1. A biaxial stretching mechanical property testing device of a multi-configuration test piece comprises an upper clamp and a lower clamp which are connected with a testing machine and are arranged in a vertically corresponding mode, and is characterized in that the upper clamp comprises an upper clamp body (2) in an orthogonal cross configuration, four extending arms of the upper clamp body (2) are upper supporting arms, the central lines of the four upper supporting arms are positioned in the same plane and have equal extending lengths, an upper clamping part used for being connected with the testing machine is fixedly arranged at the center of the upper clamp body (2), and the upper clamping part extends out towards the direction far away from the lower clamp;

the lower clamp comprises a base (4) in a cross configuration and a connecting piece (11), four extending arms of the base (4) are lower supporting arms, the central lines of the four lower supporting arms are positioned in the same plane and have the same extending length, a lower clamping part used for being connected with a testing machine is fixedly arranged at the center of the base (4), and the lower clamping part extends towards the direction far away from the upper clamp;

the four extending arms of the connecting piece (11) are connecting arms, the central lines of the four connecting arms are positioned in the same plane, the extending lengths of the four connecting arms are equal, and the extending length of the lower supporting arm is greater than that of the upper supporting arm and that of the connecting arms;

the central axis of the upper clamp body (2), the central axis of the base (4) and the central axis of the connecting piece (11) are superposed and positioned on the same vertical line;

the extending ends of the four lower supporting arms on the base (4) are correspondingly connected with the four connecting arms on the connecting piece (11) through connecting devices, and the two ends of each connecting device are rotatably connected with guide pulleys (3);

the test piece fixing device is connected to the lower supporting arm in a sliding mode, a tensioning rope (24) is connected to one side, away from the test piece fixing device, of the test piece fixing device, and the other end of the tensioning rope (24) is fixedly connected with the corresponding upper supporting arm after passing through the two guide pulleys (3) on the corresponding connecting device in a winding mode.

2. The biaxial stretching mechanical property testing device of the multi-configuration test piece as defined in claim 1, wherein the connecting device comprises a support rod (1), and two ends of the support rod (1) are respectively and fixedly connected with the corresponding connecting arm and the lower supporting arm.

3. The biaxial stretching mechanical property testing device of the multi-configuration test piece as claimed in claim 2, wherein the supporting rods (1) comprise two supporting plates parallel to each other, two guide pulleys (3) on the same supporting rod (1) are arranged between the two supporting plates, and the guide pulleys (3) are connected with the supporting plates through pin shafts; the central axis of the guide pulley (3) is vertical to the plane of the support plate connected with the guide pulley (3), and the central axis of the guide pulley (3) is parallel to the horizontal plane.

4. The biaxial stretching mechanical property testing device of the multi-configuration test piece according to claim 2, further comprising an angle adjusting structure, wherein the angle adjusting structure comprises a plurality of first connecting through holes (18) axially arranged on the lower support arm along the lower support arm, a plurality of second connecting through holes (17) axially and uniformly distributed on the support rod (1) along the support rod (1), and a plurality of third connecting through holes (16) axially arranged on the connecting arm along the connecting arm;

the central axes of the first connecting through hole (18), the second connecting through hole (17) and the third connecting through hole (16) are all parallel to the horizontal plane;

one end of the support rod (1) is fixedly connected through a connecting shaft penetrating through the first connecting through hole (18) and the second connecting through hole (17), and the other end of the support rod (1) is fixedly connected through another connecting shaft penetrating through another second through hole and the third connecting through hole (16);

the guide pulleys (3) are rotatably arranged on the supporting rod (1) between the joint of the supporting rod (1) and the connecting arm and the joint of the supporting rod (1) and the lower supporting arm;

the connecting positions of the supporting rod (1) and the connecting arm and the lower supporting arm are adjusted, and the included angle between the supporting rod (1) and the base (4) is changed.

5. The biaxial stretching mechanical property testing device of the multi-configuration test piece according to claim 4, wherein the test piece fixing device comprises a sliding block (21) slidably arranged on the lower supporting arm, a connecting piece (20) is arranged on one surface of the sliding block (21) facing the upper clamp, a pressing piece (19) is arranged on the connecting piece (20) in a pressing manner, and the pressing piece (19) is fixedly connected with the sliding block (21) through a fourth screw penetrating through the connecting piece (20);

one surfaces, far away from each other, of the sliding blocks (21) are provided with first fixing holes (23), internal threads are arranged in the first fixing holes (23), one ends of the tensioning ropes (24) are arranged in the first fixing holes (23), and are fixedly connected with the first fixing holes (23) through first screws in threaded connection with the first fixing holes (23);

the tangent line of the circle where the guide pulley (3) close to the base (4) in the two guide pulleys (3) wound by the tension rope (24) connected to the first fixing hole (23) is positioned on the same straight line with the central axis of the first fixing hole (23);

the connecting piece (20) is provided with a clamping groove, the configuration size of the clamping groove is matched with a clamping arm (26) of the end part of the test piece, which is used for connecting a clamp, the connecting arm of the test piece is arranged in the clamping groove, and the opening of one surface, facing the center of the base (4), of the clamping groove is smaller than the opening of one surface, facing the center of the base (4), of the clamping groove.

6. The biaxial stretching mechanical property testing device of multi-configuration test piece according to claim 5, characterized in that the sliding block (21) is provided with a sliding through hole, and the sliding block (21) is sleeved on the connected lower supporting arm through the sliding through hole.

