clamping end (103) of a quasi-static material testing machine, and a device for testing the pure shear creep property of an energetic material for clamping a plate-shaped test piece (101) is arranged in a temperature and humidity box (104);

and (4): debugging the position of a temperature and humidity box (104) equipped with the quasi-static material testing machine and the positions of an upper clamping end (102) and a lower clamping end (103) equipped with the quasi-static material testing machine to ensure that the positions of the upper clamping end (102) and the lower clamping end (103) of the quasi-static material testing machine are positioned in the middle area of the temperature and humidity box (104);

and (5): an upper clamping end (102) and a lower clamping end (103) of a quasi-static material testing machine are respectively connected with an upper clamping part (2) and a lower clamping part (4) of a device for testing the pure shear creep performance of an energetic material in the vertical direction, then, one end of a plate-shaped test piece (101) is fixedly arranged in a lower accommodating opening through a test piece fixing device, and the other end of the plate-shaped test piece is fixedly arranged in an upper accommodating opening through the test piece fixing device;

and (6): setting the temperature and humidity in a temperature and humidity box (104) according to the storage environment and the use working condition of the explosive columns processed and manufactured by energetic materials;

and (7): setting the loading rate of the quasi-static material testing machine according to the corresponding strain rate range when the energetic material is subjected to creep deformation;

and (8): based on a test system and control software of a quasi-static material testing machine with assembled plate-shaped test pieces (101), mechanical property tests of the energetic material under quasi-static pure shear loading under preset temperature and humidity conditions and loading rate conditions are carried out until the plate-shaped test pieces (101) are completely broken, the load and displacement conditions of the energetic material during deformation are recorded and converted into a pure shear stress-strain curve of the material, and the maximum shear stress under corresponding test working conditions is directly determined from the curveI.e. shear strength;

the creep deformation and accumulated damage testing method of the energetic material under the pure shear loading comprises the following steps:

step (1): processing a plate-shaped test piece (101) suitable for testing the pure shear creep deformation and the accumulated damage of the energetic material;

step (2): processing the device for testing the pure shear creep performance of the energetic material, which is suitable for the long-term pure shear creep performance test of the energetic material, according to the method of claim 9;

and (3): dismantling a lower clamping part (4) of a lower clamp, connecting test clamp kits (13) meeting the test requirement quantity with a clamp hoisting beam (14), installing plate-shaped test pieces (101) in the test clamp kits (13), arranging one ends of the plate-shaped test pieces (101) in an upper accommodating opening and the other ends of the plate-shaped test pieces (101) in a lower accommodating opening correspondingly when the plate-shaped test pieces (101) are installed, and fixing the plate-shaped test pieces (101) by using a test piece fixing device;

and (4): according to the estimated deformation of a plate-shaped test piece (101) in the vertical direction under the pure shear creep test stress level, adjusting the position of a device which is clamped with the plate-shaped test piece and used for testing the pure shear creep performance of the energetic material in the vertical direction, and fastening and fixing;

and (5): placing a device for testing the pure shear creep property of the energetic material of the assembled plate-shaped test piece (101) in a constant temperature and humidity box;

the sum of the estimated deformation of a plate-shaped test piece (101) in the vertical direction under a set stress level, the height of a loading device on a device for testing the pure shear creep property of an energetic material and the height of a deformation measuring component is less than the height of a working area in a constant temperature and humidity box;

and (6): setting the temperature and humidity of a working area of a constant temperature and humidity box according to the storage environment and the use working condition of the explosive columns processed and manufactured by energetic materials;

and (7): the shear strength obtained by the shear strength testing method of the energetic material under the quasi-static pure shear loadingDetermining the stress level for testing the creep performance of the energetic material under pure shear loading;

then adjusting the load of the loading device according to the stress level of the determined creep property;

and (8): starting the test, and moving and deforming the plate-shaped test piece (101) downwards along the vertical direction;

the method comprises the following steps that when a plate-shaped test piece (101) moves downwards along the vertical direction, a laser range finder emitting head (12) used for measuring deformation quantity on a device for testing the pure shear creep property of an energy-containing material starts to work until the plate-shaped test piece (101) is broken, and the distance between the emitting head (12) and the bottom of a working area in a constant temperature and humidity box and the time are recorded in real time;

and (9): calculating the change relation of the deformation of the plate-shaped test piece (101) along with the time based on the recorded distance and time;

step (10): calculating a stress level based on the time-varying relation of the deformationShear creep strain underChange over time t, and creep rateCreep complianceCreep rupture timeAnd cumulative damage amount D;

the cumulative damage amount calculation expression is:

wherein: d is the cumulative damage amount;andrespectively constant pure shear stress and corresponding time to break or creep life; n is the Leeberg stress norm, i.e. the level of shear creep stress required for the material to generate pure shear creep failure in unit time;for a linear cumulative damage index, when the cumulative damage amount D =1, the corresponding time is the pure shear creep rupture or failure time, i.e., t =。

