CN112198308A - Bidirectional tensile testing machine and method for in-vitro skin tissue mechanical property test - Google Patents

Bidirectional tensile testing machine and method for in-vitro skin tissue mechanical property test Download PDF

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CN112198308A
CN112198308A CN202011159711.5A CN202011159711A CN112198308A CN 112198308 A CN112198308 A CN 112198308A CN 202011159711 A CN202011159711 A CN 202011159711A CN 112198308 A CN112198308 A CN 112198308A
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stretching
negative
positive
stretching mechanism
tension
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阳振峰
管延智
李强
金泓
王郑
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North China University of Technology
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North China University of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/483—Physical analysis of biological material
    • G01N33/4833—Physical analysis of biological material of solid biological material, e.g. tissue samples, cell cultures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/04—Chucks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0016—Tensile or compressive
    • G01N2203/0017—Tensile
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0071—Creep
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/022—Environment of the test
    • G01N2203/0222—Temperature
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/025—Geometry of the test
    • G01N2203/0252—Monoaxial, i.e. the forces being applied along a single axis of the specimen
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/025—Geometry of the test
    • G01N2203/0254—Biaxial, the forces being applied along two normal axes of the specimen
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/026—Specifications of the specimen
    • G01N2203/0262—Shape of the specimen
    • G01N2203/0278—Thin specimens
    • G01N2203/0282—Two dimensional, e.g. tapes, webs, sheets, strips, disks or membranes

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Abstract

The invention discloses a bidirectional tensile testing machine for in-vitro skin tissue mechanical property testing, which comprises an environment box, a base, an x positive tensile mechanism, an x negative tensile mechanism, a y positive tensile mechanism and a y negative tensile mechanism, wherein the environment box is arranged on the base; the x positive stretching mechanism, the x negative stretching mechanism, the y positive stretching mechanism and the y negative stretching mechanism have the same structure; the x positive stretching mechanism, the x negative stretching mechanism, the y positive stretching mechanism and the y negative stretching mechanism are arranged and fixed on the base in a cross shape; the environment box comprises an environment box body and an environment box sealing door; and an environment box control system, a cold air pipe and a hot air pipe are arranged in the environment box body. The invention can complete the transformation ratio proportion/transformation ratio biaxial tension test of the orthogonal biaxial based on the high-precision control of the AC servo motor under the condition of being provided with a heating device, and can also perform the uniaxial tension and compression test.

Description

Bidirectional tensile testing machine and method for in-vitro skin tissue mechanical property test
Technical Field
The invention belongs to the technical field of in-vitro skin tissue mechanical property experiments, and particularly relates to a bidirectional tensile testing machine and method for in-vitro skin tissue mechanical property tests.
Background
Since skin tissue is a heterogeneous material with properties characterized by diversity, anisotropy, nonlinearity and viscoelasticity, the factors affecting the mechanical properties of skin are many, such as age, sex, location on the body, hydration, PH, relative humidity and time of day, and the adaptability and variability of skin properties between individuals, so that the skin shows very complex mechanical behavior. Therefore, the research on the skin deformation behavior is far from enough by only using the material properties obtained by the traditional unidirectional tensile test method, and the excavation of the bidirectional loading mechanical properties of the skin and the establishment of an accurate material model are urgent.
The method controls the load or displacement of two shafts to enable a central area to be in different stress strain states, so that any yield point of a double-pull area under different loading paths is obtained, and the method becomes a research hotspot in the field at present.
The existing bidirectional tension and compression testing machine is mainly based on hydraulic control and has the problems of difficulty in accurate control of a tension test, high complexity of the device, poor field sanitary conditions of the testing machine and the like.
In addition, temperature is an important influence factor influencing skin performance, and the problem of how to place the stretched in-vitro skin in a closed environment box and flexibly adjusting the temperature in the environment box according to experimental requirements is concerned.
Disclosure of Invention
The invention aims to provide a bidirectional tensile testing machine and a method for in-vitro skin tissue mechanical property testing, and aims to solve the technical problems.
