CN203981636U - A kind of nondestructive detection system based on the contact vibration of piezoelectricity disk - Google Patents
A kind of nondestructive detection system based on the contact vibration of piezoelectricity disk Download PDFInfo
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- CN203981636U CN203981636U CN201420413078.1U CN201420413078U CN203981636U CN 203981636 U CN203981636 U CN 203981636U CN 201420413078 U CN201420413078 U CN 201420413078U CN 203981636 U CN203981636 U CN 203981636U
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- disk
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Abstract
The utility model discloses a kind of nondestructive detection system based on the contact vibration of piezoelectricity disk.Nondestructive detection system of the present utility model comprises: piezoelectricity disk, traversing carriage, signal generator, power amplifier, strainmeter, data collecting card and computing machine; Wherein, piezoelectricity disk comprises disk substrate, piezoelectric patches, probe and foil gauge, piezoelectric patches be positioned at disk substrate lower surface and centered by symmetrical, probe is positioned at the lower surface circle centre position of disk substrate and perpendicular to disk substrate, foil gauge is arranged in the upper surface of disk substrate.The contact vibration of the utility model based on piezoelectricity disk and sample, by following the trail of the vibration characteristics of piezoelectricity disk, survey local contact stiffness, can be by detect to obtain the Stiffness Distribution of structure by pointwise at sample surfaces, and then complete the evaluation to structural health degree; The test philosophy that the utility model is used is simple and reliable, is applicable to thin-slab construction as the Non-Destructive Testing of composite laminated plate or soft material.
Description
Technical field
The utility model belongs to material structure safety monitoring field, is specifically related to a kind of nondestructive detection system based on the contact vibration of piezoelectricity disk.
Background technology
Dynamic Non-Destruction Measurement can complete the damage check of material or structure and health assessment, thereby has great importance in industrial development.In the situation that structure through the longer operating period or be subject to external effect may cause damage, we need to understand the health condition of inside configuration to determine whether structure can also work on, or repair for concrete degree of impairment.Especially at aerospace field, along with the composite thin plate structure of industrial expansion high-strength light is more and more applied, composite thin plate structure easily ruptures, layering, laying fold, come off and the defect such as separated, large and the serious aerospace industry of fatigue loading for load capacity, the Non-Destructive Testing that how to complete composite thin plate structure is a urgent problem.
At present methods such as ultrasonic, ray and magnetic detection of traditional Dynamic Non-Destruction Measurement, can complete the detection to most industrial structures, but to novel composite thin plate still there is larger difficulty in isostructural detection.For ultrasonic method, because the material property of compound substance exists serious anisotropy and obvious to acoustic attenuation effect, so compound substance is not suitable for ultrasonic method.And in thin plate lattice structure, usually because ultrasonic examination exists thickness blind area more, and complex structure causes the propagation reflections of sound wave complicated, and then causes the Ultrasonic Detection in grid thin-slab construction to be difficult to realize.For class electromagnetic methods such as ray and magnetic detections, because compound substance is insensitive to electromagnetism, large and to be not easy to detection in place etc. former thereby can not in the Non-Destructive Testing of grid thin-slab construction, apply to human injury.In order to complete the Non-Destructive Testing task to composite structure, need to develop the system that is applicable to thin-slab construction Non-Destructive Testing.
Utility model content
In order to solve nondestructive detection system in prior art, be difficult to the problem to composite thin plate structure detection, the utility model proposes a kind of contact vibration based on piezoelectricity disk and sample, by following the trail of the vibration characteristics of piezoelectricity disk, carry out the nondestructive detection system of the local contact stiffness of detecting material or structure.
The purpose of this utility model is to propose a kind of nondestructive detection system based on the contact vibration of piezoelectricity disk.
Nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model comprises: piezoelectricity disk, traversing carriage, signal generator, power amplifier, strainmeter, data collecting card and computing machine; Wherein, piezoelectricity disk comprises disk substrate, piezoelectric patches, probe and foil gauge, piezoelectric patches be positioned at disk substrate lower surface and centered by symmetrical, probe is positioned at the lower surface circle centre position of disk substrate and perpendicular to disk substrate, foil gauge is arranged in the upper surface of disk substrate; The circumference of the disk substrate of piezoelectricity disk is arranged on traversing carriage, by traversing carriage, drives piezoelectricity disk to move on the surface of sample; Signal generator is connected to power amplifier through data line, and power amplifier is connected to the piezoelectric patches of piezoelectricity disk by wire; The foil gauge of piezoelectricity disk is connected to strainmeter by data line; Strainmeter is connected to data collecting card by data line; Data collecting card is connected to computing machine by data line.
Disk substrate is thin plate, and the relation between thickness h and radius R meets
disk substrate, under the drive of piezoelectric patches, can inspire needed integrally bending mode of oscillation like this.The probe that is positioned at disk substrate center place is tapered, and its head is spherical; In testing process, the border of the circumference of disk substrate is fixed support boundary condition, and the head of probe contacts with the surface of sample.The height H of probe
tanand the relation between the radius R of disk substrate meets
thereby probe can met under the mobility and freedom prerequisite of structure, be unlikely to affect the harmony of piezoelectricity disk vibration itself simultaneously.Piezoelectric patches adopts centrosymmetric structure, as multi-disc be centrosymmetric fan-shaped, or the annulus concentric with disk substrate, this centrosymmetric piezoelectric patches guarantees symmetrical mode centered by the vibration of excitation piezoelectricity disk.The internal diameter R of piezoelectric patches
1with external diameter R
2meet 0.2R≤R
1< R
2≤ 0.9R; The thickness t of piezoelectric patches and disk substrate h approach, and meet 0.5h≤t≤1.5h.
Signal generator sends accumulation signal, and excitation piezoelectric patches occurs vibrate and drive disk substrate to vibrate, and further drives probe and sample to come in contact vibration; Be positioned at the strain of foil gauge perception piezoelectricity disk and then the contact resonance information of acquisition piezoelectricity disk, the i.e. strain signal of disk upper surface of base plate; Foil gauge transfers to strainmeter by the strain signal detecting by data line.The accumulation signal that signal generator sends is divided into two kinds of the signal of fixed frequency and swept-frequency signals; Correspondingly, the Dynamic Signal that strainmeter detects is divided into determines two kinds of frequency response induction signal and frequency sweep response signals.
Signal generator sends the swept-frequency signal of a plurality of cline frequency points, the response of piezoelectricity disk is also frequency sweep, the dynamic frequency sweep response signal of strainmeter collection, by extracting peak swing respective frequencies in a plurality of frequencies, find out resonant frequency, computing machine extracts resonant frequency and calculates local contact stiffness value, and this pattern is sweep check pattern; Signal generator sends the sinusoidal signal of single-frequency, the response of piezoelectricity disk is also the sinusoidal signal of single-frequency, frequency response induction signal is determined in strainmeter collection dynamically, and the amplitude of computing machine extraction sinusoidal signal carrys out the local contact stiffness value of test material, and this pattern is fixed test pattern frequently.In actual measurement process, use the Non-Destructive Testing that sweep check pattern or fixed test pattern frequently all can complete paired samples, the feature of sweep check pattern is that precision is high but speed is slow, and the fixed feature of test pattern is frequently that speed is fast but precision is low.Therefore in conjunction with these two kinds of patterns, detection that can good complete paired samples.
Strainmeter can detect Dynamic Signal, also stationary singnal can be detected.The distortion of piezoelectricity disk can be divided into two parts: whole static buckling distortion, and the distortion of the dynamic vibration of little amplitude; Static buckling distortion be due to initial contact upper after the distortion that causes of contact force, the stationary singnal by strainmeter detects; And dynamic vibration distortion is that piezoelectric patches excited vibration causes, be sinusoidal, by the dynamic signal detection of strainmeter.By stationary singnal can perception probe and sample between contact force; By Dynamic Signal, can follow the trail of obtain piezoelectricity disk dynamic vibration characteristic as resonant frequency (sweep check pattern) or vibration amplitude (fixed test pattern frequently); Further, by surveying the dynamic vibration characteristic of piezoelectricity disk, can obtain the local contact stiffness information of the contact point of sample and probe.