Background

The mechanical properties of energetic materials such as solid propellant, explosive and the like have obvious time and temperature dependence, namely, the energetic materials present thermal viscous elastic properties and are influenced by factors such as stress, strain state, environmental humidity and the like, and the creep property is one of two main properties for revealing the viscoelastic properties of the materials. Under the storage working condition, the rocket engine grain made of energetic materials such as solid propellant, explosive and the like can sink due to self weight, and accordingly, the shear load action is exerted on the energetic materials such as the solid propellant, the explosive and the like, namely, the shear creep property of the materials under the long-term action of constant shear load needs to be researched. The research of the performance needs to adopt a proper test device and a proper test method to develop a shear creep performance test, and on the basis of test results, the change of parameters such as creep curve characteristics, creep rate, creep compliance, creep rupture time, accumulated damage and the like is calculated and analyzed, finally, the change rule of the creep deformation behavior of the material under the action of shear load along with factors such as shear stress level, temperature, humidity and the like is disclosed, and a corresponding constitutive relation is established for structural integrity analysis.

At present, creep performance test researches on metal materials or a few non-metal materials such as plastics, rubber, asphalt and the like are abundant, a certain amount of test standards are formed, researches on creep performance test methods of energetic materials such as solid propellants and explosives are lacked, and corresponding national standards and industrial standards are almost blank. And the creep performance test that has developed uses unipolar tensile creep test and unipolar compression creep test as the main, and testing arrangement adopts the conventional creep testing machine of selling in the market more, also less consideration temperature and humidity control measure in the testing process usually. For non-metallic materials such as asphalt and adhesives, a few researchers have proposed some new shear creep test devices and test methods, such as the one published by the national intellectual property office under the name of application No. 201710843470.8: an explosive shear test system and test method, having application number 201620904813.8 and title: a tensile shear creep test apparatus having application number 201310078762.9 entitled: asphalt rotation shear creep and repeated creep recovery test device and method, application number 201110052024.8, name are: a test method for testing dynamic shear creep property of asphalt mixture. Besides the incomplete matching with the pure shear loading stress state, the research method also has the requirement that the test method is difficult to be applied to the shear creep property test of energetic materials such as solid propellant, explosive and the like. The method is mainly embodied in the following points: firstly, the modulus and strength of energetic materials such as solid propellant, explosive and the like are small, and the creep testing machine sold in the market at present is difficult to realize continuous and reliable work under long-time loading and small-stress level loading; secondly, a specially-made clamp is needed for carrying out mechanical property tests of energetic materials such as solid propellant, explosive and the like, and the clamp cannot be matched with devices such as a testing machine and the like in a punching or clamping mode like non-metallic materials such as metal materials, rubber and the like; thirdly, the influence effect of the temperature and the humidity on energetic materials such as solid propellant, explosive and the like is far greater than that of nonmetal materials such as metal materials, rubber and the like, so an effective temperature and humidity control method is required in the test process; fourthly, the method of extensometer deformation is adopted, so that extra local deformation is easily brought to low-strength energetic materials such as solid propellant, explosive and the like during long-term loading, the testing precision is influenced, and even the materials are damaged in advance.

In summary, a test device and a test method for effectively testing the pure shear creep performance of energetic materials such as solid propellant, explosive and the like are lacked at present, and the performance under the loading condition has important significance for establishing constitutive relation, further analyzing the structural integrity of structures such as corresponding explosive columns and the like under the storage working condition and finally evaluating the use reliability of the solid rocket engine.

Disclosure of Invention

Aiming at the defect that a mature and feasible creep property test device and a test method for energetic materials with viscoelastic properties such as solid propellants and explosives are lacked in the prior art, the invention aims to provide the test method and the test device for testing the pure shear creep property of the energetic materials, which are used for breaking through the defects existing in the current research, improving the knowledge on the viscoelastic properties of the energetic materials such as the solid propellants and the explosives, and providing data support for further establishing constitutive relation and evaluating the structural integrity of explosive columns and the like manufactured by the materials under the storage working condition. The core of the invention relates to the design of a test piece, the design of a test fixture, the design of a test device, the construction of a test system and the proposal of a corresponding test method.

