Stretching mechanism, equipment and test method for soft material

Abstract

The invention relates to the technical field of research and test of material mechanics, in particular to a stretching mechanism, equipment and a test method of a soft material, comprising a linear motor, an outer frame, a collision block, a first clamp, a second clamp, a force sensor and a control system; the movable end of the linear motor is connected with the outer frame; the collision block is arranged in the outer frame and moves in the axial direction of the outer frame. The first clamp is connected with the collision block and is used for clamping one end of a to-be-tested soft material; the second clamp is used for clamping the other end of the soft material to be tested; the force sensor is connected with the second clamp; the linear motor and the force sensor are in electric connection or communication connection with the control system. The mechanism can realize intelligent control of the sample loading process and accurate acquisition of load data in the sample loading process, and is convenient for research of dynamic deformation and failure mechanism of the sample. The problem that in the prior art, a stretching mechanism cannot meet the requirement for medium strain rate test loading of a soft material with the Young modulus being smaller than the magnitude of MPa is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of material mechanics research and testing, and in particular to a stretching mechanism, equipment and test method for soft materials, in particular to a rapid stretching mechanism, equipment and test method for soft materials with a Young's modulus below the MPa level. Background Art

[0002] At present, many soft materials are subjected to dynamic impact loads during service. Mechanical tests on these materials at different loading rates are an important method to understand the dynamic deformation and failure mechanism of the materials. These soft materials with Young's modulus below the MPa level have many application backgrounds under dynamic loads, such as foam plastics used for cushioning and shock absorption, ballistic gelatin used to simulate human tissue in ballistics, etc.

[0003] Strain rate is the change of material deformation relative to time, and is a physical quantity that measures the deformation rate of materials during loading. Mechanical tests under different strain rates need to be completed using different test methods. For example, mechanical tests within the quasi-static range can be performed on an electronic universal testing machine driven by a servo motor. 2 s -1 The above high strain rate tests can be performed on a dynamic test device represented by a split Hopkinson bar.

[0004] However, at medium strain rates (10 0 s -1 Up to 10 2 s -1 ) mechanical tests are difficult to conduct on the above-mentioned test devices due to the problem of loading speed mismatch. Conventional Hopkinson bar loading devices cannot achieve medium strain rate loading, and traditional electronic universal testing machines are limited by the acceleration capability of the servo motor and the resonance problem during fast operation, and cannot stably operate for long distances at a higher rate. At this stage, medium strain rate tests usually require specific commercial hydraulic servo mechanisms for loading, but such testing machines usually have problems such as complex drive mechanisms and high costs. In addition, the transmission mechanism in such vertical testing machines requires that the specimen has sufficient rigidity to achieve clamping of the specimen, which is not suitable for medium strain rate testing of soft materials.

[0005] Therefore, there is an urgent need for a stretching mechanism that can meet the medium strain rate test loading of soft materials with Young's modulus below the MPa level, which is of great significance for the study of the dynamic deformation and failure mechanism of soft materials with Young's modulus below the MPa level. Summary of the invention

[0006] In view of the problem that the stretching mechanism existing in the prior art cannot meet the medium strain rate test loading requirements of soft materials with Young's modulus below the MPa level, the present invention provides a stretching mechanism, equipment and test method for soft materials.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a stretching mechanism for soft materials, comprising a linear motor, an outer frame, a collision block, a first clamp, a second clamp, a force sensor and a control system; the moving end of the linear motor is connected to the outer frame; the collision block is arranged inside the outer frame and moves axially along the outer frame; the first clamp is connected to the collision block and is used to clamp one end of the soft material to be tested; the second clamp is used to clamp the other end of the soft material to be tested; the force sensor is connected to the second clamp; and the linear motor and the force sensor are both electrically connected or communicatively connected to the control system.

[0008] Optionally, a base is further included, the linear motor and the outer frame are both arranged on the base, and the outer frame is slidably connected to the base via a guide rail.

[0009] Optionally, the length of the outer frame is greater than the maximum stroke of the linear motor, and the maximum stroke of the linear motor satisfies the following conditions:

[0010] Among them, v target is the set loading speed, a set is the set acceleration.

[0011] Optionally, the collision block includes a trapezoidal buffer portion and a moving main body portion, the small end of the trapezoidal buffer portion is connected to the first clamp, the large end of the trapezoidal buffer portion is connected to the moving main body portion, and the moving main body portion is connected to the moving end of the linear motor; the front end of the outer frame is provided with an inner cavity that fits with the trapezoidal buffer portion, which is used to cooperate with the trapezoidal buffer portion for buffering.

