CN103234823A - Artificial heart valve pyrolytic carbon and testing method for fracture toughness of pyrolytic carbon composite material - Google Patents
Artificial heart valve pyrolytic carbon and testing method for fracture toughness of pyrolytic carbon composite material Download PDFInfo
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- CN103234823A CN103234823A CN201310115477XA CN201310115477A CN103234823A CN 103234823 A CN103234823 A CN 103234823A CN 201310115477X A CN201310115477X A CN 201310115477XA CN 201310115477 A CN201310115477 A CN 201310115477A CN 103234823 A CN103234823 A CN 103234823A
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Abstract
The invention relates to an artificial heart valve pyrolytic carbon and a testing method for the fracture toughness of a pyrolytic carbon composite material. A testing method for the fracture toughness of the pyrolytic carbon composite material has not been brought forward yet. The testing method provided by the invention comprises the following steps: preparing a plurality of compact tension C(T) specimens from heart valve pyrolytic carbon or a composite material thereof and prefabricating sharp cracks on each specimen, wherein the specimen is of a specification as recommended by American ASTM standard E399, a gap is processed at the central part of the specimen, and upper and lower ends of the gap are respectively provided with a loading hole; then respectively clamping the two loading holes of the gap by using clamps and erecting an extensometer on an open end of the gap; and starting a loading platform to apply an upward load increasing at a uniform speed until the specimens fracture, determining critical load and effective crack length of each specimen, calculating fracture toughness according to the critical load and the effective crack length and taking a mean value as a fracture toughness test value of the heart valve pyrolytic carbon or the composite material thereof. The method provided by the invention can accurately determine fracture toughness of pure pyrolytic carbon and a pyrolytic carbon composite material.
Description
Technical field
The present invention relates to a kind of raw material of wood-charcoal material mechanic property test method, be specifically related to a kind of heart valve pyrolytic carbon and fracture of composite materials toughness test method thereof.
Background technology
Heart valve is the substitute of people body-centered lobe, for the usefulness of cardiac valves patient replacing, and normal pure pyrolytic carbon or the pyrolytic carbon coated graphite compound substance of adopting of its limb, normal pure pyrolytic carbon or the titanium alloy of adopting of lobe ring made.Heart valve runs on decades in the interior complex physical environment of human body, needs very high permanance and structural reliability, and therefore the pyrolyzed carbon materials as its surface coating need have good fracture property.
Plane strain fracture toughness is the important parameter of pyrolyzed carbon materials fracture property, and the ability of exosyndrome material opposing crackle expansion and brittle fracture is generally used K
ICExpression.Accurately test material fracture toughness value is studied the factor that influences material fracture toughness, can clearly and improve the pyrolytic carbon fracture property, and is also significant to heart valve assembly damage tolerance and life prediction program.
Pyrolyzed carbon materials adopts the chemical vapor deposition method preparation, is a kind of typical hard brittle material.Because its preparation technology's singularity, little, the thin thickness of sample size, many traditional fracture toughness method of testings to itself and inapplicable, therefore at the test of heart valve pyrolytic carbon fracture toughness, domestic still do not have this type of report.External Ritchie, people such as Cao Hengchu, Glipin had once carried out certain research to heart valve pyrolytic carbon fracture toughness, but did not propose a cover at the method for testing of heart valve pyrolytic carbon fracture toughness.
Summary of the invention
The inventive method provides a kind of heart valve pyrolytic carbon and fracture of composite materials toughness test method thereof at the deficiencies in the prior art.This method can accurately be measured the fracture toughness of pure pyrolytic carbon and pyrolytic carbon compound substance.
The concrete steps of the inventive method are:
Step (1). heart valve pyrolytic carbon to be tested or its Composite Preparation are become the individual compact tension specimen C(T of n (n 〉=3)) sample, then at each compact tension specimen C(T) prefabricated sharp crack on the sample;
Described compact tension specimen C(T) sample is recommended specification according to U.S. ASTM standard E399, and sample is cube, middle section mechanism machining gap, breach two ends is up and down offered the loading hole respectively, described breach is straight-through v notch v, and an end is opened in the side of sample, and the other end is most advanced and sophisticated; Stress effect effective width is W, and described stress effect effective width is to be positioned at the not distance of gap end side surface of the center in loading hole on same surface and sample on the sample; The width of sample is D, and length is L, and thickness is B, and gap width is d, and the aperture that loads the hole is Φ, and loading the vertical center line in hole and the distance at breach tip is a
0W=18.8mm, a
0=4.8mm, D=1.25W, L=1.2W, B=0.5W, d=0.5W, Φ=0.25W;
Described sharp crack connects the sample front and rear surfaces, and its starting point is positioned at the breach tip, and sharp crack length is 1.5～2.5mm; Described sharp crack length is the projector distance of two end points on surface level of sharp crack; The method of described precrack adopts cyclic fatigue precrack method, and this method is ripe prior art.
