Stress-strain testing equipment and method

Abstract

The invention discloses stress-strain testing equipment which comprises a mounting table, a loading module and an actuator module, wherein the loading module and the actuator module are arranged on the mounting table. The actuator modules are detachably connected with the mounting table, and the connecting positions can be adjusted, so that the number and the positions of the actuator modules are adjusted according to loading requirements when the stress-strain test is performed on the test sample, the loading requirements of any shaft are met, the flexible adaptability of test equipment is improved, and the stress-strain test cost is saved. The fixtures of the actuator modules can fix a test sample, the fixtures of each group of actuator modules are in transmission connection with the driver of the loading module, and the driver simultaneously drives the plurality of groups of fixtures to slide, so that single-axis or multi-axis synchronous loading is realized, the consistency of the loading speed is ensured, and the loading precision is improved. Meanwhile, the invention further provides a stress-strain testing method which utilizes the stress-strain testing equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of stress testing, and in particular to a stress strain testing device and method. Background Art

[0002] The principal stress strain test is an experimental method used to measure the strain response of a material in multiple directions. This test is often used to study the anisotropy of a material (i.e., the difference in properties in different directions) and the deformation behavior of a material in multiple axes. This test usually requires the use of a specialized experimental setup that can apply controlled deformation in multiple axes. For example, some servo testing machines, which can apply force and measure strain in different directions, can achieve biaxial tension.

[0003] Common loading methods are usually divided into two categories, direct and indirect. Direct loading uses multiple servo cylinders to load the sample synchronously in different directions. The disadvantages are high cost, control accuracy is limited by the accuracy of the hydraulic cylinder, multi-axis loading synchronization control is difficult, and flexibility is poor (multi-axis modification is difficult and costly, and as the number of cylinders increases, the difficulty of synchronous control increases significantly). Indirect loading is generally modified by the tensile or compression test device through tooling. Its advantage is low cost, but the disadvantages are: 1) limited loading accuracy; 2) due to its structural principle, the axial loading speed is not consistent with the loading speed on the sample, and the sample loading speed changes continuously with the loading process, and the test variables cannot be controlled. Summary of the invention

[0004] The purpose of the present invention is to provide a stress strain testing device and method to solve the problems existing in the above-mentioned related technologies, realize synchronous loading of any axis, improve loading accuracy, improve the adaptability of stress strain testing equipment, and save testing costs.

[0005] To achieve the above object, the present invention provides the following solutions: The present invention provides a stress and strain testing device, comprising a mounting platform and: A loading module, wherein the loading module includes a driver; Actuator modules, the number of the actuator modules is multiple groups, all of the actuator modules are arranged circumferentially around the actuation axis; the actuator modules include an actuation base and a clamp, the actuation base is detachably connected to the mounting table and the connection position of the two can be adjusted, the clamp is slidably arranged on the actuation base, the clamp can slide back and forth radially along the ring formed by the actuator modules, the clamp can fix the test sample, the clamp is transmission-connected to the output end of the driver, and the driver can drive the clamp to slide.

[0006] Preferably, the output end of the driver is connected to a driving gear, and the driving gear is rotatably disposed on the mounting platform, and the rotation axis of the driving gear is coaxial with the actuation axis; the actuator module also includes a driven gear, and the driven gear is meshed with the driving gear, and the clamp is connected to the driven gear by a transmission mechanism, and the driven gear can drive the clamp to slide back and forth by the transmission mechanism.

[0007] Preferably, the transmission mechanism comprises a transmission screw and a screw slider, the transmission screw is rotatably arranged on the actuating base and connected to the driven gear, the transmission screw is threadedly connected to the screw slider, and the screw slider is connected to the clamp.

[0008] Preferably, a guide rod is provided on the actuating base, the guide rod is arranged parallel to the axis of the transmission screw, the screw slider has a guide hole matched with the guide rod, and the screw slider can be slidably sleeved on the guide rod.

