CN101477052A - Strain component lossless detection technology based on carbon nano-tube as sensing medium - Google Patents

Abstract

The invention discloses nondestructive testing technology for a strain component taking carbon nano-tubes as a sensing medium. The carbon nano-tubes are randomly adhered to the surface of a tested object or are doped in the tested object; a polarizing microscopic Raman spectrum system focuses incident laser on the surface of the tested object and backwards acquires original information of Raman spectrum; an analytic expression between a Raman frequency shift increment obtained by data processing and the plane strain component of the tested object is delta omega<(phi)>=(1/6)psi Sensor.[(3+cos2phi)epsilonX+(3-cos2phi)epsilonY-2sin2phi.gammaXY]; three different polarization directions are given; and a measurement result of the frequency shift increment is substituted into the equation set for solving to obtain the strain component. The nondestructive testing technology solves the sensing detection problem of non-Raman active materials in Raman strain measurement, can directly measure the plane strain components on the surfaces of solid materials and perform experimental analysis on micro-region strain fields, has the characteristics of non-destruction, high measurement accuracy, high spatial resolution, and so on, and can be used for the various fields such as the experimental research of micro-scale mechanical behavior, and the analysis of mechanical properties of MEMS micro-devices .

Description

Based on carbon nano-tube is the components of strain Dynamic Non-Destruction Measurement of sensor information

Technical field

The invention belongs to mechanics of materials field, be specifically related to the technology that a kind of the millimeter components of strain and the regularity of distribution thereof to the submicron-scale are measured.

Background technology

In recent years along with the fast development of material and message area science and technology, the fail-safe analysis that detects with micro devices about the mechanical property of material under macroscopic view and the micro-scale has become the multidisciplinary institute hot fields of concern jointly.In this field, Experimental Mechanics analysis and Performance Detection are being born important instrumental purpose, detect demand but present existing strain measurement technique has been difficult to satisfy new experiment.For example: the measuring point yardstick of existing strain gage testing technology is big, and the paster yardstick and belongs to the spot measurement of the contact that wiring is arranged at least on several mm-scales; In the existing optical deformation measurement technology, macroscopical photodynamics survey technology mainly is the measurement to the moderate finite deformation field, and the visual field is big and resolution is not enough.In the micrometering field, commercial high resolving power micro measurement instrument (for example atomic force microscope, scanning electron microscope, transmission electron microscope, nano-hardness tester etc.) can be realized the pattern observation of nanometer measured object to the micro-meter scale regional extent, but still unresolved under power or environmental load effect to the deformation field of measured object and the quantitative measurment problem of strain field; In addition, in the existing spectral class detection technique, the measuring point of x light diffraction techniques is big, and is restricted to material, and lack of resolution.Micro-Raman technology can realize Raman active materials such as silicon the micron zone stress and measurement, but be not suitable for non-Raman active material, and the measurement of still unresolved plane strain component (be stress and decomposition) problem is particularly with the closely-related shearing strain problems of measurement of intensity.

Therefore, detect detection demand with the fail-safe analysis of micro devices at the mechanical property of material under macroscopic view and the micro-scale, study new Experimental Mechanics measuring technique, realize having important scientific meaning and engineering background to the strain measurement of micron and sub-micron regions and to micro element key position intensity detection.Given this, the present invention's proposition is sensor information with the carbon nano-tube, is the components of strain Dynamic Non-Destruction Measurement of measurement means with micro-Raman technology, can be used for the quantitative measurment of the plane strain component (comprising normal strain and shearing strain) of material surface micron or submicron-scale measuring point, can realize the measurement of millimeter, and solve associated non-Raman active material strain detection problem to normal strain and the shearing strain component and the regularity of distribution thereof in submicron-scale zone.

Summary of the invention

The object of the present invention is to provide and a kind ofly be wireless noncontact sensor information, harmless, be used for the strain detecting technology of material mechanical performance and micro devices fail-safe analysis under macroscopic view and the micro-scale based on carbon nano-tube.