[0012] Optionally, the control system includes a drive module, a host computer and a data processing module; the host computer is connected to the drive module and the data processing module; The host computer is used to issue driving instructions to the driving module and receive data from the data processing module; The driving module is used to drive the linear motor to move according to the host computer instruction, and feed back the linear motor movement parameters to the host computer; The data processing module is used to collect the test data of the force sensor and feed it back to the host computer.

[0013] Optionally, the drive module includes a servo driver and a grating ruler; the servo driver is used to drive the linear motor to move according to the instructions of the host computer; the grating ruler is used to position the linear motor according to the instructions of the host computer, and collect the displacement signal of the linear motor and feed it back to the servo driver.

[0014] Optionally, the data processing module includes a signal conditioner and a data acquisition platform; the load collected by the force sensor is amplified by the signal conditioner in the form of a signal, and then recorded by the data acquisition platform and fed back to the host computer.

[0015] Optionally, the collision block is coated with a buffer pad on the outside.

[0016] The invention provides a stretching test device, comprising the above-mentioned soft material stretching mechanism.

[0017] A method for performing a tensile test on a soft material using the above-mentioned tensile mechanism comprises: The soft material to be tested is clamped between the first clamp and the second clamp; when clamping, the collision block is located at an end away from the soft material to be tested, so that the reading of the force sensor is zero; After the clamping is completed, the linear motor is started so that the moving end of the linear motor drives the outer frame to accelerate the movement; When the moving end of the linear motor is accelerated to a predetermined speed, the collision block is located at one end of the outer frame close to the soft material to be tested, and the collision block is driven to move, so as to perform a tensile test on the soft material to be tested; Record the load parameters during the tensile test of the soft material to be tested, and complete the tensile test process of the soft material.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a stretching mechanism for soft materials, comprising a linear motor, an outer frame, a collision block, a first clamp, a second clamp, a force sensor and a control system; the linear motor is used to load the sample, and the linear motor can directly generate linear motion during the loading process, has excellent dynamic performance and precision, is easy to be intelligently controlled, has a fast response speed, can quickly adjust the size and direction of the loading force, and realizes fast and accurate loading of the sample, is more suitable for medium strain rate test loading of soft materials, and does not require conversion of complex transmission mechanisms such as gears, belts and other components, which can greatly simplify the structure of the loading mechanism and reduce the complexity and cost of the equipment; the moving end of the linear motor is connected to the outer frame, so that the collision block moves inside the outer frame and is connected to the first clamp for clamping the sample, so as to realize the separate transmission of the loading force. The stretching mechanism adopts a separate The off-type transmission structure utilizes the interaction between the collision block and the outer frame, and utilizes the relative movement of the collision block inside the outer frame to avoid the influence of the non-constant speed of the linear motor on the sample loading process during acceleration, that is, by making the collision block move relative to the outer frame during the acceleration of the linear motor, the sample is not loaded during this process, thereby avoiding the influence of this process on the sample loading process; by completely fixing the force sensor to the base, the inertia effect of the sensor when it moves with the first fixture can be avoided. The inertia effect that may affect the collection of load data can be avoided; by electrically or communicatively connecting the force sensor and the linear motor to the control system, the intelligent control of the sample loading process can be achieved, and the accurate collection of the load data of the sample loading process can be achieved, which is convenient for the study of the dynamic deformation and failure mechanism of the sample. The stretching mechanism has a simple structure and is a horizontal stretching mechanism, which can avoid the disadvantage that soft materials cannot be directly clamped due to insufficient rigidity.

[0019] It also includes a base, on which the linear motor and the outer frame are both arranged, and the outer frame is slidably connected to the base via a guide rail. The setting of the base not only provides stable support for the entire mechanism, but also can suppress the vibration generated when the linear motor moves at high speed, reduce the displacement caused by vibration or external force, and avoid the vibration generated when the linear motor moves at high speed affecting the loading of the sample. The setting of the guide rail can not only enable the outer frame to move freely while providing support for the outer frame, but also limit the movement direction of the outer frame, thereby ensuring the stability of the entire movement process, thereby improving the stability of the sample loading.

