CN112798442B - Device and method for testing normal fatigue of rubber material - Google Patents
Device and method for testing normal fatigue of rubber material Download PDFInfo
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- CN112798442B CN112798442B CN202011462978.1A CN202011462978A CN112798442B CN 112798442 B CN112798442 B CN 112798442B CN 202011462978 A CN202011462978 A CN 202011462978A CN 112798442 B CN112798442 B CN 112798442B
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- 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
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
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- 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
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- 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
- G01N2203/0001—Type of application of the stress
- G01N2203/0005—Repeated or cyclic
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- 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
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- 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
- G01N2203/0073—Fatigue
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- 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
- G01N2203/0075—Strain-stress relations or elastic constants
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- 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
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0682—Spatial dimension, e.g. length, area, angle
Abstract
The application provides a device and a method for testing normal fatigue of a rubber material, wherein the device comprises: the clamp comprises a first abutting piece and a second abutting piece which are arranged oppositely, and the first abutting piece and the second abutting piece are respectively used for abutting against two sides which are arranged oppositely to the rubber material to be tested; the stress loading assembly is fixedly arranged with the clamp and is used for applying cyclic stress to the rubber material to be tested through the clamp so as to enable the rubber material to be tested to circularly stretch and rebound along the normal direction; the strain measurement component is used for measuring the strain value of the rubber material to be measured under the action of the current cycle times and the cyclic stress; the processor is used for obtaining a curve of compliance and cycle times according to a plurality of groups of cyclic stress, strain values and cycle times after the to-be-tested rubber material is fractured along the normal direction; obtaining an inflection point of the curve, and determining the inflection point as a fatigue critical point of the rubber material to be tested; wherein the compliance is equal to the ratio of the strain value to the maximum stress value of the cyclic stress. Through the mode, the normal mechanical property of the rubber material can be accurately measured.
Description
Technical Field
The application belongs to the technical field of testing, and particularly relates to a device and a method for testing normal fatigue of a rubber material.
Background
The glue material and the membrane material of the folding screen at the bending position are stressed in all directions, and all the stresses can be decomposed into two dimensions of a tangential direction and a normal direction in a Cartesian coordinate system. In the tangential direction, the glue material is isotropic; in the normal direction, the rubber material has anisotropy, the difference of results caused by the difference of measurement methods is large, and the traditional fatigue test method (such as a residual strain method, an internal energy consumption method and the like) suitable for the tangential direction cannot be applied to the normal direction, so that a blank of the rubber material normal performance evaluation method is caused.
Disclosure of Invention
The application provides a device and a method for testing normal fatigue of a rubber material, which aim to solve the technical problem that the normal mechanical property of the rubber material is difficult to evaluate.
In order to solve the technical problem, the application adopts a technical scheme that: the utility model provides a device of test glue material normal direction fatigue, includes: the clamp comprises a first abutting piece and a second abutting piece which are arranged oppositely, and the first abutting piece and the second abutting piece are respectively used for abutting against two sides which are arranged oppositely to the rubber material to be tested; the stress loading assembly is fixedly arranged with the clamp and used for applying cyclic stress to the rubber material to be tested through the clamp so as to enable the rubber material to be tested to circularly stretch and rebound along the normal direction; the strain measurement component is used for measuring the strain value of the rubber material to be measured under the action of the current cycle times and the cyclic stress; the processor is coupled with the stress loading assembly and the strain measuring assembly and used for obtaining a curve of compliance and cycle times according to the multiple groups of cyclic stress, strain values and cycle times after the to-be-tested rubber material is fractured along the normal direction; obtaining an inflection point of the curve, and determining the inflection point as a fatigue critical point of the to-be-tested rubber material; wherein the compliance is equal to a ratio of the strain value and a maximum stress value of the cyclic stress.
The water drop angle of the surfaces of the first abutting piece and the second abutting piece, which are contacted with the rubber material to be tested, is less than or equal to 30 degrees, so that the rubber material to be tested can not be separated from the first abutting piece and the second abutting piece in an interface separation manner in the fatigue test process.
