CN113203628B - Fracture toughness test buckling-restrained device and test method - Google Patents
Fracture toughness test buckling-restrained device and test method Download PDFInfo
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention provides a fracture toughness test buckling-restrained device which comprises a tester base, a pair of tester beams and a clamping mechanism on the tester base, wherein the clamping mechanism comprises a pair of brackets fixed on the tester base, a pair of clamps connected to the brackets in a sliding manner, two groups of clamping plates used for clamping the front side and the rear side of a test piece, and an upper supporting structure and a lower supporting structure respectively used for supporting the upper part and the lower part of the clamping plates, wherein the left end and the right end of the test piece are clamped in the pair of clamps; the clamping plate is arranged between the pair of supports, the roller wheel support is arranged at the bottom of the clamping plate, and the roller wheel support is arranged on the test piece base. The device solves the problem that the experimental result is inaccurate due to buckling deformation of the test piece, and is suitable for test pieces of various specifications; meanwhile, the invention also provides a method for carrying out a fracture toughness test by using the buckling restrained device.
Description
Technical Field
The invention belongs to the field of fracture toughness test, and particularly relates to a fracture toughness test buckling-restrained device and a test method.
Background
The metal sheet is widely applied to the connection part of the skin of the airplane body and the airplane body of the wing, and in the taking off and landing and cruising stages of the airplane, along with the continuous adjustment of the flying posture of the airplane, the airplane body is subjected to the torsion action of the wing, the wing is also subjected to the lifting action to swing up and down, and the parts are continuously subjected to random loads in the flying process of the airplane. For safety reasons in flight, there is a need for a material for the fuselage which does not crack or even break when subjected to the above forces, and therefore the fracture toughness of the skin material for the fuselage of an aircraft is a major consideration for the aircraft production and the aircraft design units. However in the fracture toughness testIn the process, the thickness of the metal sheet sample is required to be generally less than 10mm, but the length and the width of the metal sheet sample are large, and the central crack part is easy to bend in the tensile loading process. For the commonly used M (T) type test piece, when the width W is more than or equal to 406mm and the thickness B is less than or equal to 5mm, obvious buckling deformation can occur along with the increase of load in the test process, and the test result K isRThe accuracy of the curve and the Kc value is a serious concern. And in the test, the width of the test piece has a size of W500 mm or more. Therefore, it is necessary to design a buckling-restrained device which can be used for the fracture toughness test of metal sheets with various specifications and a proper test method.
Disclosure of Invention
The invention provides a buckling-restrained device for a fracture toughness test and a method for performing the fracture toughness test by using the buckling-restrained device, aiming at the problem that buckling cannot be avoided along with the increase of tensile load in the process of performing the fracture toughness test on a metal sheet test piece at present.
In order to achieve the purpose, the invention provides the following technical scheme:
a buckling-restrained device for a fracture toughness test comprises a tester base, a pair of tester beams above the tester base and a clamping mechanism used for fixing a test piece on the tester base,
the clamping mechanism comprises a pair of brackets fixed on the base of the testing machine, a pair of clamps connected to the brackets in a sliding manner, two groups of clamping plates which are used for clamping the front side and the rear side of the test piece and are mutually fixed, and an upper supporting structure and a lower supporting structure which are respectively used for supporting the upper part and the lower part of each clamping plate; wherein,
the left end and the right end of the test piece are clamped in the pair of clamps; the clamping plate is arranged between the pair of brackets, the bottom of the clamping plate is provided with a roller bracket, and the roller bracket is arranged on the test piece base; the upper supporting structure is fixed on the cross beam of the testing machine, and the lower supporting structure is fixed on the support.
Preferably, the bottom of the clamp is fixed with a sliding block, the support is provided with a corresponding sliding rail, and the sliding block can slide left and right on the sliding rail.
Preferably, every group the grip block includes a plurality of section bar splint that set up side by side, the vertical length of section bar splint is greater than the vertical length of testpieces is located both sides around the testpieces the upper and lower end of section bar splint passes through mounting detachably fixed connection.
Preferably, the middle part of the clamping plate is provided with a central observation hole.
