CN104132845A - Test method for measuring stress intensity factor at cutting-angle part of anisotropic material - Google Patents
Test method for measuring stress intensity factor at cutting-angle part of anisotropic material Download PDFInfo
- Publication number
- CN104132845A CN104132845A CN201410308765.1A CN201410308765A CN104132845A CN 104132845 A CN104132845 A CN 104132845A CN 201410308765 A CN201410308765 A CN 201410308765A CN 104132845 A CN104132845 A CN 104132845A
- Authority
- CN
- China
- Prior art keywords
- test
- stress intensity
- intensity factor
- bight
- otch
- 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
Landscapes
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a test method for measuring stress intensity factor at a cutting-angle part of an anisotropic material. A test piece is a disc consisting of two sectorial wedge-body test pieces, and the two wedge bodies are made of different materials. The cutting angel part is at the center of the disc. By taking the disc as the test piece, the test piece is subjected to single-shaft compression test, a compressive load at an arbitrary diameter direction is applied to the circumferential outer edge of the test piece for measuring the stress intensity factor at the cutting-angle part, and a load applied when the cutting-angle part is damaged is taken as the critical load. According to the test method, the disc test piece is subjected to single-shaft compression test for measuring the stress intensity factor at the cutting-angle part of the anisotropic composite material, the method is reliable in principle, uniform in loading force, high in measuring precision and accurate and recorded data and analyzed results, and is especially applicable to measure the stress intensity factor at the cutting-angle part of a composite material integrating an anisotropic composite material and an isotropic material.
Description
Technical field
The present invention relates to a kind of test method, relate in particular to a kind of test method of measuring anisotropic composite material otch bight stress intensity factor.
Background technology
Along with the commercial Application of the advanced materials such as types of functionality material, compound substance, bond material increases gradually, the interface mechanical behavior being comprised of different materials is more and more subject to people's attention.The joint portion of various types of materials and structure, as metal, being combined the combination interface etc. of interface, function element and bearing carrier with Ceramic bond interface, dissimilar metal has very important impact to the mechanical behavior of material or structural entity.Compound substance is when bearing external load, existence due to the Stress singularity in combination interface otch bight, tend to from otch bight cumulative damage, and then form the destruction that defects i.e.cracks causes compound substance, because material is concentrated in conjunction with easily having defect near interface or producing stress, thus bond material easily junction or near first destroy.
The test specimen type that has at present multiple measurement compound substance stress intensity factor, the most frequently used have asymmetric three point bending specimen, monolateral otch four-point bending test specimen, asymmetric four-point bending test specimen, disk test specimen, a limit crackle bar shaped test specimen etc.Method of testing also has a variety of, is exactly typically three point bending test.The method that represents material fracture toughness has generalized intensity factors, crack extension energy rate and J integration etc.The method of these tests has a lot of stress intensity factors that are applicable to measuring the isotropic material with stress symmetric field, but because the stress field right and wrong in anisotropic composite material otch bight are symmetric, during material damage, angle is uncertain, and it is very necessary therefore inventing a kind of test method of measuring the stress intensity factor in anisotropic composite material otch bight.
Due to the difficulty of clamping sample, and fixture clamping place easily produces stress and concentrates, and makes test specimen produce in advance destroying infection test findings.In order to solve such problem, relatively extensively adopting at present the sample of measuring material stress intensity factor is disk test specimen, and its principle is testing machine diameter in the diametric(al) of disk sample load of exerting pressure, and sample is destroyed along loading diameter.Adopt disk test specimen, and on sample, increase a pair of platform for loading parallel to each other, this is conducive to sample from center crack initiation, can avoid again concentrated force in the adverse effect of part, contact position.Therefore can utilize disk sample, from the feature of center crack initiation, measure anisotropic composite material otch bight stress intensity factor.But because disk test specimen is isotropic material, and as a whole test specimen, therefore also need disk test specimen to improve in order to measure anisotropic composite material otch bight stress intensity factor.
