CN203241319U - Frequency-method testing device for elastic modulus of rectangular dimension stock - Google Patents
Frequency-method testing device for elastic modulus of rectangular dimension stock Download PDFInfo
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- CN203241319U CN203241319U CN 201320079728 CN201320079728U CN203241319U CN 203241319 U CN203241319 U CN 203241319U CN 201320079728 CN201320079728 CN 201320079728 CN 201320079728 U CN201320079728 U CN 201320079728U CN 203241319 U CN203241319 U CN 203241319U
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Abstract
The utility model provides a frequency-method testing device for elastic modulus of rectangular dimension stock, and the device is simple in structure and convenient to test. The frequency method testing device comprises two elastic bands, a ruler, a weighing instrument, a hammer and an acceleration sensor, wherein the two elastic bands are used for hanging a test specimen along the length direction, the distances from the hanging points of the two elastic bands to the two end parts of the test specimen in the length direction are 0.0224L, and L refers to the length of the test specimen; the ruler is used for measuring the length and the width of the test specimen; the weighing instrument is used for measuring the weight of the test specimen; the hammer is used for striking the test specimen; the acceleration sensor is arranged on the test specimen and is used for reflecting the acceleration G of the test specimen, the output of the acceleration sensor is connected with a signal conditioning instrument, and the output of the signal conditioning instrument is connected with a signal collection and analysis instrument.
Description
Technical field
The utility model relates to the proving installation of rectangular parallelepiped dimension stock elastic modulus, specifically, is a kind of frequency method proving installation of SPF dimension stock elastic modulus.
Background technology
The method in the GB/T1936.2-1991 wood modulus of elasticity test method is generally adopted in the test of wood modulus of elasticity.The method test is loaded down with trivial details, and measurement result is not too accurate.
The utility model content
The purpose of this utility model provides a kind of frequency method proving installation of rectangular parallelepiped dimension stock elastic modulus of simple in structure, convenient test.
The frequency method proving installation of this rectangular parallelepiped dimension stock elastic modulus, it comprises two elastics that alongst test specimen hung up, and the hitch point of two elastics is 0.224L to the distance at the both ends of test specimen length direction, and L is the length of test specimen; Be used for measuring the ruler of test specimen length and width; Be used for measuring the weighing instrument of test specimen weight; Knock the power hammer of test specimen, be arranged on the acceleration transducer of the reaction test specimen acceleration G size on the test specimen; The output of acceleration transducer connects the signal condition instrument, and the output of signal condition instrument connects signals collecting and analyser.
The frequency method proving installation of above-mentioned elastic modulus, signal condition instrument comprise the amplifier that the output signal of acceleration transducer is carried out the wave filter of filtering, filtered signal is amplified.
The frequency method proving installation of above-mentioned elastic modulus, signals collecting and analyser comprise signal sampler and signal processing analysis instrument; Signal sampler has computer interface, dsp chip, A/D converter; The signal processing analysis instrument comprises the CPU processor; Amplifier, computer interface, dsp chip, A/D converter, CPU processor link to each other successively.
Theoretical according to the beam transverse curvature, the single order natural bending frequency of free beam:
After the conversion,
In the formula: E-tries the material dynamic modulus of elasticity (Pa), ρ-test specimen air-dry density (kg/m
3), f
1Test specimen fundamental frequency (Hz), l-test specimen length (m), h-specimen thickness (m).
That is to say, according to ρ, f
1, l, h can calculate E according to formula (1).
Firmly hammer knocks test specimen and makes its generation Free Transverse, and image data gets its frequency spectrum do Fast Fourier Transform (FFT), identification single order natural bending frequency f from spectrogram
1With ruler measurement test specimen length, width and height, calculate volume; Weigh up in test specimen weight with weighing instrument, calculate density according to weight, volume; Can calculate E according to formula (1) again.
The beneficial effects of the utility model: present technique adopts the supporting structure of elastic threads Vertical Free hang to realize free beam to test specimen, and recycling transient excite frequency method by surveying free beam test specimen single order natural bending frequency, obtains its elastic mould value.1, adopt the test of this proving installation, can objectively respond the situation of the dynamic deformation of the test specimen under the actual state, its test duration is short, informative data, accurate and reliable.2, can from the spectrogram of test specimen, obtain the data such as fundamental frequency, the analysis of the line correlation of going forward side by side.3, the utility model is simple in structure, and is easy to operate.
Description of drawings
Fig. 1 is the test block diagram of test free beam test specimen single order natural bending frequency;
Fig. 2 is free beam test specimen single order natural bending frequency spectrogram.
Embodiment
Embodiment: the transient excite frequency method is measured SPF dimension stock elastic modulus
The SPF dimension stock is the main material in the light-duty wooden construction timber, and its elastic modulus E is the index of weighing this material production elastic deformation complexity.