Based on carbon nano-tube is the components of strain Dynamic Non-Destruction Measurement of sensor information, has carbon nano-tube, testee, polarization micro Raman spectra system (as Fig. 1).The testee surface at random, is evenly disperseed and fixing carbon nano-tube adopts dual-polarization (incident light and scatter light polarization direction can be controlled and be consistent) or single polarization (only the incident light polarization direction can be controlled) Raman experimental system to carry out the resonance raman test, and Raman frequency shift increment that is obtained by experiment and the quantitative relationship between the testee plane strain component can be expressed by analytic expression.Wherein, the analytic expression between Raman frequency shift increment in the Raman spectral information and the testee plane strain component is under the dual-polarization resonance raman experiment model:

In the formula,

Represent the polarization direction to be

The time experimental system before and after distortion, gather the frequency displacement increment obtain Raman spectrum; ε _XAnd ε _YRepresent the normal strain component of testee surface X, Y direction respectively, γ _XYBe shearing strain component, Ψ _SensorBe the strain-frequency-shifting operator of carbon nano-tube strain sensing medium, i.e. Ψ _SensorBe the constant factor that characterizes as linear relationship between the Raman frequency shift of the axial strain of the carbon nano-tube of strain sensing medium and carbon nano-tube, given three different polarization directions

Be respectively With

Set up system of equations with the analytic expression between Raman frequency shift increment in the Raman spectral information and the testee plane strain component, the frequency displacement increment measurement substitution system of equations as a result of three different polarization directions is found the solution drawn the components of strain.

As get the polarization direction

Be respectively 0 °, 45 ° and 90 °, bring Raman frequency shift increment in the Raman spectral information and the analytic expression between the testee plane strain component into, draw system of equations and be:

$\left\{\begin{array}{c}{\mathrm{\&epsiv;}}_X=\frac{1}{{4\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;(5\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)}-\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(90\right)})\\ {\mathrm{\&epsiv;}}_Y=\frac{1}{{4\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;(5\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(90\right)}-\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)})\\ {\mathrm{\&gamma;}}_{\mathrm{XY}}=\frac{3}{{2\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;(\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)}+\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(90\right)}-2\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(45\right)})\end{array}\right.$

In three different polarization directions

Or

Or

When being all 45 °, be called 45 ° of Raman strain measurement methods with the angle of other two polarization directions; In three different polarization directions

Or

Or

When being all 60 °, be called 60 ° of Raman strain measurement methods with the angle of other two polarization directions; In three different polarization directions

Or

Or

When being all 120 °, be called 120 ° of Raman strain measurement methods with the angle of other two polarization directions.

Beneficial effect of the present invention and advantage are: the present invention has characteristics such as harmless, wireless noncontact, high-space resolution, can realize the components of strain ε of micro-meter scale measuring point _X, ε _YAnd γ _XYDirect measurement, and can adopt the point by point scanning mode to realize the full-field distribution measurement of each plane strain component in the film micro area, but thereby solved that microscale mechanics study and micro element fail-safe analysis needed badly existing experimental technique but is difficult to the problems of measurement, the particularly problems of measurement of shearing strain component and maximum principal strain and principal strain directions of the plane strain component of the micro-meter scale realized.The technology of the present invention compare with the resistance-strain chip technology outstanding characteristics be have wireless noncontact, measuring point yardstick little, can realize advantages such as whole audience components of strain distribution measuring; With classical photo-measuring experimental mechanics technology (for example holography method, moire method, cutting speckle method, Electronic Speckle Pattern Interferometry etc.) compare, outstanding feature of the present invention is to realize the direct measurement of strain, has experiment preparation, experimental implementation and the simple advantage of data processing in addition; Compare (based on commercial micro-platform mechanical parameter method of testings such as atomic force, scanning electron microscope, transmission electron microscope, nano-hardness testers) with the micro-photo-measuring experimental mechanics technology of high-resolution, outstanding advantage of the present invention is that laboratory sample is prepared simply, can realize the direct measurement of the plane strain component of measuring point, solve the problems of measurement of shearing strain component and maximum principal strain and principal strain directions.Compare with existing spectrum test technology, the present invention has broken through traditional Raman strain measurement technique, and requirement has the limitation of Raman active to tested object, can be in engineering be used by laminated film adhere to, chemical bonding is modified or mode such as molecule self assembly realizes the plane strain component of non-Raman active solid material surface is directly measured and the experimental analysis of film micro area strain field; Also can realize the strain of transparent inside of solid material is directly measured by means such as collosol and gel, blend doping, original position are compound.The present invention can be used for the related application occasion in a plurality of fields such as test of experimental study, the MEMS micro element mechanical property of microscale mechanical behavior.

Description of drawings

Fig. 1 is the technology of the present invention principle schematic, and wherein long broken line is an incident light, and short broken line is a scattered light.

Fig. 2 is the micro-Raman experimental system of dual-polarization, and wherein long broken line is an incident light, and short broken line is a scattered light.