Preferably, the roller support is a stamped universal ball.
Preferably, the upper supporting structure comprises a horizontal supporting beam bottom rod, an upper side stop rod and two upper side supporting beams, wherein the horizontal supporting beam bottom rod, the upper side stop rod and the two upper side supporting beams extend in the front-rear direction and are arranged outside each group of clamping plates and extend left and right; the upper side stop lever is fixed on the two upper side support beams by using an angle piece, and the inner side surface of the upper side stop lever is abutted against the outer surface of the clamping plate.
Preferably, the lower supporting structure is including fixed locating two a pair of horizontal corbel bottom plates of support inboard are located two sets of respectively a pair of downside corbel that extends about and in the grip block outside and locate two sets of a pair of downside pin that extends around and in the both sides wall about and, wherein, the both ends of downside corbel use the corner fittings to be fixed in respectively on the corbel bottom plate, the both ends of downside pin use the corner fittings respectively the vertical fixation in a pair of both sides around the test piece on the downside support.
Preferably, a polytetrafluoroethylene plate is placed between the test piece and the clamping plates on the two sides of the test piece, and a notch matched with the observation hole is formed in the polytetrafluoroethylene plate.
Preferably, the middle parts of the two groups of clamps are respectively provided with a stretching hole for connecting a chuck of the testing machine during testing.
The invention also provides a fracture toughness test method, which uses the buckling-restrained device according to any one of the above schemes, and comprises the following steps:
(1) the coaxiality of the testing machine and the clamp is tested, and fatigue crack and tensile fracture tests are carried out after the coaxiality test is passed;
(2) placing two ends of a test piece into the fixture for fixing, determining the size of the clamping plate according to the length of the test piece, and assembling the anti-buckling device;
(3) prefabricating fatigue cracks, namely installing a clamp-type extensometer for measuring the opening displacement of the cracks on the test piece, starting a testing machine, stopping prefabricating the cracks when the length of the prefabricated cracks is 0.25W-0.4W of the width W of the test piece, and performing a breaking test;
(4) starting from 0, loading the test force until the test piece is broken, and ending the test;
(5) analyzing the test result and drawing KRCurve line.
In conclusion, the invention provides the buckling-restrained device for the fracture toughness test and the test method, and the buckling-restrained device is designed to provide a restraint perpendicular to the plane of the sheet metal during the fracture toughness test, so that the difficulty that the test result is inaccurate due to buckling deformation of a test piece is solved; and the number of the section bar clamping plates in the anti-buckling device can be adjusted according to the length of an actual test piece, so that the device can be suitable for metal sheets of various specifications, and the utilization rate of the device is improved.
Drawings
Fig. 1 is a front view structural view of the fracture test buckling restrained device of the present invention.
Fig. 2 is a right side view structural view of the fracture test buckling restrained device of the present invention.
Fig. 3 is a front view structural view of the profile splint.
Fig. 4 is a top view structural view of the profile splint.
FIG. 5 is a structural view of a test piece in the example.
Fig. 6 is a front view structural view of the corner fitting.
Fig. 7 is a top view structural view of the corbel base plate.
FIG. 8 is a load-crack opening displacement curve for a fracture toughness test.
FIG. 9 shows K of the fracture toughness test of the present inventionRCurve line.
Wherein: 1. the tester comprises a tester base, 2, a support, 3, a sliding block, 4, a sliding rail, 5, a clamp, 6, a test piece, 7, a clamping plate, 8, a roller support, 9, a section bar clamping plate, 10, a polytetrafluoroethylene plate, 11, a bearing bolt, 12, a lower side stop lever, 13, a corner piece, 14, a lower side support beam, 15, a support beam bottom plate, 16, an upper side stop lever, 17, an upper side support beam, 18, a support beam bottom rod, 19, a fastening screw, 20, a tester beam, 21, a stretching hole, 22, a connecting hole, 23, an observation hole, 24, a center notch, 25 and a strain gauge.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of the present protection.
