CN110031495A - A method of based on magnetic resonance detection engineering bamboo and wood materials crackle - Google Patents
A method of based on magnetic resonance detection engineering bamboo and wood materials crackle Download PDFInfo
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- CN110031495A CN110031495A CN201910218724.6A CN201910218724A CN110031495A CN 110031495 A CN110031495 A CN 110031495A CN 201910218724 A CN201910218724 A CN 201910218724A CN 110031495 A CN110031495 A CN 110031495A
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
- G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
- G01N24/085—Analysis of materials for the purpose of controlling industrial production systems
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Abstract
The present invention provides a kind of based on nuclear magnetic resonance technique non-destructive testing engineering bamboo and wood materials crackle and studies its method developed, provides technical support to establish the failure criteria of engineering bamboo and wood materials and studying its durability.Its detection method includes: that (1) impregnates bamboo and wood materials using infuser device, (2) the moisture relaxation estate of the bamboo and wood materials after the full water of nuclear magnetic resonance spectroscopy sequencing is utilized, (3) engineering bamboo and wood materials are imaged using Magnetic resonance imaging, (4) acquired results are handled using Magnetic resonance imaging processing software, obtains reflection engineering bamboo and wood materials internal fissure image.Engineering bamboo and wood materials are carried out perspective chemical conversion picture by lossless mode by this method, observation engineering bamboo and wood materials internal structure that can be straightforward, strong technical support is provided for complicated biomass engineering investigation of materials, provides strong theories integration for high level engineering bamboo-wood structure design theory.
Description
Technical field
The present invention relates to bamboo and wood materials underbead crack non-destructive determination technical fields, and in particular to one kind is based on nuclear magnetic resonance skill
Art non-destructive testing engineering bamboo and wood materials crackle and the method for studying its development.
Background technique
Bamboo and wood materials are a kind of natural biomass materials, microcosmic upper show bubble porous structure, mainly by regular along longitudinal direction
Born of the same parents' pipe of arrangement is constituted.Bamboo and wood material is anisotropic material, that is, is parallel to the longitudinal direction (L to) of grain direction, is directed toward center of circle direction
Radial direction (R to) and tangential (T to) tangent with circle, the mechanical property difference in three directions is significant, all directions contractions
Rate difference is also very big, this will lead to its internal generation in growth, drying, industrialization processing, engineering bamboo and wood process of producing product
Crackle or crack (i.e. implicit crackle/crack), therefore engineering bamboo and wood component is work with cracking.Studies have shown that engineering bamboo and wood
Component is often in significant nonlinear damage feature under limiting condition, this non-linear nature of engineering bamboo and wood component largely due to
Its material internal crack propagation and fibrous fracture.Under external force, crack propagation can cause Stiffness Deterioration, depression of bearing force,
This is the principal element that engineering bamboo-wood structure destroys.Therefore, carrying out Limit Analysis to engineering bamboo and wood component is no longer elastoplasticity pole
Limit problem, but break limit problem.
Fracture failure criterion, the durability of research engineering bamboo and wood materials are necessarily solved in high-rise bamboo-wood structure design theory
Critical issue certainly.And engineered wood, bamboo compound bio material, composition is extremely complex with structure, and Micro influence is huge, it is difficult to
Only study with macroscopic aspect qualitative from thin see, research means are also extremely limited.
Nuclear magnetic resonance is a kind of using H proton as quick, the lossless detection means of probe, and H proton be in nature most
Common atom, detection range are extensive.Biological material itself has certain water content, or by artificially applying moisture content,
Magnetic resonance detection can be carried out to sample.
But it for being directed to engineering bamboo and wood materials, has no and is examined using latent crack of the magnetic nuclear resonance method to its inside
Survey pertinent literature.
Summary of the invention
The present invention is to solve the above problem and deficiency of the prior art, and the present invention provides one kind to be based on magnetic resonance detection
The method of engineering bamboo and wood materials crackle, it can latent crack inside non-destructive determination engineering bamboo and wood, can reflect engineering bamboo and wood
Internal recessive crack and true distribution situations of cracks study its fracture failure criterion, intensity, just in conjunction with mechanical property test
Degree and materials ' durability are applied to engineering structure for engineering bamboo and wood materials and do technical support.