The invention relates to a device for testing the pure shear creep property of an energetic material, which comprises a test fixture kit, wherein the test fixture kit comprises an upper fixture and a lower fixture which are connected in a matching manner, and a region surrounded by the upper fixture and the lower fixture is a test piece clamping region;

the upper clamp comprises an upper clamp body and an upper clamping part fixedly connected with the support frame, one end of the upper clamping part, which is far away from the support frame, is fixedly connected with the upper clamp body, an upper accommodating opening for fixing one end of a test piece is arranged on the upper clamp body, and a test piece fixing device is arranged in the upper accommodating opening;

the lower clamp comprises a lower clamp body and a lower clamping part, the lower clamp body is connected with the upper clamp body through a test piece arranged in a test piece clamping area, a lower accommodating opening used for fixing the other end of the test piece is arranged on the lower clamp body, the upper accommodating opening and the lower accommodating opening are positioned at the same vertical height, the upper accommodating opening and the lower accommodating opening are oppositely arranged, and a test piece fixing device is also arranged in the lower accommodating opening;

go up clamping part, test piece clamping area and lower clamping part along vertical direction from last to corresponding setting down.

Preferably, the upper clamp body and the lower clamp body both comprise a connecting long arm and a connecting short arm which are horizontally arranged, and one end of the connecting short arm is fixedly connected through a vertically arranged middle connecting arm;

the connecting long arm of the upper clamp body is arranged above the connecting short arm on the upper clamp body, and the connecting long arm of the lower clamp body is arranged below the connecting short arm of the lower clamp body;

the area enclosed by the long connecting arm, the short connecting arm and the middle connecting arm on the upper clamp body is an upper accommodating opening, and the area enclosed by the long connecting arm, the short connecting arm and the middle connecting arm on the lower clamp body is a lower accommodating opening;

the length of the connecting long arm on the upper clamp body is equal to that of the connecting long arm on the lower clamp body, the length of the connecting short arm on the upper clamp body is equal to that of the connecting short arm on the lower clamp body, and the length of the connecting short arm is smaller than half of that of the connecting long arm.

Preferably, the middle connecting arms on the upper clamp body and the middle connecting arms on the lower clamp body are equal in length;

when one end of the test piece is fixedly arranged in the upper accommodating opening and the other end of the test piece is fixedly arranged in the lower accommodating opening, the connecting short arm of the upper clamp body abuts against the connecting long arm of the lower clamp body, and the connecting short arm of the lower clamp body abuts against the connecting long arm of the upper clamp body.

Preferably, the test piece fixing device comprises a jacking bolt, the jacking bolt connected with the upper clamp body is an upper jacking bolt, and the jacking bolt connected with the lower clamp body is a lower jacking bolt;

the upper puller bolt penetrates through the connecting long arm of the upper clamp body and extends into the upper accommodating opening to be abutted against the test piece, the lower puller bolt penetrates through the connecting long arm of the lower clamp body and extends into the lower accommodating opening to be abutted against the test piece, the upper puller bolt is in threaded connection with the connecting long arm of the upper clamp body, and the lower puller bolt is in threaded connection with the connecting long arm of the lower clamp body.

Preferably, the test piece fixing device further comprises an adjusting clamping block, the adjusting clamping block arranged in the upper accommodating opening is an upper adjusting clamping block, and the adjusting clamping block arranged in the lower accommodating opening is a lower adjusting clamping block;

the upper adjusting clamping block is arranged between the upper puller bolt and the test piece, and the lower adjusting clamping block is arranged between the lower puller bolt and the test piece.

Preferably, the clamp further comprises a positioning plate, a V-shaped groove is formed in the connecting long arm of the lower clamp body, the positioning plate is vertically arranged, and the vertically downward end of the positioning plate is clamped in the V-shaped groove in the connecting long arm of the lower clamp body;

the test piece is a plate-shaped test piece, the test piece comprises a left clamping part and a right clamping part, the left clamping part and the right clamping part are respectively connected with a gauge length part through a trapezoidal deformation part, the width of the gauge length part is smaller than that of the left clamping part or the right clamping part, and the two trapezoidal deformation parts and the gauge length part form V-shaped grooves on two side faces of the test piece;

when the left clamping part is arranged in the upper holding opening, the right clamping part is arranged in the lower holding opening, the V-shaped groove on the connecting long arm of the lower clamp body corresponds to the V-shaped groove on the test piece in position, the vertical downward one end of the positioning plate is clamped in the V-shaped groove on the connecting long arm of the lower clamp body, the other end of the positioning plate is clamped in the V-shaped groove on one face of the connecting long arm of the lower clamp body, facing the test piece, and one end face of the positioning plate is abutted to the end face of the connecting short arm on the upper clamp body.