The invention provides a bidirectional tensile testing machine for in-vitro skin tissue mechanical property testing, which comprises an environment box, a base, an x positive tensile mechanism, an x negative tensile mechanism, a y positive tensile mechanism and a y negative tensile mechanism, wherein the environment box is provided with a plurality of grooves; the x positive stretching mechanism, the x negative stretching mechanism, the y positive stretching mechanism and the y negative stretching mechanism have the same structure;
the x positive stretching mechanism, the x negative stretching mechanism, the y positive stretching mechanism and the y negative stretching mechanism are arranged and fixed on the base in a cross shape;
the base comprises a central lathe bed, an x positive peripheral lathe bed, an x negative peripheral lathe bed, a y positive peripheral lathe bed and a y negative peripheral lathe bed; the x forward stretching mechanism is fixed on the x forward bed body; the x negative direction stretching mechanism is fixed on the x negative direction upper bed body; the y forward stretching mechanism is fixed on the y forward bed body; the y-direction stretching mechanism is fixed on the y-direction bed body;
the central lathe bed comprises a central base cover plate and a central base, and the central base cover plate is arranged on the central base; the x positive direction peripheral lathe bed, the x negative direction peripheral lathe bed, the y positive direction peripheral lathe bed and the y negative direction peripheral lathe bed have the same structure and are composed of peripheral lathe bed bases;
the environment box comprises an environment box body and an environment box sealing door; the environment box body is fixed on the central base cover plate; an environment box control system, a cold air pipe and a hot air pipe are arranged in the environment box body;
the x forward stretching mechanism comprises an x forward stretching module, and the x forward stretching module comprises a stretching cylinder; round holes are formed in four sides of the box body of the environment box, the round holes allow the stretching cylinder to horizontally move along the axis in the environment box, and the environment box is guaranteed to be relatively closed.
Furthermore, the central base and the peripheral bed body base are provided with horizontal adjusting feet for adjusting the levelness of the central base and the peripheral bed body base.
Furthermore, the x forward stretching mechanism further comprises an x forward lead screw module, an x forward linear slide rail pair, a stretching seat, a tension sensor mounting seat and a nut seat connecting plate;
the x forward lead screw module comprises a servo motor A, a motor A mounting seat, a servo elastic coupling, a first lead screw supporting seat, a servo motor B, a nut seat, a motor B mounting seat, a synchronous belt, an upper synchronous belt pulley, a lower synchronous belt pulley, a drag chain, a ball screw and a second lead screw supporting seat;
the x forward stretching module further comprises a clamp connecting plate and a clamp;
the x forward linear slide rail pair comprises a guide rail and a slide block;
the servo motor A is connected with one end of the servo elastic coupling through a bolt; the other end of the servo elastic coupling is connected with the ball screw through a key; the servo motor B is connected with the lower synchronous belt pulley through a key so as to drive the synchronous belt to enable the upper synchronous belt pulley to rotate, and then drives the screw nut to enable the ball screw to rotate, so that power transmission is realized; the first lead screw supporting seat is fixed below the lead screw mounting plate; the second screw rod supporting seat is fixed on the bottom plate, the end face of the ball screw is assembled on the second screw rod supporting seat, and the ball screw is supported by the second screw rod supporting seat; the locking nut fixes the moving end of the ball screw with the second screw support seat; the first lead screw supporting seat is assembled on the ball screw and is connected with the x forward linear sliding rail pair through a lead screw mounting plate;
the stretching cylinder is connected with the clamp connecting plate through a screw; the stretching cylinder is connected with the stretching seat through a screw and is used for driving the stretching cylinder to move in the x direction through the stretching seat;
the x forward linear sliding rail pair is connected with the stretching seat and the tension sensor mounting seat through a sliding block fastening block; the tension sensor mounting base is connected with the nut base connecting plate through a screw and used for driving the tension sensor mounting base to move on the x-direction linear sliding rail pair along the x direction through the ball screw.
Further, the x forward stretching mechanism further comprises a proximity switch, and the proximity switch is mounted on the side edge of the x forward linear sliding rail pair through a screw and used for controlling the safety position of the sliding block.
Further, the x forward stretching mechanism further comprises a stroke groove for measuring the displacement of the clamp.