7. The biaxial stretching mechanical property testing device for the multi-configuration test piece according to claim 4, wherein the end portions of the upper supporting arms are provided with tensioning rope pre-tightening devices (6), each tensioning rope pre-tightening device (6) comprises a pre-tightening hole (9) arranged on the end portion of the upper supporting arm and a second fixing hole (8) arranged on the end surface of the upper supporting arm, the central axes of the pre-tightening holes (9) are all parallel to a vertical line, the central axes of the second fixing holes (8) are all horizontally arranged, and the pre-tightening holes (9) and the second fixing holes (8) are perpendicular to each other and are communicated with each other;

the device is characterized by further comprising two supporting seats detachably connected with the end part of the upper supporting arm, wherein the supporting seats are respectively arranged on two sides of the pre-tightening hole (9), the two supporting seats are connected through a pre-tightening rod (10), the pre-tightening rod (10) is rotatably connected with the supporting seats, one end of the pre-tightening rod (10) is provided with a stop block, and the pre-tightening rod (10) positioned between the two supporting seats is provided with at least two tensioning rope through holes;

an internal thread is arranged in the second fixing hole (8), one end of the tensioning rope (24) extends into the second fixing hole (8), and is fixedly connected with the second fixing hole (8) through a second screw (25) in threaded connection with the second fixing hole (8);

when one end of the tensioning rope (24) stretches into the second fixing hole (8), the tensioning rope penetrates out of the pre-tightening hole (9), penetrates through the other tensioning rope through hole from top to bottom after penetrating through one tensioning rope through hole from bottom to top, the operation is performed in sequence according to the length of the tensioning rope (24), then the pre-tightening rod (10) is rotated, the second screw (25) is rotated after the tensioning rope (24) is pre-tightened, and the tensioning rope (24) is fixedly connected with the second fixing hole (8).

8. The device for testing the biaxial stretching mechanical properties of a multi-configuration test piece according to claim 7, wherein a connecting plug board is arranged at one end of the supporting seat connected with the upper supporting arm, a connecting jack is arranged at a corresponding position on the upper supporting arm, the connecting plug board is connected with the connecting jack in a matching manner, and the supporting seat is detachably connected with the upper supporting arm through the connecting plug board and the connecting jack which are connected in a matching manner.

9. The biaxial stretching mechanical property testing device of the multi-configuration test piece according to any one of claims 1 to 8, characterized in that the upper clamping part comprises an upper clamping block (7), and a limiting plate (13) is fixedly connected to one end of the upper clamping block (7);

a clamping block through hole (14) is formed in the center of the upper clamp body (2), a limiting groove (12) is formed in the center of one surface, facing the base (4), of the upper clamp body (2), and the clamping block through hole (14) is communicated with the limiting groove (12);

the upper clamping block (7) penetrates through the clamping block through hole (14), the limiting plate (13) is arranged in the limiting groove (12) in a matching mode, and the limiting plate (13) is fixedly connected with the upper clamp body (2) through a third screw;

the lower clamping part is a lower clamping block (22), the lower clamping block (22) is fixedly connected with the center of the base (4), and the lower clamping block (22) extends out in the direction far away from the upper clamp;

the central shafts of the upper clamping block (7) and the lower clamping block (22) are all located on the same vertical line.

10. A biaxial tensile mechanical property test method of a multi-configuration test piece, which is performed by using the biaxial tensile mechanical property test device of the multi-configuration test piece according to claim 4 or 7,

when testing the mechanical properties of a test piece under wide temperature quasi-static biaxial tensile loading, the method comprises the following steps: step (1), a temperature box and a temperature control device are arranged on a quasi-static single-axis testing machine, and the position of the temperature box arranged on the quasi-static single-axis testing machine is debugged, so that the positions of an upper clamping end and a lower clamping end of the quasi-static single-axis testing machine are positioned in the middle area of the temperature box;

step (2), an upper clamping part of the upper clamp and a lower clamping part of the lower clamp are respectively connected with an upper clamping end and a lower clamping end of the quasi-static single-axis testing machine, and after connection, the upper clamp and the lower clamp meet the coaxiality requirement in the vertical direction and are fixed;

according to the configuration size of the test piece, the connecting positions of the support rod (1) and the connecting arm and the lower support arm are adjusted, so that the included angle formed by the support rod (1) and the base (4) meets the requirement, and the connecting piece (11), the support rod (1) and the base (4) are fixedly connected through a pin shaft after adjustment;

step (3), starting the quasi-static single-axis testing machine, fixing the lower clamping end of the quasi-static single-axis testing machine, vertically moving the upper clamping end upwards to a certain preset height in a no-load mode, checking whether the connected testing system runs smoothly in the loading process, and avoiding the clamping stagnation phenomenon;

when the connected test system runs smoothly, resetting both the quasi-static single-axis testing machine and a biaxial tensile mechanical property testing device of a multi-configuration test piece, and carrying out data zero clearing;

step (5), four clamping arms (26) on the test piece are respectively connected with four test piece fixing devices which are slidably connected with the lower supporting arm, then one ends of four tensioning ropes (24) are respectively fixedly connected in first fixing holes (23) on the four test piece fixing devices and fixed through first screws, the other ends of the tensioning ropes (24) respectively wind through guide pulleys (3) on corresponding supporting rods (1), then respectively penetrate through corresponding second fixing holes (8) and pre-tensioning holes (9) in sequence, penetrate through a first tensioning rope through hole of a corresponding pre-tensioning rod (10) from bottom to top, penetrate through a second tensioning rope through hole from top to bottom, rotate the pre-tensioning rods (10) according to the length of the tensioning ropes (24), the number of rotation turns of the four pre-tensioning rods (10) is the same, and therefore the four tensioning ropes (24) keep consistent pre-tensioning force and are pre-tensioned, then, the four pre-tightened tensioning ropes (24) are fixed in the second fixing hole (8) through a second screw (25) matched with the size and the thread of the second fixing hole (8), and the whole pre-tightening work and the fixed connection work of the tensioning ropes (24) are completed;

after pre-tightening is completed, the supporting seat and the pre-tightening rod (10) are detached and penetrate out from one end of the tightening rope (24) far away from the first fixing hole (23), so that the tightening rope is separated from the upper clamp body (2);

step (6), setting the temperature in the temperature box and the loading rate of the quasi-static single-axis testing machine according to the performance analysis requirement of the test piece;

step (7), carrying out wide-temperature quasi-static biaxial tension mechanical property test under the preset temperature condition and the loading rate condition, driving a sliding device (5) to stretch a test piece through a tensioning rope (24) until the test piece is completely broken, recording the load and displacement conditions of the test piece when the test piece deforms, and converting the load and displacement conditions into corresponding stress-strain curves;

when testing the mechanical properties of a test piece under dynamic biaxial tensile loading, the method comprises the steps of:

step (1), connecting an upper clamping end and a lower clamping end of a novel single-shaft high-strain-rate hydraulic servo testing machine with an upper clamping part of an upper clamp and a lower clamping part of a lower clamp, and after connection, enabling the upper clamp and the lower clamp to meet the coaxiality requirement in the vertical direction and be fixed;

