CN103983691B - A kind of method that material loss factor is measured - Google Patents

Abstract

The invention discloses a kind of method that material loss factor is measured, belong to material damping feature measurement field.The method include standby two pieces with size with the metallic plate of material；Lay one layer of detected materials wherein on one piece of metallic plate and form composite damping board；Measure and obtain composite damping board and the bending wave spread speed of metallic plate under different pulse signal frequency；Calculating damping layer compares e with the Young's modulus of metal level；Measurement obtains composite damping board Structural parameter β；Finally it is calculated the material loss factor η of damping layer.The invention has the beneficial effects as follows: the measurement of integrated structure fissipation factor and the measurement of bending vibration velocity of wave, achieve the measurement of many cavitys damping material own material fissipation factor, compensate for that other measuring methods are soft in quality, deficiency on many cavitys damping material damping test, therefore, the proposition of the method has certain engineering significance, and the application prospect of the method is wider.

Description

A kind of method that material loss factor is measured

Technical field

The present invention relates to material damping feature measurement field, be specifically related to a kind of method that material loss factor is measured.

Background technology

The method of material loss factor test, mainly has flexural resonance method, free Attenuation Method, phase method etc..In actual work , there is a large amount of quality soft in Cheng Zhong, is contained within the damping material of cavity, as on naval vessels use all kinds of sound eliminating tiles, decoupling watt etc., by In this class damping material, typically can contain cavity, cause material shape is required strict flexural resonance beam method and phase method etc. Method can not be used for measuring the fissipation factor of such material.Free Attenuation Method is the highest to factors dictate such as the size shapes of material, The fissipation factor of structure can be obtained by the reverberation time of direct measurement structure, but owing to damping material is soft, Before using free Attenuation Method to measure, need to be sticked to by damping material on the structure backing that quality is harder, on steel plate, measure The fissipation factor gone out is the fissipation factor of damping material armor Plate, can not Damping material self damping big Little.Therefore, the particular/special requirement measured for soft ground many cavitys damping material own material fissipation factor, current is several conventional Measuring method all can not meet.

Said method cannot meet in current engineering occur the most softly, include cavity functional material damping survey Examination requirement, proposes present patent application for this, develops a kind of method that can be used for the measurement of such material loss factor.For interior Without the damping test of cavity functional material, the inventive method is equally applicable.

Summary of the invention

It is an object of the invention to: measuring problem to solve soft, many cavitys material loss factor, the present invention is at velocity of wave A kind of method that can be used for material loss factor measurement is proposed on the basis of method and free Attenuation Method.

The technical scheme is that a kind of method that material loss factor is measured, flow process is as it is shown in figure 1, include as follows Step:

Step one: standby two pieces with size with the metallic plate of material；One layer of detected materials is laid wherein on one piece of metallic plate Form composite damping board；

Step 2: paste N number of acceleration transducer in the metal covering side of composite damping board as measuring point, N >=2, exciting Device forms excitation point at the metal covering side boundary of composite damping board, and N number of measuring point is in a straight line with excitation point；

By the pulse signal input vibrator that frequency is f, pick up the bending wave signal of N number of measuring point on composite damping board, can Refering to Fig. 3, and remove the interference of boundary echo, utilize Hilbert transform be bent wave loops to composite damping board N The phase theta of individual measuring point_i(i=1,2 ... N), according to formula

Δt_i=| θ_i-θ_i+1|/(2 π f) (i=1 ... N-1)

It is calculated impulse wave from the time difference Δ t arriving measuring point i and measuring point i+1_i；Measure measuring point i and measuring point i+1 spacing From Δ d_i, utilize formula

$c=\frac{\underset{i=1}{\overset{N-1}{\mathrm{\Σ}}}\frac{{\mathrm{\Δd}}_i}{\mathrm{\Δ}{t}_i}}{N-1}$

It is calculated bending wave spread speed c on composite damping board；Obtain multiple by changing pulse signal frequency Bending wave spread speed under frequency.Bending wave spread speed test system, see Fig. 4.