[0009] Preferably, two limit blocks are provided on the actuating base, and the two limit blocks are arranged along the axial direction of the transmission screw, and the screw slider can be abutted against the limit blocks to limit the extreme position of the screw slider.

[0010] Preferably, the clamp comprises an upper clamp block and a lower clamp block, the gap opening between the upper clamp block and the lower clamp block is arranged toward the actuating axis, and the distance between the upper clamp block and the lower clamp block is adjustable.

[0011] Preferably, the actuating base is bolted to the mounting platform; The mounting platform is provided with a plurality of mounting holes matched with the actuating base, and all the mounting holes are evenly distributed around the actuating axis.

[0012] Preferably, the actuator module further comprises a force sensor, wherein the force sensor is connected to the clamp and can monitor the tensile force applied to the test sample.

[0013] The present invention also provides a stress-strain testing method, which utilizes the above-mentioned stress-strain testing equipment and includes the following steps: adjusting the number of the actuator modules and their connection positions with the mounting platform, using the clamp to fix the test sample, and the driver drives the clamp to slide along the actuation base to achieve uniaxial loading or multi-axial loading of the test sample.

[0014] Preferably, a strain gauge is provided on the test sample to measure the strain of the test sample; Alternatively, a speckle pattern is sprayed on the test sample, and image information of the speckle pattern on the test sample is collected by an image collection element.

[0015] Compared with the related art, the present invention has achieved the following technical effects: the stress-strain testing equipment of the present invention comprises a mounting platform and a loading module and an actuator module arranged on the mounting platform, the loading module comprises a driver; the number of the actuator modules is multiple groups, and all the actuator modules are arranged circumferentially around the actuation axis; the actuator module comprises an actuation base and a clamp, the actuation base and the mounting platform are detachably connected and the connection position of the two can be adjusted, the clamp is slidably arranged on the actuation base, the clamp can slide back and forth radially along the ring formed by the actuator modules, the clamp can fix the test sample, the clamp is transmission-connected to the output end of the driver, and the driver can drive the clamp to slide.

[0016] In the stress and strain testing equipment of the present invention, the actuator module is detachably connected to the mounting platform and the connection position can be adjusted. When the stress and strain test is performed on the test sample, the number and position of the actuator modules are adjusted according to the loading requirements to meet the loading requirements of any axis, thereby improving the flexibility and adaptability of the test equipment and saving the stress and strain testing cost. The clamps of the actuator modules can fix the test sample, and each group of the clamps of the actuator modules are connected to the driver of the loading module by transmission. The driver drives multiple groups of clamps to slide at the same time, realizing single-axis or multi-axis synchronous loading, ensuring the consistency of the loading speed, and improving the loading accuracy.

[0017] At the same time, the present invention also provides a stress-strain testing method. By using the above-mentioned stress-strain testing equipment, naturally, the stress-strain testing method of the present invention can also achieve the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a structural schematic diagram of a stress-strain testing device disclosed in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a loading module of a stress-strain testing device disclosed in an embodiment of the present invention; Figure 3 A schematic diagram of the structure of a driver and a driving gear of a stress-strain testing device disclosed in an embodiment of the present invention; Figure 4 A schematic diagram of uniaxial loading of a stress-strain testing device disclosed in an embodiment of the present invention; Figure 5A schematic diagram of biaxial loading of a stress-strain testing device disclosed in an embodiment of the present invention; Figure 6 A schematic diagram of triaxial loading of a stress-strain testing device disclosed in an embodiment of the present invention; Figure 7 A schematic diagram of stress and strain during testing by the stress and strain testing device disclosed in an embodiment of the present invention; Figure 8 A loading schematic diagram of application case 1 disclosed in an embodiment of the present invention; Fig. 9 This is a loading diagram of application case 2 disclosed in an embodiment of the present invention.