Computing machine is connected with data collecting card with signal generator respectively by data line, signal generator produces accumulation signal excitation piezoelectric patches, and then drive piezoelectricity disk and sample to come in contact vibration, foil gauge gathers strain signal and transfers to strainmeter, and the strain signal that data collecting card collection is nursed one's health through strainmeter is also passed to computing machine.
Traversing carriage comprises fixed mount and the mobile device of annular, the circumference of disk substrate is fixed on fixed mount, fixed mount is arranged on mobile device, thus fixing piezoelectricity disk drive piezoelectricity source tray to move on the surface of sample, and then the detection of the target area of complete paired samples.The circumference of piezoelectricity disk is fixed on annular fixed mount, and this continuously large stiffness structure is fixed, and make the periphery of whole piezoelectricity disk all in a good mechanics fixed boundary state, thereby structure is more stable.Fixed mount adopts the large material of rigidity, as materials such as stainless steels, realizes the rigidity of fixed mount by increased in size and quality.The own size of fixed mount (thickness) and quality will, much larger than piezoelectricity disk, provide a stable fixed support border by obtaining a larger inertia.
Lossless detection method based on the contact vibration of piezoelectricity disk of the present utility model, comprises the following steps:
1), according to the size of piezoelectricity disk, structure and material, determine the mechanical model of piezoelectricity disk, thereby according to mechanical model, obtain the resonant frequency f of piezoelectricity disk
nor the vibration amplitude of vibrational system, with the local contact stiffness k of sample
*between relation;
2) traversing carriage that piezoelectricity disk is installed is placed on to sample surfaces to be measured;
3) by strainmeter, detect the stationary singnal of foil gauge, obtain the contact force between probe and sample, by adjusting the height of traversing carriage, thereby adjust the contact force between probe and sample;
4) computer control signal generator sends accumulation signal, and excitation piezoelectric patches drives the vibration of disk substrate, thereby drive between probe and sample, comes in contact vibration, and piezoelectricity disk carries out stable state resonance;
5) strainmeter detects strain signal and transfers to strainmeter, transfers to data collecting card, the strain signal of data collecting card collection conditioning after strainmeter conditioning strain signal;
6) computing machine is processed by data collecting card and is gathered next strain signal, and then obtains the local contact stiffness information of measurement point sample, and the local contact stiffness information of passing through just can obtain the health degree of sample.
Above-mentioned detection method can adopt sweep check pattern, and signal generator sends dynamic swept-frequency signal, the dynamic frequency sweep response signal of strainmeter collection, and computing machine extracts resonant frequency and calculates local contact stiffness value, and this pattern is sweep check pattern; Signal generator sends the signal of fixed frequency, and frequency response induction signal is determined in strainmeter collection, and computing machine extracts vibration amplitude value and calculates local contact stiffness value, and this pattern is fixed test pattern frequently.
Advantage of the present utility model:
Detection system of the present utility model adopts the piezoelectricity disk of centrosymmetric structure, contact vibration based on piezoelectricity disk and sample, by following the trail of the vibration characteristics of piezoelectricity disk, carry out the local contact stiffness of detecting material or structure, further this piezoelectricity disk is integrated on a device that can move freely at sample surfaces, can be by detect to obtain the Stiffness Distribution of structure by pointwise at sample surfaces, and then complete the evaluation to structural health degree.Compared to existing nondestructive detection system, the test philosophy that the utility model is used is simple and reliable, is applicable to thin-slab construction as the Non-Destructive Testing of composite laminated plate or soft material.