according to the configuration size of the test piece, the connecting positions of the support rod (1) and the connecting arm and the lower support arm are adjusted, so that the included angle formed by the support rod (1) and the base (4) meets the requirement, and the connecting piece (11), the support rod (1) and the base (4) are fixedly connected through a pin shaft after adjustment;

step (3), starting a novel single-shaft high-strain-rate hydraulic servo testing machine, fixing a lower clamping end of the novel single-shaft high-strain-rate hydraulic servo testing machine immovably, enabling the upper clamping end to vertically and upwards slide along an upper clamping part of an upper clamp, completing pre-acceleration within the length range of the upper clamping part to a set loading rate, then clamping the upper clamping part and carrying out no-load operation to a certain preset height at the set loading rate, checking whether a connected testing system runs smoothly in the loading process, and avoiding the clamping stagnation phenomenon;

when the connected test system runs smoothly, resetting the novel single-shaft high-strain-rate hydraulic servo test machine and a biaxial tensile mechanical property test device of a multi-configuration test piece, and resetting data;

step (5), four clamping arms (26) on the test piece are respectively connected with four test piece fixing devices which are slidably connected with the lower supporting arm, then one ends of four tensioning ropes (24) are respectively fixedly connected in first fixing holes (23) on the four test piece fixing devices and fixed through first screws, the other ends of the tensioning ropes (24) respectively wind through guide pulleys (3) on corresponding supporting rods (1), then respectively penetrate through corresponding second fixing holes (8) and pre-tensioning holes (9) in sequence, penetrate through a first tensioning rope through hole of a corresponding pre-tensioning rod (10) from bottom to top, penetrate through a second tensioning rope through hole from top to bottom, rotate the pre-tensioning rods (10) according to the length of the tensioning ropes (24), the number of rotation turns of the four pre-tensioning rods (10) is the same, and therefore the four tensioning ropes (24) keep consistent pre-tensioning force and are pre-tensioned, then, the four pre-tightened tensioning ropes (24) are fixed in the second fixing hole (8) through a second screw (25) matched with the size and the thread of the second fixing hole (8), and the whole pre-tightening work and the fixed connection work of the tensioning ropes (24) are completed;

after pre-tightening is completed, the supporting seat and the pre-tightening rod (10) are detached and penetrate out from one end of the tightening rope (24) far away from the first fixing hole (23), so that the tightening rope is separated from the upper clamp body (2);

step (6), setting the loading rate of the novel single-shaft high-strain-rate hydraulic servo testing machine according to the performance analysis requirement of the test piece;

and (7) carrying out a dynamic biaxial tensile mechanical property test under a preset loading rate condition, driving the sliding device (5) to stretch the test piece through the tensioning rope (24) until the test piece is completely broken, recording the load and displacement conditions of the test piece when the test piece deforms, and converting into a corresponding stress-strain curve.

Background

At present, the mechanical property test research of materials under the conditions of different single shafts and different speeds and temperatures is usually carried out by adopting devices such as a conventional standard static material testing machine, a Hopkinson bar and the like. However, in the practical engineering application process, the structural member is usually in a complex stress state such as biaxial loading. Moreover, the mechanical properties of most materials are obviously affected by factors such as stress state, environmental temperature and the like. Therefore, the failure condition or service life of most structural components in actual engineering application cannot be truly and effectively evaluated only based on the failure criterion and failure criterion established by the uniaxial mechanical property test.

At present, a large quasi-static biaxial testing machine is still a main device for carrying out mechanical property test research of materials under biaxial loading. However, the device has the following disadvantages: firstly, the highest loading rate of the device is usually lower than 500mm/min, and the requirement of material mechanical property research under dynamic biaxial loading cannot be met; secondly, the device is not provided with a temperature box and a temperature control device which are adaptive to each other, and the reconstruction cost is high, namely the requirement of the mechanical property research of the material under the condition of biaxial loading at different temperatures can not be met; third, this type of device is typically bulky, heavy, and expensive to manufacture and to transport and maintain. Therefore, the above disadvantages severely limit the application of this type of device in the mechanical property test study of the material under biaxial loading.

In order to research the mechanical properties of the material under biaxial loading, the configuration of the test piece is designed according to the properties of different materials, the loading characteristics of a testing machine or a testing device and the like, namely the configuration sizes of the biaxial loading test pieces of different materials are different greatly, and the connection modes of the test piece and the testing machine are different; second, materials are more susceptible to deformation failure under tensile loading than compressive loading. Therefore, it is necessary to provide a biaxial tensile mechanical property testing apparatus and a testing method which can be adapted to multi-configuration test pieces.

Disclosure of Invention

The invention aims to provide a biaxial tensile mechanical property test device and a test method suitable for multi-configuration test pieces, which are used for overcoming the defects in the background technology, improving the understanding of the mechanical property of materials, and providing data support for further establishing failure criteria and further evaluating the failure condition or service life of corresponding structural parts.

The invention relates to a biaxial tensile mechanical property testing device of a multi-configuration test piece, which comprises an upper clamp and a lower clamp which are connected with a testing machine and are arranged in an up-and-down corresponding manner, wherein the upper clamp comprises an upper clamp body in an orthogonal cross configuration, four extending arms of the upper clamp body are upper supporting arms, the central lines of the four upper supporting arms are positioned in the same plane and have the same extending length, an upper clamping part used for being connected with the testing machine is fixedly arranged at the center of the upper clamp body, and the upper clamping part extends towards the direction far away from the lower clamp;

the lower clamp comprises a cross-shaped base and a connecting piece, four extending arms of the base are lower supporting arms, the central lines of the four lower supporting arms are positioned in the same plane and have the same extending length, a lower clamping part used for being connected with the testing machine is fixedly arranged at the center of the base, and the lower clamping part extends towards the direction far away from the upper clamp;

the four extending arms of the connecting piece are connecting arms, the central lines of the four connecting arms are positioned in the same plane, the extending lengths of the four connecting arms are equal, and the extending length of the lower supporting arm is greater than the extending length of the upper supporting arm and the extending length of the connecting arms;

the central axis of the upper clamp body, the central axis of the base and the central axis of the connecting piece are superposed and positioned on the same vertical line;

the extending ends of the four lower supporting arms on the base are correspondingly connected with the four connecting arms on the connecting piece through connecting devices, and two ends of each connecting device are rotatably connected with guide pulleys;

the test piece fixing device is connected to the lower supporting arm in a sliding mode, a tensioning rope is connected to one side, away from the test piece fixing device, of the test piece fixing device, and the other end of the tensioning rope is fixedly connected with the corresponding upper supporting arm after passing through the two guide pulleys on the corresponding connecting device in a winding mode.