By the method for this step, metallic plate is carried out wave speed measurement equally, it is thus achieved that metallic plate under different pulse signal frequencies Bending wave spread speed c₀。

Step 3: compare e according to the Young's modulus of formula calculating damping layer with metal level

$\frac{{\mathrm{mc}}^4}{m_0{c_0}^4}=\frac{1+2e(2h+3h^2+2h^3)+e^2{h}^4}{1+\mathrm{eh}}$

In formula, m, m₀Being respectively composite damping board and the surface density of metallic plate, h is the thickness ratio of damping layer and metal level；

Step 4: combine the test system shown in Fig. 5, uses free Attenuation Method to measure the decay reverberation of composite damping panel vibration Time T₆₀, reverberation time measurement can refer to GBJ76-84 " code for measurement of reverberation time in hall ",

Utilize formula

$\mathrm{\β}=\frac{2.2}{f{T}_{60}}$

Be calculated composite damping board with the Structural parameter β under same frequency f in step 2.

Step 5: material loss factor η calculates

The Structural parameter β of above-mentioned acquisition, damping layer are substituted into formula with the Young's modulus of metal level than parameters such as e

$\mathrm{\η}=\mathrm{\β}\·\frac{\mathrm{eh}}{1+\mathrm{eh}}\frac{3+6h+4h^2+2e{h}^3+e^2{h}^4}{1+2e(2h+3h^2+2h^3)+e^2{h}^4}$

Obtain the material loss factor η of detected materials.

The invention has the beneficial effects as follows: the measurement of integrated structure fissipation factor and the measurement of bending vibration velocity of wave, it is achieved that The measurement of many cavitys damping material own material fissipation factor, compensate for other measuring methods cavity soft in quality, many damping material Deficiency on material damping test, therefore, the proposition of the method has certain engineering significance, and the application prospect of the method is relatively Extensively.

Accompanying drawing explanation

The method flow block diagram that the material loss factor that Fig. 1 present invention proposes is measured

Pulse excitation signal in Fig. 2 embodiment

Wave speed measurement schematic diagram in Fig. 3 embodiment

Fig. 4 embodiment step 2 is measured the measurement system diagram of test specimen velocity of wave

The measurement system diagram of Structural parameter in Fig. 5 embodiment step 4

Excitation point and the layout of measuring point in Fig. 6 embodiment

The velocity of wave curve of composite damping board, steel plate in Fig. 7 embodiment

The Young's modulus ratio of damping layer and metal level in Fig. 8 embodiment

The Structural parameter of composite damping board in Fig. 9 embodiment

The material loss factor of damping layer in Figure 10 embodiment

Embodiment

Test apparatus and method in the present embodiment are for carrying out material damage to a kind of soft damping layer including cavity The consumption factor is measured, and this measuring method comprises the steps:

Step one: in the present embodiment, employs the steel plate of two pieces of same sizes, long generous be respectively 1.7m, 1.5m, 5.5mm, the detected materials that one of steel plate lays one layer of 3cm forms composite damping board；

Step 2: refering to Fig. 6, pastes 3 acceleration transducers in the metal covering side of composite damping board plate, and vibrator exists The metal covering side of composite damping board forms excitation point, and 3 measuring points are in a straight line with excitation point, test system such as Fig. 4 Shown in；

By the pulse signal input vibrator that frequency shown in Fig. 2 is f, the bending wave of 3 measuring points on pickup composite damping board Signal, refering to Fig. 3, and removes the interference of boundary echo, utilizes Hilbert transform to be bent wave loops to composite damping The phase theta of 3 measuring points on plate_i(i=1,2,3), according to formula

Δt_i=| θ_i-θ_i+1|/(2 π f) (i=1,2)

It is calculated impulse wave from the time difference Δ t arriving measuring point i and measuring point i+1_i；Measure measuring point i and measuring point i+1 spacing From Δ d_i, utilize formula

$c=\frac{\underset{i=1}{\overset{N-1}{\mathrm{\Σ}}}\frac{{\mathrm{\Δd}}_i}{\mathrm{\Δ}{t}_i}}{N-1}$

It is calculated bending wave spread speed c on composite damping board；Correspondence is obtained by changing pulse signal frequency Bending wave spread speed under multiple frequencies.

By the method for this step, steel plate is carried out wave speed measurement equally, it is thus achieved that the bending of different pulse signal frequency lower steel plates Velocity of wave propagation c₀。

In the present embodiment, the interval of pulse signal frequency f is [100Hz, 5000Hz], is spaced 100Hz, it is thus achieved that composite damping Plate, steel plate each velocity of wave curve is as shown in Figure 7.

