A kind of microresistivity survey grip device and using method detecting damage of metal material
Technical field
The present invention relates to the technical field of micro-resistance and micro-resistance change measurement, specifically a kind of resistance measurement grip device carrying out the evolution of characterizing metal material damage by detecting micro-resistance variations, and introduce the using method of this resistance measurement grip device.
Background technology
Metal and alloy material thereof use usually used as structured material, and the component be made up of it needs the effect of bearing various complex load and environment in process under arms, and thus its mechanical property is in the process of a deterioration gradually.Material damage detects the basis being not only structural intergrity assessment, is also the basis of engineering machinery and structural damage tolerance design.Therefore, for metal material various simple or complex load (stretch, compression, bending, to reverse and combination loads) measurement of the lower hierarchical loading damage of effect, the measurement damaged under the measurement damaged under especially creep, fatigue, creep-fatigue interaction and environmental activity just become Strength of Metallic Materials theoretical with apply in basic work.About the characterizing method of damage of metal material, both can adopt the change of the mechanical property parameters of metal material, mechanical performance parameter to measure, and also can adopt the change of Physical Properties of Metallicmateriais parameter to measure.Because resistance has accuracy and susceptibility to damaging the metal material microstructure change caused, and the resistance measurement of metal material is simple, and the damage of metal material sign thus based on electric-resistivity method is used widely.But in the process of measuring resistance, because the resistance of test specimen own is little, the feature that test specimen loads or after environmental activity, resistance change is less, if do not adopt custom-designed resistance measurement fixture, then brings very large difficulty can to the measurement of micro-resistance.
Under the load modes such as hierarchical loading, fatigue, creep loading or environmental activity, the resistance of metal specimen is change in process amount, needs to take multiple measurements.General measuring method is the two ends two probes directly being ridden over test specimen, or rides over specimen test segment mark line position place.But the method for this measuring resistance can not ensure that each probe rides over same position, meanwhile, always shake during people's handheld probe or be subject to the interference of other extraneous factors.The uncertainty of probe location, the shake of probe in test specimen measuring point and the slip in surface of test piece, all can cause the instability of resistance readings, and the accuracy and precision of resistance measurement is not high, is difficult to differentiate the faint change of resistance under load or environmental activity.Therefore, be necessary the microresistivity survey grip device designing a kind of effective detection damage of metal material, and introduce the using method of this device, in order to accurately to measure the initial value resistance of test specimen and the current resistance under load or environmental activity, application resistance change rate carrys out the damage development process of characterizing metal material.
Summary of the invention
The invention provides a kind of the microresistivity survey grip device and the using method that detect damaged metal, have simple to operate, data stability good, measuring accuracy is high, accuracy of measurement is high, measuring error is little, the advantage of applied range.
A kind of microresistivity survey grip device detecting damage of metal material of the present invention comprises: two pieces of upper test specimen stators 2 for fixing metal test specimen 1 and lower test specimen stator 3(test specimen stator 2 and 3 material are metal, the equal centre punching of stator 2 and 3); Two for measuring the probe 4 and 5 of metal specimen resistance; Two pieces of upper probe stators 6 for stationary probe and lower probe stator 7(probe stator 6 and 7 material are metal; The equal centre punching of probe stator 6 and 7, aperture is less than probe nib upper boss diameter, and aperture is greater than a probe body diameter); Two for being connected in series screw rod 8 and the screw rod 9 of upper and lower test specimen stator (2 and 3) and upper and lower probe stator (6 and 7); Two nuts 10 for fixing upper test specimen stator 2 and nut 11(nut configuration pad); Two nuts 12 for fixing lower test specimen stator 3 and nut 13(nut configuration pad); Two nuts 14 for fixing upper probe stator 6 and nut 15(nut configuration pad); Two nuts 16 for fixing lower probe stator 7 and nut 17(nut configuration pad); Two pieces for the upper insulation spacer 18 that insulate between test specimen and test specimen stator 6 and 7 and lower insulation spacer 19, insulation spacer centre punching, aperture is less than the aperture of test specimen stator 2 and 3 and suitable with probe tip diameter, to ensure that probe 4 and 5 effectively to contact with test specimen and to prevent the relative sliding between probe and test specimen end face.
The invention provides a kind of using method detecting the microresistivity survey grip device of damage of metal material, adopt following technical scheme.
Step one, test specimen is placed between upper test specimen stator 2 and lower test specimen stator 3 vertically, rotate test specimen stator nut 10,11,12,13, test specimen stator 2 and lower test specimen stator 3 are slowly drawn close, until specimen holder is fixed by upper test specimen stator 2 and lower test specimen stator 3, and ensure that the axis of test specimen 1, upper test specimen stator 2 and the lower test specimen stator 3 central through hole line of centres, upper insulation spacer 18 and the lower insulation spacer 19 central small hole line of centres three line overlap.
