CN112697618A - Method for measuring fatigue life of thin film constrained by flexible substrate - Google Patents
Method for measuring fatigue life of thin film constrained by flexible substrate Download PDFInfo
- Publication number
- CN112697618A CN112697618A CN202011460173.3A CN202011460173A CN112697618A CN 112697618 A CN112697618 A CN 112697618A CN 202011460173 A CN202011460173 A CN 202011460173A CN 112697618 A CN112697618 A CN 112697618A
- Authority
- CN
- China
- Prior art keywords
- fatigue
- sample
- flexible substrate
- film
- strain
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000758 substrate Substances 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 29
- 239000010409 thin film Substances 0.000 title claims abstract description 19
- 239000010408 film Substances 0.000 claims abstract description 36
- 238000005452 bending Methods 0.000 claims abstract description 14
- 238000002474 experimental method Methods 0.000 claims abstract description 8
- 238000012360 testing method Methods 0.000 claims abstract description 4
- 238000009661 fatigue test Methods 0.000 claims description 19
- 239000002131 composite material Substances 0.000 claims description 8
- 239000011159 matrix material Substances 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 5
- 125000004122 cyclic group Chemical group 0.000 claims description 4
- 230000007423 decrease Effects 0.000 claims description 2
- 230000000977 initiatory effect Effects 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 10
- 229910052751 metal Inorganic materials 0.000 abstract description 4
- 239000002184 metal Substances 0.000 abstract description 4
- 238000011056 performance test Methods 0.000 abstract description 2
- 238000011156 evaluation Methods 0.000 abstract 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 4
- 239000010931 gold Substances 0.000 description 4
- 229910052737 gold Inorganic materials 0.000 description 4
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 3
- 239000004642 Polyimide Substances 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 239000011733 molybdenum Substances 0.000 description 3
- 229910052755 nonmetal Inorganic materials 0.000 description 3
- 229920001721 polyimide Polymers 0.000 description 3
- 239000002356 single layer Substances 0.000 description 3
- 229910052721 tungsten Inorganic materials 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- 238000007906 compression Methods 0.000 description 2
- 239000013590 bulk material Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Images
Classifications
-
- 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
-
- 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
-
- 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
- G01N2203/0023—Bending
-
- 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
- G01N2203/006—Crack, flaws, fracture or rupture
- G01N2203/0062—Crack or flaws
-
- 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
-
- 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
-
- 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
-
- 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
- G01N2203/0298—Manufacturing or preparing specimens
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
本发明涉及一种受柔性基体约束薄膜疲劳寿命的测量方法，属于薄膜材料疲劳性能试验技术领域。该方法包括四个步骤：将柔性基体上的薄膜制备成疲劳试样、对制备的疲劳试样在一定的挠度下进行应变标定、对疲劳试样进行相同挠度下的一定周次的弯曲疲劳实验、在固定周次疲劳加载下的试样上，确定薄膜样品中最远裂纹处所对应的临界疲劳失效应变。采用本发明提出的受柔性基体约束薄膜疲劳寿命的测量方法，此实验方法基于动态弯曲悬臂梁试验，通过直接观察薄膜表面疲劳裂纹，进而简单有效地确定柔性基体上金属薄膜以及非金属薄膜的疲劳寿命，为柔性基体薄膜的疲劳性能评价提供了新的思路。The invention relates to a method for measuring the fatigue life of a thin film constrained by a flexible substrate, and belongs to the technical field of the fatigue performance test of thin film materials. The method includes four steps: preparing a thin film on a flexible substrate into a fatigue specimen, performing strain calibration on the prepared fatigue specimen under a certain deflection, and performing a certain cycle of bending fatigue experiments on the fatigue specimen under the same deflection. , Determine the critical fatigue failure strain corresponding to the farthest crack in the film sample on the specimen under fixed cycle fatigue loading. The method for measuring the fatigue life of a thin film constrained by a flexible substrate proposed in the present invention is based on the dynamic bending cantilever beam test. By directly observing the fatigue cracks on the surface of the thin film, the fatigue life of the metal thin film and the non-metallic thin film on the flexible substrate can be determined simply and effectively. life, which provides a new idea for the evaluation of fatigue properties of flexible substrate films.