The first abutting piece comprises a first fixed seat and a first abutting part fixedly arranged on the first fixed seat; the second abutting piece comprises a second fixed seat and a second abutting part fixedly arranged on the second fixed seat; the first abutting portion and the second abutting portion are respectively used for abutting against two sides of the to-be-tested rubber material in a back-to-back mode, and the first fixing seat and the second fixing seat are detachably fixed with the stress loading assembly respectively.
The first abutting portion and the second abutting portion are made of metal, and the water drop angle of the surfaces, opposite to each other, of the first abutting portion and the second abutting portion is smaller than or equal to 30 degrees.
The first abutting part and/or the second abutting part comprise abutting seats, adhesive layers and base materials which are arranged in a stacked mode, the abutting seats are fixedly connected with the fixing seats at the corresponding positions, and one side surface, away from the adhesive layers, of the base materials is used for abutting against the to-be-tested adhesive material; the modulus of the adhesive layer is at least three orders of magnitude higher than that of the to-be-detected adhesive material, and the water drop angle of the surface of the base material, which is far away from one side of the adhesive layer, is less than or equal to 30 degrees.
The outer contours of the surfaces, which are oppositely arranged, of the first abutting part and the second abutting part are the same. Preferably, the first fixing seat, the second fixing seat, the first abutting portion and the second abutting portion are cylinders, and axes of the first fixing seat, the second fixing seat, the first abutting portion and the second abutting portion are overlapped.
Wherein the stress loading assembly comprises: the device comprises a first base, a second base and a driving piece, wherein the first base and the second base are oppositely arranged; the first base and the second base are respectively fixed with the first abutting piece and the second abutting piece, and the driving piece is used for driving the second base to move close to or away from the first base.
In order to solve the above technical problem, another technical solution adopted by the present application is: there is provided a method for testing normal fatigue of a glue material, using the apparatus described in any of the above embodiments, the method comprising: placing a rubber material to be tested between the first abutting piece and the second abutting piece which are oppositely arranged; applying cyclic stress to the rubber material to be tested through the stress loading assembly so as to enable the rubber material to be tested to circularly stretch and rebound along the normal direction, and obtaining the current cycle number and a strain value under the cyclic stress through the strain measuring assembly; responding to the breakage of the to-be-tested rubber material along the normal direction, and obtaining a curve of compliance and the cycle times according to multiple groups of the cycle times, the cycle stress and the strain value, wherein the compliance is equal to the ratio of the strain value to the maximum stress value of the cycle stress; and obtaining an inflection point of the curve, and determining the inflection point as a fatigue critical point of the to-be-tested rubber material.
Wherein, through the stress loading subassembly is to the step of the gluey material application cyclic stress that awaits measuring includes: and applying sinusoidal or rectangular or triangular or pulse or oscillating cyclic stress to the rubber material to be tested through the stress loading assembly.
Wherein, said respond to the glue material that awaits measuring along the normal direction breaks and according to the multiunit the cycle number, cyclic stress and strain value obtain the compliance with between the curve of cycle number, still include: judging whether at least partial surfaces of the first abutting piece and the second abutting piece are exposed out of the rubber material to be detected; if so, discarding the current test data.
Being different from the prior art situation, the beneficial effect of this application is: the device and the method for testing the normal fatigue of the rubber material can determine the fatigue critical point through the compliance inflection point, fill up the blank of evaluating the normal fatigue performance of the rubber material, and open up a new direction for subsequent evaluation of the normal performance of the rubber material or a normal and tangential combined mechanical model.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:
FIG. 1 is a schematic structural view of an embodiment of a bent rubber material;
FIG. 2 is a schematic structural diagram of an embodiment of an apparatus for testing normal fatigue of a plastic material according to the present application;
FIG. 3 is a schematic structural view of another embodiment of the clamp of FIG. 2;
FIG. 4 is a schematic flow chart illustrating an embodiment of a method for testing normal fatigue of a glue material according to the present application;
FIG. 5 is a graph illustrating one embodiment of order and compliance for different maximum stress values;
fig. 6 is a graph illustrating the times and the rubber material stress for an embodiment with the maximum stress value of 4.75N.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
As shown in fig. 1, in a cartesian coordinate system, the stress applied to the bending vertex when the rubber material 10 is bent can be decomposed into two dimensions of a tangential direction X and a normal direction Y, and the normal direction Y can be understood as the thickness direction of the rubber material 10. Due to the small thickness of the rubber material 10, it is difficult for the clamp in the prior art to perform the stretching and compressing motion of the rubber material 10 along the normal direction, which results in a blank of the method for evaluating the normal performance of the rubber material 10.