Step (2). each sample is clamped two two ends that load the hole respectively with two U-shaped anchor clamps, and two bearing pins pass two sides and the corresponding loading hole of two U-shaped anchor clamps respectively, and U-shaped anchor clamps are fixedlyed connected with sample; Extensometer is erected on the open end that breach is positioned at the sample sidewall, and two pins of extensometer are separately fixed at the upper and lower knife-edge part of breach; Described extensometer adopts electronic extensometer, in order to the amount of opening of test sample mechanism machining gap leading edge;
The end face center of the U-shaped anchor clamps on sample top vertically is set with load bar, and weighted platform is connected with load bar; Described weighted platform can apply load upwards to load bar;
The bottom center of the U-shaped anchor clamps of sample bottom vertically is set with fixed bar, offers through hole on the stationary platform, and fixed bar passes the movable setting of through hole, and the bottom of fixed bar is provided with spacer pin, and the size of spacer pin is greater than the aperture of through hole.
Step (3). start-up loading platform, weighted platform apply the upwards load that at the uniform velocity increases, and upwards the rate of loading of load is 0.6～0.8 N/S, until sample breakage; Critical load P when determining each sample breakage
qWith effective crack length a;
Record size and the gap opened amount of the different imposed loads constantly of each sample, until sample breakage; According to size and the gap opened amount of difference moment imposed load, be that initial point, imposed load P are that ordinate, gap opened amount are horizontal ordinate curve plotting figure with 0; This curve comprises linear segment straight line and non-linear partial curve, and the intersection of linear segment straight line and non-linear partial curve draws the straight line that is set out by initial point for some A with the slope of 0.95 times of OA, and the intersection point of this straight line and non-linear partial curve is some B; Get the A point imposed load corresponding with the point of ordinate maximum in the B point non-linear partial curve before and be this sample critical load p
q
The mean value of sharp crack length when described effective crack length a is each sample breakage specifically is on the sample breakage face section to be divided into m (m 〉=3) five equilibrium along thickness, gets the mean value of the sharp crack length of m-1 division surface and two end faces.
Step (4). calculate fracture toughness K
IC:
If P
Max/ P
qBe less than or equal to 1.1, be calculated as follows the material fracture toughness K of each sample
IC, P
MaxBe the maximum imposed load in the curve map
；
Calculate the material fracture toughness K of n sample
ICMean value, as the fracture toughness test value of heart valve pyrolytic carbon or its compound substance;
If P
Max/ P
qGreater than 1.1, then test again.
The inventive method has fully taken into account factors such as the hard fragility of pyrolyzed carbon materials and preparation size limitation, all adjusts and improves at aspects such as extensometer, U-shaped anchor clamps, precrack methods, has guaranteed test procedure feasibility and test result reliability.
Description of drawings
Fig. 1 is compact tension specimen C(T among the present invention) the structures of samples synoptic diagram;
Fig. 2 is the proving installation structural representation.
Embodiment
Below in conjunction with accompanying drawing and example the concrete implementation step of the present invention is described further.
Heart valve pyrolytic carbon and fracture of composite materials toughness test method thereof, concrete steps are:
Step (1). heart valve pyrolytic carbon to be tested or its Composite Preparation are become the individual compact tension specimen C(T of n (n 〉=3)) sample, then at each compact tension specimen C(T) prefabricated sharp crack on the sample;
As shown in Figure 1, compact tension specimen C(T) sample is according to U.S. ASTM standard E399 recommendation specification, and sample 1 is cube, and middle section mechanism machining gap 1-1, breach 1-1 two ends up and down offer loading hole 1-2 respectively.Breach 1-1 is straight-through v notch v, and an end is opened in the side of sample 1, and the other end is most advanced and sophisticated; Stress effect effective width W is positioned at the not distance of gap end side surface of the center of loading hole 1-2 on same surface and sample 1, W=18.8mm on the sample 1; Width D=the 1.25W of sample 1, length L=1.2W, thickness B=0.5W, gap width d=0.5W, load the aperture Φ=0.25W in hole, load the vertical center line in hole and breach tip apart from a
0=4.8mm, above size is accurate to 0.1 ﹪.