Summary of the invention
The object of this invention is to provide a kind of test method of measuring anisotropic material otch bight stress intensity factor.The method is the method based on disc test and makes improvements.
Of the present invention a kind of for measuring the test specimen of anisotropic composite material otch bight stress intensity factor, comprise the disk jointly being formed by material 1 and the tight wedge shape combination of material 2, wherein material 2 accounts for 1/4th of disk, and the key groove of material 2 is 90o, and the key groove of material 1 is 270 °.
This test specimen is placed in Material Testing Machine and carries out uniaxial compression test, and platen applies compressive load along the diametric(al) of disk sample in circumferential outer edge, take anisotropic composite material otch bight to occur that breakage is as critical load.
When applying compressive load, must keep upper pressing disc parallel with disc centre centering, until breakage appears in otch bight, pressure when record is damaged and damage location data analysis are obtained a result.
The invention has the beneficial effects as follows, adopt test method of the present invention can obtain easily the value of anisotropic composite material otch bight stress intensity factor, a kind of test method that anisotropic composite material otch bight has the stress intensity factor value of asymmetric stresses field of measuring is provided.This test method principle is reliable, and loading force is even, and test accuracy is high, and record data and to analyze data accurate have great importance for performance development and the optimal design of material.
Accompanying drawing explanation
Fig. 1 is geometric configuration and the load load mode of testing test specimen in the present invention.Test specimen is by material 1 and material 2 wedge shapes disk cemented together.The key groove of material 1 is 270 °, and the key groove of material 2 is 90o, and material 1 represents anisotropic composite material, and material 2 represents metallic briquette.Load
pwith
xthe angle of axle is α.
Fig. 2 is test fixture and loading principle schematic diagram.Comprise platen 3 and pressing disc 4, and the test test specimen being formed by material 1 and material 2.
Fig. 3 is the destruction closed curve based on measuring anisotropic composite material otch bight stress intensity factor.What record under each load load angle
kvalue record with
k 1/
k 1Cfor horizontal ordinate,
k 2/
k 2Con coordinate system for ordinate, adjacent two loading angles
kvalue connects the destruction closed curve that can obtain anisotropic composite material otch bight stress intensity factor with straight line.
Embodiment
Below by embodiment, illustrate test method and the process of measuring anisotropic composite material otch bight stress intensity factor.
1. test specimen condition:
(1) material 1, for carbon fiber strengthens composite plastic (CFRP) laminate, belongs to anisotropic material, and material 2 is cast iron briquetting, belongs to isotropic material.The two fits tightly formation thickness by wedge shape is 7 ± 1mm, the disc test sample that diameter is 17 ± 1.5mm.Each is loaded to angle and make 3～4 test specimens, and record corresponding disk diameter and thickness.
(2) test fixture: go up as shown in Figure 2 platen 3 parallel with disc centre centering with pressing disc 4, test specimen is in the center of upper pressing disc.
2. process of the test:
Diameter and the thickness of first record test test specimen are standby, in Material Testing Machine, test specimen are installed to fixture afterwards, adjust the upper pressing disc line of centres through disc centre axis and perpendicular during installation, and the direction of exerting pressure is along disk diameter direction.Then each test specimen is carried out respectively to uniaxial compression test, with the speed of the load angle stipulated and 0.05mm/min, load, until that material cut bight occurs is damaged, pressure and damage location when record is damaged.
3. test result analysis:
(1) the otch bight stress intensity factor of this material can be obtained by following formula:
In formula: subscript " FEM " and " exp " represent respectively the value of finite element analysis and the value that experiment records;
pthe failing load (N) that represents test specimen;
twith
rthe thickness (mm) and the radius (mm) that represent respectively test specimen;
λ k for characteristic exponent.Wherein,
p fEM =100N,
t fEM =1mm,
r fEM =1mm.