Accompanying drawing explanation
Fig. 1 is the structural representation of a kind of nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model;
Fig. 2 is the schematic diagram of an embodiment of the piezoelectricity disk of the nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model, wherein, (a) being the schematic diagram of the upper surface of piezoelectricity disk, is (b) schematic diagram of the lower surface of the fan-shaped piezoelectricity disk that is centrosymmetric of multi-disc for piezoelectric patches;
Fig. 3 is that the piezoelectric patches of the nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model is the schematic diagram of the lower surface of annular piezoelectricity disk;
Fig. 4 is the sectional view of the first rank mode of oscillation of ejecting of piezoelectric patches that the nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model is centrosymmetric;
Fig. 5 is the schematic diagram of mechanical model of the piezoelectricity disk vibration system of the nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model;
Fig. 6 is the resonant frequency f of the piezoelectricity disk of the nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model
nlocal contact stiffness k with sample
*between the curve map of relation;
The schematic diagram that the probe of the local contact stiffness detection system that Fig. 7 (a) is beam type contacts with sample, (b) is the schematic diagram that the probe of the piezoelectricity disk of the nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model contacts with sample.
Embodiment
Below in conjunction with accompanying drawing, by specific embodiment, further set forth the utility model.
As shown in Figure 1, the nondestructive detection system based on the contact vibration of piezoelectricity disk of the present utility model comprises: piezoelectricity disk 2, traversing carriage, signal generator 4, strainmeter 5, data collecting card 6 and computing machine 7; Wherein, piezoelectricity disk 2 comprises disk substrate 21, piezoelectric patches 22, probe 23 and foil gauge 24, piezoelectric patches 22 be positioned at disk substrate lower surface and centered by symmetric figure, probe 23 is positioned at the lower surface circle centre position of disk substrate and perpendicular to disk substrate 21, as shown in Fig. 2 (b), foil gauge 24 is arranged in the upper surface of disk substrate 21, as shown in Fig. 2 (a); The circumference of the disk substrate 21 of piezoelectricity disk 2 is arranged on traversing carriage, by traversing carriage, drives piezoelectricity disk 2 to move on the surface of sample 1; Signal generator 4 is connected to power amplifier 41 by data line, and power amplifier 41 is connected to the piezoelectric patches 22 of piezoelectricity disk through wire; The foil gauge 24 of piezoelectricity disk 2 is connected to strainmeter 5 by data line; Strainmeter 5 is connected to data collecting card 6 by data line; Data collecting card 6 is connected to computing machine 7 by data line.
The mobile device 32 of traversing carriage adopts universal wheels, is arranged on equably annular fixed mount 31 times.
In the present embodiment, disk substrate 21 all adopts stainless steel material with fixed mount 31; Piezoelectric patches 22 adopts PZT-5H piezoelectric.Radius R=the 100mm of disk substrate 21, thickness h=2mm; The height H of probe
tan=20mm; The thickness t of piezoelectric ring sheet is 2mm, its internal diameter R
1with external diameter R
2be respectively 40mm and 80mm.
Further, hand-held handle 8 is installed on annular fixed mount 31, is formed handle type detection architecture, the line of 2 that the two ends of hand-held handle 8 are arranged on annular fixed mount 31 passes through the center of circle.By ambulatory handheld handle 8, can allow this detection architecture move at sample surfaces; In moving process, probe 23 and the sample 1 of piezoelectricity disk keep in touch; By moving on the surface of sample 1, just can complete the Non-Destructive Testing to interested surveyed area.
Piezoelectric patches 22 adopts centrosymmetric structure, can for multi-disc be centrosymmetric fan-shaped, as shown in Fig. 2 (b); Or be the annulus concentric with disk substrate, as shown in Figure 3, this centrosymmetric structure can motivate the mode of center vibration, as shown in Figure 4.
The lossless detection method that the utility model proposes based on piezoelectricity disk contact vibration survey the local contact stiffness for the treatment of geodesic structure, elaborate ultimate principle of the present utility model here.
The border of piezoelectricity disk is: the boundary condition of circumference is fixed support; Circle centre position contacts with sample by probe, and the boundary condition of circle centre position is resiliency supported.The circumference of piezoelectricity disk is fixed and probe and the sample contact vibration at center form piezoelectricity disk vibration system, by vibration mechanics correlation theory, obtained, it is around the mechanical model clamped, center is resiliency supported that this vibrational system can be reduced to, as shown in Figure 5, in this mechanical model, interaction between probe and sample is simulated with a spring, and the elasticity coefficient of spring is k
*, this elasticity coefficient k
*be the local contact stiffness k of sample
*.