The invention also provides a biaxial tension method using the biaxial tension tester, which comprises the following steps:
step S1, respectively clamping four clamping edges of the tested test piece by a clamp of the x positive stretching mechanism, a clamp of the x negative stretching mechanism, a clamp of the y positive stretching mechanism and a clamp of the y negative stretching mechanism;
step S2, the input end of the upper computer is respectively connected with the tension sensor, the travel switch and the environment box control system of each stretching mechanism; the output end of the upper computer is respectively connected with the servo motors of the stretching mechanisms;
step S3, setting initial parameters on the interface of the upper computer, including: load, the rotating speed of a servo motor of each stretching mechanism and the temperature of an environmental chamber;
step S4, the upper computer controls the temperature change of the environmental box according to the initial parameters, drives the servo motors of each stretching mechanism to act, and carries out bidirectional stretching on the test piece under the driving of the servo motors, namely: simultaneously stretching the test piece in the positive x direction, the negative x direction, the positive y direction and the negative y direction; in the process of performing biaxial tension on the test piece, the tension sensors of the tension mechanisms detect the change information of the tension borne by the test piece in real time, and upload the change information of the tension borne by the test piece to an upper computer in real time, and the change information is stored by the upper computer; in addition, in the process of carrying out biaxial tension on the test piece, the two proximity switches detect whether the slide block reaches the shortest stroke and the longest stroke in real time, so that the motion range of each tension mechanism is controlled, and the test safety is ensured;
and the upper computer obtains the biaxial tension performance of the tested piece by analyzing the change information of the tensile force applied to the test piece and the position change information of the sliding table in a correlation manner.
Compared with the prior art, the invention has the beneficial effects that:
1) the 4 groups of stretching mechanisms are arranged around the central seat in a cross shape. The base is in a welding form, and has high strength and high rigidity.
2) The whole machine is of an independent four-shaft structure, and each shaft is driven by an independent servo motor. The biaxial synchronous equal-proportion stretching of the cross test piece can be realized, and the biaxial variable-proportion stretching of the cross test piece and the in-situ synchronous stretching of a single-pull test piece can also be realized.
3) And each shaft is arranged by adopting a guide rail, so that the high rigidity and high precision of the whole machine in the test process are ensured.
4) The stretching cylinder is square, has high rigidity and is beneficial to sealing.
5) The chuck is convenient and flexible to disassemble, and can be replaced according to different materials and shapes of test pieces.
6) The temperature in the environment box can be flexibly adjusted according to test requirements, and the lifting speed of the temperature is flexible and adjustable. The environment box is provided with a defrosting system, so that the wall surface of the box body can be prevented from frosting in a low-temperature environment.
7) Each shaft is provided with a zero point and a positive limit, and the chuck automatically returns to the original position after the test is finished.
8) And a high-precision tension sensor (the data acquisition precision can reach 0.03%) is adopted, and the measurement precision of the tension is ensured.
9) Proximity switches are used to limit the travel of the stretching mechanism and the position of the starting point.
10) The force and displacement data acquisition, processing, display and storage functions can be realized.
11) Can realize two control modes of force and displacement.
Drawings
FIG. 1 is a schematic perspective view of a biaxial tension tester for mechanical property test of in vitro skin tissue according to the present invention;
FIG. 2 is an overall top view of the biaxial tension tester for in vitro skin tissue mechanical property test according to the invention;
FIG. 3 is a front view of a base of a biaxial tension tester for in vitro skin tissue mechanical property testing according to the invention;
FIG. 4 is a front view of the stretching mechanism of the present invention;
FIG. 5 is a top view of the lead screw module of the present invention;
FIG. 6 is a first left side view of the stretching mechanism of the present invention;
fig. 7 is a second left side view of the stretching mechanism of the present invention.
Detailed Description
The present invention is described in detail with reference to the embodiments shown in the drawings, but it should be understood that these embodiments are not intended to limit the present invention, and those skilled in the art should understand that functional, methodological, or structural equivalents or substitutions made by these embodiments are within the scope of the present invention.
The biaxial tensile testing machine for in-vitro skin tissue mechanical property testing provided in this embodiment can perform a transformation ratio/transformation ratio biaxial tensile test of orthogonal biaxial based on high-precision control of an ac servo motor under the condition of being equipped with a heating device, and can also perform uniaxial tensile and compression tests.
Referring to fig. 1 and 3, the bidirectional tensile testing machine for in-vitro skin tissue mechanical property testing comprises an environment box, a base, an x positive tensile mechanism 3-1, an x negative tensile mechanism 3-2, a y positive tensile mechanism 3-3 and a y negative tensile mechanism 3-4; the 4 stretching mechanisms are fixed by the base and are arranged in a cross-shaped circumference. The environment box comprises a box body 1-1 and an environment box sealing door 1-2. The tester can perform a biaxial transformation ratio/transformation ratio biaxial tension test of an orthogonal biaxial, and can also perform a uniaxial tension test and a compression test; the heating device is equipped, so that the double-pull test of the in-vitro skin tissue in a high-temperature environment can be realized; the device has the functions of load control, displacement control, strain control and the like.