Preferably, the connecting device comprises a supporting rod, and two ends of the supporting rod are respectively and fixedly connected with the corresponding connecting arm and the lower supporting arm.

Preferably, the support rods comprise two support plates which are parallel to each other, two guide pulleys positioned on the same support rod are arranged between the two support plates, and the guide pulleys are connected with the support plates through pin shafts; the central axis of the guide pulley is perpendicular to the plane of the support plate connected with the guide pulley, and the central axis of the guide pulley is parallel to the horizontal plane.

Preferably, the support device further comprises an angle adjusting structure, wherein the angle adjusting structure comprises a plurality of first connecting through holes axially arranged on the lower support arm along the lower support arm, a plurality of second connecting through holes axially and uniformly distributed on the support rod along the support rod, and a plurality of third connecting through holes axially arranged on the connecting arm along the connecting arm;

the central axes of the first connecting through hole, the second connecting through hole and the third connecting through hole are all parallel to the horizontal plane;

one end of the supporting rod is fixedly connected through a connecting shaft penetrating through the first connecting through hole and the second connecting through hole, and the other end of the supporting rod is fixedly connected through another connecting shaft penetrating through another second through hole and the third connecting through hole;

the guide pulleys are rotatably arranged on the supporting rod between the connecting part of the supporting rod and the connecting arm and the connecting part of the supporting rod and the lower supporting arm;

the connecting positions of the supporting rod, the connecting arm and the lower supporting arm are adjusted, and the included angle between the supporting rod and the base is changed.

Preferably, the test piece fixing device comprises a sliding block which is arranged on the lower supporting arm in a sliding mode, a connecting sheet is arranged on one surface, facing the upper clamp, of the sliding block, a pressing sheet is arranged on the connecting sheet in a pressing mode, and the pressing sheet is fixedly connected with the sliding block through a fourth screw which penetrates through the connecting sheet;

one surfaces, far away from each other, of the sliding blocks are provided with first fixing holes, internal threads are arranged in the first fixing holes, and one ends of the tensioning ropes are arranged in the first fixing holes and are fixedly connected with the first fixing holes through first screws in threaded connection with the first fixing holes;

the tangent line of a circle where the guide pulley close to the base is located in the two guide pulleys wound by the tension rope connected to the first fixing hole is positioned on the same straight line with the central axis of the first fixing hole;

the connecting piece is provided with a clamping groove, the configuration size of the clamping groove is matched with a clamping arm of the end part of the test piece, which is used for connecting the clamp, the connecting arm of the test piece is arranged in the clamping groove, and the opening of the clamping groove, facing the center of the base, is smaller than the opening of the clamping groove, facing the center of the base.

Preferably, a sliding through hole is formed in the sliding block, and the sliding block is sleeved on the lower supporting arm connected with the sliding through hole.

Preferably, the end parts of the upper support arms are respectively provided with a tensioning rope pre-tightening device, each tensioning rope pre-tightening device comprises a pre-tightening hole arranged on the end part of the upper support arm and a second fixing hole arranged on the end surface of the upper support arm, the central axes of the pre-tightening holes are parallel to a vertical line, the central axes of the second fixing holes are horizontally arranged, and the pre-tightening holes and the second fixing holes are mutually perpendicular and mutually communicated;

the device is characterized by also comprising two supporting seats detachably connected with the end part of the upper supporting arm, wherein the supporting seats are respectively arranged on two sides of the pre-tightening hole, the two supporting seats are connected through a pre-tightening rod, the pre-tightening rod is rotationally connected with the supporting seats, one end of the pre-tightening rod is provided with a stop block, and the pre-tightening rod positioned between the two supporting seats is provided with at least two tensioning rope through holes;

an internal thread is arranged in the second fixing hole, one end of the tensioning rope extends into the second fixing hole and is fixedly connected with the second fixing hole through a second screw in threaded connection with the second fixing hole;

when one end of the tensioning rope stretches into the second fixing hole, the tensioning rope penetrates out of the pre-tightening hole, penetrates through the other tensioning rope through hole from top to bottom after penetrating through one tensioning rope through hole from bottom to top, the tensioning rope is sequentially arranged according to the length of the tensioning rope, then the pre-tightening rod is rotated, the second screw is rotated after the tensioning rope is pre-tightened, and the tensioning rope is fixedly connected with the second fixing hole.

Preferably, one that supporting seat and last bracing arm link to each other serves and is provided with connection insertion plate, it is provided with interface jack to go up the last corresponding position of bracing arm, and connection insertion plate matches with interface jack and links to each other, the supporting seat can be dismantled with last bracing arm through the connection insertion plate and the interface jack that match and link to each other and be connected.

Or preferably, the upper clamping part comprises an upper clamping block, and one end of the upper clamping block is fixedly connected with a limiting plate;

a clamping block through hole is formed in the center of the upper clamp body, a limiting groove is formed in the center of one surface, facing the base, of the upper clamp body, and the clamping block is communicated with the limiting groove through the hole;

the upper clamping block penetrates through the clamping block and penetrates through the hole, the limiting plate is arranged in the limiting groove in a matching mode, and the limiting plate is fixedly connected with the upper clamp body through a third screw;

the lower clamping part is a lower clamping block, the lower clamping block is fixedly connected with the center of the base, and the lower clamping block extends out in the direction far away from the upper clamp;

the central shafts of the upper clamping block and the lower clamping block are both positioned on the same vertical line.