To achieve the goals above, The technical solution adopted by the invention is as follows:
Method of the present invention based on magnetic resonance detection engineering bamboo and wood materials crackle, comprising the following steps: (1)
Engineering bamboo and wood materials test specimen impregnates in water, so that reaching test specimen moisture content reaches 10% or more；(2) nuclear-magnetism is carried out to test specimen to be total to
Vibration detection by carrying out CPMG pulse sequence and IR inversion recovery pulse sequencing to sample, and is handled by data reconstruction,
Lateral relaxation time T2 spectrum, longitudinal relaxation time T1 spectrum are obtained, (3) are imaged test specimen using MRI software,
(4) gained imaging is handled using Magnetic resonance imaging processing software, obtains reflection engineering bamboo and wood materials internal fissure figure
Picture.
As to the above-mentioned further improvements in methods based on magnetic resonance detection engineering bamboo and wood materials crackle, step
(1) in, test specimen is impregnated with water under vacuum conditions, soaking time is greater than 1h, and water is tap water or pure water.
As to the above-mentioned further improvements in methods based on magnetic resonance detection engineering bamboo and wood materials crackle, step
(2) processing of data reconstruction described in is to be measured using NMR relaxation time reversal fitting software to through CPMG pulse sequence
Spin echo string deamplification carry out inverting, obtain lateral relaxation time T2 spectrum；It is quasi- using NMR relaxation time reversal
It closes software and inverting is carried out to the spin echo string deamplification through IR inversion recovery pulse sequencing, obtain longitudinal relaxation time
T1 spectrum.
As to the above-mentioned further improvements in methods based on magnetic resonance detection engineering bamboo and wood materials crackle, step
(3) Magnetic resonance imaging in carries out proton density imaging, proton density imaging and the H in sample using spin echo SE sequence
Proton density is related, and the relationship of signal strength and proton density is as follows:
Wherein, S indicates the signal strength of the point；A indicates the proton density of the point；TR indicates the repetition time, refers to twice
Time interval between 90 ° of pulses；TE indicates the echo time, refers to 90 ° of pulses to the time interval between echo peak dot；T1 table
Show that the longitudinal relaxation time of the point, T2 indicate the lateral relaxation time of the point.
Work as TR " T1, TE " when T2, above-mentioned formula be can simplify are as follows:
S≈A
So proton density is higher, imaging signal is stronger, and what is showed in the picture is brighter.
As to the above-mentioned further improvements in methods based on magnetic resonance detection engineering bamboo and wood materials crackle, TR is by anti-
Turn to restore the decision of sequential experimentation result, TE is determined by CPMG experimental result and instrument, wherein TR " T1, TE ≈ T2 or instrument are most short
Echo time TEmin.
As to the above-mentioned further improvements in methods based on magnetic resonance detection engineering bamboo and wood materials crackle, TR ≈
The most short echo time TEmin=5.7-6ms of 5T1=500ms, TE ≈ instrument.
As to the above-mentioned further improvements in methods based on magnetic resonance detection engineering bamboo and wood materials crackle, TR ≈
5T1=500ms, TE=18-18.5ms.
As to the above-mentioned further improvements in methods based on magnetic resonance detection engineering bamboo and wood materials crackle, step
(3) the Magnetic resonance imaging parameter in, sampling thickness=3-5mm sample the number of plies=8-12, and the sampling interval=0.5mm adds up secondary
Number=8.
As to the above-mentioned further improvements in methods based on magnetic resonance detection engineering bamboo and wood materials crackle, step
(4) the Magnetic resonance imaging processing software in can carry out unified gray proces or Pseudo-color technology to image.