Preferably, a loading device is arranged on the connecting long arm of the lower clamp body;

the loading device is a weight, a hook is arranged on the upper end surface of the weight, and the weight is connected with the lower clamp body through the hook and a lifting ring arranged on a connecting long arm of the lower clamp body;

a pin hole is formed in the middle of the connecting long arm of the lower clamp body, the hanging ring is connected with the connecting long arm of the lower clamp body through a pin shaft matched with the pin hole, and the symmetrical center plane of the V-shaped groove and the vertical plane of the central axis of the pin shaft are located in the same plane;

still including the laser range finder who is used for measuring the deformation volume, fixedly connected with transmitting head on the laser range finder, transmitting head is connected with the laser range finder electricity, and the fixed setting of laser range finder is in the weight bottom, and the transmitting head stretches out towards the direction of keeping away from the weight in vertical orientation.

Preferably, the upper clamping part is an upper clamping plate, the lower clamping part is a lower clamping plate, the upper clamping plate and the connecting long arm on the upper clamp body are integrally formed, and the lower clamping plate is fixedly connected with the connecting long arm on the lower clamp body through a bolt.

Preferably, the test fixture comprises a support frame, a plurality of test fixture kits are arranged on the support frame, the support frame comprises a fixture hoisting beam which is horizontally arranged, two ends of the fixture hoisting beam are fixedly connected with mounting sleeves, internal threads are arranged in the mounting sleeves, the mounting sleeves are connected with tripod bases through telescopic support rods, and the telescopic support rods are in threaded connection with the mounting sleeves;

and the upper clamping part on the test fixture suite is connected with the fixture hoisting crossbeam through a connecting pin.

A method for testing the pure shear creep property of an energetic material comprises a shear strength test method of the energetic material under quasi-static pure shear loading and a creep deformation and accumulated damage test method of the energetic material under pure shear loading;

the shear strength test method of the energetic material under the quasi-static pure shear loading comprises the following steps:

step (1): processing a plate-shaped test piece suitable for a mechanical property test under pure shear loading of an energetic material;

step (2): arranging one end of a plate-shaped test piece in an upper accommodating opening of a device for testing the pure shear creep property of the energetic material, arranging the other end of the plate-shaped test piece in a lower accommodating opening, and fixing the plate-shaped test piece by using a test piece fixing device;

and (3): respectively connecting an upper clamping part of an upper clamp and a lower clamping part of a lower clamp with an upper clamping end and a lower clamping end of a quasi-static material testing machine, and arranging a device for testing the pure shear creep property of an energetic material for clamping a plate-shaped test piece in a temperature and humidity box;

and (4): debugging the positions of a temperature and humidity box equipped by a quasi-static material testing machine and the positions of an upper clamping end and a lower clamping end equipped by the quasi-static material testing machine to enable the positions of the upper clamping end and the lower clamping end of the quasi-static material testing machine to be in the middle area of the temperature and humidity box;

and (5): connecting an upper clamping end and a lower clamping end of a quasi-static material testing machine with an upper clamping part and a lower clamping part of a device for testing the pure shear creep property of an energetic material respectively in the vertical direction, then fixedly arranging one end of a plate-shaped test piece in a lower accommodating opening through a test piece fixing device, and fixedly arranging the other end of the plate-shaped test piece in an upper accommodating opening through a test piece fixing device;

and (6): setting the temperature and humidity in the temperature and humidity box according to the storage environment and the use working condition of the explosive columns processed and manufactured by the energetic materials;

and (7): setting the loading rate of the quasi-static material testing machine according to the corresponding strain rate range when the energetic material is subjected to creep deformation;

and (8): based on a test system and control software of a quasi-static material testing machine with assembled plate-shaped test pieces, a mechanical property test of the energetic material under quasi-static pure shear loading under preset temperature and humidity conditions and loading rate conditions is carried out until the plate-shaped test pieces are completely broken, the load and displacement conditions of the energetic material during deformation are recorded and converted into a pure shear stress-strain curve of the material, and the maximum shear stress under corresponding test working conditions is directly determined from the curveI.e. shear strength;

the creep deformation and accumulated damage testing method of the energetic material under the pure shear loading comprises the following steps:

step (1): processing a plate-shaped test piece suitable for testing pure shear creep deformation and accumulated damage of an energetic material;

step (2): processing a device for testing the pure shear creep property of the energetic material, which is suitable for a multi-test-piece long-time pure shear creep property test of the energetic material;

and (3): removing the lower clamping part of the lower clamp, connecting the test clamp kits meeting the test requirement quantity with the clamp hoisting beam, mounting a plate-shaped test piece in the test clamp kits, arranging one end of the plate-shaped test piece in the upper accommodating opening and the other end of the plate-shaped test piece in the lower accommodating opening correspondingly when the plate-shaped test piece is mounted, and fixing the plate-shaped test piece by using a test piece fixing device;