To solve the technical problem, please refer to fig. 2, fig. 2 is a schematic structural diagram of an embodiment of the device for testing normal fatigue of a rubber material according to the present application; the apparatus 30 includes a fixture 20, a stress loading assembly (not labeled), a strain measurement assembly (not shown), and a processor.
The clamp 20 includes a first abutting member 200 and a second abutting member 202, which are disposed oppositely, and are used for abutting against two opposite sides of the to-be-tested adhesive material 10. The adhesive material 10 to be tested can be any high polymer material with adhesion, such as optical adhesive OCA, pressure-sensitive adhesive PSA, and the like, which are commonly used in foldable screens; and gel-like materials, for example.
The stress loading assembly is fixedly arranged opposite to the clamp 20, and is used for applying cyclic stress required by a fatigue test to the rubber material 10 to be tested through the clamp 20 so as to enable the rubber material 10 to be tested to perform cyclic tensile rebound along a normal direction (as shown by a dashed double-headed arrow in fig. 2). The cyclic stress mentioned above can be sinusoidal or rectangular or triangular or pulse or oscillation cyclic stress; the oscillating cyclic stress is stress with periodically changing magnitude along with time, and the stress value gradually changes from the maximum value to the minimum value in the same period. Optionally, in this embodiment, the stress loading assembly includes a first base 300 and a second base 302, which are oppositely disposed, and a driving member (not shown); the first base 300 and the second base 302 are respectively fixed to the first abutting part 200 and the second abutting part 202, and the driving part drives the second base 302 to move close to or away from the first base 300, so that the rubber material 10 to be tested is subjected to cyclic stretching rebound along the normal direction, and cyclic stress is applied to the rubber material 10 to be tested.
The strain measurement component is used for measuring a strain value generated by the to-be-measured rubber material 10 under the action of the current cycle times and the cyclic stress; optionally, a mechanical sensor may be disposed at the position of the second base 302, and a strain value may be obtained through calculation of the mechanical sensor and software; alternatively, the strain measurement component includes a displacement detection element (e.g., an optical encoder, etc.), and the strain value generated by the rubber material 10 to be measured under the action of the cyclic stress is directly detected and obtained by the displacement detection element.
The processor is coupled with the stress loading assembly and the strain measuring assembly and is used for controlling the cyclic stress applied by the stress loading assembly and receiving the strain value obtained by the test of the strain measuring assembly. After the to-be-tested adhesive material 10 is broken along the normal direction, the processor can obtain a curve of compliance and cycle times according to multiple groups of cyclic stress, strain values and cycle times, further obtain an inflection point from the curve, and determine the inflection point as a fatigue critical point of the to-be-tested adhesive material 10; wherein the compliance is equal to the ratio of the strain value to the maximum stress value of the cyclic stress. The analysis process for a particular processor will be described in detail in the methods section that follows.
Through the design mode, the device for testing the normal fatigue of the rubber material can determine the fatigue critical point through the compliance inflection point, fills the blank of evaluating the normal fatigue performance of the rubber material, and opens up a new direction for subsequent evaluation of the normal performance or normal and tangential combined mechanical model of the rubber material.
In the present embodiment, the above-mentioned apparatus 30 can be formed by modifying any existing mechanical instrument with cyclic stress/strain function, for example, the first base 300 and the second base 302 in fig. 2 can be existing on the original dynamic thermomechanical analyzer DMA, and the driving members in the clamp 20 and the stress loading assembly 300 can be newly added. Through the design mode, the hardware cost of the device 30 for testing the normal fatigue of the rubber material can be reduced.