Sharp crack 1-3 connects sample 1 front and rear surfaces, and its starting point is positioned at breach 1-1 tip, and sharp crack length a is 1.5～2.5mm.Sharp crack length is the projector distance of two end points on surface level of sharp crack 1-3.The method of precrack adopts cyclic fatigue precrack method.
Step (2). as shown in Figure 2, two U-shaped anchor clamps 4 of each sample 1 usefulness are clamped two two ends that load hole 1-2 respectively, and two bearing pins 5 pass two sides and the corresponding loading hole 1-2 of two U-shaped anchor clamps 4 respectively, and U-shaped anchor clamps 4 are fixedlyed connected with sample 1; Extensometer 6 is erected on the open end that breach 1-1 is positioned at the sample sidewall, and two pins of extensometer 6 are separately fixed at the upper and lower edge of a knife of breach 7 places (local amplifier section among the figure), and extensometer 6 adopts electronic extensometers.
The end face center of the U-shaped anchor clamps on sample 1 top vertically is set with load bar 3, and weighted platform 2 is connected with load bar 3, and weighted platform 2 can apply load upwards to load bar 2.
The bottom center of the U-shaped anchor clamps of sample 1 bottom vertically is set with fixed bar 8, offers through hole on the stationary platform 9, and fixed bar 8 passes the movable setting of through hole, and the bottom of fixed bar 8 is provided with spacer pin 10, and the size of spacer pin 10 is greater than the aperture of through hole.
Step (3). start-up loading platform 2, weighted platform 2 apply the upwards load (direction of arrow among the figure) that at the uniform velocity increases, and upwards the rate of loading of load is 0.6～0.8 N/S, until sample breakage; Critical load P when determining each sample breakage
qWith effective crack length a;
Record size and the gap opened amount of the different imposed loads constantly of each sample, until sample breakage; According to size and the gap opened amount (detecting the amount of opening of breach leading edges by extensometer 6) of difference moment imposed load, be that initial point, imposed load P are that ordinate, gap opened amount are horizontal ordinate curve plotting figure with 0; This curve comprises linear segment straight line and non-linear partial curve, and the intersection of linear segment straight line and non-linear partial curve draws the straight line that is set out by initial point for some A with the slope of 0.95 times of OA, and the intersection point of this straight line and non-linear partial curve is some B; Get the A point imposed load corresponding with the point of ordinate maximum in the B point non-linear partial curve before and be this sample critical load p
q
The mean value of sharp crack length specifically was on the sample breakage face section to be divided into m (m 〉=3) five equilibrium along thickness when effectively crack length a was each sample breakage, got the mean value of the sharp crack length of m-1 division surface and two end faces.
Step (4). calculate fracture toughness K
IC:
If P
Max/ P
qBe less than or equal to 1.1, be calculated as follows the material fracture toughness K of each sample
IC, P
MaxBe the maximum imposed load in the curve map
；
Calculate the material fracture toughness K of n sample
ICMean value, as the fracture toughness test value of heart valve pyrolytic carbon or its compound substance;
If P
Max/ P
qGreater than 1.1, then test again.
Though the present invention discloses as above with preferred embodiments and result; so it is not in order to limit the present invention; any person of ordinary skill in the field; without departing from the spirit and scope of the invention; can do a little change and improvement, so the present invention's protection domain is as the criterion when looking the claim person of defining.