[0020] In the figure: 100, stress-strain testing equipment; 1. Mounting table; 2. Loading module; 3. Actuator module; 4. Driver; 5. Actuating base; 6. Fixture; 601. Upper clamping block; 602. Lower clamping block; 7. Driving gear; 8. Driven gear; 9. Transmission screw; 10. Screw slider; 11. Guide rod; 12. Limit block; 13. Mounting hole; 14. Test sample. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The purpose of the present invention is to provide a stress strain testing device and method to solve the problems existing in the above-mentioned related technologies, realize synchronous loading of any axis, improve loading accuracy, improve the adaptability of stress strain testing equipment, and save testing costs.

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Embodiment 1 This embodiment provides a stress strain testing device 100, please refer to Figure 1-Figure 6, including a mounting platform 1 and a loading module 2 and an actuator module 3 arranged on the mounting platform 1, the loading module 2 including a driver 4; the number of the actuator modules 3 is multiple groups, and all the actuator modules 3 are arranged circumferentially around the actuation axis; the actuator module 3 includes an actuation base 5 and a clamp 6, the actuation base 5 is detachably connected to the mounting platform 1 and the connection position of the two can be adjusted, the clamp 6 is slidably arranged on the actuation base 5, the clamp 6 can reciprocate along the radial direction of the ring surrounded by the actuator modules 3, the clamp 6 can fix the test sample 14, the clamp 6 is transmission-connected to the output end of the driver 4, and the driver 4 can drive the clamp 6 to slide.

[0025] In the stress strain testing device 100 of the present invention, the actuator module 3 is detachably connected to the mounting platform 1 and the connection position can be adjusted. When the stress strain test is performed on the test sample 14, the number and position of the actuator modules 3 are adjusted according to the loading requirements to meet the loading requirements of any axis, thereby improving the flexibility and adaptability of the testing device and saving the stress strain testing cost. The clamp 6 of the actuator module 3 can fix the test sample 14, and each group of the clamps 6 of the actuator module 3 is connected to the driver 4 of the loading module 2 by transmission. The driver 4 drives multiple groups of clamps 6 to slide at the same time, realizing single-axis or multi-axis synchronous loading, ensuring the consistency of the loading speed, and improving the loading accuracy.

[0026] In this specific embodiment, the driver 4 adopts a motor, and the output end of the driver 4 is connected to a driving gear 7, which is rotatably arranged on the mounting table 1, and the rotation axis of the driving gear 7 is coaxial with the actuation axis; the actuator module 3 also includes a driven gear 8, which is meshed with the driving gear 7, and the fixture 6 is connected to the driven gear 8 by a transmission mechanism, and the driven gear 8 can drive the fixture 6 to slide back and forth by the transmission mechanism. The driver 4 uses the driving gear 7 and the driven gear 8 to achieve smooth transmission of power, and the gear transmission has high precision and reliable transmission, which improves the working reliability of the test equipment. The driving gear 7 and the driven gear 8 are both bevel gears, and the driven gear 8 corresponds to the fixture 6 one by one, so that synchronous loading in all directions can be achieved by using the same driver 4. In other specific embodiments that can be realized by the present invention, the driver 4 can also use other types of transmission structures to achieve smooth transmission of power, such as sprocket chain, belt drive and other transmission methods. It is also necessary to explain here that a gear transmission structure can be added between the output end of the driver 4 and the driving gear 7 according to the output torque requirement to achieve the purpose of adjusting the output torque; adjusting the speed of the driver 4 and the parameters of the gear transmission structure can achieve the purpose of adjusting the loading speed to meet different test conditions. In addition, the driver 4 can be fixed on the mounting table 1 or other mounting fixed foundation, such as the foundation or other platform where the test equipment is located. Selecting a suitable installation position for the driver 4 to provide a stable installation foundation for the driver 4 is a common method used by those skilled in the art and will not be repeated here.