In one embodiment, referring to fig. 2 again, the water drop angle of the surface of the clamp 20 where the first supporting member 200 and the second supporting member 202 contact the to-be-tested glue material 10 is less than or equal to 30 ° (e.g., 25 °, 20 °, 15 °, etc.), so that the surface of the clamp 20 contacting the to-be-tested glue material 10 has high surface energy, and the to-be-tested glue material 10 does not have interface separation with the first supporting member 200 and the second supporting member 202 during the normal (i.e., thickness direction) stretching or compressing process of the to-be-tested glue material 10; when the rubber material 10 to be tested fails due to fatigue, the rubber material 10 to be tested remains on the surfaces of the first abutting piece 200 and the second abutting piece 202, and neither the first abutting piece 200 nor the second abutting piece 202 is exposed out of the rubber material 10 to be tested on the surfaces. The design method enables the position of the to-be-tested rubber material 10, which fails in the fatigue test process, to be in the to-be-tested rubber material 10, so that the test result can accurately reflect the normal mechanical property of the to-be-tested rubber material 10.
In the present embodiment, as shown in fig. 2, the first abutting piece 200 includes a first fixing seat 2000 and a first abutting portion 2002 fixedly disposed on the first fixing seat 2000; the second abutting piece 202 comprises a second fixed seat 2020 and a second abutting portion 2022 fixedly arranged on the second fixed seat 2020; the first abutting portion 2002 and the second abutting portion 2022 are respectively used for abutting against two sides of the to-be-tested glue material 10, which are arranged opposite to each other, that is, a water drop angle of the surface of the first abutting portion 2002 and the surface of the second abutting portion 2022 abutting against the to-be-tested glue material 10 is less than or equal to 30 degrees; the first fixing seat 2000 and the second fixing seat 2020 are respectively configured to be detachably fixed to the stress loading assembly, for example, at least one threaded hole may be provided on the first fixing seat 2000 and the second fixing seat 2020, and the first fixing seat 2000 and the second fixing seat 2020 may be detachably fixed to the stress loading assembly by using a screw or the like; the subsequent stress loading assembly can apply cyclic stress to the rubber material 10 to be tested through the clamp 20. The structure of the fixture 20 is simple, and the fixture can be detachably fixed to any mechanical instrument with cyclic stress/strain function (e.g., a dynamic thermomechanical analyzer DMA, etc.) through the first fixing base 2000 and the second fixing base 2020, so as to reduce the hardware cost required for testing the normal mechanical property of the rubber material 10.
Alternatively, the first abutting portion 2002 and the second abutting portion 2022 in fig. 2 are made of metal, for example, stainless steel, and the like, and a water drop angle of a surface where the first abutting portion 2002 and the second abutting portion 2022 are oppositely disposed is less than or equal to 30 °, for example, by means of fine grinding with sandpaper. The first abutting portion 2002 and the second abutting portion 2022 can easily achieve the purpose of high surface energy.
Alternatively, as shown in fig. 3, fig. 3 is a schematic structural diagram of another embodiment of the clamp in fig. 2. The first abutting portion 2002a comprises a first abutting seat 20020, a first adhesive layer 20022 and a first base material 20024 which are arranged in a stacked mode, the first abutting seat 20020 is fixedly connected with the first fixing seat 2000, and one side surface, away from the first adhesive layer 20022, of the first base material 20024 is used for abutting against the to-be-tested adhesive material 10; that is, the water drop angle of the surface of the first substrate 20024 away from the first adhesive layer 20022 is less than or equal to 30 °, the material of the first substrate 20024 may be polyethylene terephthalate PET, and the water drop angle of the surface of the first supporting seat 20020 is not limited. In addition, the modulus of the first adhesive layer 20022 is at least three orders of magnitude higher than that of the adhesive material 10 to be tested, and at this time, the first adhesive layer 20022 can be regarded as a rigid body in the fatigue test process of the adhesive material 10 to be tested, and the first adhesive layer 20022 and the first base material 20024 and the first abutting base 20020 on the two sides do not have interface separation. The first abutting portion 2002a is simple in design and easy to implement; for example, a high surface energy adhesive tape (i.e., the first adhesive layer 20022 and the first substrate 20024) can be directly attached to the first holder 20020 without limitation on the water drop angle, so as to achieve the requirement of high surface energy of the fixture 20.