Claims (3)
1. heart valve pyrolytic carbon and fracture of composite materials toughness test method thereof is characterized in that the concrete steps of this method are:
Step (1). heart valve pyrolytic carbon to be tested or its Composite Preparation are become n compact tension specimen C(T) sample, then at each compact tension specimen C(T) prefabricated sharp crack on the sample, n 〉=3;
Described compact tension specimen C(T) sample is recommended specification according to U.S. ASTM standard E399, and sample is cube, middle section mechanism machining gap, breach two ends is up and down offered the loading hole respectively, described breach is straight-through v notch v, and an end is opened in the side of sample, and the other end is most advanced and sophisticated; Stress effect effective width is W, and described stress effect effective width is to be positioned at the not distance of gap end side surface of the center in loading hole on same surface and sample on the sample; The width of sample is D, and length is L, and thickness is B, and gap width is d, and the aperture that loads the hole is Φ, and loading the vertical center line in hole and the distance at breach tip is a
0W=18.8mm, a
0=4.8mm, D=1.25W, L=1.2W, B=0.5W, d=0.5W, Φ=0.25W;
Described sharp crack connects the sample front and rear surfaces, and its starting point is positioned at the breach tip, and sharp crack length is 1.5～2.5mm; Described sharp crack length is the projector distance of two end points on surface level of sharp crack;
Step (2). each sample is clamped two two ends that load the hole respectively with two U-shaped anchor clamps, and two bearing pins pass two sides and the corresponding loading hole of two U-shaped anchor clamps respectively, and U-shaped anchor clamps are fixedlyed connected with sample; Extensometer is erected on the open end that breach is positioned at the sample sidewall, and two pins of extensometer are separately fixed at the upper and lower knife-edge part of breach;
The end face center of the U-shaped anchor clamps on sample top vertically is set with load bar, and weighted platform is connected with load bar; Described weighted platform can apply load upwards to load bar;
The bottom center of the U-shaped anchor clamps of sample bottom vertically is set with fixed bar, offers through hole on the stationary platform, and fixed bar passes the movable setting of through hole, and the bottom of fixed bar is provided with spacer pin, and the size of spacer pin is greater than the aperture of through hole;
Step (3). start-up loading platform, weighted platform apply the upwards load that at the uniform velocity increases, and upwards the rate of loading of load is 0.6～0.8 N/S, until sample breakage; Critical load P when determining each sample breakage
qWith effective crack length a;
Record size and the gap opened amount of the different imposed loads constantly of each sample, until sample breakage; According to size and the gap opened amount of difference moment imposed load, be that initial point, imposed load P are that ordinate, gap opened amount are horizontal ordinate curve plotting figure with 0; This curve comprises linear segment straight line and non-linear partial curve, and the intersection of linear segment straight line and non-linear partial curve draws the straight line that is set out by initial point for some A with the slope of 0.95 times of OA, and the intersection point of this straight line and non-linear partial curve is some B; Get the A point imposed load corresponding with the point of ordinate maximum in the B point non-linear partial curve before and be this sample critical load p
q
The mean value of sharp crack length specifically was on the sample breakage face section to be divided into the m five equilibrium along thickness when described effective crack length a was each sample breakage, got the mean value of the sharp crack length of m-1 division surface and two end faces, m 〉=3;
Step (4). calculate fracture toughness K
IC:
If P
Max/ P
qBe less than or equal to 1.1, be calculated as follows the material fracture toughness K of each sample
IC, P
MaxBe the maximum imposed load in the curve map;
Calculate the material fracture toughness K of n sample
ICMean value, as the fracture toughness test value of heart valve pyrolytic carbon or its compound substance;
If P
Max/ P
qGreater than 1.1, then test again.
2. heart valve pyrolytic carbon as claimed in claim 1 and fracture of composite materials toughness test method thereof is characterized in that the method for precrack in the step (1) adopts cyclic fatigue precrack method.
3. heart valve pyrolytic carbon as claimed in claim 1 and fracture of composite materials toughness test method thereof is characterized in that the extensometer described in the step (2) adopts electronic extensometer, in order to the amount of opening of test sample mechanism machining gap leading edge.