Example 1
As shown in fig. 1 and fig. 2, the present embodiment provides a fracture toughness test buckling-restrained device, which comprises a tester base 1, a pair of horizontal tester beams 20 above the tester base 1, and a clamping mechanism on the tester base 1 for fixing a test piece 6, the clamping mechanism comprises a pair of brackets 2 fixed on the tester base 1, a pair of clamps 5 connected on the brackets 2 in a sliding way, two groups of clamping plates 7 which are used for clamping the front side and the rear side of the test piece 6 and are mutually fixed, an upper supporting structure and a lower supporting structure which are respectively used for supporting the upper part and the lower part of the clamping plates 7, wherein the left end and the right end of the test piece 6 are respectively clamped in the pair of clamps 5, the clamping plate 7 is arranged between the pair of brackets 2, the bottom of the clamping plate 7 is provided with a roller bracket 8, and the roller bracket 8 is arranged on the test piece base 1; the upper supporting structure is fixed on the tester beam 20, and the lower supporting structure is fixed on the pair of brackets 2.
Further, a sliding block 3 is fixed at the bottom of the clamp 5, and the corresponding sliding rail 4 is arranged on the support 2, so that the clamp 5 can be adjusted in the left-right direction on the support 2 by means of the sliding block 3 on the sliding rail 4.
Further, every group grip block 7 includes a plurality of section bar splint 9 that set up side by side, the quantity of section bar splint 9 can be according to the width of testpieces 6 is adjusted, just the vertical length of section bar splint 9 is greater than the vertical length of testpieces 6 is located both sides around the testpieces 6 the upper and lower end of section bar splint 9 is fixed through bearing bolt 11 and nut detachably respectively.
Further, as shown in fig. 1 and 5, since the central slit 24 for crack extension is formed in the middle of the test piece 6, in order to observe the splitting of the central slit 24, the profile clamping plates 9 located in the middle of each set of clamping plates 7 are formed with observation holes 23. In this embodiment, each group of clamping plates 7 is composed of seven profile clamping plates 9 in parallel, specifically, the profile clamping plates 9 are structured as shown in fig. 3 and 4, and the observation hole 23 of the profile clamping plate 9 located in the middle of the clamping plate 7 is a cross-shaped observation hole.
In this embodiment, it is preferred, the gyro wheel support 8 is the universal ball of punching press, and a universal ball of punching press is all installed to the bottom both sides of every section bar splint 9, and the universal ball of installation punching press can reduce the friction of grip block 7 on testing machine base 1, improves the precision of test data.
Further, as shown in fig. 1 and fig. 2, the upper supporting structure includes a horizontal supporting beam bottom rod 18, a horizontal upper side stop rod 16, and two upper side supporting beams 17 extending in the front-rear direction, which are disposed outside each group of clamping plates 7 and extend from left to right, the supporting beam bottom rod 18, the upper side supporting beam 17, and the upper side stop rod 16 are fixedly connected in sequence from bottom to top, wherein the supporting beam bottom rod 18 is fixed on the testing machine cross beam 20 by using fastening screws 19, the two upper side supporting beams 17 are respectively and vertically fixed on two sides of the supporting beam bottom rod 18 by using corner fittings 13, and the inner side end of the upper side supporting beam 17 abuts against the clamping plates 7; the upper stop bars 16 are fixed to the two upper support beams 17 using corner fittings, and the inner side surfaces of the upper stop bars 16 abut against the outer surface of the holding plate 7.
Further, the lower supporting structure is including being fixed in two a pair of horizontal corbel bottom plate 15 of 2 inboard supports is located two sets of grip blocks 7 outsides and is controlled a pair of downside corbel 14 that extends respectively to and locate two sets of grip blocks 7 left and right sides wall and a pair of downside blend stop 12 that extends around, wherein, the both ends of downside corbel 14 use corner fittings 13 to be fixed in a pair of respectively on the corbel bottom plate 15, the both ends of downside blend stop 12 use corner fittings 13 respectively the vertical fixation on a pair of downside corbel 14 of both sides around the test piece 6. In the present embodiment, as shown in fig. 6 and 7, the corner fitting 13 is preferably an L-shaped connecting plate, and the joist base plate 15 is provided with a mounting through hole for connecting to the lower side joist 14 and the bracket 2.