The base and the stretching mechanism are described in detail below:
base and environment box
With reference to fig. 1 and 2, a schematic three-dimensional structure diagram of the bidirectional tensile testing machine for in-vitro skin tissue mechanical property testing provided by the invention is shown, wherein the base comprises a central bed body, an x positive peripheral bed body, an x negative peripheral bed body, a y positive peripheral bed body and a y negative peripheral bed body; the environmental box body 1-1 is fixed on the central bed body.
The central lathe bed comprises a central base cover plate 2-1 and a central base 2-2;
referring to fig. 3, the central base 2-2 and the peripheral bed body base 2-3 are provided with horizontal adjusting feet 2-4; and horizontal adjusting feet 2-4 are respectively arranged on the x positive direction peripheral bed body, the x negative direction peripheral bed body, the y positive direction peripheral bed body and the y negative direction peripheral bed body and are used for adjusting the levelness of the base.
(II) stretching mechanism
Referring to FIG. 1, an x positive stretching mechanism 3-1, an x negative stretching mechanism 3-2, a y positive stretching mechanism 3-3 and a y negative stretching mechanism 3-4 are arranged and fixed on a base in a cross shape.
The x forward stretching mechanism 3-1 is fixed on the x forward bed body; the x negative direction stretching mechanism 3-2 is fixed on the x negative direction upper bed body; the y forward stretching mechanism 3-3 is fixed on the y forward bed body; and the y-direction stretching mechanism 3-4 is fixed on the y-direction bed body.
The x positive stretching mechanism 3-1, the x negative stretching mechanism 3-2, the y positive stretching mechanism 3-3 and the y negative stretching mechanism 3-4 are identical in structure. The following description will be given only by taking an x-direction stretching mechanism as an example:
with reference to fig. 4 to 7, the drawing mechanism of the present invention is a front view, and includes an x forward lead screw module, an x forward drawing module, an x forward linear slide rail, a front drawing base 3-1-1, a tension sensor 3-1-2, a tension sensor mounting base 3-1-3, and a nut base connecting plate 3-1-4.
For the x forward lead screw module, comprising: 3-1-5 parts of a servo motor A, 3-1-6 parts of a motor A mounting seat, 3-1-7 parts of a servo elastic coupling, 3-1-8 parts of a first screw rod supporting seat, 3-1-9 parts of a servo motor B, 3-1-10 parts of a screw nut seat, 3-1-11 parts of a motor B mounting seat, 3-1-12 parts of a synchronous belt, 3-1-20 parts of an upper synchronous belt wheel, 3-1-21 parts of a lower synchronous belt wheel, 3-1-13 parts of a drag chain, 3-1-14 parts of a ball screw and 3-1-15 parts of a second screw rod supporting seat; for the x-direction stretch module, comprising: 3-1-16 parts of a stretching cylinder, 3-1-17 parts of a clamp connecting plate, 3-1-18 parts of a clamp and 3-1-19 parts of a locking nut; for the x-forward linear slide pair, comprising: guide rail 3-1-22, slide block 3-1-23.
For the x forward lead screw module, a servo motor A3-1-5 is connected with one end of a servo elastic coupling 3-1-7 through a bolt; the other end of the servo elastic coupling 3-1-7 is connected with a ball screw 3-1-14 through a key; meanwhile, the servo motor B3-1-9 is connected with the lower belt wheel 3-1-21 through a key to drive the synchronous belt wheel 3-1-12 to enable the upper belt wheel 3-1-20 to rotate, and then drives the nut to enable the ball screw 3-1-14 to rotate, so that power transmission is achieved; the first screw rod supporting seat 3-1-8 is fixed below the screw rod mounting plate 3-1-24; the second screw rod supporting seat 3-1-15 is fixed on the bottom plate, the end face of the ball screw rod 3-1-14 is assembled on the second screw rod supporting seat 3-1-15, and the locking nut 3-1-19 fixes the moving end of the ball screw rod 3-1-14 and the second screw rod supporting seat 3-1-15; the ball screw 3-1-14 is supported by a second screw support seat 3-1-15; the first screw rod supporting seat 3-1-8 is assembled on the ball screw rod 3-1-14 and is connected with the linear slide rail pair through a screw rod mounting plate 3-1-24.