Description
Technical Field
The invention relates to the technical field of fatigue performance tests of thin film materials, in particular to a method for measuring fatigue life of a thin film constrained by a flexible substrate.
Background
Metallic or non-metallic thin films with substrate support are widely used for interconnect line or electrode structures in microelectronic devices. In particular, in recent years, the rapid development of flexible electronic devices has led to a great deal of attention being paid to the mechanical properties of thin films on deformable flexible substrates. When the device is repeatedly deformed by stretching, bending, twisting, or the like, the film material is inevitably subjected to cyclic load, and further fatigue damage or failure occurs. However, the experimental method for fatigue damage of thin film materials is not complete, and currently, the critical fatigue failure frequency of the materials is generally determined by measuring the physical parameter change (such as the rigidity change or the resistance change of the sample) of the sample. These methods have the disadvantages of difficult sample preparation, complicated experimental process, etc., and are not suitable for testing non-conductive non-metallic films. Therefore, it is necessary to develop a universal fatigue test method for thin film materials to simply and effectively evaluate the fatigue performance of metal or non-metal thin films and determine the fatigue life thereof.
Disclosure of Invention
Aiming at the problem of how to determine the fatigue life of a metal and non-metal film constrained by a flexible substrate, the invention aims to provide a method for measuring the fatigue life of the film constrained by the flexible substrate, which introduces cyclic tension-compression strain in the film through repeated bending fatigue loading, and is similar to the traditional tension-compression fatigue test of a bulk material. Meanwhile, the method is easy to operate, the sample preparation is simple, and a series of critical fatigue failure strains epsilon under different loading cycles N can be obtainedcI.e. corresponding to the strain amplitude εcThe fatigue life of the film under load was N weeks. Obtained epsiloncAnd the-N curve is a film fatigue strain amplitude-life curve. The method provides a new idea for evaluating the fatigue performance of the flexible matrix film.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method for measuring fatigue life of a thin film constrained by a flexible substrate, the method comprising the steps of:
(1) preparing a film on a flexible substrate into a fatigue test sample;
(2) carrying out strain calibration on a fatigue sample under certain deflection;
(3) performing a bending fatigue test on the fatigue sample under the same deflection, and stopping the test at a fixed cycle N;
(4) and determining the critical fatigue failure strain corresponding to the farthest crack position of the fatigue test sample under the fixed cycle loading. I.e., equivalent to a fatigue life of the film of N cycles under this strain loading.
In the step (1), the preparation process of the fatigue sample comprises the following steps: the film is prepared on a flexible substrate to obtain a film-substrate composite material, and then the film-substrate composite material is cut into a rectangular fatigue sample.
In the step (2), the process of performing strain calibration includes: firstly, applying a certain deflection to a fatigue sample by using a strain calibration device to enable the sample to be bent and deformed; and then acquiring an image of the cross section profile of the sample and fitting a cubic polynomial to the profile curve to obtain a fitting equation y (x), wherein the origin of coordinates is established at the clamping root of the sample, x is the distance between each point and the y axis when the sample is bent, and y is the applied deflection. By the theory of the elastic beam, the external strain epsilon of each point along the length direction of the fatigue sample can be theoretically calculated when the fatigue sample is bent; strain epsilon is h/2R, wherein h is the total thickness of the film-matrix composite material, and R is the curvature radius of each point when the point is bent; the radius of curvature R can be represented by the formula
Obtaining; the strain maximum occurs at the clamping root and gradually decreases along the length of the fatigue specimen.
In the step (3), the bending fatigue test is implemented on a cantilever beam dynamic bending fatigue device, one end of the sample is fixed, and the other end of the sample is loaded by adopting calibrated deflection; cyclic loading is achieved by reciprocating vibration of an electromagnetic driver at a certain frequency (f); the experiment was terminated when the cycle reached the desired cycle.