Test findings is all with the arithmetic mean value representation of test figure.
(2) test specimen failure criteria: the data substitution above formula of the value of the generalized intensity factors that finite element analysis is obtained and experiment gained can obtain the value of the stress intensity factor under each load angle.
Because otch bight is having singularity along glide direction with vertical glide direction, therefore
kthere are two values.Due to
k 1with
k 2unit different, so propose the expression formula of a Generalized Stress Intensity Factor based on failure criteria, be:
Wherein,
k 1Cwith
k 2Ccan be obtained by (1) formula,
ψfor name fracture mixed mode phasing degree, can be obtained by following formula:
Utilize
ψwith
κ c(
ψ) these two parameters just can define a destruction closed curve based on evaluating Generalized Stress Intensity Factor criterion, as shown in Figure 3.With
k 1/
k 1Cfor horizontal ordinate,
k 2/
k 2Cfor ordinate, utmost point footpath is
κ c(
ψ), polar angle is
ψcurve map.In curve, represent place of safety, extra curvature represents unsafe region.
Claims (5)
1. one kind for measuring the test method of anisotropic composite material otch bight stress intensity factor, it is characterized in that disk test specimen after improving as test test specimen, its otch bight is in disc centre, by test specimen is carried out to uniaxial compression test, circumferential outer edge is applied along the compressive load of arbitrary diameter direction, measure its otch bight stress intensity factor, take anisotropic composite material otch bight occur breakage as test basic point.
2. test test specimen according to claim 1 is characterized in that the disk being combined by two fan-shaped wedge body test specimens, two sphenoids can be the materials of unlike material, its otch bight is at the center of disk, the key groove of tested anisotropic composite material is 270o, the key groove of another metallic briquette is 90o, the two closely combines formation thickness by wedge shape is 7 ± 1mm, diameter is the disc test sample of 17 ± 1.5mm, each is loaded to angle and make 3～4 test specimens, and record corresponding disk diameter and thickness.
3. the test method of measurement stress intensity factor according to claim 1, when it is characterized in that installing test specimen and testing, adjust the upper pressing disc line of centres through disc centre axis and perpendicular, the direction of exerting pressure is along disk diameter direction, then each test specimen is carried out respectively to uniaxial compression test, with the load angle of regulation and the speed of 0.05mm/min, load, until breakage appears in material cut bight, pressure when record is damaged and damage location data analysis are obtained a result.
4. data analysis according to claim 3, is characterized in that the otch bight stress intensity factor of this material can be obtained by following formula:
In formula: subscript " FEM " and " exp " represent respectively the value of finite element analysis and the value that experiment records;
pthe failing load (N) that represents test specimen;
twith
rthe thickness (mm) and the radius (mm) that represent respectively test specimen;
λ k for characteristic exponent, wherein,
p fEM =100N,
t fEM =1mm,
r fEM =1mm.