Step 2, probe 4 syringe needle pass the central small hole of insulation spacer 18 also slowly near test specimen, until probe just touches test specimen, rotating probe stator nut 14,15, probe stator 6 is moved, probe 4 is fixed, to prevent probe 4 and test specimen from coming off, ensure the stability that probe 4 contacts with test specimen.
Step 3, probe 5 syringe needle pass the central small hole of insulation spacer 19 also slowly near test specimen, until probe just touches test specimen, rotating probe stator nut 16,17, probe stator 7 is moved, probe 5 is fixed, to prevent probe 5 and test specimen from coming off, ensure the stability that probe 5 contacts with test specimen.
Step 4, probe to be picked out by wire, coordinate sense resistance bridge diagram, measure the initial resistance resistance of metal specimen.
Step 5, successively reverse rotation probe stator nut 16,17, unclamp probe stator 7, probe tip be separated with test specimen; Reverse rotation test specimen stator nut 12,13, unclamps test specimen stator 3, is taken out by test specimen.
Step 6, by specimen holder in Material Testing Machine, carry out fatigue, creep, creep-fatigue interaction test, or temperature, corrosive atmosphere test.
Step 7, will experience certain load history or the test specimen of environmental activity lower a period of time take out, repeat step one, step 3.
Step 8, probe wire to be picked out, coordinate sense resistance bridge diagram, measure the current resistance of metal specimen after experience load or environmental activity, calculate resistance change rate.
Step 9, repeat step 5, step 6, step 7, step 8, measure metal specimen resistance under different loads or environment course successively, record each resistance test data, until test specimen reaches damage tolerance and lost efficacy.
The present invention is a kind of microresistivity survey grip device and using method of detecting damage of metal material, and compared with prior art, innovative point of the present invention and beneficial effect comprise the following aspects.
1. the present invention is in the micro-resistance of detection and micro-resistance variations, has simple to operate, that measuring resistance data stability is good, measuring accuracy is high feature.Resistance has accuracy and susceptibility to damaging the metal material microstructure change caused, and under load or environmental activity, the resistance of test specimen is a change in process amount, needs to take multiple measurements.The initial resistance resistance of metal specimen is very little, and after experiencing certain load or environmental activity, the current resistance of test specimen is compared with initial resistance resistance, and its variable quantity is less.Adopt this resistance measurement grip device, can ensure that each probe contacts at same position with test specimen, probe is fixed at test piece end, avoid the shake of probe and the slip in surface of test piece, when ensureing to measure test specimen resistance, the stability of resistance reading, effectively can improve the degree of accuracy of microresistivity survey.
2. a kind of microresistivity survey grip device detecting damage of metal material of the present invention coordinates sense resistance bridge diagram, both the resistance measuring system error because the control of test method, surveying instrument used, test condition and the subjective factor of experimenter itself cause can have been reduced, also the using method of experimenter in strict accordance with microresistivity survey grip device and microresistivity survey testing regulations can be pointed out to handle affairs, avoid the human error in microresistivity survey process as far as possible, improve the accuracy of metal material test specimen microresistivity survey.
3. the present invention a kind of detect damage of metal material microresistivity survey grip device and using method applied widely, both be applicable to metal specimen various simple or complex load (stretch, compression, bending, to reverse and combination loads) measurement that the lower hierarchical loading of effect is damaged, be also applicable to the measurement that metal specimen is damaged under creep, fatigue, creep-fatigue interaction; Both be applicable to the measurement that metal specimen is damaged under normal temperature static load or Under Dynamic Load, be also applicable to the measurement that metal specimen is damaged under high temperature static load or Under Dynamic Load; Both be applicable to the measurement that metal specimen is damaged under load effect, be also applicable to the measurement that metal specimen is damaged under environmental activity.
On the whole, a kind of microresistivity survey grip device and using method detecting damage of metal material of the present invention, there is simple to operate, that data stability good, measuring accuracy is high, accuracy of measurement is high, measuring error is little advantage, the damage check of metal material test specimen under various load or environmental activity can be applied to, follow the tracks of the subtle change of metal material resistance, utilize the damage of resistance change rate characterizing metal material.The present invention is applicable to micro-resistance and micro-resistance change measurement field.
Accompanying drawing explanation
Fig. 1 is one-piece construction figure of the present invention.
Fig. 2 is one-piece construction outboard profile.
Fig. 3 is one-piece construction sectional view.
Fig. 4 is test specimen stator 2 three-view diagram.
Fig. 5 is test specimen stator 3 three-view diagram.
Fig. 6 is probe stator 6(7) three-view diagram.
1-metal specimen, 2-upper test specimen stator, 3-lower test specimen stator, 4,5-probe, 6-upper probe stator, 7-lower probe stator, 8-left screw rod, 9-right screw rod, 10,11,12,13,14,15,16,17-nut, 18-upper insulation spacer, 19-lower insulation spacer.
Fig. 7 is according to the test result figure of the embodiment of the present invention.