Specific embodiment

Below by embodiment method of the present invention is described further.

Be the components of strain Dynamic Non-Destruction Measurement (as Fig. 1) of sensor information based on carbon nano-tube as previously mentioned, have carbon nano-tube 1, testee 2, polarization micro Raman spectra system 3.Carbon nano-tube 1 is at random attached to the surface of testee 2 or be doped in the inside of testee.Polarization micro Raman spectra system 3 (as Fig. 2) comprises LASER Light Source 4, half-wave plate 5, polaroid 6, microscope 7 and Raman spectrometer 8.The incident light of LASER Light Source 4 outgoing is incident on testee 2 surfaces through half-wave plate 5 and polaroid 6 backs by microscope 7 successively, and microscope 7 and the scattered light of collecting dorsad enter Raman spectrometer 8 through polaroid 6 and half-wave plate 4 successively and form Raman spectral information.Control the polarization angle of incident light and scattered light by the polarization axle of joint rotation half-wave plate 5 and polaroid 6.The Raman system of single polarization can not have polaroid or scattered light without polaroid in addition, only realizes polarization of incident light is controlled.

To measure " the strain regime analysis of Polyvinylchloride thin sheet surface " be embodiment, and employing is that the components of strain Dynamic Non-Destruction Measurement of sensor information is as follows to the implementation step that testee carries out strain testing based on carbon nano-tube:

The first step, specimen preparation: with purity is that 90% Single Walled Carbon Nanotube is mixed according to mass ratio 1:999 with liquid-state epoxy resin, after the ultrasonic dispersion mixed liquor press mold on the Polyvinylchloride thin plate is solidified, thereby make the thick coherent film of 30 μ m at the PVC thin sheet surface, carbon nano-tube evenly distributes at random in the film.With same approach obtain carbon nano-tube with content from the body film as calibration sample.

In second step, experimental system is prepared: the micro-Raman experimental system experiment of the polarization light path of adjusting dual-polarization with reference to Fig. 2; The 632.8nm laser that adopts the He-Ne laser instrument is as incident light, and Single Walled Carbon Nanotube is in the resonance raman state, is applicable to 45 ° of Raman strain measurement normal equation groups, i.e. formula under the dual-polarization system resonance Raman modes

$\left\{\begin{array}{c}{\mathrm{\&epsiv;}}_X=\frac{1}{{4\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;(5\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)}-\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(90\right)})\\ {\mathrm{\&epsiv;}}_Y=\frac{1}{{4\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;(5\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(90\right)}-\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)})\\ {\mathrm{\&gamma;}}_{\mathrm{XY}}=\frac{3}{{2\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;(\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)}+\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(90\right)}-2\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(45\right)})\end{array}\right.$

In the 3rd step, demarcate sensor information strain-frequency-shifting operator Ψ _Sensor: calibration sample is in given strain regime, be placed on the micro-platform of Raman system, focus on incident light to sample surfaces, (as Fig. 2) controls the polarization direction of incident light and scattered light by the polarization axle of half-wave plate 5 and polaroid 6 in the joint rotation polarization micro Raman spectra system, with 0.04% strain is that step-length is carried out the uniaxial tension experiment to calibration sample, under each loaded-up condition, a plurality of measuring positions, calibration sample surface are gathered the Raman spectrum that the polarization direction is 0 ° and 90 ° respectively, handle experimental data and extract frequency displacement information (as table 1), bringing above-mentioned formula first formula into (is ε _X) find the solution, be averaged the result and draw Ψ _Sensor=1815cm ^-1, the zero load frequency displacement is 2624cm ^-1

Table 1 measurement data

ε X(％)	0	0.04	0.08	0.12	0.16	0.2	0.24	0.28	0.32
										Ω (0)(cm -1)	2623.79	2623.62	2622.48	2622.44	2621.88	2621.53	2620.78	2620.67	2619.59
Ω (90)(cm -1)	2623.83	2624.27	2624.51	2624.49	2624.34	2624.52	2624.68	2625.54	2625.03
										ε X(‰)	0.36	0.4	0.44	0.48	0.52	0.56	0.6	0.64	0.68
Ω (0)(cm -1)	2618.9	2618.83	2617.56	2616.98	2616.64	2615.88	2615.82	2615.23	2614.89
										Ω (90)(cm -1)	2625.2	2625.24	2625.42	2625.77	2625.23	2625.31	2625.65	2626.1	2625.94