and (4): adjusting the position of a device for testing the pure shear creep performance of the energetic material clamped with the plate-shaped test piece in the vertical direction according to the estimated deformation of the plate-shaped test piece in the vertical direction under the pure shear creep test stress level, and fastening and fixing;

and (5): placing a device for testing the pure shear creep property of the energetic material with the plate-shaped test piece assembled in a constant temperature and humidity box;

the sum of the estimated deformation of a plate-shaped test piece in the vertical direction under a set stress level, the height of a loading device on a device for testing the pure shear creep property of an energetic material and the height of a deformation measuring part is less than the height of a working area in a constant temperature and humidity box;

and (6): setting the temperature and humidity of a working area of a constant temperature and humidity box according to the storage environment and the use working condition of the explosive columns processed and manufactured by energetic materials;

and (7): the shear strength obtained by the shear strength testing method of the energetic material under the quasi-static pure shear loadingDetermining the stress level for testing the creep performance of the energetic material under pure shear loading;

then adjusting the load of the loading device according to the stress level of the determined creep property;

and (8): starting the test, and moving the plate-shaped test piece downwards along the vertical direction to deform;

the method comprises the following steps that when a plate-shaped test piece moves downwards along the vertical direction, a laser range finder emitting head used for measuring deformation quantity on a device for testing the pure shear creep property of an energy-containing material starts to work until the plate-shaped test piece is broken, and the distance between the emitting head and the bottom of a working area in a constant temperature and humidity box and the time are recorded in real time;

and (9): calculating the change relation of the deformation of the plate-shaped test piece along with the time based on the recorded distance and time;

step (10): calculating a stress level based on the time-varying relation of the deformationShear creep strain underChange over time t, and creep rateCreep complianceCreep rupture timeAnd cumulative damage amount D;

the cumulative damage amount calculation expression is:

wherein: d is the cumulative damage amount;andrespectively constant pure shear stress and corresponding time to break or creep life; n is the Leeberg stress norm, i.e. the level of shear creep stress required for the material to generate pure shear creep failure in unit time;for a linear cumulative damage index, when the cumulative damage amount D =1, the corresponding time is the pure shear creep rupture or failure time, i.e., t =。

Compared with the prior art, the invention has the following beneficial effects:

1. the device disclosed by the invention is simple in configuration and structure, simple and easy to implement in testing method, strong in universality, capable of realizing the tests of the shear strength and the creep property of various energetic materials such as solid propellant, explosive and the like under pure shear loading, breaking through the limitation of the existing testing method for the pure shear creep property of the energetic materials, and capable of meeting the requirements of long-term stable and reliable tests.

2. The stress level of the pure shear creep performance test is determined based on the shear strength obtained by the pure shear test, the range from low to high can be covered more accurately by setting the stress level, the creep performance of energetic materials such as solid propellant, explosive and the like under different pure shear stress levels can be more comprehensively disclosed, and the pertinence of developing the creep test is improved.

3. According to the device, the test piece is compressed by adjusting the clamping block, so that the problems of phenomena such as stress concentration and the like caused by punching on the test piece and directly clamping the test piece are avoided, additional damage caused by fixing the test piece is reduced, and the reliability of a test result is improved; in addition, the upper clamp is supported in the vertical direction through the lower clamp, so that extra damage to a test piece caused by the gravity of the upper clamp before the test is avoided, and the reliability of a test result is further improved.

4. The device can simultaneously meet the test of a plurality of plate-shaped test pieces, can reduce the error of test results by an averaging method under the same test condition, obviously shortens the test period, greatly improves the test efficiency, and obviously reduces the test cost and the time cost.

5. Compared with the traditional methods such as an extensometer, a scale and the like, the method can ensure real-time monitoring, improve the testing precision, is simpler and more convenient, and can avoid direct contact between a deformation measuring device and the test piece, namely reduce the introduction of initial damage to the test piece.

6. The height of the clamp hoisting beam is adjusted through the telescopic base supporting rod, so that the creep deformation testing of energetic materials such as solid propellant, explosive and the like can be met when the stress levels are different, the device is suitable for the heights of working areas of different constant temperature and humidity boxes, namely, the temperature and humidity in the testing process can be fully controlled, and the reliability of the testing result can be improved.

7. The device can ensure that a pure shear creep stress load is constantly applied to the test piece in the test process under the action of gravity.

Drawings

FIG. 1 is a schematic structural diagram of an apparatus for testing pure shear creep performance of an energetic material in a multi-specimen long-time pure shear creep performance test according to the present invention.

FIG. 2 is a schematic structural view of a plate-like test piece.