The stretching cylinder 3-1-16 is connected with the clamp mounting seat 3-1-17 through a screw, the stretching cylinder 3-1-16 is connected with the front stretching seat 3-1-1 through a screw, and the stretching cylinder 3-1-16 is driven to move in the x direction through the front stretching seat 3-1-1.
The front stretching seat 3-1-1 and the tension sensor mounting seat 3-1-3 are connected through a slide block fastening block; the tension sensor mounting base 3-1-3 is connected with the nut base connecting plate 3-1-4 through a screw, so that the tension sensor mounting base 3-1-3 can be driven to move on the x positive linear slide rail along the x direction through the ball screw 3-1-14.
The x forward stretching mechanism further comprises a proximity switch, and the proximity switch is mounted on the side edge of the x forward linear sliding rail pair through a screw and used for controlling the safety position of the sliding blocks 3-1-15.
The proximity switches are arranged in three numbers and are respectively arranged at the starting position and the two end positions of the movement of the sliding block. And the proximity switch is used for limiting the stroke of the sliding block so as to prevent the stroke from being exceeded, equipment from being damaged and a vehicle from being collided.
The x-direction stretching mechanism further comprises a stroke groove which can be used for measuring the displacement of the clamps 3-1-18.
The biaxial tension method using the biaxial tension tester comprises the following steps:
step S1, respectively clamping four clamping edges of the tested test piece by a clamp of the x positive stretching mechanism, a clamp of the x negative stretching mechanism, a clamp of the y positive stretching mechanism and a clamp of the y negative stretching mechanism;
step S2, the input end of the upper computer is respectively connected with the tension sensor, the travel switch and the environment box control system of each stretching mechanism; the output end of the upper computer is respectively connected with the servo motors of the stretching mechanisms;
step S3, setting initial parameters on the interface of the upper computer, including: load, the rotating speed of a servo motor of each stretching mechanism and the temperature of an environmental chamber;
step S4, the upper computer controls the temperature change of the environmental box according to the initial parameters and drives the servo motors of each stretching mechanism to act, the servo motors are connected with the servo elastic couplings, the screw rods are connected with the servo elastic couplings to complete power transmission and drive the screw rods to move, the x forward linear slide rail is connected with the screw rods and the screw nuts through the nut seat connecting plate, and the stretching seats and the tension sensors are both connected with the x forward linear slide rail to realize the movement of the stretching cylinders; through the above operations, the test piece can be subjected to bidirectional synchronous equal-proportion stretching, namely: the test piece is stretched towards the positive direction x, the negative direction x, the positive direction y and the negative direction y at the same time, and besides, the biaxial variable-proportion stretching of the test piece and the in-situ synchronous stretching of a single-pulled test piece can also be realized; in the process of performing biaxial tension on the test piece, the tension sensors of the tension mechanisms detect the change information of the tension borne by the test piece in real time, and upload the change information of the tension borne by the test piece to an upper computer in real time, and the change information is stored by the upper computer; in addition, in the process of carrying out biaxial tension on the test piece, two proximity switches detect whether the sliding table reaches the shortest stroke and the longest stroke in real time, and then control the motion range of each stretching mechanism to do, guarantee the test safety.
And the upper computer obtains the biaxial tension performance of the tested piece by analyzing the change information of the tensile force applied to the test piece and the position change information of the sliding table in a correlation manner.
The function and design parameters of the biaxial tension tester are as follows:
(1) the tensile test of skin tissues under different temperatures and humidities can be realized;
(2) the device has the unidirectional and orthogonal bidirectional stretching functions, and can realize the two-dimensional stretching, relaxation and creep tests of a square sample;
(3) the orthogonal bidirectional pull-up test of alternating load and variable proportion load can be realized;
(4) the environmental temperature range conditions of the test chamber reach: -10 ℃ to 60 ℃;
(5) test speed (mm/s): 0 to 100
(6) The protection of load and displacement limit positions is provided;
(7) the force and displacement control system has two control modes of force and displacement and has the functions of force and displacement data acquisition, processing and storage;
(8) test automatic zero setting, sensor automatic identification, Ethernet and USB dual interface
(9) The test data can be imported into EXCEL for storage and processing.
The drawing mechanism is characterized in that:
(1) and four-axis coordinated motion in two directions is completed based on a servo motion control system. Load, displacement and strain closed-loop control, high response speed and high control precision.