[0020] The length of the outer frame is greater than the maximum stroke of the linear motor, and the maximum stroke of the linear motor satisfies the following conditions:

[0021] Among them, v target is the set loading speed, a setFor the set acceleration, this design can effectively offset the movement distance generated during the acceleration process of the linear motor, thereby avoiding the influence of the linear motor acceleration process on the specimen tensile test due to the unstable speed, and further improving the reliability of the test results.

[0022] The collision block includes a trapezoidal buffer part and a moving main body part, the small end of the trapezoidal buffer part is connected to the first clamp, the large end of the trapezoidal buffer part is connected to the moving main body part, and the moving main body part is connected to the moving end of the linear motor; the front end of the outer frame is provided with an inner cavity that fits with the trapezoidal buffer part, which is used to cooperate with the trapezoidal buffer part for buffering. The design of the trapezoidal buffer part enables it to effectively absorb and disperse energy during the collision process, thereby improving the stability and reliability of the mechanism. Due to the characteristics of the trapezoidal shape, when a collision occurs, the collision force will gradually disperse along the inclined surface of the trapezoid, thereby reducing the impact force per unit area and playing a good buffering role. This buffering effect helps to protect the mechanism from collision damage, has good adaptability and flexibility, and extends the service life of the system.

[0023] The control system includes a drive module, a host computer and a data processing module; the host computer is connected to the drive module and the data processing module; the host computer, as a control center, can accurately issue instructions to the drive module to control the movement of the linear motor. The drive module drives the linear motor to perform precise movement according to the instructions of the host computer, and feeds back real-time movement parameters such as position, speed, acceleration, etc. to the host computer. This high-precision control and feedback mechanism enables the mechanism to achieve high-precision positioning and speed control, meeting the loading requirements of medium strain rate tests of soft materials with Young's modulus below the MPa level; the data processing module is responsible for collecting test data from force sensors, and the collected data is fed back to the host computer in real time. The host computer can process and analyze these data in real time, thereby realizing the study of dynamic deformation and failure mechanism of soft materials during the test process.

[0024] The drive module includes a servo driver and a grating ruler; the servo driver can accurately control the movement of the linear motor according to the instructions of the host computer, including the processes of starting, accelerating, decelerating and stopping; the grating ruler, as a high-precision displacement measurement element, can monitor the displacement of the linear motor in real time and feed back the displacement signal to the servo driver, so that the servo driver can make real-time adjustments according to the deviation between the current position and the target position; through the coordinated work of the servo driver and the grating ruler, the mechanism can achieve high-precision control and positioning of the linear motor to meet the medium strain rate test loading of soft materials with Young's modulus below the MPa level.

[0025] The data processing module includes a signal conditioner and a data acquisition platform; the load collected by the force sensor is amplified by the signal conditioner in the form of an electrical signal, recorded by the data acquisition platform and fed back to the host computer. The main function of the signal conditioner is to amplify the weak signal collected by the force sensor to ensure that the signal strength is high enough to be accurately recorded by the data acquisition platform. The amplification process not only increases the amplitude of the signal, but also helps to improve the signal-to-noise ratio and reduce the interference of noise on the signal; the data acquisition platform is responsible for receiving the signal amplified and filtered by the signal conditioner, and records the changes in the load signal in real time and accurately, and feeds it back to the host computer, providing a reliable data basis for subsequent data analysis and processing.

[0026] The collision block is coated with a buffer pad on the outside. The buffer pad can absorb the energy generated by the collision through deformation and compression during the collision between the collision block and the outer frame, thereby reducing the influence of the vibration generated by the collision on the loading test.

[0027] A tensile test device, including the above-mentioned soft material tensile mechanism, can realize effective clamping and loading of medium strain rate test of soft materials with Young's modulus below MPa level, realize intelligent loading and intelligent analysis of samples, and provide a reliable basis for the study of dynamic deformation and failure mechanism of soft materials with Young's modulus below MPa level. The device has simple structure, low cost, good safety and high precision.