A biaxial stretching mechanical property test method of a multi-configuration test piece is completed by adopting a biaxial stretching mechanical property test device of the multi-configuration test piece,

when testing the mechanical properties of a test piece under wide temperature quasi-static biaxial tensile loading, the method comprises the following steps: step (1), a temperature box and a temperature control device are arranged on a quasi-static single-axis testing machine, and the position of the temperature box arranged on the quasi-static single-axis testing machine is debugged, so that the positions of an upper clamping end and a lower clamping end of the quasi-static single-axis testing machine are positioned in the middle area of the temperature box;

step (2), an upper clamping part of the upper clamp and a lower clamping part of the lower clamp are respectively connected with an upper clamping end and a lower clamping end of the quasi-static single-axis testing machine, and after connection, the upper clamp and the lower clamp meet the coaxiality requirement in the vertical direction and are fixed;

adjusting the connecting positions of the supporting rod, the connecting arm and the lower supporting arm according to the configuration size of the test piece, so that the included angle formed by the supporting rod and the base meets the requirement, and fixedly connecting the connecting piece, the supporting rod and the base through a pin shaft after adjustment;

step (3), starting the quasi-static single-axis testing machine, fixing the lower clamping end of the quasi-static single-axis testing machine, vertically moving the upper clamping end upwards to a certain preset height in a no-load mode, checking whether the connected testing system runs smoothly in the loading process, and avoiding the clamping stagnation phenomenon;

when the connected test system runs smoothly, resetting both the quasi-static single-axis testing machine and a biaxial tensile mechanical property testing device of a multi-configuration test piece, and carrying out data zero clearing;

step (5), the four clamping arms on the test piece are respectively connected with the four test piece fixing devices which are slidably connected with the lower supporting arm, then one ends of four tensioning ropes are respectively and fixedly connected in first fixing holes on the four test piece fixing devices and fixed through first screws, the other ends of the tensioning ropes are respectively wound through guide pulleys on corresponding supporting rods, then the tensioning ropes respectively penetrate through corresponding second fixing holes and pre-tensioning holes in sequence, penetrate through first tensioning rope through holes of corresponding pre-tensioning rods from bottom to top and then penetrate through second tensioning rope through holes from top to bottom, the pre-tensioning rods are sequentially rotated according to the lengths of the tensioning ropes, the rotation turns of the four pre-tensioning rods are the same, so that the four tensioning ropes keep consistent pre-tensioning force and are pre-tensioned, then the four pre-tensioned tensioning ropes are fixed in second fixing holes through second screws matched with the sizes of the second fixing holes and threads, the whole pre-tightening work and the fixed connection work of the tensioning rope are completed;

after pre-tightening is completed, the supporting seat and the pre-tightening rod are detached and penetrate out from one end of the tensioning rope, which is far away from the first fixing hole, so that the tensioning rope is separated from the upper fixture body;

step (6), setting the temperature in the temperature box and the loading rate of the quasi-static single-axis testing machine according to the performance analysis requirement of the test piece;

step (7), carrying out wide-temperature quasi-static biaxial tension mechanical property test under the preset temperature condition and the loading rate condition, driving a sliding device to stretch a test piece through a tensioning rope until the test piece is completely broken, recording the load and displacement conditions of the test piece during deformation, and converting the load and displacement conditions into corresponding stress-strain curves;

when testing the mechanical properties of a test piece under dynamic biaxial tensile loading, the method comprises the steps of:

step (1), connecting an upper clamping end and a lower clamping end of a novel single-shaft high-strain-rate hydraulic servo testing machine with an upper clamping part of an upper clamp and a lower clamping part of a lower clamp, and after connection, enabling the upper clamp and the lower clamp to meet the coaxiality requirement in the vertical direction and be fixed;

adjusting the connecting positions of the supporting rod, the connecting arm and the lower supporting arm according to the configuration size of the test piece, so that the included angle formed by the supporting rod and the base meets the requirement, and fixedly connecting the connecting piece, the supporting rod and the base through a pin shaft after adjustment;

step (3), starting a novel single-shaft high-strain-rate hydraulic servo testing machine, fixing a lower clamping end of the novel single-shaft high-strain-rate hydraulic servo testing machine immovably, enabling the upper clamping end to vertically and upwards slide along an upper clamping part of an upper clamp, completing pre-acceleration within the length range of the upper clamping part to a set loading rate, then clamping the upper clamping part and carrying out no-load operation to a certain preset height at the set loading rate, checking whether a connected testing system runs smoothly in the loading process, and avoiding the clamping stagnation phenomenon;

when the connected test system runs smoothly, resetting the novel single-shaft high-strain-rate hydraulic servo test machine and a biaxial tensile mechanical property test device of a multi-configuration test piece, and resetting data;

step (5), the four clamping arms on the test piece are respectively connected with the four test piece fixing devices which are slidably connected with the lower supporting arm, then one ends of four tensioning ropes are respectively and fixedly connected in first fixing holes on the four test piece fixing devices and fixed through first screws, the other ends of the tensioning ropes are respectively wound through guide pulleys on corresponding supporting rods, then the tensioning ropes respectively penetrate through corresponding second fixing holes and pre-tensioning holes in sequence, penetrate through first tensioning rope through holes of corresponding pre-tensioning rods from bottom to top and then penetrate through second tensioning rope through holes from top to bottom, the pre-tensioning rods are sequentially rotated according to the lengths of the tensioning ropes, the rotation turns of the four pre-tensioning rods are the same, so that the four tensioning ropes keep consistent pre-tensioning force and are pre-tensioned, then the four pre-tensioned tensioning ropes are fixed in second fixing holes through second screws matched with the sizes of the second fixing holes and threads, the whole pre-tightening work and the fixed connection work of the tensioning rope are completed;

after pre-tightening is completed, the supporting seat and the pre-tightening rod are detached and penetrate out from one end of the tensioning rope, which is far away from the first fixing hole, so that the tensioning rope is separated from the upper fixture body;

step (6), setting the loading rate of the novel single-shaft high-strain-rate hydraulic servo testing machine according to the performance analysis requirement of the test piece;

and (7) carrying out a dynamic biaxial tensile mechanical property test under a preset loading rate condition, driving the sliding device to stretch the test piece through the tensioning rope until the test piece is completely broken, recording the load and displacement conditions of the test piece when the test piece deforms, and converting into a corresponding stress-strain curve.

The beneficial effects of the invention are as follows:

1. the device has stronger universality, reduces the number of testing devices required by biaxial tensile mechanical property tests for adapting to test pieces with different configurations, and saves the cost, namely, the requirement of biaxial tensile mechanical property tests for the test pieces with different configuration sizes can be met by adjusting the included angle formed by the supporting rod and the base; the requirements of biaxial tensile mechanical property tests of test pieces with different thicknesses made of materials with different strengths and moduli can be met only by adjusting the structural forms of the connecting parts such as the clamping grooves on the connecting piece of the testing device and the shape and the thickness of the pressing piece; the length of the upper clamping part of the testing device is adjusted only, so that the testing device can be matched with different types of material testers.