Similarly, as shown in fig. 3, a structure similar to that of the first abutting portion 2002a described above may be adopted for the second abutting portion 2022a at the same time or separately. Specifically, the second abutting portion 2022a includes a second abutting base 20220, a second adhesive layer 20222 and a second base 20224, which are stacked, the second abutting base 20220 is fixedly connected to the second fixing base 2020, and a side surface of the second base 20224 away from the second adhesive layer 20222 is used for abutting against the to-be-tested adhesive material 10; that is, the water drop angle of the surface of the second base 20224 away from the second adhesive layer 20222 is less than or equal to 30 °, the material of the second base 20224 may be PET, and the water drop angle of the surface of the second abutting base 20220 is not limited. In addition, the modulus of the second adhesive layer 20222 is at least three orders of magnitude higher than the modulus of the to-be-tested adhesive material 10, and at this time, the second adhesive layer 20222 can be regarded as a rigid body during the fatigue test of the to-be-tested adhesive material 10, and the second adhesive layer 20222 and the second base material 20224 and the second abutment 20220 on both sides do not have interface separation.
Referring to fig. 2, the outer contours of the surfaces of the first abutting portion 2002 and the second abutting portion 2022 opposite to each other are the same, for example, the surfaces of the first abutting portion 2002 and the second abutting portion 2022 opposite to each other are circular with the same shape and area. The design mode can ensure that the cross-sectional area of the rubber material 10 to be tested is constant in the fatigue test process, and then the subsequent stress-strain detection is more accurate. Certainly, in some cases, the second abutting portion 2022 may be connected to a pressure sensor, so as to make the pressure sensor detect more sensitively, a weight reduction process may be performed on the second abutting portion 2022 and the second fixing base 2020, and an outer contour area of a surface of the second abutting portion 2022 contacting the to-be-detected rubber material 10 may be smaller than an outer contour area of a surface of the first abutting portion 2002 contacting the to-be-detected rubber material 10.
Optionally, in this embodiment, the first fixing seat 2000, the second fixing seat 2020, the first abutting portion 2002 and the second abutting portion 2022 are cylinders, and axes of the first fixing seat 2000, the second fixing seat 2020, the first abutting portion 2002 and the second abutting portion 2022 are overlapped. The design method can ensure that the whole glue material 10 to be tested is stressed more uniformly.
The method for performing the fatigue test on the rubber material 10 to be tested by using the above-mentioned apparatus 30 will be described in detail. Referring to fig. 2 and 4 together, fig. 4 is a schematic flow chart of an embodiment of a method for testing normal fatigue of a rubber material according to the present application, the method specifically includes:
s101: the rubber material 10 to be tested is placed between the first abutting piece 200 and the second abutting piece 202 which are oppositely arranged.
Specifically, before the step S101, the method further includes: providing a whole rubber material 10, wherein release films can be arranged on two opposite sides of the whole rubber material 10; the cutting knife is used to cut a sample with a predetermined size from the whole rubber material 10 as the rubber material 10 to be measured, and the shape and area of the cut rubber material 10 to be measured can be the same as the surfaces of the first abutting piece 200 and the second abutting piece 202 used for contacting with the rubber material 10 to be measured. The step S101 specifically includes: removing the release film on one side of the adhesive material 10 to be tested, and contacting the exposed adhesive material 10 to be tested with the first abutting piece 200 or the second abutting piece 202; then, the release film on the other side is removed, and the exposed adhesive material 10 to be tested is contacted with the second abutting piece 202 or the first abutting piece 200.
S102: and applying cyclic stress to the rubber material 10 to be tested through the stress loading assembly so as to enable the rubber material 10 to be tested to perform cyclic stretching rebound along the normal direction, and obtaining the current cycle number and a strain value under the cyclic stress through the strain measuring assembly.
Specifically, a sinusoidal, rectangular, triangular, pulse or oscillating cyclic stress can be applied to the rubber material 10 to be tested through the stress loading assembly; for example, the second base 302 in the stress loading assembly can move toward or away from the first base 300, so as to apply a cyclic stress to the adhesive material 10 to be tested; and during the application process, a counter can be arranged in the processor to record the cycle number of the currently applied cyclic stress.