1 general introduction
1.1 test philosophy
As previously mentioned, under the condition that sample dimensions is given and test specimen material density is known, elastic modulus E can be crooked solid by frequency f by the single order of free beam
1Reckoning obtains:
In the formula: the E-examination material dynamic modulus of elasticity (Pa), ρ-test specimen air-dry density (kg/m
3), f
1-test specimen fundamental frequency (Hz), l-test specimen length (m), h-specimen thickness (m).
In addition, for surveying the air-dry density of this batch SPF test specimen, according to GB/T1933-2009 " Method for determination of the density of wood ", intercept the cube that size is 20mm * 20mm * 20mm from every test specimen, after photoelectric analytical balance is weighed, try to achieve one by one.
1.2 method of testing, test specimen and instrument
Knock SPF dimension stock test specimen with the transient excite frequency method with rubber mallet and make it produce Free Transverse, image data gets its frequency spectrum do Fast Fourier Transform (FFT), identification single order natural bending frequency f from spectrogram
1
This paper tests totally 12 of used Canadian SPF dimension stock finished parts test specimens, and it is the II level that its face must identify rank,
Specification is 367mm (l) * 138mm (b) * 37mm (h), air-dry density ρ=390-492kg/m
3, water percentage MC=6～8%.
Measure worker's measuring device tool: two elastics 5 that alongst test specimen 9 hung up, the hitch point of 6, two elastics are 0.224L to the distance at the both ends of test specimen length direction, and L is the length of test specimen.Measure the ruler of test specimen length and width; 1 of TG328B type photoelectric analytical balance (0.001g).Knock power hammer (rubber hammer) 7 of test specimen.Be arranged on 8 one of the CA-YD-126 type piezoelectric acceleration transducers of the reaction test specimen acceleration G size on the test specimen, its charge sensitivity is 0.34pc/m/s
2, quality 4g.Nanjing peace is (Nanjing pacify positive soft project Ltd) CRAS vibration and dynamic signal acquisition analytic system one cover just.
Nanjing peace is (Nanjing pacify positive soft project Ltd) CRAS vibration and dynamic signal acquisition analytic system one cover just, is comprised of signal condition instrument 1, signal sampler 2, SsCras signals and systems analysis software 3 and computing machine 4 etc.Signal condition instrument 1 comprises anti alias filter and signal amplifier, and signal sampler 2 has computer interface, digital signal device processing DSP chip, A/D converter etc.The signal processing analysis instrument comprises the CPU processor in the computing machine 4 etc.
The output signal of anti alias filter degree of will speed up sensor is carried out filtering, then the signal entering signal Acquisition Instrument 2 after signal amplifier amplifies.The simulating signal that collects as calculated machine interface enters digital signal device processing DSP chip and carries out digital signal processing, then convert digital signal to through A/D converter, the signal input part by the CPU processor in the signal processing analysis instrument enters the CPU processor and carries out Treatment Analysis by CPU processor and system controlling software thereof.The SsCras signals and systems analysis software that adopts Nanjing to pacify positive soft project Ltd carries out spectrum analysis, and the frequency spectrum wave crest, the trough that obtain are clear and legible.
2 transient excite frequency method testing procedures
2.1 hang SPF dimension stock finished product test specimen with elastic, elastic suspension place is respectively 0.224L apart from the left and right end of test specimen, to realize free beam.
2.2 the single order corner frequency of transient batting method test test specimen.Arrange in the parameter of vibration signals collecting, repeatedly mixed for preventing frequency, the upper frequency limit of low-pass filter is selected in this test, and namely frequency filtering is made as 50Hz; Analysis frequency is made as 50Hz, and FFT length is 2048, and the frequency test precision can reach 0.0625Hz, 1 of data block, and voltage range ± 5000mV, the regulating instrument enlargement ratio is made as 100, and frequency filtering is established 50Hz.
Whether before the actual measurement, enter the oscillography mode, knock continuously test specimen, connect with the inspection apparatus connecting line, whether waveform is reasonable etc., will reset it when unreasonable.During formal the measurement, knock test specimen by rubber mallet, the triggering collection signal carries out the Dynamic Signal spectrum analysis, and reads the fundamental frequency value by the 1st peak value of power spectrum chart, as shown in Figure 2.Horizontal ordinate among Fig. 6 represents frequency (Hz), and ordinate is amplitude (EU).Above-mentioned to every test specimen duplicate measurements 2 times, gather 2 blocks of data at every turn.Get its frequency averaging value as the frequency of calculating elastic modulus.
2.3 accelerometer is installed on test specimen left end or right-hand member, rubber hammer knocks the test specimen span centre.Span centre is the crooked node of vibration mode of second order position, so that the peak value of second order frequency do not occur on the spectrogram of 50Hz analysis frequency, filtering 50Hz guarantees can not occur the mixed repeatedly frequency of three rank natural frequencys on frequency spectrum.
