Viscoelastic material testing support and testing system

Abstract

The utility model belongs to the field of viscous-elastic material testing, and particularly relates to a viscous-elastic material testing support and a testing system, and the viscous-elastic material testing support comprises a support and a plurality of groups of deformation and pressure testing clamps which are not in contact with one another; a mounting hole is formed in the bracket, the bracket is used for placing a to-be-tested material, and the to-be-tested material covers the mounting hole; the deformation and pressure test fixture comprises a first chuck, an elastic sheet and a second chuck which are arranged in sequence, the other end of the first chuck is used for being connected to one of two parallel sides of a to-be-tested material, and the other end of the second chuck is used for being connected to the other of the two parallel sides of the to-be-tested material; and a strain gauge is pasted on the elastic sheet. The viscous-elastic material testing bracket provided by the utility model is accurate and reliable in displacement data measurement of a to-be-tested material under hydrostatic pressure. Therefore, deformation of all planes on the to-be-tested material and installation of the pressure test fixture are realized, and the isotropic performance of the material can be measured conveniently.

Description

Technical Field

[0001] This utility model belongs to the field of viscoelastic material testing, specifically relating to a viscoelastic material testing bracket and testing system. Background Technology

[0002] Propellant grains are particulate-reinforced composite materials whose mechanical properties are time-dependent, degrading with prolonged storage. Currently, propellant grain integrity assessment primarily relies on numerical simulation analysis. Bulk modulus is a crucial material parameter in propellant grain structural integrity simulation calculations, but current numerical simulation analyses suffer from limited measurement accuracy. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a viscoelastic material testing bracket and testing system that can accurately measure and simultaneously perform bulk modulus testing and creep experiments.

[0004] This utility model provides a viscoelastic material testing bracket, including a bracket and several sets of non-contact deformation and pressure testing fixtures;

[0005] The bracket is provided with mounting holes, which are used to place the material to be tested, and the material to be tested covers the mounting holes;

[0006] The deformation and pressure testing fixture includes a first clamp, a spring clip, and a second clamp arranged in sequence. The other end of the first clamp is used to connect to one of the two parallel sides of the material to be tested, and the other end of the second clamp is used to connect to the other parallel side of the material to be tested. In one set of deformation and pressure testing fixtures, the first clamp is used to connect to the bottom surface of the material to be tested through the mounting hole, and the second clamp is used to connect to the top surface of the material to be tested.

[0007] A full-bridge strain gauge is attached to the spring.

[0008] Furthermore, the ends of the first and second clamps are connected to the material to be tested via universal joints.

[0009] Furthermore, the universal joint includes a base, a sleeve, and a ball joint;

[0010] The base has a connecting plane at one end and a spherical groove at the other end;

[0011] The sleeve is fitted onto the side wall of the base, and one end of the sleeve is provided with a through hole. The inner wall of the through hole is a spherical groove. The spherical groove and the spherical channel together form a spherical cavity, and the through hole connects to the spherical cavity.

[0012] The ball head includes a ball head and a shaft connected to each other. The shaft size is smaller than the through hole size. The ball head is rotatably set in a spherical cavity. The shaft passes through the through hole and out of the sleeve. The end of the shaft is used to connect the first chuck and the second chuck.

[0013] Furthermore, the end of the rod is a screw, and the first and second chucks are provided with screw holes;

[0014] The end of the rod is threaded into the screw holes of the first chuck and the second chuck.

[0015] Furthermore, the spring clip is detachably and fixedly connected to the first and second chucks via the chucks.

[0016] This utility model also provides a viscoelastic material testing system, including a pressure tank and the aforementioned viscoelastic material testing bracket disposed inside the pressure tank;

[0017] The pressure vessel is used to inject liquid insulating medium.

[0018] Furthermore, the pressure tank includes an openable cavity, a filling / draining port connecting to the cavity, an exhaust valve, and a pressure sensor.