Fig. 3 is a schematic structural diagram of a test system for shear strength test of an energetic material under quasi-static pure shear loading according to an embodiment of the present invention.

FIG. 4 is a drawing 25 of an embodiment of the present invention^oC. The shear stress-strain curve of the three-component hydroxyl-terminated polybutadiene composite solid propellant under the pure shear loading of 40% humidity and 2 mm/min.

Reference numerals: 1-upper clamp body, 2-upper clamp body, 3-lower clamp body, 4-lower clamp body, 5-upper puller bolt, 6-lower puller bolt, 7-upper adjusting clamp block, 8-lower adjusting clamp block, 9-positioning plate, 10-weight, 11-lifting ring, 12-launching head, 13-test clamp suite, 14-clamp hoisting beam, 15-mounting sleeve, 16-telescopic supporting rod, 17-tripod base, 18-connecting pin, 19-left clamp body, 20-trapezoidal deformation part, 21-scale distance part, 101-plate-shaped test piece, 102-upper clamp body, 103-lower clamp body, and 104-temperature and humidity box.

Detailed Description

The invention relates to a device for testing the pure shear creep property of an energetic material, which comprises a test fixture kit 13, wherein the test fixture kit 13 comprises an upper fixture and a lower fixture which are connected in a matching manner, and a region surrounded by the upper fixture and the lower fixture is a test piece clamping region;

the upper clamp comprises an upper clamp body 1 and an upper clamping part 2 fixedly connected with the support frame, one end, far away from the support frame, of the upper clamping part 2 is fixedly connected with the upper clamp body 1, an upper accommodating opening used for fixing one end of a test piece is formed in the upper clamp body 1, and a test piece fixing device is arranged in the upper accommodating opening;

the lower clamp comprises a lower clamp body 3 and a lower clamping part 4, the lower clamp body 3 is connected with the upper clamp body 1 through a test piece arranged in a test piece clamping area, a lower accommodating opening used for fixing the other end of the test piece is arranged on the lower clamp body 3, the upper accommodating opening and the lower accommodating opening are positioned at the same vertical height, the upper accommodating opening and the lower accommodating opening are oppositely arranged, and a test piece fixing device is also arranged in the lower accommodating opening;

go up clamping part 2, test piece clamping area and lower clamping part 4 along vertical direction from last to corresponding setting down.

The upper clamp body 1 and the lower clamp body 3 respectively comprise a connecting long arm and a connecting short arm which are horizontally arranged, and one end of each connecting short arm is fixedly connected through a vertically arranged middle connecting arm;

the connecting long arm of the upper clamp body 1 is arranged above the connecting short arm on the upper clamp body 1, and the connecting long arm of the lower clamp body 3 is arranged below the connecting short arm of the lower clamp body 3;

the area surrounded by the long connecting arm, the short connecting arm and the middle connecting arm on the upper clamp body 1 is an upper accommodating opening, and the area surrounded by the long connecting arm, the short connecting arm and the middle connecting arm on the lower clamp body 3 is a lower accommodating opening;

the length of the long connecting arm on the upper clamp body 1 is equal to that of the long connecting arm on the lower clamp body 3, the length of the short connecting arm on the upper clamp body 1 is equal to that of the short connecting arm on the lower clamp body 3, and the length of the short connecting arm is smaller than half of that of the long connecting arm.

The length of the middle connecting arm on the upper clamp body 1 is equal to that of the middle connecting arm on the lower clamp body 3;

when one end of the test piece is fixedly arranged in the upper accommodating opening and the other end of the test piece is fixedly arranged in the lower accommodating opening, the connecting short arm of the upper clamp body 1 abuts against the connecting long arm of the lower clamp body 3, and the connecting short arm of the lower clamp body 3 abuts against the connecting long arm of the upper clamp body 1.

The test piece fixing device comprises a puller bolt, the puller bolt connected with the upper clamp body 1 is an upper puller bolt 5, and the puller bolt connected with the lower clamp body 3 is a lower puller bolt 6;

the upper puller bolt 5 penetrates through the connecting long arm of the upper clamp body 1 and extends into the upper accommodating opening to be abutted against a test piece, the lower puller bolt 6 penetrates through the connecting long arm of the lower clamp body 3 and extends into the lower accommodating opening to be abutted against the test piece, the upper puller bolt 5 is in threaded connection with the connecting long arm of the upper clamp body 1, and the lower puller bolt 6 is in threaded connection with the connecting long arm of the lower clamp body 3.