In the step (4), the surface cracks of the sample after the fatigue test are observed, the crack density is gradually reduced along the length direction from the clamping root, and a critical position for fatigue crack initiation exists; determining the distance L from the farthest position of the fatigue crack to the clamping root in the length direction of the samplec，LcEquivalent to at the critical distance xcArc length, L, of the bending specimen corresponding theretocAnd xcThe quantitative relationship between the two can be represented by the formula
Represents; x is the number ofcThe corresponding strain is the critical fatigue failure strain epsilon under the loading cyclec。
The invention has the following advantages:
1. the invention provides a method for measuring the fatigue life of a film constrained by a flexible substrate, and perfects a test method for the fatigue performance of a film material. The method is simple and feasible in sample preparation and experiment process, and can accurately measure the critical failure strain of the film material under a certain cycle.
2. The method for measuring the fatigue life of the film constrained by the flexible substrate has wide applicability, and the critical fatigue failure point is determined by directly observing the structural failure of the sample instead of measuring the physical parameter change of the sample, so that the metal film and the nonmetal film can be tested.
3. The method for measuring the fatigue life of the film constrained by the flexible substrate can measure the fatigue strain amplitude-life curve of the film material. Practice proves that the tested fatigue curve meets the Coffin-Manson relation, and the slope of the fitting straight line is between-0.1 and-0.4 of the film material, thereby proving the effectiveness of the experimental method.
Drawings
Fig. 1 is a schematic view of a fatigue test specimen prepared in example 1.
FIG. 2 is a photograph showing the cross-sectional profile of the fatigue specimen in example 1 with an applied deflection of 2 mm.
Fig. 3 is a polynomial fit curve corresponding to the cross-sectional profile in example 1.
FIG. 4 is a graph showing the applied strain at various positions in the longitudinal direction of the specimen in example 1 where the theoretically calculated deflection was 2 mm.
Fig. 5 is a surface damage observation of the sample after fatigue loading in example 1.
FIG. 6 is a graph of critical fatigue failure strain amplitude versus cycle number for a 170nm thick gold film on a 125 μm thick flexible polyimide substrate and a 100nm thick molybdenum/tungsten multilayer film with a total thickness of 600nm monolayer thickness as measured in example 2.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
Example 1
This example is an on-cycle loading 10 to determine a 170nm thick gold film on a 125 μm thick flexible polyimide substrate6The critical fatigue failure strain after the week comprises the following specific steps:
step 1: the film-matrix composite sample was cut into a rectangular fatigue test specimen with a width of 2mm and a total length of 11mm, wherein the length of the gauge length was 6mm, as shown in fig. 1.
Step 2: the cross-sectional profile of the fatigue test specimen was collected and calibrated for strain with an imposed deflection of 2mm, as shown in fig. 2. A rectangular coordinate system is established by taking the root of the clamping end as the origin of coordinates in the figure.
And step 3: and performing polynomial curve fitting on the cross-sectional profile, wherein the fitted curve is as shown in figure 3, and the fitted equation is-0.00813 +0.07743x +0.06291x2-0.00344x3。
And 4, step 4: the strain of the fatigue test specimen in the length direction at a deflection of 2mm was theoretically calculated, as shown in fig. 4. In this example, the value of the strain at each point on the fatigue test specimen was calculated by the formula ∈ 0.12517/2R, where
And 5: the fatigue sample is subjected to bending fatigue loading with the deflection of 2mm, and the loading cycle is 106Stopping the experiment in week, taking down the sample and observing the surface, and determining the distance L between the farthest crack position and the clamping sectioncAs in fig. 5. L in the present embodimentcThe measurement was 2.463 mm. Thereby determining the critical distance xc2.4055 mm. The corresponding critical fatigue failure strain at this time was 0.403%.
Example 2
In this embodiment, a critical fatigue failure strain amplitude-cycle curve of a 170nm thick gold thin film on a 125 μm thick flexible polyimide substrate and a 100nm thick molybdenum/tungsten multilayer film with a total thickness of 600nm single layer is determined, which specifically includes the following steps:
step 1: and cutting the two film-matrix composite material samples into a plurality of rectangular fatigue test samples with the width of 2mm and the total length of 11mm, wherein the length of the gauge length is 6 mm.
Step 2: and (3) carrying out strain calibration with the deflection of 2mm on each fatigue sample, wherein the calibration process is the same as the calibration process from the step (2) to the step (4) in the example 1. The strain value of each point on a 170nm gold film fatigue sample is obtained by calculation according to the formula epsilon of 0.12517/2R, and the strain value of each point on a molybdenum/tungsten multilayer film fatigue sample with the total thickness of 600nm single-layer thickness of 100nm is obtained by calculation according to the formula epsilon of 0.1256/2R.