The 4th step, the formal measurement: the Polyvinylchloride thin sheet surface that will be under the loaded state places on the micro-platform of Raman system, focus on incident light to sample surfaces strain measurement position, (as Fig. 2) controls the polarization direction of incident light and scattered light by the polarization axle of half-wave plate 5 and polaroid 6 in the joint rotation polarization micro Raman spectra system, gather the polarization direction respectively and be the Raman spectrum of 0 °, 45 ° and 90 °, handle experimental data and extract frequency displacement information and draw respectively:

Δ Ω ⁽⁰⁾=-9.287cm ^-1, Δ Ω ⁽⁴⁵⁾=-9.226cm ^-1With Δ Ω ⁽⁹⁰⁾=-9.408cm ^-1, the above-mentioned system of equations of substitution:

$\left\{\begin{array}{c}{\mathrm{\&epsiv;}}_X=\frac{1}{4\&times;(-1815)}\&times;[5\&times;(-9.287)-(-9.408)]=0.51\%\\ {\mathrm{\&epsiv;}}_Y=\frac{1}{4\&times;(-1815)}\&times;[5\&times;(-9.408)-(-9.287)]=0.52\%\\ {\mathrm{\&gamma;}}_{\mathrm{XY}}=\frac{3}{4\&times;(-1815)}\&times;[(-9.287)+(-9.408)-2\&times;(-9.226)]=0.02\%\end{array}\right.$

As seen ε _X≈ ε _YAnd γ _XY≈ 0, and therefore tested its measuring position of Polyvinylchloride thin plate sample is in " waiting biaxial stretch-formed loaded-up condition ".

Claims (3)

1. based on carbon nano-tube the components of strain Dynamic Non-Destruction Measurement of sensor information, have carbon nano-tube (1), testee (2), polarization micro Raman spectra system (3), it is characterized in that carbon nano-tube (1) is at random attached to the surface of testee (2) or be doped in the inside of testee, polarization micro Raman spectra system (3) focuses on incident laser testee (2) surface and gathers original Raman spectral information dorsad, and the analytic expression between Raman frequency shift increment in the Raman spectral information and testee (2) the plane strain component is:

In the formula,

Represent the polarization direction to be

The time experimental system before and after distortion, gather the frequency displacement increment obtain Raman spectrum; ε X and ε Y represent the normal strain component of testee surface X, Y direction respectively, and γ XY is the shearing strain component, Ψ _SensorBeing the strain-frequency-shifting operator of carbon nano-tube strain sensing medium, is the constant factor that characterizes as linear relationship between the Raman frequency shift of the axial strain of the carbon nano-tube of strain sensing medium and carbon nano-tube, given three different polarization directions

Be respectively

With

Set up system of equations with the analytic expression between Raman frequency shift increment in the Raman spectral information and the testee plane strain component, with the frequency displacement increment measurement result of three different polarization directions With

The substitution system of equations is found the solution and is drawn the components of strain.

2. described according to claim 1 is the components of strain Dynamic Non-Destruction Measurement of sensor information based on carbon nano-tube, it is characterized in that getting described polarization direction

With Be respectively 0 °, 45 ° and 90 °, bring Raman frequency shift increment in the described Raman spectral information and the analytic expression between testee (2) the plane strain component into, draw system of equations and be:

$\left\{\begin{array}{c}{\mathrm{\&epsiv;}}_X=\frac{1}{{4\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;\left(5\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)}-{\mathrm{\&Delta;\&Omega;}}^{\left(90\right)}\right)\\ {\mathrm{\&epsiv;}}_Y=\frac{1}{4{\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;(5\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(90\right)}-\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)})\\ {\mathrm{\&gamma;}}_{\mathrm{XY}}=\frac{3}{2{\mathrm{\&Psi;}}_{\mathrm{Sensor}}}\&CenterDot;(\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(0\right)}+\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(90\right)}-2\mathrm{\&Delta;}{\mathrm{\&Omega;}}^{\left(45\right)})\end{array}\right.$

According to claim 1 or 2 described be the components of strain Dynamic Non-Destruction Measurement of sensor information based on carbon nano-tube, it is characterized in that in described three different polarization directions

Or

Or

When being all 5 °, be called 45 ° of Raman strain measurement methods with the angle of other two polarization directions; In described three different polarization directions

Or

Or

When being all 60 °, be called 60 ° of Raman strain measurement methods with the angle of other two polarization directions; In described three different polarization directions

Or

Or

When being all 120 °, be called 120 ° of Raman strain measurement methods with the angle of other two polarization directions.

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