The present invention by adopting the above-described technical solution, the invention has the following advantages that
(1) nothing to engineering bamboo and wood materials can be achieved using nuclear magnetic resonance technique research engineering bamboo and wood component crackle and development
Damage detection, it is not damaged to experimental subjects, internal structure is directly visited, does not influence subsequent use, saves research cost；
(2) using nuclear magnetic resonance technique research engineering bamboo and wood component crackle and development method not by sample to be tested form,
Color, glossiness influence, and measure as former state, easy to operate without complicated pre-treatment；
(3) two dimension can be carried out to sample using nuclear magnetic resonance technique research engineering bamboo and wood component crackle and the method for development
Any angle, multilayer Surface scan, meet the imaging demand of different parts different level；
(4) using nuclear magnetic resonance technique research engineering bamboo and wood component crackle and the method for development can be complicated biomass
Investigation of materials means provide strong technical support；
(5) using nuclear magnetic resonance technique research engineering bamboo and wood component crackle and the method for development can be high-rise bamboo-wood structure
Design provides strong theories integration.
Engineering bamboo and wood materials are carried out perspective chemical conversion picture, observation engineering that can be straightforward by lossless mode by this method
Bamboo and wood materials internal structure provides strong technical support for complicated biomass engineering investigation of materials, for high-rise engineering bamboo
Timber structure design theory provides strong theories integration.
Detailed description of the invention
It, below will be to embodiment or existing in order to illustrate more clearly of present example or technical solution in the prior art
Required attached drawing, which is done, in technical description simply introduces, it should be apparent that, the accompanying drawings in the following description is only of the invention
Some examples to those skilled in the art, can also be according to these attached drawings under the premise of not paying creativeness
Obtain other attached drawings.
Fig. 1 is the present invention to wherein one layer of gray scale in the imaging of proton density formed by large-scale mechanical and electrical packaging engineering bamboo wood
Figure；
Fig. 2 is that the present invention passes through nuclear magnetic resonance image processing software to proton formed by large-scale mechanical and electrical packaging engineering bamboo wood
The wherein pcolor (pcolor of Fig. 1) after one layer of image procossing in density imaging.
Fig. 3 is the grayscale image of Fig. 2.
The lateral relaxation time T2 spectrum of sample, Before represent the relaxation spectrum before full water in Fig. 4 embodiment 1, and After is represented
Relaxation spectrum after full water.
Longitudinal relaxation time T1 spectrum in Fig. 5 embodiment 1 after the full water of sample.
Specific embodiment
Below in conjunction with present example, technical scheme in the embodiment of the invention is clearly and completely described, shows
So, described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.Based on the implementation in invention
Example, every other embodiment obtained by those of ordinary skill in the art without making creative efforts belong to
The scope of protection of the invention.
The method of the nuclear magnetic resonance technique non-destructive testing engineering bamboo and wood materials crackle is the following steps are included: (1) utilizes very
Empty infuser device impregnates engineering bamboo and wood materials, and immersion liquid is tap water, pure water, and soaking time is greater than 1h, vacuum
Degree is 0.09MPa, so that the moisture content of engineering bamboo and wood materials is reached 12% or so (2) and soaked using nuclear magnetic resonance spectroscopy sequencing
The moisture relaxation estate of engineering bamboo and wood materials after bubble.The nuclear magnetic resonance spectroscopy sequence that the magnetic nuclear resonance method uses for
Carr-Purcell-Meiboom-Gill (CPMG) sequence and inversion recovery pulse sequence IR, CPMG sequence are surveyed with IR sequence
As a result it needs to handle by data reconstruction, and result is denoted as lateral relaxation time T2 spectrum respectively and is composed with longitudinal relaxation time T1.(3)
Engineering bamboo and wood materials are imaged using Magnetic resonance imaging.Magnetic resonance imaging carries out H matter using spin echo SE sequence
Sub- density imaging.Proton density imaging repetition waiting time TR used determines that TE is by CPMG by inversion-recovery sequence experimental result
Experimental result and instrument determine, wherein TR " T1, TE ≈ T2 or the most short echo time TEmin of instrument.Magnetic resonance imaging parameter is such as
Sampling thickness samples the number of plies, and in the sampling interval, accumulative frequency will optimize according to the actual situation, to be obtained using the shortest time
To optimal image.(4) acquired results are handled using Magnetic resonance imaging processing software, obtains reflection engineering bamboo and wood material
Expect internal fissure image.Magnetic resonance imaging processing software can carry out unified gray proces and Pseudo-color technology to image.