And step 3: the fatigue test sample is subjected to bending fatigue loading with the deflection of 2mm, and the loading frequency is 104、105、106And 107The experiment was stopped at week time, the sample was observed for surface damage, the position of the farthest crack at the corresponding week time was determined, and the corresponding critical fatigue failure strain was determined, as shown by the data points in fig. 6. Fitting the data points found that the fatigue curves of both films satisfied the traditional Coffin-Manson relationship, with fitting slopes of-0.12 and-0.13, respectively.
Claims (5)
1. A method for measuring the fatigue life of a thin film constrained by a flexible substrate is characterized in that: the method comprises the following steps:
(1) preparing a film on a flexible substrate into a fatigue test sample;
(2) carrying out strain calibration on the sample prepared in the step (1) under a certain deflection;
(3) performing a bending fatigue test on the fatigue sample prepared in the step (1) under the same deflection as that of the step (2), and stopping the test at a fixed cycle N;
(4) for the fatigue test sample under fixed cycle loading, the critical fatigue failure strain corresponding to the farthest crack position; i.e., equivalent to a fatigue life of the film of N cycles under this strain loading.
2. A method for measuring the fatigue life of a film constrained by a flexible substrate according to claim 1, wherein: in the step (1), the preparation process of the fatigue sample comprises the following steps: the film is prepared on a flexible substrate to obtain a film-substrate composite material, and then the film-substrate composite material is cut into a rectangular fatigue sample.
3. A method for measuring the fatigue life of a film constrained by a flexible substrate according to claim 1, wherein: in the step (2), the process of performing strain calibration comprises the following steps: firstly, applying a certain deflection to a fatigue sample by using a strain calibration device to enable the sample to be bent and deformed; acquiring an image of the cross section contour of the sample and performing cubic polynomial fitting on a contour curve to obtain a fitting equation y (x), wherein the origin of coordinates is established at the clamping root of the sample, x is the distance between each point and the y axis when the sample is bent, and y is the applied deflection; by the theory of the elastic beam, the external strain epsilon of each point along the length direction of the fatigue sample can be theoretically calculated when the fatigue sample is bent; strain epsilon is h/2R, wherein h is the total thickness of the film-matrix composite material, and R is the curvature radius of each point when the point is bent; the radius of curvature R can be represented by the formula
Obtaining; the strain maximum occurs at the clamping root and gradually decreases along the length of the fatigue specimen.
4. A method for measuring the fatigue life of a film constrained by a flexible substrate according to claim 1, wherein: in the step (3), a bending fatigue test is implemented on a cantilever beam dynamic bending fatigue device, one end of a sample is fixed, and the other end of the sample is loaded by adopting calibrated deflection; the cyclic loading is realized by reciprocating vibration of the electromagnetic driver at a certain vibration frequency (f); the experiment was terminated when the cycle reached the desired cycle.