[0019] The beneficial effects of this utility model are as follows: The viscoelastic material testing bracket provided by this utility model, wherein the deformation and pressure testing fixture connects the two parallel sides of the material to be tested through a first clamp and a second clamp, and the first clamp and the second clamp are connected by a spring. On the one hand, this makes the deformation and pressure testing fixture a bidirectional loaded curved beam, which, compared with the conventional cantilever beam structure, makes the deformation data fed back by the spring more accurate. Specifically, firstly, when a traditional cantilever beam structure is loaded, a displacement perpendicular to the test direction occurs, i.e., lateral slippage occurs. This application effectively solves this problem, thereby improving the test accuracy. Secondly, the bidirectional loaded curved beam testing system of this utility model has better linearity. Because there is no lateral slippage, only deformation occurs in the test direction, and the correspondence between measurement and measured quantity is simpler and more direct. Thirdly, the system is more sensitive to displacement. Compared with the traditional scheme where two cantilever beams in one direction are independent structures, and each spring only corresponds to half of the displacement to be measured, in this application, one spring corresponds to the entire displacement in the corresponding direction. On the other hand, by simply adjusting the dimensions of the first clamp, the spring clip, and the second clamp, multiple sets of non-contact, intersecting arrangements can be easily made. This allows for simultaneous testing of multiple parallel sides of the material under test, enabling isotropic performance measurements. Specifically, when measuring the deformation of a cubic specimen in three directions under hydrostatic pressure, if the deformation in the three directions is consistent, it verifies that the material is isotropic; if the deformation in the three directions is inconsistent, it is an anisotropic material, and the properties of the anisotropic material in each direction can be studied. Furthermore, by setting the initial state of the spring clip, the first and second clamps can generate clamping force to hold the material against the parallel sides of the material under test. At this time, the spring clip can also be used to install the deformation and pressure testing fixture (at this time, the first and second clamps abut against the side of the material under test, i.e., the first and second clamps are connected to the side of the material under test) or pre-install (during initial installation, the clamping force generated by the spring clip can be used to connect and fix the first and second clamps to the side of the material under test after the position is determined). At this time, the spring is used to measure the deformation displacement of the material under test and to install the deformation and pressure test fixture on the material under test. At this time, it can also ensure that the deformation and pressure test fixture can always fit and fix with the material under test as the volume of the material under test shrinks, thus maintaining measurement accuracy.

[0020] The mounting holes on the bracket serve two purposes: firstly, they allow the pressure of the liquid medium inside the pressure tank to act on the bottom surface of the material under test, ensuring uniform hydrostatic pressure across all sides of the material. Secondly, they allow for the mounting of deformation and pressure testing fixtures on the relatively parallel bottom and top surfaces of the material, enabling the installation of deformation and pressure testing fixtures on all planes of the material and facilitating the measurement of the material's isotropic properties. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the viscoelastic material testing bracket in this utility model;

[0022] Figure 2 This is a front sectional view of the viscoelastic material testing bracket of this utility model;

[0023] Figure 3 for Figure 2 A magnified view of a section at point A in the middle;

[0024] Figure 4 This is a schematic diagram of the viscoelastic material testing system of this utility model;

[0025] Figure 5 This is a cross-sectional view of the viscoelastic material testing system of this utility model.

[0026] In the diagram, 1-bracket; 11-mounting hole; 2-deformation and pressure testing fixture; 21-first chuck; 22-spring; 23-second chuck; 24-universal head; 241-base; 2411-connecting plane; 2412-spherical groove; 242-sleeve; 2421-through hole; 2422-spherical groove; 243-ball head rod; 2431-ball head; 2432-rod body; 3-pressure tank; 31-cavity; 32-filling / discharging port; 33-exhaust valve; 34-pressure sensor; 4-material to be tested. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0029] Furthermore, in this utility model, the use of terms such as "first," "second," etc., is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal connection of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0031] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0032] like Figures 1-5 As shown, this utility model provides a viscoelastic material testing bracket for supporting and fixing the material to be tested 4 in a pressure tank 3 and measuring the deformation on the material to be tested 4. Specifically, it includes a bracket 1 and several sets of non-contact deformation and pressure testing fixtures 2. The number of deformation and pressure testing fixtures 2 is related to the number of mutually parallel surfaces on the material to be tested 4. For example, when the material to be tested 4 is a regular hexahedron, there are three sets of mutually parallel surfaces on the material to be tested 4, and a total of three sets of deformation and pressure testing fixtures 2 are provided.

[0033] The support 1 has mounting holes 11 for placing the test material 4, which is a sample of viscoelastic material, specifically a solid propellant sample, with a hexahedral structure. The test material 4 covers the mounting holes 11, meaning that when the test material 4 is placed on the support 1, it presses against the mounting holes 11.

[0034] The deformation and pressure testing fixture 2 includes a first clamp 21, a spring 22, and a second clamp 23 arranged in sequence. The other end of the first clamp 21 is used to connect to one of the two parallel sides of the material to be tested 4, and the other end of the second clamp 23 is used to connect to the other parallel side of the material to be tested 4. That is, the first clamp 21 and the second clamp 23 are arranged opposite to each other, and the first clamp 21, the spring 22, and the second clamp 23 are arranged in a "U" shape.