S103: responding to the normal fracture of the rubber material 10 to be tested, and obtaining a curve of the compliance and the cycle times according to a plurality of groups of cycle times, cycle stress and strain values; wherein, compliance C f Equal to the ratio of the strain value epsilon to the maximum stress value sigma of the cyclic stress, i.e. C f ＝ε/σ。
Specifically, in this embodiment, in order to ensure that the data in the obtained curve can faithfully reflect the normal failure condition of the rubber material 10 to be tested, rather than the interface failure between the rubber material 10 to be tested and the fixture, the step S103, between the step of responding to the breakage of the rubber material 10 to be tested along the normal direction and obtaining the curve of the compliance and the cycle number according to the multiple sets of cycle number, cycle stress and strain value, further includes: judging whether at least partial surfaces of the first abutting piece 200 and the second abutting piece 202 are exposed out of the rubber material 10 to be detected; if yes, discarding the current test data; further, the adhesive material 10 to be tested can be cut again, and the test can be performed again under the test condition to obtain data.
S104: and obtaining an inflection point of the curve, and determining the inflection point as a fatigue critical point of the rubber material 10 to be tested.
Specifically, an inflection point may be determined according to the slope of the tangent at each point on the curve, for example, if the slope of the tangent at the certain point exceeds a threshold, the point may be determined as the inflection point. Preferably, when the X-axis abscissa of the curve is a predetermined number of times and the Y-axis ordinate is the compliance, if the tangent at a certain point position is approximately parallel to the Y-axis, the point may be determined as an inflection point. In addition, the section where the number of times corresponding to the fatigue critical point is from 0 time can be used as the fatigue section of the rubber material 10 to be tested.
Referring to fig. 5, fig. 5 is a graph illustrating an embodiment of cycle number and compliance under different maximum stress values. As can be seen from fig. 5, as the number of stress cycles increases, the compliance of the to-be-tested adhesive material 10 gradually increases, after a certain cycle interval, the compliance of the to-be-tested adhesive material 10 rapidly increases after passing through an inflection point, and then the to-be-tested adhesive material 10 fails in the normal direction, and the testing modulus (reciprocal of the compliance) rapidly returns to zero; and it can be seen that the smaller the maximum stress value, the slower the inflection point comes.
To confirm the accuracy of determining the fatigue critical point of the adhesive material 10 to be tested by using the compliance, please refer to fig. 6, in which fig. 6 is a graph illustrating the frequency of the maximum stress value of 4.75N and the adhesive material stress according to an embodiment. As can be seen from fig. 6, as the number of cycles increases, the stress of the rubber material 10 to be measured decreases, the modulus decreases, and the compliance increases; and in fig. 6 at a cycle number of 10 4 To 10 5 In between, the stress of the rubber material 10 to be tested has a rapid descending trend, which indicates that the cycle number of the rubber material 10 to be tested is 10 4 To 10 5 And the results are consistent with those in fig. 6.
In conclusion, the testing method provided by the application has universality, can be applied to wider material stress tests, and opens up a new direction for subsequent evaluation of the normal performance or normal and tangential combined mechanical model of the rubber material.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.
Claims (11)
1. The utility model provides a device that test glued material normal direction is tired which characterized in that includes:
the clamp comprises a first abutting piece and a second abutting piece which are arranged oppositely, and the first abutting piece and the second abutting piece are respectively used for abutting against two sides which are arranged oppositely to the rubber material to be tested;
the stress loading assembly is fixedly arranged with the clamp and used for applying cyclic stress to the rubber material to be tested through the clamp so as to enable the rubber material to be tested to circularly stretch and rebound along the normal direction;
the strain measurement component is used for measuring a strain value of the to-be-measured rubber material under the action of the current cycle times and the cyclic stress;
the processor is coupled with the stress loading assembly and the strain measuring assembly and used for obtaining a curve of compliance and cycle times according to the multiple groups of cyclic stress, strain values and cycle times after the rubber material to be measured is fractured along the normal direction; obtaining the tangent slope of each point position on the curve, responding to the fact that the tangent slope exceeds a threshold value, taking a point corresponding to the tangent slope as an inflection point, and determining the inflection point as a fatigue critical point of the rubber material to be tested; wherein the compliance is equal to a ratio of the strain value and a maximum stress value of the cyclic stress.
2. The apparatus of claim 1,
the water drop angle of the surfaces of the first abutting piece and the second abutting piece, which are contacted with the rubber material to be tested, is less than or equal to 30 degrees, so that the rubber material to be tested can not be separated from the first abutting piece and the second abutting piece in the fatigue test process.