[0028] The present invention provides a method for conducting a tensile test on a soft material using the above-mentioned tensile mechanism, wherein the soft material to be tested is clamped between a first clamp and a second clamp; during clamping, the collision block is located at an end away from the soft material to be tested, so that the reading of the force sensor is zero; after the clamping is completed, the linear motor is started, so that the moving end of the linear motor drives the outer frame to accelerate; when the moving end of the linear motor accelerates to a predetermined speed, the collision block is located at an end of the outer frame close to the soft material to be tested, and drives the collision block to move, and a tensile test is performed on the soft material to be tested; the load parameters during the tensile test of the soft material to be tested are recorded until the tensile test process of the soft material is completed. This method can not only effectively characterize the strain rate of the soft material 10 0 s -1 Up to 10 2 s -1 It not only improves the stress-strain relationship within the material, but also improves the accuracy and reliability of mechanical property testing of soft materials, and provides strong support for material research and innovation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure is a schematic structural diagram of a stretching mechanism for a soft material according to the present invention.

[0030] Figure 2The figure is a schematic diagram of the control system structure of a stretching mechanism for a soft material of the present invention.

[0031] Figure 3 The present invention is a flow chart of a tensile test method for soft materials.

[0032] Among them, 1-linear motor, 2-outer frame, 3-collision block, 4-first clamp, 5-second clamp, 6-force sensor, 7-control system, 8-guide rail, 9-buffer pad, 10-base, 11-first clamp base, 12-second clamp base, 13-second transmission rod, 14-first transmission rod, 31-trapezoidal buffer part, 32-moving body part, 71-drive module, 72-host computer, 73-data processing module, 711-servo drive, 712-grating ruler, 731-signal conditioner, 732-data acquisition platform. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0035] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0036] Example 1 See also Figure 1The present invention provides a stretching mechanism for soft materials, comprising a linear motor 1, an outer frame 2, a collision block 3, a first clamp 4, a second clamp 5, a force sensor 6 and a control system 7; the outer frame 2 at the moving end of the linear motor 1; the collision block 3 is arranged inside the outer frame 2 and moves axially along the outer frame 2; the first clamp 4 is connected to the collision block 3 and is used to clamp one end of the soft material to be tested; the second clamp 5 is used to clamp the other end of the soft material to be tested; the force sensor 6 is connected to the second clamp 5; the linear motor 1 and the force sensor 6 are both electrically connected or communicatively connected to the control system 7.

[0037] The mechanism loads the sample by using a linear motor 1. The linear motor 1 can directly generate linear motion during the loading process, has excellent dynamic performance and precision, is easy to intelligently control, has a fast response speed, can quickly adjust the size and direction of the loading force, and realizes fast and accurate loading of the sample. It is more suitable for medium strain rate test loading of soft materials, and there is no conversion of complex transmission mechanisms such as gears, belts and other components, which can greatly simplify the structure of the loading mechanism and reduce the complexity and cost of the equipment; by connecting the moving end of the linear motor 1 to the outer frame 2, the collision block 3 is moved inside the outer frame 2, and the first clamp 4 for clamping the sample is connected to realize the separate transmission of the loading force. The stretching mechanism adopts a separate transmission structure, and utilizes the interaction between the collision block 3 and the outer frame 2, so that the linear motor 1 does not load the sample during the acceleration process, thereby avoiding the influence of this process on the sample loading process; by electrically connecting the force sensor 6 and the linear motor 1 to the control system 7 or by communication connection, it is possible to realize intelligent control of the sample loading process while realizing accurate collection of load data of the sample loading process, which is convenient for studying the dynamic deformation and failure mechanism of the sample. The stretching mechanism has a simple structure and is a horizontal stretching mechanism, which can avoid the disadvantage that soft materials cannot be directly clamped due to insufficient rigidity.

[0038] Example 2 See also Figure 1The present invention provides a stretching mechanism for soft materials, comprising a base 10, wherein the base 10 comprises two vibration isolation platforms parallel to each other, and a linear motor 1 is arranged on the base 10, wherein the linear motor 1 is an ironless linear motor, wherein the stator of the linear motor 1 is horizontally fixed on the base 1, and the mover is mounted on the stator, and the mover can move linearly along the magnetic track direction of the stator; the mover is connected to an outer frame 2 through a first transmission rod 14, and the outer frame 2 is slidably connected to the base 1 through a guide rail 8; a collision block 3 is slidably connected inside the outer frame 2, and the distance that the collision block 3 moves inside the outer frame 2 is greater than the distance that the moving end of the linear motor 1 moves from starting to a predetermined movement speed; the collision block 3 is connected to a first fixture base 11 through a second transmission rod 13, and the first fixture base 11 is connected to a first fixture 4; a second fixture base 12 is arranged opposite to the first fixture 4, and the second fixture base 12 is connected to a force sensor 6, and the force sensor 6 is connected to a second fixture 5; the force sensor 6 and the linear motor 1 are both electrically connected or communicatively connected to a control system 7; The length of the outer frame 2 is greater than the maximum stroke of the linear motor 1, and the maximum stroke of the linear motor 1 satisfies the following conditions:

[0039] Among them, v target is the set loading speed, a set is the set acceleration.