2. The device is simple in connection with the test piece, the connection time with the test piece is short, the parts of the device do not need to be replaced after the test, and the requirement of mass repeatability tests can be met; secondly, the device of the invention can not cause pre-damage to the test piece, thereby improving the reliability of the test result.

3. The method provided by the testing device provided by the invention breaks through the defects existing in the test research of the biaxial tensile mechanical property of the current material. The method can meet the requirements of mechanical property test research of the material under wide-temperature quasi-static biaxial stretching loading, further analyzes the influence of temperature and loading rate on the mechanical property of the material, constructs a biaxial failure criterion and criterion containing the influence of temperature and loading rate, and can effectively evaluate the deformation and structural integrity of the material and the structure under wider temperature use conditions; and secondly, the requirements of mechanical property test research of materials under dynamic biaxial tensile loading such as impact can be met, the influence of dynamic biaxial tensile load on the mechanical property of the materials is further analyzed, a biaxial failure criterion and a criterion considering the influence of dynamic loading are constructed, and deformation and structural integrity of the materials and the structures under working conditions such as impact can be effectively evaluated.

4. The method provided by the testing device based on the invention is simple and convenient, has high reliability, can easily realize the simultaneity of biaxial loading on the test piece during the biaxial mechanical property test, the stability of the speed in the loading process and the observation of the deformation of the test piece, and has higher reliability of the test result.

5. Compared with a large quasi-static biaxial testing machine sold in the market, the device disclosed by the invention is relatively small in size, relatively light in weight, convenient to carry and low in carrying cost; secondly, the test system built based on the test device of the invention has lower cost and maintenance cost and better economic benefit.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention.

Fig. 2 is a schematic view of the overall structure of the upper clamp of the present invention.

FIG. 3 is a schematic view of the overall structure of the lower clamp of the present invention.

Fig. 4 is a schematic structural view of an upper clamp of the present invention.

FIG. 5 is a schematic view of the upper clamping portion of the upper clamp of the present invention.

Fig. 6 is a schematic view of the structure of a pre-tightening rod of the pre-tightening device of the upper clamp.

Fig. 7 is a schematic view of a supporting seat structure of the pre-tightening device of the upper clamp according to the present invention.

Fig. 8 is a schematic view of the connection of the tension rope and the second fixing hole of the present invention.

Fig. 9 is a schematic view of a connector structure of the lower clamp of the present invention.

Fig. 10 is a schematic view of a support rod structure of the lower clamp of the present invention.

FIG. 11 is a schematic view of a base structure of the lower clamp of the present invention.

Fig. 12 is a schematic view showing the entire structure of the sliding apparatus of the lower clamp according to the present invention.

Fig. 13 is a schematic view of a slider structure of the sliding device of the lower clamp of the present invention.

FIG. 14 is a view showing a connecting piece structure of the sliding apparatus of the lower jig of the invention.

FIG. 15 is a schematic view showing a pressing sheet structure of a slide device of the lower jig of the present invention.

FIG. 16 is a schematic view of the connection of the connecting piece of the present invention to a test piece.

Reference numerals: 1-supporting rod, 2-upper clamp body, 3-guide pulley, 4-base, 5-sliding device, 6-pre-tightening device, 7-upper clamping block, 8-second fixing hole, 9-pre-tightening hole, 10-pre-tightening rod, 11-connecting piece, 12-limiting groove, 13-limiting plate, 14-clamping block through hole, 16-third connecting through hole, 17-second connecting through hole, 18-first connecting through hole, 19-pressing piece, 20-connecting piece, 21-sliding block, 22-lower clamping block, 23-first fixing hole, 24-tensioning rope, 25-second screw and 26-clamping arm.

Detailed Description

The invention relates to a biaxial tensile mechanical property testing device of a multi-configuration test piece, which comprises an upper clamp and a lower clamp which are connected with a testing machine and are arranged up and down correspondingly, wherein the upper clamp comprises an upper clamp body 2 in an orthogonal cross configuration, four extending arms of the upper clamp body 2 are upper supporting arms, the central lines of the four upper supporting arms are positioned in the same plane and have the same extending length, an upper clamping part used for being connected with the testing machine is fixedly arranged at the center of the upper clamp body 2, and the upper clamping part extends out towards the direction far away from the lower clamp;

the lower clamp comprises a base 4 in a cross structure and a connecting piece 11, the size of the base 4 is larger than that of the whole upper clamp, operation and control are convenient, and the stretching moment is small. The four extending arms of the base 4 are lower supporting arms, the central lines of the four lower supporting arms are positioned in the same plane, the extending lengths of the four lower supporting arms are equal, a lower clamping part used for being connected with the testing machine is fixedly arranged at the center of the base 4, and the lower clamping part extends towards the direction far away from the upper clamp;

the four extending arms of the connecting piece 11 are connecting arms, the central lines of the four connecting arms are positioned in the same plane, the extending lengths of the four connecting arms are equal, and the extending length of the lower supporting arm is greater than the extending length of the upper supporting arm and the extending length of the connecting arm;

the central axis of the upper clamp body 2, the central axis of the base 4 and the central axis of the connecting piece 11 are superposed and positioned on the same vertical line;

the extending ends of the four lower supporting arms on the base 4 are correspondingly connected with the four connecting arms on the connecting piece 11 through connecting devices, and two ends of each connecting device are rotatably connected with guide pulleys 3;

the test piece fixing device is connected to the lower supporting arm in a sliding mode, a tensioning rope 24 is connected to one side, away from the test piece fixing device, of the test piece fixing device, and the other end of the tensioning rope 24 is fixedly connected with the corresponding upper supporting arm after passing through the two guide pulleys 3 on the corresponding connecting device in a winding mode.

The connecting device comprises a supporting rod 1, and two ends of the supporting rod 1 are respectively fixedly connected with the corresponding connecting arm and the corresponding lower supporting arm.

The supporting rods 1 respectively comprise two supporting plates which are parallel to each other, two guide pulleys 3 which are positioned on the same supporting rod 1 are respectively arranged between the two supporting plates, and the guide pulleys 3 are connected with the supporting plates through pin shafts; the central axis of the guide pulley 3 is perpendicular to the plane of the support plate connected with the guide pulley 3, and the central axis of the guide pulley 3 is parallel to the horizontal plane.