[0027] In this specific embodiment, the transmission mechanism includes a transmission screw 9 and a screw slider 10. The transmission screw 9 is rotatably arranged on the actuating base 5 and connected to the driven gear 8. The transmission screw 9 is threadedly connected to the screw slider 10, and the screw slider 10 is connected to the fixture 6. The driven gear 8 drives the transmission screw 9 to rotate, and the transmission screw 9 and the screw slider 10 form a ball screw mechanism to convert the rotational motion into a linear reciprocating motion, drive the screw slider 10 to slide back and forth, and thus drive the fixture 6 to slide back and forth along the radial direction of the ring surrounded by all the actuator modules 3 to load the test sample. The ball screw mechanism has high transmission accuracy and transmission efficiency, and has low friction, which can effectively improve the working stability of the actuator module 3. In other specific embodiments that can be realized by the present invention, the transmission mechanism can also adopt other structures, such as a gear rack mechanism, a crank slider structure, etc.

[0028] In order to improve the reciprocating motion accuracy of the lead screw slider 10, a guide rod 11 is provided on the actuating base 5. The guide rod 11 is arranged parallel to the axis of the transmission screw 9. The lead screw slider 10 has a guide hole adapted to the guide rod 11. The lead screw slider 10 can be slidably sleeved on the guide rod 11 to improve the reciprocating motion accuracy of the lead screw slider 10, thereby further improving the loading accuracy. In practical applications, two sets of guide rods 11 can be provided, and the two guide rods 11 are respectively located on both sides of the transmission screw 9. While improving the motion accuracy of the lead screw slider 10, the force uniformity of the lead screw slider 10 is improved, the motion stability of the lead screw slider 10 is ensured, and the working reliability of the actuator module 3 is further improved.

[0029] Specifically, two limit blocks 12 are provided on the actuating base 5, and the two limit blocks 12 are arranged along the axial direction of the transmission screw 9. The screw slider 10 can be against the limit blocks 12 to limit the extreme position of the screw slider 10, thereby improving the movement safety system of the screw slider 10 and the clamp 6 and improving the loading reliability.

[0030] More specifically, the clamp 6 includes an upper clamp block 601 and a lower clamp block 602, the slit opening between the upper clamp block 601 and the lower clamp block 602 is arranged toward the actuation axis, and the spacing between the upper clamp block 601 and the lower clamp block 602 can be adjusted to ensure the stability of the clamping of the test sample 14. In practical applications, a clamping positioning structure such as a positioning groove can be arranged on the clamping surfaces opposite to the upper clamp block 601 and the lower clamp block 602 to ensure that the axis of the clamping part of the test sample 14 intersects with the actuation axis after the clamping, thereby ensuring the accuracy of the loading direction and improving the loading reliability.

[0031] In this specific embodiment, the actuating base 5 is connected to the mounting platform 1 by bolts, and the connection is tight and the assembly and disassembly are convenient, thereby improving the operating convenience of the test equipment.

[0032] In order to facilitate the adjustment of the position of the actuator module 3 on the mounting platform 1, the mounting platform 1 has multiple groups of mounting holes 13 that are compatible with the actuating base 5. All the mounting holes 13 are evenly distributed around the actuating axis, which is convenient for adjusting the installation position of the actuating base 5, and then adjusting the position of the actuator module 3; in this specific embodiment, the central angle corresponding to the axis of the mounting holes 13 of adjacent groups is 15°. In practical applications, the number of groups of mounting holes 13 can be adjusted according to test requirements. The number of each group of mounting holes 13 is multiple, so as to avoid the misalignment of the actuator module 3. In practical applications, the mounting platform 1 can be set as a disc-shaped structure, the actuating axis coincides with the disc axis, the mounting holes 13 are arranged around the axis of the mounting platform 1, and each group of mounting holes 13 is arranged along the radial direction of the mounting platform 1, so as to facilitate the adjustment of the installation position of the actuator module 3 to meet different loading requirements.