[0040] For example, set the loading speed to 1.2 m / s and the acceleration to 4.5 m / s 2 , the required displacement of the acceleration section is 0.16m, which is less than the designed length of the outer frame 2 of 0.3m, which can ensure that the movement speed of the outer frame 2 has reached the set speed when the collision transmission occurs. Similarly, when changing the loading speed, it is only necessary to adjust the acceleration accordingly to ensure that the required stroke for acceleration is less than the designed length of the outer frame 2 to ensure that the influence of the movement distance generated during the acceleration process of the linear motor 1 on the experimental results is effectively offset.

[0041] During the medium strain rate test of soft materials with Young's modulus below the MPa level, the soft material to be tested is clamped between the first clamp 4 and the second clamp 5, and the linear motor 1 is controlled by the control system 7 to perform acceleration motion. After the acceleration motion of the linear motor 1 is completed, the collision block 3 is driven to move by the outer frame 2 to start loading the soft material to be tested. The load parameters in the strain process are recorded by the force sensor 6 and fed back to the control system 7, so as to realize the study of the dynamic deformation and failure mechanism of the medium strain rate of the soft material with Young's modulus below the MPa level.

[0042] Example 3 See also Figure 1The present invention provides a rapid stretching mechanism for soft materials, including a base 1, which is composed of two vibration isolation platforms. In the entire mechanism, it is mainly used to suppress the vibration generated when the motor moves at high speed. A linear motor 1 is arranged on the base 1, and the linear motor 1 is an ironless linear motor including a stator and a mover. The mover is connected to a first transmission rod 14 and an outer frame 2 in sequence; a guide rail 8 is arranged on the base 1, and the outer frame 2 is slidably connected to the guide rail 8; a collision block 3 is arranged inside the outer frame 2, and the collision block 3 moves axially along the outer frame 2. The collision block 3 includes a trapezoidal buffer portion 31 and a moving main body portion 32. The small end of the trapezoidal buffer portion 31 is connected to a first clamp base 11 through a second transmission rod 13, and the first clamp base 11 is connected to the second A clamp 4, wherein the large end of the trapezoidal buffer portion 31 is connected to the moving main body portion 32, and the moving main body portion 32 is connected to the mover of the linear motor 1; the front end of the outer frame 2 is provided with an inner cavity that fits the trapezoidal buffer portion 31, and is used to cooperate with the trapezoidal buffer portion 31 for buffering; the outside of the collision block 3 is wrapped with a buffer pad 9, preferably, the buffer pad 9 is a silicone buffer pad, and the buffer pad 9 is completely wrapped around the outside of the collision block 3 or half wrapped around the outside of the collision block 3. When the buffer pad 9 is half wrapped around the outside of the collision block 3, effective buffering of the collision part between the collision block 3 and the outer frame 2 is ensured; the first clamp 4 is oppositely provided with a second clamp base 12, and the second clamp base 12 is connected to a force sensor 6, and the force sensor 6 is connected to a second clamp 5.

[0043] During the acceleration of the linear motor 1, the mover drives the outer frame 2 to move, and the first clamp 4 remains stationary. When the outer frame 2 is accelerated to the set speed, the collision block 3 is driven to move by collision, and moves coaxially with the outer frame 2 along the linear guide rail 8. The force sensor 6 is placed horizontally. The second clamp 5 remains stationary during the stretching process, and the first clamp 4 is driven to move linearly along the direction of the guide rail 8 to achieve tensile loading on the sample.

[0044] See also Figure 2 , the control system 7 includes a driving module 71, a host computer 72 and a data processing module 73; the host computer 72 is connected to the driving module 71 and the data processing module 73; The host computer 72 is used to issue driving instructions to the driving module 71 and receive data from the data processing module 73; The driving module 71 is used to drive the linear motor 1 to move according to the instructions of the host computer 72, and to feed back the motion parameters of the linear motor 1 to the host computer 72, including a servo driver 711 and a grating ruler 712; the servo driver 711 is used to drive the linear motor 1 to move according to the instructions of the host computer 72; the grating ruler 712 is used to position the linear motor 1 according to the instructions of the host computer 72, and to collect the displacement signal of the linear motor 1 and feed it back to the servo driver 711.