[0035] One set of deformation and pressure testing fixtures 2 has a first clamp 21 for passing through the mounting hole 11 and connecting to the bottom surface of the fitting bracket 1 of the material to be tested 4, and a second clamp 23 for connecting to the top surface of the material to be tested 4. That is, the first clamp 21 and the second clamp 23 can be used to clamp, fix and measure the side surface of the material to be tested 4 fixed on the bracket 1 and its relative parallel surface.

[0036] Strain gauges are attached to the spring 22. The strain gauges are used to reflect the deformation of the spring 22, and the displacement of the two parallel sides of the material 4 under test can be calculated. Four strain gauges are set on the spring 22, and the four strain gauges form a full-bridge circuit to amplify the electrical signal.

[0037] The viscoelastic material testing bracket provided by this utility model includes a deformation and pressure testing fixture 2 in which the two parallel sides of the material to be tested 4 are connected by a first clamp 21 and a second clamp 23, which are connected by a spring plate 22. This design makes the deformation and pressure testing fixture 2 a bidirectionally loaded curved beam, resulting in more accurate deformation data feedback from the spring plate 22 compared to conventional cantilever beam structures. Specifically, firstly, traditional cantilever beam structures experience a displacement perpendicular to the test direction under load, i.e., lateral slippage. This application effectively solves this problem, improving testing accuracy. Secondly, the bidirectionally loaded curved beam testing system of this utility model has better linearity. Because there is no lateral slippage, only deformation occurs in the test direction, making the correspondence between measurement and the measured quantity simpler and more direct. Thirdly, the system is more sensitive to displacement. Compared to the traditional scheme where two cantilever beams in one direction are independent structures, each spring plate corresponds to only half of the displacement to be measured, while in this application, one spring plate corresponds to the entire displacement in that direction. On the other hand, by simply adjusting the dimensions of the first clamp 21, the spring 22, and the second clamp 23, multiple sets of cross-shaped, non-contact arrangements can be easily made, allowing simultaneous testing of multiple sets of parallel sides of the test material 4. This enables isotropic performance measurements. Specifically, when measuring the deformation of a cubic specimen in three directions under hydrostatic pressure, if the deformation in the three directions is consistent, it verifies that the test material is isotropic; if the deformation in the three directions is inconsistent, it is an anisotropic material, and the properties of the anisotropic material in each direction can be studied. On the other hand, by setting the initial state of the spring piece (specifically by setting the initial clamping length of the ball head rod 243), the spring piece 22 can cause the first clamp 21 and the second clamp 23 to generate clamping force and clamp against the parallel sides of the material to be tested 4. At this time, the spring piece 22 can also be used to realize the installation of the deformation and pressure test fixture 2 (at this time, the first clamp 21 and the second clamp 23 abut against the side of the material to be tested 4, that is, the first clamp 21 and the second clamp 23 are connected to the side of the material to be tested 4) or pre-installation (during the initial installation, the clamping force generated by the spring piece 22 can be used to realize the connection and fixation of the first clamp 21 and the second clamp 23 to the side of the material to be tested 4 after the position is determined). At this time, the spring piece 22 is used to measure the deformation displacement of the material 4 to be tested, and also to realize the installation of the deformation and pressure test fixture 2 and the material 4 to be tested. At this time, it can also ensure that the deformation and pressure test fixture 2 can always fit and fix with the material 4 to be tested as the volume of the material 4 to be tested shrinks, thus maintaining the measurement accuracy.

[0038] The mounting holes 11 on the bracket 1 serve two purposes: firstly, they allow the pressure of the liquid medium inside the pressure tank 3 to act on the bottom surface of the material under test 4, ensuring uniform hydrostatic pressure on all sides of the material under test 4; secondly, they allow for the installation of deformation and pressure testing fixtures 2 on the relatively parallel bottom and top surfaces of the material under test 4, enabling the installation of deformation and pressure testing fixtures 2 on all planes of the material under test 4, facilitating the measurement of the isotropic properties of the material.

[0039] refer to Figure 2 and Figure 3 In one embodiment, the ends of the first clamp 21 and the second clamp 23 are connected to the material 4 to be tested via a universal joint 24. The universal joint 24 eliminates non-axial force interference; that is, viscoelastic materials may experience non-uniform expansion / contraction under high pressure, causing slight changes in the contact angle between the clamp and the material surface. Traditional rigid connections would generate lateral shear forces. This invention, by connecting the material 4 to the first clamp 21 and the second clamp 23 via the universal joint 24, eliminates lateral shear forces while ensuring proper fit between the universal joint 24 and the material 4. Furthermore, when the first clamp 21 and the second clamp 23 provide clamping force to hold and fix themselves to the material 4, they are not perfectly parallel due to the need for clamping force. The universal joint 24 ensures complete contact and abutment between the first clamp 21, the second clamp 23, and the surface of the material 4, achieving a uniform contact pressure distribution. Forming parallel contact surfaces avoids stress concentration issues and reduces adverse effects on the specimen compared to line or point contact. Furthermore, viscoelastic materials undergo continuous creep under constant pressure, causing the contact point position to drift slowly over time. The universal joint 24 allows the clamp to slide freely tangentially, following the material surface in real time without generating additional constraint torque.