5. A method for measuring the fatigue life of a film constrained by a flexible substrate according to claim 1, wherein: in the step (4), the surface cracks of the sample after the fatigue test are observed, the crack density is gradually reduced along the length direction from the clamping root, and a critical position for fatigue crack initiation exists; it doesDetermining the distance L between the farthest position of the fatigue crack formed in the length direction of the sample and the clamping rootc，LcEquivalent to at the critical distance xcArc length, L, of the bending specimen corresponding theretocAnd xcThe quantitative relationship between the two can be represented by the formula
Represents; x is the number ofcThe corresponding strain is the critical fatigue failure strain epsilon under the loading cyclec。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011460173.3A CN112697618A (en) | 2020-12-11 | 2020-12-11 | Method for measuring fatigue life of thin film constrained by flexible substrate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011460173.3A CN112697618A (en) | 2020-12-11 | 2020-12-11 | Method for measuring fatigue life of thin film constrained by flexible substrate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112697618A true CN112697618A (en) | 2021-04-23 |
Family
ID=75508987
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011460173.3A Pending CN112697618A (en) | 2020-12-11 | 2020-12-11 | Method for measuring fatigue life of thin film constrained by flexible substrate |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112697618A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116296774A (en) * | 2023-03-16 | 2023-06-23 | 江南大学 | In-situ loading three-point bending clamp and method for assisting microscopic characterization |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101226163A (en) * | 2008-01-22 | 2008-07-23 | 西安交通大学 | Test method for fatigue life of metal thin films on flexible substrates |
| CN103364285A (en) * | 2013-06-20 | 2013-10-23 | 西南交通大学 | Test method for testing bending fatigue life of film |
| CN109163990A (en) * | 2018-08-28 | 2019-01-08 | 中国科学院金属研究所 | A kind of measurement method of axially loaded high cycle fatigue crack initiating life |
-
2020
- 2020-12-11 CN CN202011460173.3A patent/CN112697618A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101226163A (en) * | 2008-01-22 | 2008-07-23 | 西安交通大学 | Test method for fatigue life of metal thin films on flexible substrates |
| CN103364285A (en) * | 2013-06-20 | 2013-10-23 | 西南交通大学 | Test method for testing bending fatigue life of film |
| CN109163990A (en) * | 2018-08-28 | 2019-01-08 | 中国科学院金属研究所 | A kind of measurement method of axially loaded high cycle fatigue crack initiating life |
Non-Patent Citations (1)
| Title |
|---|
| 郑思学: "柔性电子器件用金薄膜的疲劳行为研究", 《中国优秀博硕士学位论文全文数据库(硕士)工程科技Ⅰ辑》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116296774A (en) * | 2023-03-16 | 2023-06-23 | 江南大学 | In-situ loading three-point bending clamp and method for assisting microscopic characterization |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9702798B1 (en) | Method for evaluating fracture toughness using instrumented indentation testing | |
| EP2199775B1 (en) | Method for evaluation of coated parts | |
| EP3076153B1 (en) | Method for calculating an indenter area function and quantifying a deviation from the ideal shape of an indenter | |
| CN110672417A (en) | A method for obtaining elastic-plastic properties of ultra-thin materials by small punch test | |
| CN106644711B (en) | A kind of ductile material single shaft constitutive relation test method | |
| US20050103120A1 (en) | Determination of young's modulus and poisson's ratio of coatings from indentation data | |
| Zheng et al. | A novel evaluation strategy for fatigue reliability of flexible nanoscale films | |
| CN108844824B (en) | A method for the determination of residual stress in known materials based on a conical indenter | |
| CN102426068A (en) | A Prediction Method of Surface Film Residual Stress | |
| CN110763132A (en) | A kind of omnidirectional sensing bionic strain sensor and preparation method thereof | |
| CN112697618A (en) | Method for measuring fatigue life of thin film constrained by flexible substrate | |
| CN107345875A (en) | The rigidity appraisal procedure of Reinforced Concrete Members with Flexure based on sound emission Ring-down count | |
| CN112629725B (en) | A kind of residual stress test method of piston rod spray coating | |
| Sam-Daliri et al. | Condition monitoring of crack extension in the reinforced adhesive joint by carbon nanotubes | |
| Bharadwaj et al. | Study of cyclic plastic zone ahead of the fatigue crack tip using Digital Image Correlation system | |
| CN101063647A (en) | Method for nondestructively measuring M integral | |
| KR100994933B1 (en) | Tensile test specimen for micro-compression tester having a single tensile test section and its manufacturing method | |
| CN117664756A (en) | Small punch testing method for fracture toughness and ductile-brittle transition temperature of anisotropic material | |
| Yan et al. | A robust in situ TEM experiment for characterizing the fracture toughness of the interface in nanoscale multilayers | |
| Oliva et al. | Poisson’s ratio determination of Au nanofilms by piezoresistive measurements | |
| CN104677753A (en) | Method for evaluating fracture toughness of Cu series brittle metal nano multilayer film material | |
| CN117233012A (en) | Method for testing strength performance of metal material by instrumented indentation | |
| Park et al. | Tensile and high cycle fatigue tests of NiCo thin films | |
| JP2016128787A (en) | Strain measurement method in metallic material | |
| CN104749053A (en) | Method for predicting fatigue failure of ultra-thin film based on nanoindentation test technology |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210423 |
|
| RJ01 | Rejection of invention patent application after publication |