[0045] The data processing module 73 is used to collect the test data of the force sensor 6 and feed it back to the host computer 72, including a signal conditioner 731 and a data acquisition platform 732; the load collected by the force sensor 6 is amplified in the form of a signal by the signal conditioner 731, recorded by the data acquisition platform 732 and fed back to the host computer 72. The control process of the control system 7 is as follows: Step 1: The system is powered on, and the drive module 71 and the data processing module 73 are initialized; Step 2: The servo driver 711 drives the linear motor 1 to move to the initial position; at this time, the tensile specimen can be manually clamped, and after clamping, it is ensured that the initial reading of the force sensor 6 is zero, and the collision block 3 is placed at the farthest end of the outer frame 2; Step 3: After the sample is clamped, the linear motor 1 is started and the linear motor 1 is accelerated; Step 4: After the linear motor 1 accelerates to the set speed, the outer frame 2 drives the collision block 3 to move, and the first clamp 4 also moves at a relatively uniform speed to stretch the soft material sample to be tested; Step 5: After the linear motor 1 reaches the set displacement, it decelerates until it stops, and the loading process is completed.

[0046] Among them, step one mainly completes the parameter initialization of the control system 7. After the system is powered on, the linear motor is enabled, and the supporting software of the drive module 71 and the data acquisition platform 732 are initialized.

[0047] When executing step 2, the mover of the linear motor 1 is in the initial stretching position, and during the clamping process of the soft material sample to be tested, it is ensured that the sample has no pre-stretching deformation, that is, the force sensor 6 has no initial reading; after clamping, the load channel and the displacement channel are both in the pre-trigger state.

[0048] When executing step three, the linear motor 1 is in the acceleration process, at which time the outer frame 2 connected to the mover is driven to move linearly, and all the fixtures remain stationary.

[0049] When executing step four, the linear motor 1 has reached the preset speed after acceleration and is in a uniform motion state. The outer frame 2 collides with the collision block 3 and drives all components connected to the collision block 3 to move at a preset speed. At this time, the first clamp 4 also moves accordingly, thereby stretching the sample.

[0050] When executing step five, the linear motor 1 moves to the set displacement, the sample stretching is completed, the entire mechanism is decelerated in sections, and the test process ends.

[0051] The present invention provides a tensile test device, including the above-mentioned tensile mechanism for soft materials, which can realize effective clamping and loading of medium strain rate tests on soft materials with Young's modulus below the MPa level, realize intelligent loading and intelligent analysis of samples, and provide a reliable basis for the study of dynamic deformation and failure mechanism of soft materials with Young's modulus below the MPa level. The device has a simple structure, low cost, good safety, and high precision.

[0052] See also Figure 3 The present invention provides a method for performing a tensile test on a soft material using the above-mentioned tensile mechanism, comprising: S1: clamp the soft material to be tested between the first clamp 4 and the second clamp 5; when clamping, make the collision block 3 located at the end away from the soft material to be tested, so that the reading of the force sensor 6 is zero; S2: After the clamping is completed, the linear motor 1 is started, so that the moving end of the linear motor 1 drives the outer frame 2 to accelerate the movement; S3: When the moving end of the linear motor 1 is accelerated to a predetermined speed, the collision block 3 is located at one end of the outer frame 2 close to the soft material to be tested, and the collision block 3 is driven to move, so as to perform a tensile test on the soft material to be tested; S4: Record the load parameters during the tensile test of the soft material to be tested, and complete the tensile test process of the soft material.

[0053] This method can not only effectively characterize the strain rate of soft materials 0 s -1 Up to 10 2 s -1 It not only improves the stress-strain relationship within the material, but also improves the accuracy and reliability of mechanical property testing of soft materials, and provides strong support for material research and innovation.