3. The apparatus of claim 2,
the first abutting piece comprises a first fixed seat and a first abutting part fixedly arranged on the first fixed seat; the second abutting piece comprises a second fixed seat and a second abutting part fixedly arranged on the second fixed seat;
the first abutting portion and the second abutting portion are used for abutting against two sides of the to-be-tested rubber material in a back-to-back mode respectively, and the first fixing seat and the second fixing seat are detachably fixed with the stress loading assembly respectively.
4. The apparatus of claim 3,
the first abutting portion and the second abutting portion are made of metal, and the water drop angle of the surfaces, opposite to each other, of the first abutting portion and the second abutting portion is smaller than or equal to 30 degrees.
5. The apparatus of claim 3,
the first abutting part and/or the second abutting part comprise abutting seats, adhesive layers and base materials which are arranged in a stacked mode, the abutting seats are fixedly connected with the fixing seats at the corresponding positions, and one side surface, away from the adhesive layers, of the base materials is used for abutting against the to-be-tested adhesive materials;
the modulus of the adhesive layer is at least three orders of magnitude higher than that of the adhesive material to be tested, and the water drop angle of the surface of the base material, which is far away from one side of the adhesive layer, is less than or equal to 30 degrees.
6. The apparatus of claim 3,
the outer contours of the surfaces of the first abutting part and the second abutting part which are oppositely arranged are the same.
7. The apparatus of claim 6,
the first fixing seat, the second fixing seat, the first abutting portion and the second abutting portion are cylindrical, and axes of the first fixing seat, the second fixing seat, the first abutting portion and the second abutting portion are overlapped.
8. The apparatus of claim 1, wherein the stress loading assembly comprises:
the device comprises a first base, a second base and a driving piece, wherein the first base and the second base are oppositely arranged; the first base and the second base are respectively fixed with the first abutting piece and the second abutting piece, and the driving piece is used for driving the second base to move close to or away from the first base.
9. A method of testing the normal fatigue of a glue material, using the apparatus of any one of claims 1 to 8, the method comprising:
placing a rubber material to be tested between the first abutting piece and the second abutting piece which are oppositely arranged;
applying cyclic stress to the rubber material to be tested through the stress loading assembly so as to enable the rubber material to be tested to circularly stretch and rebound along the normal direction, and obtaining the current cycle number and a strain value under the cyclic stress through the strain measuring assembly;
responding to the breakage of the to-be-tested rubber material along the normal direction, and obtaining a curve of compliance and the cycle times according to multiple groups of the cycle times, the cycle stress and the strain value, wherein the compliance is equal to the ratio of the strain value to the maximum stress value of the cycle stress;
and acquiring the tangent slope at each point position on the curve, responding to the fact that the tangent slope exceeds a threshold value, taking a point corresponding to the tangent slope as an inflection point, and determining the inflection point as the fatigue critical point of the rubber material to be tested.
10. The method of claim 9, wherein the step of applying cyclic stress to the glue material to be tested by the stress loading assembly comprises:
and applying sinusoidal or rectangular or triangular cyclic stress to the rubber material to be tested through the stress loading assembly.
11. The method of claim 9, wherein said responding to said failure of said glue material under test along said normal direction and said obtaining compliance versus said cycle time curves from said plurality of sets of said cycle time, cyclic stress and strain values further comprises:
judging whether at least partial surfaces of the first abutting piece and the second abutting piece are exposed out of the rubber material to be detected;
if so, discarding the current test data.
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| DE10118541A1 (en) * | 2001-04-14 | 2002-10-17 | Alstom Switzerland Ltd | Assessing life of thermal insulation layers subjected to temperature cycling, takes into account boundary layer stressing and growth of oxide layer |
| US7168327B2 (en) * | 2003-04-28 | 2007-01-30 | Harrell Jr E Ray | Method of prediction of in-vivo polymer performance by external experimentation |
| CN102262012A (en) * | 2011-04-21 | 2011-11-30 | 西北工业大学 | Tetrahedral straight-waist-shaped test piece for testing tension and compression performance of composite thick laminated plate |
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| CN110082200A (en) * | 2018-11-28 | 2019-08-02 | 北京林业大学 | A kind of rubber fatigue tension test platform and rubber fatigue stretching test method |
| KR20200071162A (en) * | 2018-12-10 | 2020-06-19 | 삼성디스플레이 주식회사 | Method for evaluating of adhesive |
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