(2) The screw rod and linear slide rail structure is adopted, the repeated positioning precision is high, the rigidity is good, and the working environment of experimenters is quiet and clean.
(3) The four shafts are relatively independent, not only can be subjected to biaxial tension tests and unidirectional tension tests, but also can be subjected to unidirectional compression tests, namely loading and unloading tests, so that a foundation is provided for researching material resilience, and the machine is multifunctional.
(4) The tension sensor is arranged, the purpose is to test the real-time change of the tension borne by the cross-shaped test piece, and the device is compact in structure, high in measurement precision and strong in unbalance loading resistance.
(5) The two sides of the lead screw mounting plate are provided with stroke grooves for controlling the movement position of the stretching mechanism, namely ensuring that the slide block cannot exceed the range.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (6)

1. A bidirectional tensile testing machine for in-vitro skin tissue mechanical property testing is characterized by comprising an environment box, a base, an x positive tensile mechanism (3-1), an x negative tensile mechanism (3-2), a y positive tensile mechanism (3-3) and a y negative tensile mechanism (3-4); the x positive stretching mechanism (3-1), the x negative stretching mechanism (3-2), the y positive stretching mechanism (3-3) and the y negative stretching mechanism (3-4) have the same structure;
the x positive stretching mechanism (3-1), the x negative stretching mechanism (3-2), the y positive stretching mechanism (3-3) and the y negative stretching mechanism (3-4) are arranged and fixed on the base in a cross shape;
the base comprises a central lathe bed, an x positive peripheral lathe bed, an x negative peripheral lathe bed, a y positive peripheral lathe bed and a y negative peripheral lathe bed; the x forward stretching mechanism (3-1) is fixed on the x forward bed body; the x negative direction stretching mechanism (3-2) is fixed on the x negative direction upper bed body; the y forward stretching mechanism (3-3) is fixed on the y forward bed body; the y-direction stretching mechanism (3-4) is fixed on the y-direction bed body;
the central lathe bed comprises a central base cover plate (2-1) and a central base (2-2), and the central base cover plate (2-1) is arranged on the central base (2-2); the x positive direction peripheral lathe bed, the x negative direction peripheral lathe bed, the y positive direction peripheral lathe bed and the y negative direction peripheral lathe bed have the same structure and are composed of peripheral lathe bed bases (2-3);
the environment box comprises an environment box body (1-2) and an environment box sealing door (1-2); the environment box body (1-2) is fixed on the central base cover plate (2-1); an environment box control system, a cold air pipe and a hot air pipe are arranged in the environment box body (1-1);
the x forward stretching mechanism (3-1) comprises an x forward stretching module which comprises a stretching cylinder (3-1-16); round holes are formed in four sides of the environment box body (1-2), and the round holes allow the stretching cylinders (3-1-16) to horizontally move along the axis of the stretching cylinders in the environment box, so that the environment box is relatively closed.
2. The biaxial tension testing machine for ex vivo skin tissue mechanical property testing according to claim 1, characterized in that the central base (2-2) and the peripheral bed base (2-3) are provided with horizontal adjustment feet (2-4) for adjusting levelness of the central base (2-2) and the peripheral bed base (2-3).