The angle adjusting mechanism comprises a plurality of first connecting through holes 18 axially arranged on the lower supporting arm along the lower supporting arm, a plurality of second connecting through holes 17 axially and uniformly distributed on the supporting rod 1 along the supporting rod 1, and a plurality of third connecting through holes 16 axially arranged on the connecting arm along the connecting arm;

the central axes of the first connecting through hole 18, the second connecting through hole 17 and the third connecting through hole 16 are all parallel to the horizontal plane;

one end of the support rod 1 is fixedly connected through a connecting shaft penetrating through the first connecting through hole 18 and the second connecting through hole 17, and the other end of the support rod 1 is fixedly connected through another connecting shaft penetrating through another second through hole and the third connecting through hole 16;

the guide pulleys 3 are rotatably arranged on the supporting rod 1 between the joint of the supporting rod 1 and the connecting arm and the joint of the supporting rod 1 and the lower supporting arm;

the connecting positions of the supporting rod 1, the connecting arm and the lower supporting arm are adjusted, and the included angle between the supporting rod 1 and the base 4 is changed.

The test piece fixing device comprises a sliding block 21 which is arranged on the lower supporting arm in a sliding mode, a connecting piece 20 is arranged on one surface, facing the upper clamp, of the sliding block 21, a pressing piece 19 is arranged on the connecting piece 20 in a pressing mode, and the pressing piece 19 is fixedly connected with the sliding block 21 through a fourth screw which penetrates through the connecting piece 20;

the surfaces, far away from each other, of the sliding blocks 21 are provided with first fixing holes 23, internal threads are arranged in the first fixing holes 23, and one ends of the tensioning ropes 24 are arranged in the first fixing holes 23 and fixedly connected with the first fixing holes 23 through first screws in threaded connection with the first fixing holes 23;

the tangent line of the circle where the guide pulley 3 close to the base 4 in the two guide pulleys 3 wound by the tension rope 24 connected to the first fixing hole 23 is positioned on the same straight line with the central axis of the first fixing hole 23;

the connecting sheet 20 is provided with a clamping groove, the configuration size of the clamping groove is matched with the clamping arm 26 of the end part of the test piece for connecting the clamp, the connecting arm of the test piece is arranged in the clamping groove, and the opening of one surface of the clamping groove facing the center of the base 4 is smaller than the opening of one surface of the clamping groove far away from the center of the base 4.

The sliding block 21 is provided with a sliding through hole, and the sliding block 21 is sleeved on the lower supporting arm connected with the sliding through hole. The sliding block 21 is made of a material with high rigidity and strength and light weight so as to reduce inertia and improve the accuracy of a test result.

The end parts of the upper supporting arms are respectively provided with a tensioning rope pre-tightening device 6, each tensioning rope pre-tightening device 6 comprises a pre-tightening hole 9 formed in the end part of each upper supporting arm and a second fixing hole 8 formed in the end face of each upper supporting arm, the central axes of the pre-tightening holes 9 are parallel to a vertical line, the central axes of the second fixing holes 8 are horizontally arranged, and the pre-tightening holes 9 and the second fixing holes 8 are perpendicular to each other and are communicated with each other;

the device is characterized by further comprising two supporting seats detachably connected with the end part of the upper supporting arm, wherein the supporting seats are respectively arranged on two sides of the pre-tightening hole 9, the two supporting seats are connected through a pre-tightening rod 10, the pre-tightening rod 10 is rotatably connected with the supporting seats, one end of the pre-tightening rod 10 is provided with a stop block, and the pre-tightening rod 10 positioned between the two supporting seats is provided with at least two tensioning rope through holes;

an internal thread is arranged in the second fixing hole 8, one end of the tensioning rope 24 extends into the second fixing hole 8, and is fixedly connected with the second fixing hole 8 through a second screw 25 in threaded connection with the second fixing hole 8;

when one end of the tensioning rope 24 extends into the second fixing hole 8, the tensioning rope penetrates out of the pre-tightening hole 9, penetrates through the other tensioning rope through hole from top to bottom after penetrating through one tensioning rope through hole from bottom to top, the tensioning rope is sequentially stretched according to the length of the tensioning rope 24, then the pre-tightening rod 10 is rotated, the second screw 25 is rotated after the tensioning rope 24 is pre-tightened, and the tensioning rope 24 is fixedly connected with the second fixing hole 8.

One of the supporting seat links to each other with last bracing arm is served and is provided with connection plug board, it is provided with interface jack to go up the last corresponding position of bracing arm, and connection plug board matches with interface jack and links to each other, the supporting seat can be dismantled with last bracing arm through the connection plug board and the interface jack that match and link to each other.

The upper clamping part comprises an upper clamping block 7, and one end of the upper clamping block 7 is fixedly connected with a limiting plate 13;

a clamping block through hole 14 is formed in the center of the upper clamp body 2, a limiting groove 12 is formed in the center of one surface, facing the base 4, of the upper clamp body 2, and the clamping block is communicated with the limiting groove 12 through the hole 14;

the upper clamping block 7 penetrates through the clamping block through hole 14, the limiting plate 13 is arranged in the limiting groove 12 in a matching mode, and the limiting plate 13 is fixedly connected with the upper clamp body 2 through a third screw;

the lower clamping part is a lower clamping block 22, the lower clamping block 22 is fixedly connected with the center of the base 4, and the lower clamping block 22 extends out in the direction far away from the upper clamp;

the central axes of the upper clamping block 7 and the lower clamping block 22 are all located on the same vertical line.