Embodiment
Detect microresistivity survey grip device and the using method of damage of metal material, can be used for measuring the resistance variations situation of metal specimen under load or environmental activity in real time, in order to the damage development process of characterizing metal test specimen.Below in conjunction with embodiment also with reference to accompanying drawing, set forth the present invention further.
Embodiment 1.
Detecting microresistivity survey grip device and the using method of damage of metal material, for measuring test specimen resistance variations situation in fatigue and damage experiment, characterizing the damage development process of test specimen.
Step one, test specimen is placed on vertically between upper test specimen stator 2 and lower test specimen stator 3, the center of insulation spacer 18 and lower insulation spacer 19 is aimed at the center at test specimen two ends respectively, rotate test specimen stator nut 10, 11, 12, 13, test specimen stator 2 and lower test specimen stator 3 are slowly drawn close, until specimen holder is fixed by upper test specimen stator 2 and lower test specimen stator 3, and ensure the axis of test specimen 1, upper test specimen stator 2 and lower test specimen stator 3 central through hole line, upper insulation spacer 18 and the lower insulation spacer 19 central small hole line of centres three line overlap.
Step 2, probe 4 syringe needle pass the central small hole of insulation spacer 18 also slowly near test specimen, until probe just touches test specimen, rotating probe stator nut 14,15, probe stator 6 is moved, probe 4 is fixed, to prevent probe 4 and test specimen from coming off, ensure the stability that probe 4 contacts with test specimen.
Step 3, probe 5 syringe needle pass the central small hole of insulation spacer 19 also slowly near test specimen, until probe just touches test specimen, rotating probe stator nut 16,17, probe stator 7 is moved, probe 5 is fixed, to prevent probe 5 and test specimen from coming off, ensure the stability that probe 5 contacts with test specimen.
Step 4, probe to be picked out by wire, coordinate precision resister surveying instrument QJ57 type direct current resistance electric bridge (measurement range is 0.01 μ Ω ~ 1111.10 Ω), measure the initial resistance resistance of test specimen.
Step 5, successively reverse rotation probe stator nut 16,17, unclamp probe stator, probe tip be separated with test specimen; Reverse rotation test specimen stator nut 12,13, unclamps test specimen stator, is taken out by test specimen.
Step 6, by specimen holder on fatigue tester, carry out torture test.
Step 7, every certain tired cycle, unclamp torture test machine clamp, test specimen is taken out, repeat step one, step 3, probe wire is picked out, coordinate QJ57 type direct current resistance electric bridge, after measuring the certain tired cycle of experience, the current resistance of test specimen.
Step 8, repetition step 5, step 6, step 7, test specimen resistance under the different fatigue of measurement experience successively cycle, records each test figure, until test specimen reaches damage tolerance and lost efficacy.
Step 9, test figure to be processed, calculate corresponding different fatigue cycle, the resistance change rate of test specimen, and adopt resistance change rate to carry out the damage development process of characterizing metal material.
Under Cyclic Load, the micromechanism of material can change, and namely cyclic loading causes the damage of material.The generation of these microdefects, makes the parameters such as the elastic modulus of material, effective bearing area, density and resistance change.Injury tolerance
ddefinition be
D=1-(
A/
A 0)(1)
In formula,
afor impaired rear effective bearing area,
a 0for impaired front effective bearing area.
For high-cycle fatigue test, if suppose, impaired front and back piece lengths and resistivity remain unchanged, then according to the relation of resistance and cross-sectional area, can obtain
D=1-(
R 0/
R)=Δ
R/(
R 0+Δ
R)(2)
In formula,
rfor impaired rear test specimen resistance,
r 0for impaired front test specimen resistance, Δ
r=
r-
r 0for the resistance change of impaired front and back.
Chaboche damage model is adopted to describe Metal Material Fatigue accumulated damage evolutionary process, namely
d
D/d
N={
σ a/[
b(1-
D)]}
β (1-
D)
-
β1
(3)
In formula,
nrepresent tired cycle,
σ afor stress amplitude,
bwith
b 1for material constant, and
b=
b 0(1-
b 1 σ m),
b 0with
b 1for material constant,
σ mfor mean stress.
To formula (3) integration,
D=1-[1-(1+
β+
β 1)(
σ a/
b)
β N]
1/(1+
β+
β1)
(4)
According to the starting condition of fatigue damage (
n=0,
d=0) and final value condition (
n=
n f,
d=1;
n ffor fatigue lifetime), formula (4) can be rewritten as
D=1-[1-(
N/
N f)]
1/(1+
β+
β1)
(5)
Formula (2) is substituted into formula (5), can obtain
Δ
R/
R 0=[1-(
N/
N f)]
-1/(1+
β+
β1)
-1(6)
Formula (6) is the damage of metal material EVOLUTION EQUATION characterized with resistance change rate.
Carry out high-cycle fatigue test to certain titanium alloy test specimen, the resistance change rate collected changes test figure as shown in symbol in Fig. 7 " ■ " with tired cycle.Applying equation (6) carries out nonlinear regression analysis to test figure, and its damage development curve is as shown in solid line in Fig. 7.