5. otch according to claim 4 bight stress intensity factor, is characterized in that can being used for obtaining the expression formula of a Generalized Stress Intensity Factor based on failure criteria:
Wherein,
k 1Cwith
k 2Ccan be obtained by (1) formula,
ψfor name fracture mixed mode phasing degree, can be obtained by following formula:
Utilize
ψwith
κ c(
ψ) these two parameters just can define a destruction closed curve based on evaluating Generalized Stress Intensity Factor criterion, as shown in Figure 3, with
k 1/
k 1Cfor horizontal ordinate,
k 2/
k 2Cfor ordinate, utmost point footpath is
κ c(
ψ), polar angle is
ψcurve map, in curve, represent place of safety, extra curvature represents unsafe region.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410308765.1A CN104132845A (en) | 2014-07-01 | 2014-07-01 | Test method for measuring stress intensity factor at cutting-angle part of anisotropic material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410308765.1A CN104132845A (en) | 2014-07-01 | 2014-07-01 | Test method for measuring stress intensity factor at cutting-angle part of anisotropic material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104132845A true CN104132845A (en) | 2014-11-05 |
Family
ID=51805611
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410308765.1A Pending CN104132845A (en) | 2014-07-01 | 2014-07-01 | Test method for measuring stress intensity factor at cutting-angle part of anisotropic material |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104132845A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106802202A (en) * | 2017-03-15 | 2017-06-06 | 哈尔滨工业大学 | A kind of method for measuring anisotropic material plane stress |
| CN109916686A (en) * | 2019-04-04 | 2019-06-21 | 上海交通大学 | A kind of test sample of the anisotropy breaking strength of sheet metal |
| CN111024520A (en) * | 2019-12-20 | 2020-04-17 | 中国矿业大学(北京) | Calculation method, experimental method and experimental device for V-shaped grooving tip stress intensity factor under pure shear loading |
-
2014
- 2014-07-01 CN CN201410308765.1A patent/CN104132845A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106802202A (en) * | 2017-03-15 | 2017-06-06 | 哈尔滨工业大学 | A kind of method for measuring anisotropic material plane stress |
| CN109916686A (en) * | 2019-04-04 | 2019-06-21 | 上海交通大学 | A kind of test sample of the anisotropy breaking strength of sheet metal |
| CN111024520A (en) * | 2019-12-20 | 2020-04-17 | 中国矿业大学(北京) | Calculation method, experimental method and experimental device for V-shaped grooving tip stress intensity factor under pure shear loading |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110672417B (en) | Method for obtaining elastic-plastic property of ultrathin material through small punch test | |
| CN104596845A (en) | Measuring method for real stress-strain curve of metal welding structure | |
| CN104132845A (en) | Test method for measuring stress intensity factor at cutting-angle part of anisotropic material | |
| WO2020199235A1 (en) | Method for calculating fracture toughness using indentation method | |
| CN104344998A (en) | Test specimen hydraulic bulging test method and device | |
| CN105372103B (en) | Composite test sample | |
| Lu et al. | Correlation between tensile strength and hardness of electron beam welded TC4-DT joints | |
| CN103760017A (en) | Carbon fiber reinforced composite laminate compression test clamp and test method using same | |
| Serati et al. | Modified Brazilian test for indirect measurement of tensile strength of brittle materials | |
| JP2014174148A (en) | Standard test piece, analyzer, mechanical component, and method of manufacturing standard test piece | |
| CN103994842A (en) | Method for measuring residual stress of composite material annular part based on cutting and bending method | |
| Masláková et al. | Applications of the strain gauge for determination of residual stresses using Ring-core method | |
| Wang et al. | Micro-mechanical behaviour of artificially cemented sands under compression and shear | |
| CN101819115B (en) | Method for testing shear strength of brittle material by utilizing concentric cylindrical test sample | |
| CN102788546B (en) | Special checking fixture for profile degree of end face of cylinder sleeve | |
| KR101467078B1 (en) | Inclusion valuation method of high frequency heat material | |
| CN105699204B (en) | A kind of microspecimen and a kind of hydraulic bulging test method | |
| Lim et al. | Development of a multi-joint robotic ultrasonic inspection system to secure the integrity of composite structures | |
| Ghosh et al. | Failure investigation of high temperature stud | |
| CN104596875B (en) | A kind of detection method of composite polycrystal-diamond heat endurance | |
| CN103323520B (en) | Utilize electrochemical noise technique to measure method and noise probe and the method for making of material local corrosion | |
| CN220356828U (en) | Device for measuring fatigue crack growth rate of metal sheet | |
| CN202250929U (en) | Improved internal spherical detection device for stereo type water pump blade | |
| RU115480U1 (en) | SAMPLE FOR TESTING METAL OF PIPES AT BIAXIAL VOLTAGE STATE | |
| Nonaka et al. | Full size internal pressure creep test for welded P91 hot reheat elbow |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20141105 |