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|---|---|---|---|---|
| CN103604694A (en) * | 2013-10-14 | 2014-02-26 | 中国石油天然气集团公司 | Method for measuring fracture toughness of pipeline steel by using unilateral notched tensile test |
| CN104142266A (en) * | 2014-07-31 | 2014-11-12 | 浙江大学 | Clamp for compact tension specimen of material testing machine under high pressure hydrogen environment |
| CN105136531A (en) * | 2015-07-23 | 2015-12-09 | 成都航天龙宇质检技术有限公司 | Compact tensile sample used in material performance test |
| CN107389460A (en) * | 2017-07-21 | 2017-11-24 | 中国工程物理研究院化工材料研究所 | The material horizontal fracture detection of hydraulic loading test machine and security processing control method |
| CN109342209A (en) * | 2018-10-08 | 2019-02-15 | 上海纽脉太惟医疗科技有限公司 | A kind of leaflet test device |
| CN109540694A (en) * | 2018-11-27 | 2019-03-29 | 浙江工业大学 | Precrack for testing II type crack fracture toughness biases 3 points of curved experimental rigs |
| CN111678667A (en) * | 2020-06-17 | 2020-09-18 | 哈尔滨工业大学 | High-frequency testing machine, compact tensile test fixture switching device and using method |
| CN112748002A (en) * | 2020-12-17 | 2021-05-04 | 杭州电子科技大学 | Method for measuring notch opening amount in measurement of fracture toughness of pyrolytic carbon for artificial heart valve |
| CN113466038A (en) * | 2021-06-21 | 2021-10-01 | 长江存储科技有限责任公司 | Detection sample for fracture toughness and detection method thereof |
| CN113740152A (en) * | 2020-05-27 | 2021-12-03 | 中国航发商用航空发动机有限责任公司 | CT test piece, CT test method and CT test device |
| CN113834730A (en) * | 2021-07-14 | 2021-12-24 | 滁州职业技术学院 | Mechanical property experiment device and method based on hydraulic assembly |
| CN114184467A (en) * | 2020-09-15 | 2022-03-15 | 中国航发商用航空发动机有限责任公司 | Test piece for fracture performance test and preparation method thereof |
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| CN103604694A (en) * | 2013-10-14 | 2014-02-26 | 中国石油天然气集团公司 | Method for measuring fracture toughness of pipeline steel by using unilateral notched tensile test |
| CN103604694B (en) * | 2013-10-14 | 2016-08-10 | 中国石油天然气集团公司 | Utilize the method that pipe line steel fracture toughness is measured in SEN tension test |
| CN104142266B (en) * | 2014-07-31 | 2016-08-24 | 浙江大学 | High pressure hydrogen environment Material Testing Machine compact tensile specimen fixture |
| CN104142266A (en) * | 2014-07-31 | 2014-11-12 | 浙江大学 | Clamp for compact tension specimen of material testing machine under high pressure hydrogen environment |
| CN105136531B (en) * | 2015-07-23 | 2018-06-29 | 四川航天谦源科技有限公司 | For the compact tensile specimen of material properties test |
| CN105136531A (en) * | 2015-07-23 | 2015-12-09 | 成都航天龙宇质检技术有限公司 | Compact tensile sample used in material performance test |
| CN107389460A (en) * | 2017-07-21 | 2017-11-24 | 中国工程物理研究院化工材料研究所 | The material horizontal fracture detection of hydraulic loading test machine and security processing control method |
| CN107389460B (en) * | 2017-07-21 | 2019-12-24 | 中国工程物理研究院化工材料研究所 | Material horizontal fracture detection method of hydraulic loading tester |
| CN109342209A (en) * | 2018-10-08 | 2019-02-15 | 上海纽脉太惟医疗科技有限公司 | A kind of leaflet test device |
| CN109342209B (en) * | 2018-10-08 | 2021-03-16 | 上海纽脉太惟医疗科技有限公司 | Valve leaflet testing arrangement |
| CN109540694A (en) * | 2018-11-27 | 2019-03-29 | 浙江工业大学 | Precrack for testing II type crack fracture toughness biases 3 points of curved experimental rigs |
| CN109540694B (en) * | 2018-11-27 | 2024-05-03 | 浙江工业大学 | Prefabricated crack bias three-point bending test device for testing fracture toughness of II type crack |
| CN113740152A (en) * | 2020-05-27 | 2021-12-03 | 中国航发商用航空发动机有限责任公司 | CT test piece, CT test method and CT test device |
| CN113740152B (en) * | 2020-05-27 | 2023-10-27 | 中国航发商用航空发动机有限责任公司 | CT test piece, CT test method and CT test device |
| CN111678667A (en) * | 2020-06-17 | 2020-09-18 | 哈尔滨工业大学 | High-frequency testing machine, compact tensile test fixture switching device and using method |
| CN114184467A (en) * | 2020-09-15 | 2022-03-15 | 中国航发商用航空发动机有限责任公司 | Test piece for fracture performance test and preparation method thereof |
| CN114184467B (en) * | 2020-09-15 | 2024-04-26 | 中国航发商用航空发动机有限责任公司 | Test piece for testing fracture performance and preparation method thereof |
| CN112748002A (en) * | 2020-12-17 | 2021-05-04 | 杭州电子科技大学 | Method for measuring notch opening amount in measurement of fracture toughness of pyrolytic carbon for artificial heart valve |
| CN113466038A (en) * | 2021-06-21 | 2021-10-01 | 长江存储科技有限责任公司 | Detection sample for fracture toughness and detection method thereof |
| CN113834730A (en) * | 2021-07-14 | 2021-12-24 | 滁州职业技术学院 | Mechanical property experiment device and method based on hydraulic assembly |
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