[0054] In summary, the present invention provides a stretching mechanism, equipment and test method for soft materials, which adopts a linear motor 1 as a loading device, adopts a separate transmission structure, utilizes the interaction between the collision block 3 and the outer frame 2, and utilizes the relative movement of the collision block 3 inside the outer frame 2 to offset the influence of the linear motor's speed instability on the sample loading process during acceleration. By electrically or communicatively connecting the force sensor 6 and the linear motor 1 to the control system 7, the intelligent control of the sample loading process is realized, and the accurate collection of the load data of the sample loading process is realized, which is convenient for the study of the dynamic deformation and failure mechanism of the sample. It is of great significance to the study of the dynamic deformation and failure mechanism of soft materials with Young's modulus below the MPa level.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A stretching mechanism for soft materials, characterized in that: The invention comprises a linear motor (1), an outer frame (2), a collision block (3), a first clamp (4), a second clamp (5), a force sensor (6) and a control system (7); the moving end of the linear motor (1) is connected to the outer frame (2); the collision block (3) is arranged inside the outer frame (2) and moves axially along the outer frame (2); the first clamp (4) is connected to the collision block (3) and is used to clamp one end of the soft material to be tested; the second clamp (5) is used to clamp the other end of the soft material to be tested; the force sensor (6) is connected to the second clamp (5); and the linear motor (1) and the force sensor (6) are both electrically connected or communicatively connected to the control system (7).

2. The stretching mechanism for soft materials according to claim 1, characterized in that: It also comprises a base (10), the linear motor (1) and the outer frame (2) are both arranged on the base (10), and the outer frame (2) is slidably connected to the base (10) via a guide rail (8).

3. The stretching mechanism for soft materials according to claim 1, characterized in that: The length of the outer frame (2) is greater than the maximum stroke of the linear motor (1), and the maximum stroke of the linear motor (1) satisfies the following conditions: Among them, v target is the set loading speed, a set is the set acceleration.

4. The stretching mechanism for soft materials according to claim 1, characterized in that: The collision block (3) comprises a trapezoidal buffer portion (31) and a moving main portion (32), the small end of the trapezoidal buffer portion (31) being connected to the first clamp (4), the large end of the trapezoidal buffer portion (31) being connected to the moving main portion (32), and the moving main portion (32) being connected to the moving end of the linear motor (1); the front end of the outer frame (2) is provided with an inner cavity fitted with the trapezoidal buffer portion (31) for cooperating with the trapezoidal buffer portion (31) for buffering.

5. The stretching mechanism for soft materials according to claim 1, characterized in that: The control system (7) comprises a drive module (71), a host computer (72) and a data processing module (73); the host computer (72) is connected to the drive module (71) and the data processing module (73); The host computer (72) is used to issue driving instructions to the driving module (71) and receive data from the data processing module (73); The driving module (71) is used to drive the linear motor (1) to move according to the instruction of the host computer (72), and to feed back the movement parameters of the linear motor (1) to the host computer (72); The data processing module (73) is used to collect test data of the force sensor (6) and feed it back to the host computer (72).

6. The stretching mechanism for soft materials according to claim 5, characterized in that: The drive module (71) comprises a servo driver (711) and a grating ruler (712); the servo driver (711) is used to drive the linear motor (1) to move according to the instructions of the host computer (72); the grating ruler (712) is used to position the linear motor (1) according to the instructions of the host computer (72), and to collect displacement signals of the linear motor (1) and feed them back to the servo driver (711).

7. The stretching mechanism for soft materials according to claim 5, characterized in that: The data processing module (73) comprises a signal conditioner (731) and a data acquisition platform (732); the load collected by the force sensor (6) is amplified in the form of a signal by the signal conditioner (731), and then recorded by the data acquisition platform (732) and fed back to the host computer (72).

8. The stretching mechanism for soft materials according to any one of claims 1 to 7, characterized in that: The collision block (8) is externally coated with a buffer pad (9).

9. A tensile testing device, characterized in that: A stretching mechanism for a soft material comprising any one of claims 1-8.

10. A method for conducting a tensile test on a soft material using the tensile mechanism according to any one of claims 1 to 8, characterized in that: include: The soft material to be tested is clamped between the first clamp (4) and the second clamp (5); when clamping, the collision block (3) is located at an end away from the soft material to be tested, so that the reading of the force sensor (6) is zero; After the clamping is completed, the linear motor (1) is started, so that the moving end of the linear motor (1) drives the outer frame (2) to perform accelerated motion; When the moving end of the linear motor (1) is accelerated to a predetermined speed, the collision block (3) is located at one end of the outer frame (2) close to the soft material to be tested, and the collision block (3) is driven to move, so as to perform a tensile test on the soft material to be tested; Record the load parameters during the tensile test of the soft material to be tested, and complete the tensile test process of the soft material.

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