According to vibration mechanics knowledge, obtain, in above-mentioned piezoelectricity disk vibration system, the resonant frequency f of piezoelectricity disk
nlocal contact stiffness k with sample
*relation can be with an analytical expression f
n=H (k
*) describe, and, when the elasticity coefficient k* of spring is higher, the resonant frequency f of this vibrational system
nalso larger, the resonant frequency f of piezoelectricity disk
nlocal contact stiffness k with sample
*relation meet curve as shown in Figure 6.Resonant frequency f
nwith local contact stiffness k
*relation, relevant with size, the structure and material of piezoelectricity disk, corresponding unique analytic solution.
By using a swept-frequency signal exciting piezoelectricity disk, follow the trail of the resonant frequency f of piezoelectricity disk
n, and then follow the trail of the local contact stiffness k that obtains sample
*information, such test pattern is sweep check pattern.Equally, by using the signal exciting piezoelectricity disk of a fixed frequency, when the local contact stiffness k* of sample is different, the vibration amplitude of this vibrational system is also different.Therefore can follow the trail of the vibration amplitude of vibrational system by using this system of signal exciting that frequency is fixing, and then follow the trail of the local contact stiffness information that obtains sample, this pattern is fixed test pattern frequently.
Compare with the local contact stiffness detection system of beam type, the local contact stiffness sniffer of the disc type that the utility model proposes has following difference and advantage:
1, beam type design torsional rigidity is very low, the needle point of probe is when sample surfaces moves, the transverse force existing can make semi-girder be distorted, and then affect structure phychology and detectable signal, and the design of employing disc type, formed a kind of brand-new centrosymmetric structure, this structure is when sample surfaces moves, because all directions rigidity of structure is all very high, thereby laterally disturb and can reduce much compared with the design of beam type, the interference that detectable signal is brought still less and even completely cancellation, thereby solved contact and surveyed existing transverse force problem, therefore disc type design is more suitable for the mobile monitoring at sample surfaces,
2, only at one end there is a point of fixity in beam type design, and the surrounding of piezoelectricity disk is all used continuously large stiffness structure to fix, whole disc circumference is all in a good mechanics fixed boundary state, thereby structure is more stable, signal to noise ratio (S/N ratio) is also higher, so disc type design is more suitable for applying in method for oscillating compared with beam type design;
3, beam type design adopts unjointed beam to be all piezoelectric design or in the lower surface arrangement piezoelectric patches design of semi-girder, its dynamics and the deformation state ejecting are all very complicated, and the design of disc type adopts centrosymmetric piezoelectric patches group or toroidal design, being designed with of Central Symmetric helps inspire needed " the first center, rank vibration " mode, as shown in Figure 4, and suppress the appearance of unwanted interference modal, so disc type design is more suitable for the application in contact vibration method compared with beam type design;
4, the probe of beam type design comes in contact with sample under pressure, because pressure is to be passed over by semi-girder, thereby probe is stressed and asymmetric, usually can there is the bending of off-axis, as shown in Fig. 7 (a), this departing from can cause probe vibration shape complexity and bring undesired signal into, and in disc type design, the axis place of probe in centrosymmetric structure, therefore stressed even, probe can keep vertical with sample, as shown in Fig. 7 (b), there is not the problem of beam type design, thereby the stability of the more favourable increase detection of the design of disc type;
5, transverse force can be more obvious during transverse shifting on curved surface for the probe of beam type design, and adopt disc type design and pass through to coordinate universal wheels, will make disc type design be more suitable at complex surface as the hand-held mobile detection of the curved surface of wing etc.
Finally it should be noted that, publicize and implement routine object and be to help further to understand the utility model, but it will be appreciated by those skilled in the art that: within not departing from the spirit and scope of the utility model and appended claim, various substitutions and modifications are all possible.Therefore, the utility model should not be limited to the disclosed content of embodiment, and the scope that the claimed scope of the utility model defines with claims is as the criterion.