The test piece fixing device also comprises an adjusting clamping block, wherein the adjusting clamping block arranged in the upper accommodating opening is an upper adjusting clamping block 7, and the adjusting clamping block arranged in the lower accommodating opening is a lower adjusting clamping block 8;

the upper adjusting clamping block 7 is arranged between the upper puller bolt 5 and a test piece, and the lower adjusting clamping block 8 is arranged between the lower puller bolt 6 and the test piece.

The clamp is characterized by further comprising a positioning plate 9, a V-shaped groove is formed in the connecting long arm of the lower clamp body 3, the positioning plate 9 is vertically arranged, and the vertically downward end of the positioning plate 9 is clamped in the V-shaped groove in the connecting long arm of the lower clamp body 3;

the test piece is a plate-shaped test piece 101, the test piece comprises a left clamping part 19 and a right clamping part, the left clamping part 19 and the right clamping part are respectively connected with a gauge length part 21 through a trapezoidal deformation part 20, the width of the gauge length part 21 is smaller than that of the left clamping part 19 or the right clamping part, and two trapezoidal deformation parts 20 and the gauge length part 21 form V-shaped grooves on two side surfaces of the test piece;

when the left clamping part 19 is arranged in the upper accommodating opening, the right clamping part is arranged in the lower accommodating opening, the V-shaped groove on the connecting long arm of the lower clamp body 3 corresponds to the V-shaped groove on the test piece in position, the vertical downward one end of the positioning plate 9 is clamped in the V-shaped groove on the connecting long arm of the lower clamp body 3, the other end of the positioning plate is clamped in the V-shaped groove on one surface of the connecting long arm of the lower clamp body 3, facing the test piece, and one end surface of the positioning plate 9 is abutted to the end surface of the connecting short arm on the upper clamp body 1.

A loading device is arranged on the connecting long arm of the lower clamp body 3;

the loading device is a weight 10, a hook is arranged on the upper end face of the weight 10, and the weight 10 is connected with the lower clamp body 3 through the hook and a hanging ring 11 arranged on a connecting long arm of the lower clamp body 3;

a pin hole is formed in the middle of the connecting long arm of the lower clamp body 3, the hanging ring 11 is connected with the connecting long arm of the lower clamp body 3 through a pin shaft matched with the pin hole, and the symmetrical center plane of the V-shaped groove and the vertical plane of the central axis of the pin shaft are located in the same plane;

still including the laser range finder who is used for measuring the deformation volume, fixedly connected with emission head 12 on the laser range finder, emission head 12 is connected with the laser range finder electricity, and the fixed setting of laser range finder is in weight 10 bottoms, and the orientation of keeping away from weight 10 of emission head 12 on vertical orientation stretches out.

Go up clamping part 2 and be last grip block, lower clamping part 4 is lower grip block, go up the long arm integrated into one piece of being connected on grip block and the last anchor clamps body 1, the long arm of being connected on lower grip block and the lower anchor clamps body 3 passes through the bolt fastening and links to each other.

The testing fixture comprises a supporting frame, wherein a plurality of testing fixture kits 13 are arranged on the supporting frame, the supporting frame comprises a fixture hoisting beam 14 which is horizontally arranged, two ends of the fixture hoisting beam 14 are fixedly connected with mounting sleeves 15, internal threads are arranged in the mounting sleeves 15, the mounting sleeves 15 are connected with a tripod base 17 through telescopic supporting rods 16, and the telescopic supporting rods 16 are in threaded connection with the mounting sleeves 15;

the upper clamping part 2 on the test fixture suite 13 is connected with the fixture hoisting beam 14 through a connecting pin 18.

A method for testing the pure shear creep property of an energetic material comprises a shear strength test method of the energetic material under quasi-static pure shear loading and a creep deformation and accumulated damage test method of the energetic material under pure shear loading;

the shear strength test method of the energetic material under the quasi-static pure shear loading comprises the following steps:

step (1): processing a plate-shaped test piece 101 suitable for a mechanical performance test under pure shear loading of an energetic material;

step (2): arranging one end of a plate-shaped test piece 101 in an upper accommodating opening of a device for testing the pure shear creep property of an energetic material, arranging the other end of the plate-shaped test piece 101 in a lower accommodating opening, and fixing the plate-shaped test piece 101 by using a test piece fixing device;

and (3): an upper clamping part 2 of an upper clamp and a lower clamping part 4 of a lower clamp are respectively connected with an upper clamping end 102 and a lower clamping end 103 of a quasi-static material testing machine, and a device for testing the pure shear creep performance of an energetic material for clamping a plate-shaped test piece 101 is arranged in a temperature and humidity box 104;

and (4): debugging the position of a temperature and humidity box 104 equipped with the quasi-static material testing machine and the positions of an upper clamping end 102 and a lower clamping end 103 equipped with the quasi-static material testing machine, so that the positions of the upper clamping end 102 and the lower clamping end 103 of the quasi-static material testing machine are positioned in the middle area of the temperature and humidity box 104;