A biaxial stretching mechanical property test method of a multi-configuration test piece is completed by adopting a biaxial stretching mechanical property test device of the multi-configuration test piece,

when testing the mechanical properties of a test piece under wide temperature quasi-static biaxial tensile loading, the method comprises the following steps: step (1), a temperature box and a temperature control device are arranged on a quasi-static single-axis testing machine, and the position of the temperature box arranged on the quasi-static single-axis testing machine is debugged, so that the positions of an upper clamping end and a lower clamping end of the quasi-static single-axis testing machine are positioned in the middle area of the temperature box;

step (2), an upper clamping part of the upper clamp and a lower clamping part of the lower clamp are respectively connected with an upper clamping end and a lower clamping end of the quasi-static single-axis testing machine, and after connection, the upper clamp and the lower clamp meet the coaxiality requirement in the vertical direction and are fixed;

according to the configuration size of a test piece, the connecting positions of the support rod 1, the connecting arm and the lower support arm are adjusted, so that the included angle formed by the support rod 1 and the base 4 meets the requirement, and the connecting piece 11, the support rod 1 and the base 4 are fixedly connected through a pin shaft after adjustment;

step (3), starting the quasi-static single-axis testing machine, fixing the lower clamping end of the quasi-static single-axis testing machine, vertically moving the upper clamping end upwards to a certain preset height in a no-load mode, checking whether the connected testing system runs smoothly in the loading process, and avoiding the clamping stagnation phenomenon;

when the connected test system runs smoothly, resetting both the quasi-static single-axis testing machine and a biaxial tensile mechanical property testing device of a multi-configuration test piece, and carrying out data zero clearing;

step (5), the four clamping arms 26 on the test piece are respectively connected with the four test piece fixing devices which are slidably connected with the lower supporting arm, then one ends of the four tensioning ropes 24 are respectively fixedly connected in the first fixing holes 23 on the four test piece fixing devices and fixed through first screws, the other ends of the tensioning ropes 24 respectively wind through the guide pulleys 3 on the corresponding supporting rods 1, then sequentially penetrate out of the corresponding second fixing holes 8 and the pre-tightening holes 9 respectively, penetrate through the first tensioning rope through holes of the corresponding pre-tightening rods 10 from bottom to top, then penetrate through the second tensioning rope through holes from top to bottom, sequentially rotate the pre-tightening rods 10 according to the lengths of the tensioning ropes 24, the rotation turns of the four pre-tightening rods 10 are the same, so that the four tensioning ropes 24 keep consistent pre-tightening force and pre-tightening, then the pre-tightened four tensioning ropes 24 are fixed in the second fixing holes 8 through second screws 25 which are matched with the sizes and the threads of the second fixing holes 8, the whole pre-tightening work and the fixed connection work of the tensioning rope 24 are completed;

after pre-tightening is completed, the supporting seat and the pre-tightening rod 10 are detached and penetrate out from one end of the tensioning rope 24 far away from the first fixing hole 23, so that the tensioning rope is separated from the upper fixture body 2;

step (6), setting the temperature in the temperature box and the loading rate of the quasi-static single-axis testing machine according to the performance analysis requirement of the test piece;

step (7), carrying out wide-temperature quasi-static biaxial tension mechanical property test under the preset temperature condition and the loading rate condition, driving the sliding device 5 to stretch the test piece through the tensioning rope 24 until the test piece is completely broken, recording the load and displacement conditions of the test piece when the test piece deforms, and converting the load and displacement conditions into corresponding stress-strain curves;

when testing the mechanical properties of a test piece under dynamic biaxial tensile loading, the method comprises the steps of:

step (1), connecting an upper clamping end and a lower clamping end of a novel single-shaft high-strain-rate hydraulic servo testing machine with an upper clamping part of an upper clamp and a lower clamping part of a lower clamp, and after connection, enabling the upper clamp and the lower clamp to meet the coaxiality requirement in the vertical direction and be fixed;

according to the configuration size of a test piece, the connecting positions of the support rod 1, the connecting arm and the lower support arm are adjusted, so that the included angle formed by the support rod 1 and the base 4 meets the requirement, and the connecting piece 11, the support rod 1 and the base 4 are fixedly connected through a pin shaft after adjustment;

step (3), starting a novel single-shaft high-strain-rate hydraulic servo testing machine, fixing a lower clamping end of the novel single-shaft high-strain-rate hydraulic servo testing machine immovably, enabling the upper clamping end to vertically and upwards slide along an upper clamping part of an upper clamp, completing pre-acceleration within the length range of the upper clamping part to a set loading rate, then clamping the upper clamping part and carrying out no-load operation to a certain preset height at the set loading rate, checking whether a connected testing system runs smoothly in the loading process, and avoiding the clamping stagnation phenomenon;

when the connected test system runs smoothly, resetting the novel single-shaft high-strain-rate hydraulic servo test machine and a biaxial tensile mechanical property test device of a multi-configuration test piece, and resetting data;

step (5), the four clamping arms 26 on the test piece are respectively connected with the four test piece fixing devices which are slidably connected with the lower supporting arm, then one ends of the four tensioning ropes 24 are respectively fixedly connected in the first fixing holes 23 on the four test piece fixing devices and fixed through first screws, the other ends of the tensioning ropes 24 respectively wind through the guide pulleys 3 on the corresponding supporting rods 1, then sequentially penetrate out of the corresponding second fixing holes 8 and the pre-tightening holes 9 respectively, penetrate through the first tensioning rope through holes of the corresponding pre-tightening rods 10 from bottom to top, then penetrate through the second tensioning rope through holes from top to bottom, sequentially rotate the pre-tightening rods 10 according to the lengths of the tensioning ropes 24, the rotation turns of the four pre-tightening rods 10 are the same, so that the four tensioning ropes 24 keep consistent pre-tightening force and pre-tightening, then the pre-tightened four tensioning ropes 24 are fixed in the second fixing holes 8 through second screws 25 which are matched with the sizes and the threads of the second fixing holes 8, the whole pre-tightening work and the fixed connection work of the tensioning rope 24 are completed;

after pre-tightening is completed, the supporting seat and the pre-tightening rod 10 are detached and penetrate out from one end of the tensioning rope 24 far away from the first fixing hole 23, so that the tensioning rope is separated from the upper fixture body 2;

step (6), setting the loading rate of the novel single-shaft high-strain-rate hydraulic servo testing machine according to the performance analysis requirement of the test piece;

and (7) carrying out a dynamic biaxial tensile mechanical property test under a preset loading rate condition, driving the sliding device 5 to stretch the test piece through the tensioning rope 24 until the test piece is completely broken, recording the load and displacement conditions of the test piece during deformation, and converting the load and displacement conditions into corresponding stress-strain curves.

In the above method, the thickness of the connecting piece 20 and the size of the engaging groove are adjusted according to the strength and modulus of the test piece material and the size of the test piece, and the number of the pressing pieces 19 is increased or decreased correspondingly, or the thickness of the pressing pieces 19 is adjusted.