Embodiment 1:
Latent crack in the large-scale electromechanical Packaging Engineering bamboo wood of measurement.
Full water process is carried out to engineering bamboo wood using device is soaked in vacuum.The engineering bamboo sample size is 5.5*5.1*
2.8cm, immersion liquid select tap water, soaking time 4h, so that the test specimen moisture content reaches 14% or so.
Using Carr-Purcell-Meiboom-Gill (CPMG) sequence and inversion recovery pulse sequence IR to full water after
Engineering bamboo wood is measured, and need to be handled by data reconstruction measured result, and lateral relaxation time T2 spectrum (referring to fig. 4) is obtained
(referring to Fig. 5) is composed with longitudinal relaxation time T1.
Bamboo and wood contains 1 relaxation peak before full water as can be seen from Figure 4, includes three kinds of moisture phases in the timber after water of satisfying.
Wherein, T21 (0.01~5ms) is to combine water, and T22 (5~100ms) is irreducible water, the crackle in corresponding bamboo and wood, T23 (>
200ms) it is Free water, belongs to the water of a small amount of non-wiped clean in bamboo-wood structure surface.
Proton density imaging is carried out using spin echo SE sequence, wherein TR ≈ 5T1=500ms, TE ≈ instrument most short time
Wave time TEmin=5.885ms.
For this experiment, Magnetic resonance imaging parameter is as follows: sampling thickness=5mm, the sampling number of plies=8, and the sampling interval=
0.5mm, accumulative frequency=8.
Unified gray proces and Pseudo-color technology are carried out to sample using Magnetic resonance imaging processing software, obtain required imaging
Figure, as a result as shown in Figure 1 and Figure 2.Fig. 3 is the grayscale image of Fig. 2.
Since the relaxation time of bamboo and wood itself is short (< 5ms), the signal of this part is not acquired in imaging, in imaging
Dark signal is shown as, and the crack of full water inlet shows as bright signal due to being caught in signal containing water, when so being imaged, therefore
It will be seen from figure 1 that the position (ellipse irises out part in figure) that signal is brighter is the crackle of bamboo and wood.As can be seen from Figure 2 bamboo
The wooden crackle shows as highlighted red and yellow signal (ellipse irises out part in figure), and for Fig. 3, bamboo and wood crackle is shown as
High bright part (ellipse irises out part in figure).
Embodiment 2:
Latent crack in the large-scale electromechanical Packaging Engineering bamboo wood of measurement.
Full water process is carried out to engineering bamboo wood using device is soaked in vacuum.The engineering bamboo sample size is 4.1*3.8*
3.2cm immersion liquid selects tap water, soaking time 3h, so that the test specimen moisture content reaches 10%.
(1) using Carr-Purcell-Meiboom-Gill (CPMG) sequence and inversion recovery pulse sequence IR to full water
Engineering bamboo wood afterwards is measured, and need to be handled measured result, obtain lateral relaxation time T2 spectrum and be indulged by data reconstruction
It is composed to relaxation time T1.
(2) proton density imaging is carried out using spin echo SE sequence, wherein TR=500ms, TE=18.125ms.
(3) for this experiment, Magnetic resonance imaging parameter is as follows: sampling thickness=3mm samples the number of plies=12, between sampling
Every=0.5mm, accumulative frequency=8.
(4) unified gray proces and Pseudo-color technology are carried out to sample using Magnetic resonance imaging processing software, needed for obtaining
Image.
Claims (9)
1. a kind of method based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterised in that: the following steps are included: (1)
Engineering bamboo and wood materials test specimen is impregnated in water, so that test specimen moisture content reaches 10% or more；(2) nuclear magnetic resonance is carried out to test specimen
Detection by carrying out CPMG pulse sequence and IR inversion recovery pulse sequencing to sample, and is handled by data reconstruction, is obtained
To lateral relaxation time T2 spectrum, longitudinal relaxation time T1 spectrum；(3) test specimen is imaged using MRI software；(4)
Gained imaging is handled using Magnetic resonance imaging processing software, obtains reflection engineering bamboo and wood materials internal fissure image.