Step 3: calculate the detected materials layer Young's modulus with steel plate than e: according to formula

$\frac{{\mathrm{mc}}^4}{m_0{c_0}^4}=\frac{1+2e(2h+3h^2+2h^3)+e^2{h}^4}{1+\mathrm{eh}}$

In formula, m, m₀Being respectively composite damping board and the surface density of steel plate, h is the thickness ratio of detected materials layer and steel plate； In the present embodiment, m=90kg/m²、m₀=43kg/m², h=5.4545；The present embodiment obtains detected materials layer and steel plate layer Young's modulus is than e as shown in Figure 8.

Step 4: combine the test system shown in Fig. 5, uses free Attenuation Method to measure the decay reverberation of composite damping panel vibration Time T₆₀, the reverberation time, measurement was with reference to GBJ76-84 " code for measurement of reverberation time in hall ".

Utilize formula

$\mathrm{\β}=\frac{2.2}{f{T}_{60}}$

It is calculated composite damping board Structural parameter β, the frequency interval [100Hz, 5000Hz] of f in formula, Every 100Hz；In the present embodiment, test obtains composite damping board Structural parameter curve as shown in Figure 9.

Step 5: the calculating of material loss factor η

The Structural parameter β of above-mentioned acquisition, damping layer are substituted into formula with the Young's modulus of steel plate than parameters such as e

$\mathrm{\η}=\mathrm{\β}\·\frac{\mathrm{eh}}{1+\mathrm{eh}}\frac{3+6h+4h^2+2e{h}^3+e^2{h}^4}{1+2e(2h+3h^2+2h^3)+e^2{h}^4}$

Obtain the material loss factor η of detected materials.The present embodiment is calculated damping layer material fissipation factor curve As shown in Figure 10.

Claims (1)

1. the method that material loss factor is measured, comprises the steps:

Step one: standby two pieces with size with the metallic plate of material；Lay one layer of detected materials wherein on one piece of metallic plate to be formed Composite damping board；

Step 2: paste N number of acceleration transducer in the metal covering side of composite damping board and exist as measuring point, N >=2, vibrator The metal covering side of composite damping board forms excitation point, and N number of measuring point is in a straight line with excitation point；

By the pulse signal input vibrator that frequency is f, the bending wave signal of N number of measuring point on pickup composite damping board, and remove The interference of boundary echo, utilize Hilbert transform be bent wave loops to composite damping board the phase theta of N number of measuring point_i (i=1,2 ... N), according to formula

Δt_i=| θ_i-θ_i+1|/(2 π f) (i=1 ... N-1)

It is calculated impulse wave from the time difference Δ t arriving measuring point i and measuring point i+1_i；Measure measuring point i and measuring point i+1 spacing Δ d_i, utilize formula

$c=\frac{\underset{i=1}{\overset{N-1}{\Σ}}\frac{{\mathrm{\Δd}}_i}{{\mathrm{\Δt}}_i}}{N-1}$

It is calculated bending wave spread speed c on composite damping board；Obtain corresponding multiple by changing pulse signal frequency Bending wave spread speed under frequency；

By the method for this step, metallic plate is carried out wave speed measurement equally, it is thus achieved that the bending of metallic plate under different pulse signal frequencies Velocity of wave propagation c₀；

Step 3: compare e according to the Young's modulus of formula calculating damping layer with metal level

$\frac{{\mathrm{mc}}^4}{m_0{c_0}^4}=\frac{1+2e(2h+3h^2+2h^3)+e^2{h}^4}{1+eh}$

In formula, m, m₀Being respectively composite damping board and the surface density of metallic plate, h is the thickness ratio of damping layer and metal level；

Step 4: use free Attenuation Method to measure composite damping panel vibration decay reverberation time T₆₀, utilize formula

$\mathrm{\β}=\frac{2.2}{{\mathrm{fT}}_{60}}$

Be calculated composite damping board with the Structural parameter β under same frequency f in step 2；

Step 5: material loss factor η calculates

The Structural parameter β of above-mentioned acquisition, damping layer are substituted into formula with the Young's modulus of metal level than e parameter

$\mathrm{\η}=\mathrm{\β}\·\frac{eh}{1+eh}\frac{3+6h+4h^2+2{\mathrm{eh}}^3+e^2{h}^4}{1+2e(2h+3h^2+2h^3)+e^2{h}^4}$

Obtain the material loss factor η of detected materials.