[0033] When two sets of actuator modules 3 are provided, and the angle between the two sets of actuator modules 3 is 180°, the fixtures 6 of the two sets of actuator modules 3 respectively fix the two ends of the test sample 14, and the driver 4 drives the actuator modules 3 to move, so that single-axis loading can be achieved. For details, see Figure 4 When four sets of actuator modules 3 are provided, the angle between two adjacent actuator modules 3 is 90°, and biaxial loading of the test sample 14 can be achieved. Figure 5 When three groups of actuator modules 3 are provided, the angle between two adjacent actuator modules 3 is 120°, and the test sample 14 can be subjected to triaxial loading. Figure 6 In the actual test process, the number and distribution of the actuator modules 3 can be adjusted according to specific test requirements and different specifications of the test sample 14 to meet different loading test conditions, such as symmetrical or asymmetrical loading test conditions.

[0034] In addition, the actuator module 3 also includes a force sensor, which is connected to the fixture 6. The force sensor can monitor the tensile force applied to the test sample 14, thereby improving the test efficiency.

[0035] Embodiment 2 The present invention also provides a stress-strain testing method, which utilizes the stress-strain testing device 100 of the first embodiment, and includes the following steps: adjusting the number of actuator modules 3 and their connection positions with the mounting platform 1, fixing the test sample 14 with a clamp 6, and driving the clamp 6 to slide along the actuating base 5 by a driver 4 to achieve uniaxial loading or multi-axial loading of the test sample 14.

[0036] During the test, the number and setting position of the actuator modules 3 can be adjusted according to specific test requirements to achieve symmetrical, asymmetrical, single-axis, multi-axis and other loading to meet various test conditions.

[0037] It should also be noted that during the test process, a strain gauge may be provided on the test sample 14 to measure the strain of the test sample 14 and improve the test work efficiency.

[0038] In addition, a speckle pattern may be sprayed on the test sample 14, and an image acquisition element may be used to acquire image information of the speckle pattern on the test sample 14, so as to realize the test by using a non-contact full-field strain measurement method, and realize the test by the speckle pattern on the surface of the sample. The image acquisition element may be a camera, etc., and the image acquisition element may acquire image information of the speckle pattern on the test sample 14 above the test sample 14 and at different angles, so as to improve the test accuracy.

[0039] Embodiment 3 The stress-strain testing device 100 of the first embodiment is used to measure the principal stress and principal strain of different materials under two-dimensional conditions.

[0040] Under plane stress state, the strain component of a point is known , , , we want to rotate counterclockwise to the horizontal direction The linear strain and shear strain in the angular direction can be respectively found out according to the geometric conditions of small elastic deformation due to the known strain components of the micro-unit (rectangle) , , The linear strain induced in this direction Shear strain (See Figure 7 ), and then using the superposition principle, we can get: (1.1) (1.2) Determine the principal strains The principal strain is the extreme value of the positive strain, according to the condition , the in-plane principal strain can be obtained as: (1.3) If the principal strain Direction and The angle between the axes is , then: (1.4) In experimental stress analysis, strain gauges are often used to measure the strain at a certain point on the surface of a load-bearing component. Then, using the knowledge of stress and strain analysis, the stress condition of the component can be determined. It is not easy to measure, so generally the linear strain along several directions at the measuring point is measured first. Using the measurement results, strain analysis can be performed according to formula (1.1), formula (1.3) and formula (1.4) to determine the principal strain of the measuring point.

[0041] The following is a further explanation through specific application cases.

[0042] Application Case 1. Take the angle between the three actuator modules as 45° as an example. Figure 8 , the material principal stress is calculated as follows: Measure strain in three directions , and , using formula (1.3) and formula (1.4), the magnitude and direction of the principal strain are obtained as follows: (1.7) (1.8) Since the measuring point is in a biaxial stress state, the two principal stresses can be solved by the generalized Hooke's law formula:

[0043] Among them, E is the elastic modulus of the material and ν is the Poisson's ratio of the material.