In order to reduce the sliding friction between the clamping plate 7 and the test piece 6, further, a teflon plate 10 is placed between the clamping plate 7 and the test piece 6, the teflon plate 10 is fixed by clamping the clamping plate 7 on both sides of the test piece 6, and a notch (not shown in the figure) is also formed in the position, corresponding to the central notch 24 of the test piece 6, on the teflon plate 10.
Furthermore, the middle parts of the two groups of clamps 5 are respectively provided with a stretching hole 21 for connecting a chuck of the testing machine during testing.
In summary, the buckling-restrained device clamps the two surfaces of the test piece 6 by using the clamping plates 7 to prevent the test piece 6 from buckling and deforming, and the size of the clamping plates 7 can be adjusted by increasing or decreasing the number of the section clamping plates 9 according to the size of the test piece 6; simultaneously through the universal ball of installation punching press in the bottom of every section bar splint 9 to reduce the friction of section bar splint 9 and testing machine base 1, guarantee the reliability of test data.
Example 2
The embodiment provides a method for performing a fracture toughness test by using the buckling restrained device, which comprises the following steps:
1. and (3) coaxiality inspection: before the tensile test is started, in order to ensure the accuracy of a test result, a debugging piece is required to check whether the coaxiality of the testing machine and the clamp 5 meets the requirement, the specifications of the debugging piece and a test piece 6 to be tested are the same, and the coaxiality detection is in accordance with the standard ASTM E1012-14, and the method comprises the following specific steps:
(1) as shown in fig. 1 and 5, the strain gauge 25 of the strain acquisition system is firstly attached to the corresponding symmetrical positions on the two sides of the debugging member, and then the two ends of the clamp 5 are fixedly connected with the chuck of the testing machine through the stretching hole 21 by using bolts; and inserting the two ends of the adjusting piece into the fixture 5, inserting the loading bolt into the connecting holes 22 correspondingly formed in the fixture 5 and the test piece 6, and screwing and fixing the loading bolt by using a 40 N.m torque wrench to ensure that the loading bolt can be screwed, wherein in the embodiment, the adjusting piece is an aluminum alloy plate, the length and the width of the plate are 1940mm and 1200mm respectively, and 6 symmetrical strain gages 25 are respectively stuck to the two sides of the adjusting piece, and are respectively numbered 1-6 and 9-14.
(2) Starting a static tensile test: the static stretching process was loaded with 10kN each time. Because the out-of-plane bending exists in the initial state of the test adjusting piece, in order to eliminate the influence of the initial bending effect on the axial strain, the numerical value of each test point strain gauge 25 is cleared when the static load is 30 kN.
(3) Carrying out formal tests: the method comprises the steps of firstly calculating a corresponding load value when a test piece is subjected to plastic deformation, setting different gradient load value test groups according to the load value, and recording strain values of detection points under different load values, wherein the maximum set value of the load value of the test groups is generally smaller than half of the load value when the plastic deformation occurs, and when the set maximum load value is reached, keeping for 1min so as to check whether the maximum range of the testing machine meets the design requirements.
(4) Respectively recording strain values epsilon of two strain gauges 25 at the upper and lower or left and right symmetrical positions of the debugging partA、εBSubstituting into a coaxiality calculation formula, and the coaxiality epsilon of the strain dataA-BThe calculation formula is as follows:
the coaxiality calculation result is not more than 5% according to the requirements of the standard ASTM E1012-14.
Specifically, in this embodiment, after the measured data of the left-right symmetric positions of each set of strain gauges on both sides of the debugging member is calculated by the coaxiality formula, the results are shown in table 1,
TABLE 1 percent coaxiality results
As shown in the results in Table 1, the coaxiality calculation results of all the groups are less than 5%, which indicates that the coaxiality of the detection device is good, and the next prefabricated fatigue crack and tensile failure test can be carried out.