[0040] In one embodiment, the universal joint 24 includes a base 241, a sleeve 242, and a ball joint 243;

[0041] The base 241 has a connecting plane 2411 at one end and a spherical groove 2412 at the other end;

[0042] The sleeve 242 is fitted onto the side wall of the base 241, and one end of the sleeve 242 is provided with a through hole 2421. The inner wall of the through hole 2421 is a spherical groove 2422. The spherical groove 2422 and the spherical groove 2412 surround to form a spherical cavity, and the through hole 2421 connects to the spherical cavity.

[0043] The ball head 243 includes a ball head 2431 and a rod body 2432 connected to each other. The size of the rod body 2432 is smaller than the size of the through hole 2421, that is, the rod body 2432 can rotate freely within the inner diameter range of the through hole 2421. The ball head 2431 is rotatably set in the spherical cavity. The rod body 2432 passes through the through hole 2421 and exits the sleeve 242. The end of the rod body 2432 is used to connect the first chuck 21 and the second chuck 23.

[0044] In this embodiment, the universal joint 24 is easy and quick to assemble and disassemble. The connecting plane 2411 can be directly abutted against the plane of the material to be tested 4, or it can be glued to the plane of the material to be tested 4, thereby improving the connection stability.

[0045] In one embodiment, the end of the rod 2432 is a screw, and the first chuck 21 and the second chuck 23 are provided with screw holes;

[0046] The end of the rod 2432 is threaded to the threaded holes of the first chuck 21 and the second chuck 23. This configuration allows for adjustment of the clamping force of the first chuck 21 and the second chuck 23, ensuring stable installation and preventing excessive pressure on the test material 4, which could affect the accuracy of the hydrostatic test.

[0047] In one embodiment, the spring piece 22 is detachably and fixedly connected to the first clamp 21 and the second clamp 23 via clamps. This configuration facilitates the replacement of the spring piece 22, thereby making it easier to adapt to test materials 4 of different sizes.

[0048] refer to Figure 4 and Figure 5 The present invention also provides a viscoelastic material testing system, including a pressure tank 3 and the aforementioned viscoelastic material testing bracket disposed inside the pressure tank 3;

[0049] Pressure tank 3 is used to inject liquid insulating medium.

[0050] In this viscoelastic material testing system, the viscoelastic material testing bracket is used to support the material to be tested 4 inside the pressure tank 3. A creep experiment is performed on the material to be tested 4, and the deformation in each direction is measured. Then, by obtaining the pressure of the liquid medium inside the pressure tank 3, the bulk modulus value of the material to be tested 4 can be accurately calculated.

[0051] Specifically, this viscoelastic material testing system has the following effects:

[0052] 1. The viscoelastic material testing system directly obtains the volume change of the test material 4 through multiple sets of deformation and pressure testing fixtures 2, instead of characterizing the volume change of the test material 4 by the overall volume change within the pressure tank 3. This direct measurement method effectively eliminates systematic errors in the hydraulic device, such as poor sealing, deformation of the metal container itself, and compression of the medium liquid, thus improving the system accuracy of the test. Furthermore, the traditional method for eliminating systematic errors in the hydraulic device involves calibration experiments, requiring corresponding loaded and unloaded tests for each pressure setting. Since the volume deformation of the test material 4 is directly measured, repeated calibration experiments to eliminate the influence of medium liquid compression, container deformation, etc., are unnecessary, simplifying the testing process.

[0053] 2. This device can accurately measure the multi-directional displacement change of the test material 4 under hydrostatic pressure. Figure 1 The test material 4 shown is a regular hexahedron (the change in displacement is triaxial). The consistency of the multiaxial displacements can be compared to observe whether the material is isotropic. In other words, this measuring device is well-suited for measuring the bulk modulus of non-isotropic materials, while also allowing for the observation and analysis of the material's isotropic properties.

[0054] 3. This device has high measurement accuracy, down to the micrometer level. It can capture the multi-directional displacement of the test material 4 under hydrostatic pressure down to the micrometer scale, accurately reflecting the volumetric deformation of the test material 4 under test conditions, thus obtaining an accurate value of the bulk modulus of the viscoelastic material.