[0044] Application Case 2: Take the loading with the angle between the three actuator modules being 60° as an example, see Fig. 9 , the principal strain of the material can be calculated by the following method.

[0045] (1.5) (1.6) The measuring point is in a biaxial stress state. Similarly, the two principal stresses can be solved as follows:

[0046] It should be explained that, in this specific embodiment, ε is the strain symbol, σ is the stress symbol, x , y is the coordinate axis direction, A , B, D, P, Q They are all reference coordinate points at different positions of the microunit during the test, which are convenient for testers to obtain the strain of the microunit and then calculate the stress. Determining the strain and calculating the stress are common knowledge for those skilled in the art and will not be repeated here.

[0047] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A stress-strain testing device, characterized in that: It includes a mounting platform and: A loading module, wherein the loading module includes a driver; Actuator modules, the number of the actuator modules is multiple groups, all of the actuator modules are arranged circumferentially around the actuation axis; the actuator modules include an actuation base and a fixture, the actuation base is detachably connected to the mounting table and the connection position of the two can be adjusted, the fixture is slidably arranged on the actuation base, the fixture can reciprocate along the radial direction of the ring surrounded by the actuator modules, the fixture can fix the test sample, the fixture is transmission-connected to the output end of the driver, and the driver can drive the fixture to slide; The output end of the driver is connected to a driving gear, and the driving gear is rotatably disposed on the mounting platform, and the rotation axis of the driving gear is coaxial with the actuation axis; the actuator module also includes a driven gear, and the driven gear is meshed with the driving gear, and the clamp is connected to the driven gear by a transmission mechanism, and the driven gear can drive the clamp to slide back and forth by the transmission mechanism.

2. The stress-strain testing device according to claim 1, characterized in that: The transmission mechanism includes a transmission screw and a screw slider. The transmission screw is rotatably arranged on the actuating base and connected to the driven gear. The transmission screw is threadedly connected to the screw slider, and the screw slider is connected to the fixture.

3. The stress-strain testing device according to claim 2, characterized in that: The actuating base is provided with a guide rod, the guide rod is arranged parallel to the axis of the transmission screw rod, the screw slider has a guide hole matched with the guide rod, and the screw slider can be slidably sleeved on the guide rod.

4. The stress-strain testing device according to claim 2, characterized in that: Two limit blocks are arranged on the actuating base, and the two limit blocks are arranged along the axial direction of the transmission screw rod. The screw slider can abut against the limit blocks to limit the extreme position of the screw slider.

5. The stress-strain testing device according to any one of claims 1 to 4, characterized in that: The clamp comprises an upper clamp block and a lower clamp block, the slit opening between the upper clamp block and the lower clamp block is arranged toward the actuating axis, and the distance between the upper clamp block and the lower clamp block can be adjusted.

6. The stress-strain testing device according to any one of claims 1 to 4, characterized in that: The actuating base is connected with the mounting platform by bolts; The mounting platform is provided with a plurality of mounting holes matched with the actuating base, and all the mounting holes are evenly distributed around the actuating axis.

7. The stress-strain testing device according to any one of claims 1 to 4, characterized in that: The actuator module further comprises a force sensor connected to the clamp, and the force sensor is capable of monitoring the tensile force applied to the test sample.

8. A stress-strain testing method, characterized in that: The stress-strain testing device according to any one of claims 1 to 7 comprises the following steps: adjusting the number of the actuator modules and the connection positions thereof with the mounting platform, fixing the test sample with the clamp, and the driver driving the clamp to slide along the actuation base to achieve uniaxial loading or multi-axial loading of the test sample.

9. The stress-strain testing method according to claim 8, characterized in that: Disposing a strain gauge on the test sample to measure the strain of the test sample; Alternatively, a speckle pattern is sprayed on the test sample, and image information of the speckle pattern on the test sample is collected by an image collection element.

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