2. Fracture toughness test: according to the figure 1, a test piece 6 and an anti-buckling device are installed, and the fracture toughness test method is according to the standard document ASTM E561-19, and the specific steps are as follows:
(1) placing two ends of a test piece 6 to be tested into a clamp 5, fixing by using a loading bolt, and fastening the loading bolt by using a 40 N.m torque wrench in the same way as the installation of the test piece; a load of 5kN was then applied to the test piece 6 to eliminate the gap during installation.
(2) Mounting the buckling prevention device: determining the size of the clamping plates 7 according to the size of the test piece 6 so as to determine the number of section bar clamping plates 9 of each group of clamping plates 7, placing the clamping plates 7 at two sides of the test piece 6 in the middle, aligning the middle position of a cross observation hole 23 in the middle of the clamping plates 7 with a central notch 24 of the test piece, inserting two polytetrafluoroethylene plates 10 between the clamping plates 7 and the test piece 6 from one side in tandem, and adjusting the middle notches of the polytetrafluoroethylene plates 10 to be aligned with the observation holes 23; after the placement is completed, the front and rear corresponding profile clamping plates 9 on the upper side and the lower side of the test piece 6 are fixedly connected by using the bearing bolts 11, and specifically, the bearing bolts 11 are screwed by using a 1.5N · m torque wrench.
(3) An upper side stop lever 16, an upper side support beam 17 and a support beam bottom lever 18 of an upper support structure of the clamping plate 7 are fixedly installed in sequence, and the support beam bottom lever 18 is fixed on a testing machine cross beam 20 through a fastening screw 19; then, the lower side stop lever 12, the lower side corbel 14 and the corbel bottom plate 15 of the lower supporting structure are fixedly connected in sequence through the corner fittings 13, and the corbel bottom plate 15 is fixed inside the bracket 2 by using screws.
(4) Prefabricating fatigue cracks: after the anti-buckling device is installed, a bearing bolt 11 on the section bar clamping plate is further screwed by using a torque wrench of 80 N.m, a clamp-type extensometer for measuring the crack opening displacement is installed on a test piece 6, the test machine is started, and the stress intensity factor K when the crack is prefabricated is set to be 10-12 MPa.m1/2And the stress R is 0.1. And when the length of the prefabricated crack is 0.25W-0.4W of the width W of the test piece 6, stopping the prefabricated crack, and carrying out the next step of the stretch-breaking test.
(5) The test force loading is carried out from 0, and the rate is controlled so that the change rate of the stress intensity factor K is 0.55-2.75 MPa.m1/2And s. And ending the test until the test piece is broken.
Example 3
This example K is plotted according to the results of the fracture toughness test of the above examplesRCurve line.
In the above embodiment, after the pre-crack is performed by using the stress ratio R of 0.1, the initial crack length is 314mm, then the snap test is started, the load-crack opening displacement curve in the test process is shown in fig. 8, it can be seen from fig. 8 that the curve shape is relatively smooth and smooth in the whole and does not have a sawtooth shape or a wave shape in the linear elastic stage of the curve and the load reduction stage after yielding, which indicates that the test piece does not have obvious buckling with the continuous increase of the load in the test process, and further illustrates that the buckling prevention device in the present invention has a good effect in preventing the buckling deformation of the test piece 6.
After analyzing the result of the load-crack opening displacement, the effective crack growth amount delta a is taken as a horizontal coordinate, and the effective crack strength factor is taken as a vertical coordinateCoordinate KeffTest piece KeffThe curve of- Δ a is plotted on the coordinate axis, as shown in FIG. 9, which is the K measured in the fracture toughness test of the test piece of the present inventionRCurve and KRThe shape of the curve is overall stable and smooth.