3. The bidirectional tensile testing machine for in-vitro skin tissue mechanical property testing according to claim 1, wherein the x forward tensile mechanism (3-1) further comprises an x forward lead screw module, an x forward linear sliding rail pair, a tensile seat (3-1-1), a tension sensor (3-1-2), a tension sensor mounting seat (3-1-3) and a nut seat connecting plate (3-1-4);
the x forward lead screw module comprises a servo motor A (3-1-5), a motor A mounting seat (3-1-6), a servo elastic coupling (3-1-7), a first lead screw supporting seat (3-1-8), a servo motor B (3-1-9), a screw seat (3-1-10), a motor B mounting seat (3-1-11), a synchronous belt (3-1-12), an upper synchronous belt pulley (3-1-20), a lower synchronous belt pulley (3-1-21), a drag chain (3-1-13), a ball lead screw (3-1-14) and a second lead screw supporting seat (3-1-15);
the x forward stretching module further comprises a clamp connecting plate (3-1-17), a clamp (3-1-18) and a locking nut (3-1-19);
the x forward linear sliding rail pair comprises a guide rail (3-1-22) and a sliding block (3-1-23);
the servo motor A (3-1-5) is connected with one end of the servo elastic coupling (3-1-7) through a bolt; the other end of the servo elastic coupling (3-1-7) is connected with the ball screw (3-1-14) through a key; the servo motor B (3-1-9) is connected with the lower synchronous belt wheel (3-1-21) through a key to drive the synchronous belt (3-1-12) to enable the upper synchronous belt wheel (3-1-20) to rotate, and then drives the screw nut to enable the ball screw (3-1-14) to rotate, so that power transmission is achieved; the first screw rod supporting seat (3-1-8) is fixed below the screw rod mounting plate (3-1-24); the second screw rod supporting seat (3-1-15) is fixed on the bottom plate, the end face of the ball screw rod (3-1-14) is assembled on the second screw rod supporting seat (3-1-15), and the ball screw rod (3-1-14) is supported by the second screw rod supporting seat (3-1-15); the locking nut (3-1-19) fixes the moving end of the ball screw (3-1-14) and the second screw support seat (3-1-15); the first screw rod supporting seat (3-1-8) is assembled on the ball screw rod (3-1-14) and is connected with the x forward linear sliding rail pair through a screw rod mounting plate (3-1-24);
the stretching cylinder (3-1-16) is connected with the clamp connecting plate (3-1-17) through a screw; the stretching cylinder (3-1-11) is connected with the stretching seat (3-1-1) through a screw and is used for driving the stretching cylinder (3-1-16) to move in the x direction through the stretching seat (3-1-1);
the x forward linear sliding rail pair is connected with the stretching seat (3-1-1) and the tension sensor mounting seat (3-1-3) through a sliding block fastening block; the tension sensor mounting seat (3-1-3) is connected with the nut seat connecting plate (3-1-4) through a screw and used for driving the tension sensor mounting seat (3-1-3) to move on the x forward linear sliding rail pair along the x direction through the ball screw (3-1-14).
4. The biaxial tension tester oriented to the ex vivo skin tissue mechanical property test of claim 3, wherein the x forward tension mechanism further comprises a proximity switch, and the proximity switch is mounted on the side of the x forward linear sliding rail pair through a screw and used for controlling the safety position of the sliding block (3-1-23).
5. The biaxial tension tester oriented to the ex vivo skin tissue mechanical property test of claim 4, wherein the x-direction stretching mechanism further comprises a stroke slot for measuring the displacement of the clamp (3-1-18).
6. A biaxial stretching method using the biaxial stretching testing machine according to any one of claims 1 to 5, characterized by comprising the steps of:
step S1, respectively clamping four clamping edges of the tested test piece by a clamp of the x positive stretching mechanism, a clamp of the x negative stretching mechanism, a clamp of the y positive stretching mechanism and a clamp of the y negative stretching mechanism;
step S2, the input end of the upper computer is respectively connected with the tension sensor, the travel switch and the environment box control system of each stretching mechanism; the output end of the upper computer is respectively connected with the servo motors of the stretching mechanisms;
step S3, setting initial parameters on the interface of the upper computer, including: load, the rotating speed of a servo motor of each stretching mechanism and the temperature of an environmental chamber;
step S4, the upper computer controls the temperature change of the environmental box according to the initial parameters, drives the servo motors of each stretching mechanism to act, and carries out bidirectional stretching on the test piece under the driving of the servo motors, namely: simultaneously stretching the test piece in the positive x direction, the negative x direction, the positive y direction and the negative y direction; in the process of performing biaxial tension on the test piece, the tension sensors of the tension mechanisms detect the change information of the tension borne by the test piece in real time, and upload the change information of the tension borne by the test piece to an upper computer in real time, and the change information is stored by the upper computer; in addition, in the process of carrying out biaxial tension on the test piece, the two proximity switches detect whether the slide block reaches the shortest stroke and the longest stroke in real time, so that the motion range of each tension mechanism is controlled, and the test safety is ensured;
and the upper computer obtains the biaxial tension performance of the tested piece by analyzing the change information of the tensile force applied to the test piece and the position change information of the sliding table in a correlation manner.
CN202011159711.5A 2020-10-26 2020-10-26 Bidirectional tensile testing machine and method for in-vitro skin tissue mechanical property test Pending CN112198308A (en)

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Application Number Priority Date Filing Date Title
CN202011159711.5A CN112198308A (en) 2020-10-26 2020-10-26 Bidirectional tensile testing machine and method for in-vitro skin tissue mechanical property test

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CN112198308A true CN112198308A (en) 2021-01-08

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