2. the method according to claim 1 based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterized in that: step
(1) in, test specimen is impregnated with water under vacuum conditions, soaking time is greater than 1h, and water is tap water or pure water.
3. the method according to claim 1 based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterized in that: step
(2) processing of data reconstruction described in is to be measured using NMR relaxation time reversal fitting software to through CPMG pulse sequence
Spin echo string deamplification carry out inverting, obtain lateral relaxation time T2 spectrum；It is quasi- using NMR relaxation time reversal
It closes software and inverting is carried out to the spin echo string deamplification through IR inversion recovery pulse sequencing, obtain longitudinal relaxation time
T1 spectrum.
4. the method according to claim 1 based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterized in that: step
(3) Magnetic resonance imaging in carries out proton density imaging, proton density imaging and the H in sample using spin echo SE sequence
Proton density is related, and the relationship of signal strength and proton density is as follows:
Wherein, S indicates the signal strength of the point；A indicates the proton density of the point；TR indicates the repetition time, refers to 90 ° of arteries and veins twice
Time interval between punching；TE indicates the echo time, refers to 90 ° of pulses to the time interval between echo peak dot；T1 is indicated should
The longitudinal relaxation time of point, T2 indicate the lateral relaxation time of the point.
5. the method according to claim 4 based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterized in that: TR is by anti-
Turn to restore the decision of sequential experimentation result, TE is determined by CPMG experimental result and instrument, wherein TR " T1, TE ≈ T2 or instrument are most short
Echo time TEmin.
6. the method according to claim 4 based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterized in that: TR ≈
The most short echo time TEmin=5.7-6ms of 5T1=500ms, TE ≈ instrument.
7. the method according to claim 4 based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterized in that: TR ≈
5T1=500ms, TE=18-18.5ms.
8. the method according to claim 1 based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterized in that: step
(3) the Magnetic resonance imaging parameter in, sampling thickness=3-5mm sample the number of plies=8-12, and the sampling interval=0.5mm adds up secondary
Number=8.
9. the method according to claim 1 based on magnetic resonance detection engineering bamboo and wood materials crackle, it is characterized in that: step
(4) the Magnetic resonance imaging processing software in carries out unified gray proces or Pseudo-color technology to image.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114047092A (en) * | 2021-11-16 | 2022-02-15 | 内蒙古农业大学 | Method for measuring cell wall free water content of balanced wood and application thereof |
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| EP0406082A1 (en) * | 1989-06-29 | 1991-01-02 | Magnetech | Nuclear magnetic resonance three-dimensional imaging method |
| CN104237284A (en) * | 2014-10-17 | 2014-12-24 | 西安石油大学 | Nuclear magnetic resonance detection method for brittle and hard shale microcrack damage |
| CN108982568A (en) * | 2018-06-15 | 2018-12-11 | 武汉大学 | The method of downfield nuclear magnetic resonance non-destructive testing Concrete Sulfate Attack damage |
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2019
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0406082A1 (en) * | 1989-06-29 | 1991-01-02 | Magnetech | Nuclear magnetic resonance three-dimensional imaging method |
| CN104237284A (en) * | 2014-10-17 | 2014-12-24 | 西安石油大学 | Nuclear magnetic resonance detection method for brittle and hard shale microcrack damage |
| CN108982568A (en) * | 2018-06-15 | 2018-12-11 | 武汉大学 | The method of downfield nuclear magnetic resonance non-destructive testing Concrete Sulfate Attack damage |
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| Title |
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| FRANK C. BEALL: "INDUSTRIALAPPLICATIONS AND OPPORTUNITIES FOR NONDESTRUCTIVE EVALUATION OF STRUCTURAL WOOD MEMBERS", 《MADERAS: CIENCIA Y TECNOLOGÍA》 * |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114047092A (en) * | 2021-11-16 | 2022-02-15 | 内蒙古农业大学 | Method for measuring cell wall free water content of balanced wood and application thereof |
| CN114047092B (en) * | 2021-11-16 | 2023-06-23 | 内蒙古农业大学 | Method for measuring free water content of cell wall of balance wood and application thereof |
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Application publication date: 20190719 |