and (5): an upper clamping end 102 and a lower clamping end 103 of a quasi-static material testing machine are respectively connected with an upper clamping part 2 and a lower clamping part 4 of a device for testing the pure shear creep property of an energetic material in the vertical direction, then, one end of a plate-shaped test piece 101 is fixedly arranged in a lower accommodating opening through a test piece fixing device, and the other end of the plate-shaped test piece is fixedly arranged in an upper accommodating opening through the test piece fixing device;

and (6): setting the temperature and humidity in the temperature and humidity box 104 according to the storage environment and the use working condition of the explosive columns processed and manufactured by the energetic materials;

and (7): setting the loading rate of the quasi-static material testing machine according to the corresponding strain rate range when the energetic material is subjected to creep deformation;

and (8): based on a test system and control software of a quasi-static material testing machine with an assembled plate-shaped test piece 101, a mechanical property test of an energetic material under quasi-static pure shear loading under preset temperature and humidity conditions and loading rate conditions is carried out until the plate-shaped test piece 101 is completely broken, the load and displacement conditions of the energetic material during deformation are recorded and converted into a pure shear stress-strain curve of the material, and the maximum shear stress under corresponding test working conditions is directly determined from the curveI.e. shear strength;

the creep deformation and accumulated damage testing method of the energetic material under the pure shear loading comprises the following steps:

step (1): processing a plate-shaped test piece 101 suitable for testing the pure shear creep deformation and the accumulated damage of the energetic material;

step (2): processing a device for testing the pure shear creep property of the energetic material, which is suitable for a multi-test-piece long-time pure shear creep property test of the energetic material;

and (3): the lower clamping part 4 of the lower clamp is disassembled, the test clamp suite 13 meeting the test requirement number is connected with the clamp hoisting beam 14, the plate-shaped test piece 101 is installed in the test clamp suite 13, when the plate-shaped test piece 101 is installed, one end of the plate-shaped test piece 101 is arranged in the upper accommodating opening, the other end of the plate-shaped test piece 101 is correspondingly arranged in the lower accommodating opening, and the plate-shaped test piece 101 is fixed by using a test piece fixing device;

and (4): according to the estimated deformation of the plate-shaped test piece 101 in the vertical direction under the pure shear creep test stress level, the fishbone deformation can be obtained empirically, and also can be obtained according to the shear strength of the shear strength test method of the energetic material under the quasi-static pure shear loading, the position of a device for testing the pure shear creep performance of the energetic material, which is clamped with the plate-shaped test piece, in the vertical direction is adjusted, and the device is fastened and fixed;

and (5): placing a device for testing the pure shear creep property of the energetic material with the plate-shaped test piece 101 assembled in a constant temperature and humidity box;

the sum of the estimated deformation of the plate-shaped test piece 101 in the vertical direction under the set stress level, the height of a loading device on a device for testing the pure shear creep property of the energetic material and the height of a deformation measuring component is less than the height of a working area in the constant temperature and humidity box;

and (6): setting the temperature and humidity of a working area of a constant temperature and humidity box according to the storage environment and the use working condition of the explosive columns processed and manufactured by energetic materials;

and (7): the shear strength obtained by the shear strength testing method of the energetic material under the quasi-static pure shear loadingDetermining the stress level for testing the creep performance of the energetic material under pure shear loading;

then adjusting the load of the loading device according to the stress level of the determined creep property;

and (8): starting the test, and moving and deforming the plate-shaped test piece 101 downwards along the vertical direction;

the method comprises the following steps that when a plate-shaped test piece 101 moves downwards along the vertical direction, a laser range finder emitting head 12 used for measuring deformation quantity on a device for testing the pure shear creep property of an energy-containing material starts to work until the plate-shaped test piece 101 is broken, and the distance between the emitting head 12 and the bottom of a working area in a constant temperature and humidity box and the time are recorded in real time;

and (9): calculating the change relationship of the deformation of the plate-shaped test piece 101 with time based on the recorded distance and time;

step (10): calculating a stress level based on the time-varying relation of the deformationShear creep strain underChange over time t, and creep rateCreep complianceCreep rupture timeAnd cumulative damage amount D;

the cumulative damage amount calculation expression is:

wherein: d is the cumulative damage amount;andrespectively constant pure shear stress and corresponding time to break or creep life; n is the Leeberg stress norm, i.e. the level of shear creep stress required for the material to generate pure shear creep failure in unit time;for a linear cumulative damage index, when the cumulative damage amount D =1, the corresponding time is the pure shear creep rupture or failure time, i.e., t =。