3 test results and analysis
The measurement and calculation of 12 test specimens the results are shown in Table 1.In the table 1, air-dry density is according to GB/T1933-2009 " Method for determination of the density of wood ", intercepts the cube that size is 20mm * 20mm * 20mm from every test specimen, tries to achieve one by one after photoelectric analytical balance is weighed.In the table 1, the calculating of elastic modulus is that the single order natural bending frequency substitution formula (1) of sample dimensions, air-dry density and measurement is tried to achieve.
Basic parameter and the measured value table (transient excite frequency method) of table 1SPF test specimen
Fig. 2 is the measurement frequency spectrum of No. 4 finished product test specimens of SPF dimension stock in the table 1, is not difficult to read the single order corner frequency from spectrogram, and namely fundamental frequency is 13.88Hz.Also see on Fig. 2 two little peaks also having occurred near 2Hz, they are corresponding respectively to be the translation of test specimen rigid body and to rotate mode, adopts calculating that elastic modulus can be managed.Frequency about 2Hz can be used to estimate the stiffness coefficient of test specimen heifer muscle, and computing formula is k=M (2 π f
0)
2(stiffness coefficients of two elastics).Wherein, M is the test specimen quality.
Among the GB50005-2003 " Code for design of timber structures ", the II of range estimation classification import SPF dimension stock
CLevel elastic modulus design load is 9700MPa.Obviously, in this batch only the elastic mould value of No. 4 finished product test specimens actual measurement be lower than II
CThe designing requirement of level regulation.
The transient excite frequency method that this patent provides and testing program are to be based upon in the frequency measurement that realizes free beam one first order mode, and elastic hangs test specimen and realizes free beam, and the measurement of frequency also is reliably and has enough precision.Check, the quality grading work performance that this nondestructive determination can be the stiffness index performance of the materials such as the SPF dimension stock effect of checking on reliably has higher using value and realistic meaning to the detection technique work of the industries such as light-duty wooden building.
Claims (3)
1. the frequency method proving installation of rectangular parallelepiped dimension stock elastic modulus, it is characterized in that: it comprises two elastics that alongst test specimen hung up, the hitch point of two elastics is 0.224L to the distance at the both ends of test specimen length direction, and L is the length of test specimen; Be used for measuring the ruler of test specimen length and width; Be used for measuring the weighing instrument of test specimen weight; Knock the power hammer of test specimen, be arranged on the acceleration transducer of the reaction test specimen acceleration G size on the test specimen; The output of acceleration transducer connects the signal condition instrument, and the output of signal condition instrument connects signals collecting and analyser.
2. the frequency method proving installation of elastic modulus as claimed in claim 1 is characterized in that: the signal condition instrument comprises the amplifier that the output signal of acceleration transducer is carried out the wave filter of filtering, filtered signal is amplified.
3. the frequency method proving installation of elastic modulus as claimed in claim 2, it is characterized in that: signals collecting and analyser comprise signal sampler and signal processing analysis instrument; Signal sampler has computer interface, dsp chip, A/D converter; The signal processing analysis instrument comprises the CPU processor; Amplifier, computer interface, dsp chip, A/D converter, CPU processor link to each other successively.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106093197A (en) * | 2016-06-07 | 2016-11-09 | 北京林业大学 | Large scale wood-based plate elastic modelling quantity and the lossless detection method of In-plane Shear Modulus |
| CN106596100A (en) * | 2017-01-09 | 2017-04-26 | 温州大学 | Four-step machine tool spindle elastic modulus nondestructive detection method and device |
| CN106769560A (en) * | 2017-01-09 | 2017-05-31 | 温州大学 | A kind of I-beam mechanics parameter lossless detection method based on vibration |
-
2013
- 2013-02-21 CN CN 201320079728 patent/CN203241319U/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106093197A (en) * | 2016-06-07 | 2016-11-09 | 北京林业大学 | Large scale wood-based plate elastic modelling quantity and the lossless detection method of In-plane Shear Modulus |
| CN106093197B (en) * | 2016-06-07 | 2019-04-05 | 北京林业大学 | The lossless detection method of large scale wood-based plate elasticity modulus and In-plane Shear Modulus |
| CN106596100A (en) * | 2017-01-09 | 2017-04-26 | 温州大学 | Four-step machine tool spindle elastic modulus nondestructive detection method and device |
| CN106769560A (en) * | 2017-01-09 | 2017-05-31 | 温州大学 | A kind of I-beam mechanics parameter lossless detection method based on vibration |
| CN106596100B (en) * | 2017-01-09 | 2018-10-30 | 温州大学 | A kind of four-step machine tool chief axis elasticity modulus lossless detection method and device |
| CN106769560B (en) * | 2017-01-09 | 2019-05-03 | 温州大学 | A kind of I-beam mechanics parameter lossless detection method based on vibration |
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| C14 | Grant of patent or utility model | ||
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20131016 Termination date: 20160221 |
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| CF01 | Termination of patent right due to non-payment of annual fee |