[0055] 4. The test data of this device is easy to obtain. The hydraulic system can provide a stable pressure in the pressure tank 3. Therefore, this device can be used to conduct creep tests on viscoelastic materials to accurately measure the change curve of bulk modulus over time, analyze the creep mechanical properties of viscoelastic materials, and lay a solid foundation for the structural integrity analysis of solid rocket engines.

[0056] 5. The significance of using this device is that it directly obtains the bulk modulus of viscoelastic materials from experiments rather than through numerical iteration, eliminating the cumulative error caused by the calculated bulk modulus, and is not limited by the asymmetry of the material under tension and compression. At the same time, it can accurately reflect the time-varying characteristics of viscoelastic materials.

[0057] In one embodiment, the pressure vessel 3 includes an openable cavity 31, an inlet / outlet 32 ​​connected to the cavity 31, an exhaust valve 33, and a pressure sensor 34. The cavity 31 is used to house the test material 4, the viscoelastic material test holder, and the liquid medium. The inlet / outlet 32 ​​is used to inject or expel the liquid medium into the cavity 31. The exhaust valve 33 is used to expel air when the liquid is injected into the cavity 31, and the pressure sensor 34 is used to monitor the pressure of the liquid medium within the cavity 31.

[0058] The above description is merely an embodiment and does not constitute any limitation on this utility model. Any person skilled in the art can make many possible variations, modifications, or alterations to the technical solution of this utility model without departing from its scope. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this utility model, without departing from its scope, should fall within the protection scope of this utility model.

Claims

1. A test fixture for viscoelastic materials, characterized in that, Includes a support (1) and several sets of non-contact deformation and pressure testing fixtures (2); The bracket (1) is provided with mounting holes (11), the bracket (1) is used to place the material to be tested (4), and the material to be tested (4) covers the mounting holes (11). The deformation and pressure test fixture (2) includes a first clamp (21), a spring (22), and a second clamp (23) arranged in sequence. The other end of the first clamp (21) is used to connect to one of the two parallel sides of the material to be tested (4), and the other end of the second clamp (23) is used to connect to the other side of the two parallel sides of the material to be tested (4). One set of deformation and pressure test fixtures (2) has a first clamp (21) for connecting to the bottom surface of the material to be tested (4) through the mounting hole (11), and a second clamp (23) for connecting to the top surface of the material to be tested (4); A full-bridge strain gauge is attached to the spring sheet (22).

2. The viscoelastic material testing bracket as described in claim 1, characterized in that, The ends of the first clamp (21) and the second clamp (23) are connected to the material to be tested (4) via a universal joint (24).

3. The viscoelastic material testing bracket as described in claim 2, characterized in that, The universal joint (24) includes a base (241), a sleeve (242), and a ball joint (243). The base (241) has a connecting plane (2411) at one end and a spherical groove (2412) at the other end. The sleeve (242) is fitted onto the side wall of the base (241), and one end of the sleeve (242) is provided with a through hole (2421). The inner wall of the through hole (2421) is a spherical groove (2422). The spherical groove (2422) and the spherical groove (2412) enclose a spherical cavity, and the through hole (2421) connects to the spherical cavity. The ball head rod (243) includes a ball head (2431) and a rod body (2432) connected to each other. The size of the rod body (2432) is smaller than the size of the through hole (2421). The ball head (2431) is rotatably disposed in the spherical cavity. The rod body (2432) passes through the through hole (2421) and exits the sleeve (242). The end of the rod body (2432) is used to connect the first chuck (21) and the second chuck (23).

4. The viscoelastic material testing bracket as described in claim 3, characterized in that, The end of the rod (2432) is a screw, and the first chuck (21) and the second chuck (23) are provided with screw holes; The end of the rod (2432) is threaded to the screw holes of the first chuck (21) and the second chuck (23).

5. The viscoelastic material testing bracket as described in any one of claims 1-4, characterized in that, The spring clip (22) is detachably and fixedly connected to the first clamp (21) and the second clamp (23) via the clamps.

6. A viscoelastic material testing system, characterized in that, Includes a pressure vessel (3) and a viscoelastic material testing bracket as described in any one of claims 1-5 disposed within the pressure vessel (3); The pressure vessel (3) is used to inject liquid insulating medium.

7. The viscoelastic material testing system as described in claim 6, characterized in that, The pressure tank (3) includes an openable cavity (31), an inlet / outlet (32) connected to the cavity (31), an exhaust valve (33), and a pressure sensor (34).

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