Claims (7)
1. the nondestructive detection system based on the contact vibration of piezoelectricity disk, it is characterized in that, described nondestructive detection system comprises: piezoelectricity disk (2), traversing carriage, signal generator (4), power amplifier (41), strainmeter (5), data collecting card (6) and computing machine (7); Wherein, described piezoelectricity disk (2) comprises disk substrate (21), piezoelectric patches (22), probe (23) and foil gauge (24), piezoelectric patches (22) be positioned at disk substrate lower surface and centered by symmetrical, probe (23) is positioned at the lower surface circle centre position of disk substrate and perpendicular to disk substrate (21), foil gauge (24) is arranged in the upper surface of disk substrate (21); The circumference of the disk substrate (21) of described piezoelectricity disk (2) is arranged on traversing carriage, by traversing carriage, drives piezoelectricity disk (2) to move on the surface of sample (1); Described signal generator (4) is connected to power amplifier (41) by data line, and power amplifier (41) is connected to the piezoelectric patches (22) of piezoelectricity disk through wire; The foil gauge (24) of described piezoelectricity disk (2) is connected to strainmeter (5) by data line; Described strainmeter (5) is connected to data collecting card (6) by data line; Described data collecting card (6) is connected to computing machine (7) by data line.
2. nondestructive detection system as claimed in claim 1, is characterized in that, the thickness h of described disk substrate (21) and the relation between radius R meet
3. nondestructive detection system as claimed in claim 1, is characterized in that, the height H of described probe
tanand the relation between the radius R of disk substrate meets
4. nondestructive detection system as claimed in claim 1, is characterized in that, the internal diameter R of described piezoelectric patches (22)
1with external diameter R
2meet 0.2R≤R
1< R
2≤ 0.9R; The thickness t of piezoelectric patches meets 0.5h≤t≤1.5h, and wherein, R is the radius of disk substrate, and h is the thickness of disk substrate.
5. nondestructive detection system as claimed in claim 1, is characterized in that, the accumulation signal that described signal generator (4) sends is divided into two kinds of the signal of fixed frequency and swept-frequency signals; Correspondingly, the Dynamic Signal that described strainmeter (5) detects is divided into determines two kinds of frequency response induction signal and frequency sweep response signals.
6. nondestructive detection system as claimed in claim 1, it is characterized in that, described traversing carriage comprises fixed mount (31) and the mobile device (32) of annular, it is upper that the circumference of described disk substrate (21) is fixed on fixed mount (31), and described fixed mount (31) is arranged on mobile device (32).
7. nondestructive detection system as claimed in claim 1, is characterized in that, further comprises hand-held handle (8), and described hand-held handle (8) is arranged on traversing carriage.
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|---|---|---|---|
| CN201420413078.1U CN203981636U (en) | 2014-07-24 | 2014-07-24 | A kind of nondestructive detection system based on the contact vibration of piezoelectricity disk |
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|---|---|---|---|
| CN201420413078.1U CN203981636U (en) | 2014-07-24 | 2014-07-24 | A kind of nondestructive detection system based on the contact vibration of piezoelectricity disk |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104122331A (en) * | 2014-07-24 | 2014-10-29 | 北京大学 | Non-destructive testing system and method based on contact vibration of piezoelectric disk |
| CN106248323A (en) * | 2016-07-11 | 2016-12-21 | 重庆大学 | Rotor damage detection method based on coupling Piezoelectric Impedance |
-
2014
- 2014-07-24 CN CN201420413078.1U patent/CN203981636U/en not_active Withdrawn - After Issue
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104122331A (en) * | 2014-07-24 | 2014-10-29 | 北京大学 | Non-destructive testing system and method based on contact vibration of piezoelectric disk |
| CN106248323A (en) * | 2016-07-11 | 2016-12-21 | 重庆大学 | Rotor damage detection method based on coupling Piezoelectric Impedance |
| CN106248323B (en) * | 2016-07-11 | 2019-10-29 | 重庆大学 | Rotor damage detection method based on coupling Piezoelectric Impedance |
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|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20141203 Effective date of abandoning: 20160817 |
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| C25 | Abandonment of patent right or utility model to avoid double patenting |