The above description is only exemplary of the present invention and should not be taken as limiting, and any modification, equivalent replacement or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A fracture toughness test buckling-restrained device comprises a tester base, a pair of tester beams above the tester base and a clamping mechanism on the tester base for fixing a test piece, and is characterized in that,
the clamping mechanism comprises a pair of supports A fixed on the base of the testing machine, a pair of clamps connected to the supports A in a sliding mode, two groups of clamping plates used for clamping the front side and the rear side of the test piece and mutually fixed, and an upper supporting structure and a lower supporting structure which are respectively used for supporting the upper portion and the lower portion of each clamping plate; wherein,
the clamping plates are placed in the middle on two sides of the test piece, each group of clamping plates comprises a plurality of section bar clamping plates arranged in parallel, the vertical length of each section bar clamping plate is greater than that of the test piece, and the upper ends and the lower ends of the section bar clamping plates on the front side and the rear side of the test piece are detachably and fixedly connected through fixing pieces;
the left end and the right end of the test piece are clamped in the pair of clamps; the clamping plate is arranged between the pair of brackets A, the bottom of the clamping plate is provided with a roller bracket, and the roller bracket is arranged on the test piece base; the upper supporting structure is fixed on the cross beam of the testing machine, and the lower supporting structure is fixed on the bracket A;
the upper supporting structure comprises a horizontal supporting beam bottom rod, an upper side stop rod and two upper side supporting beams, wherein the horizontal supporting beam bottom rod, the upper side stop rod and the two upper side supporting beams extend in the front-rear direction and are arranged outside each group of clamping plates and extend leftwards and rightwards; the upper side blocking rods are fixed on the two upper side supporting beams by using corner pieces, and the inner side surfaces of the upper side blocking rods are abutted against the outer surfaces of the clamping plates;
the under bracing structure is including fixed locating two a pair of horizontal corbel bottom plates of support A inboard are located two sets of respectively the grip block outside and control a pair of downside corbel that extends, and locate two sets of a pair of downside pin that extends around the both sides wall of grip block left and right sides wall and, wherein, the both ends of downside corbel use the corner fittings to be fixed in respectively on the corbel bottom plate, the both ends of downside pin use the corner fittings respectively vertical fixation in a pair of both sides around the test piece on the downside corbel.
2. The fracture toughness test buckling-restrained device according to claim 1, wherein a sliding block is fixed at the bottom of the fixture, a corresponding sliding rail is arranged on the bracket A, and the sliding block can slide left and right on the sliding rail.
3. The fracture toughness test buckling-restrained device according to claim 1, wherein a central observation hole is formed in the middle of the clamping plate.
4. The fracture toughness test buckling restrained device of claim 1, wherein the roller bracket is a stamped universal ball.
5. The fracture toughness test buckling-restrained device according to claim 3, wherein a polytetrafluoroethylene plate is placed between the test piece and the clamping plates on the two sides of the test piece, and a notch matched with the observation hole is formed in the polytetrafluoroethylene plate.
6. The fracture toughness test buckling-restrained device of claim 1, wherein the middle parts of the two groups of clamps are respectively provided with a tensile hole for connecting with a chuck of a testing machine during testing.
7. A fracture toughness test method using the buckling restrained device according to any one of claims 1 to 6, comprising the steps of:
(1) the coaxiality of the testing machine and the clamp is tested, and fatigue crack and tensile fracture tests are carried out after the coaxiality test is passed;
(2) placing two ends of a test piece into the fixture for fixing, determining the size of the clamping plate according to the length of the test piece, and assembling the anti-buckling device;
(3) prefabricating fatigue cracks, namely installing a clamp-type extensometer for measuring the opening displacement of the cracks on the test piece, starting a testing machine, stopping prefabricating the cracks when the length of the prefabricated cracks is 0.25W-0.4W of the width W of the test piece, and performing a breaking test;
(4) starting from 0, loading the test force until the test piece is broken, and ending the test;
(5) analyzing the test result and drawing KRCurve line.
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000149238A (en) * | 1998-11-16 | 2000-05-30 | Fujitsu Ltd | Head strength evaluation tester |
| JP2001056275A (en) * | 1999-08-18 | 2001-02-27 | Shimadzu Corp | Electromagnetic force type minute material testing machine with microscope |
| CN104949883A (en) * | 2015-05-27 | 2015-09-30 | 中国航空工业集团公司北京航空材料研究院 | Device for testing fracture toughness of sheet center crack tensile sample |
| CN105258994A (en) * | 2015-10-20 | 2016-01-20 | 南京航空航天大学 | Device and method for preparing fiber in-plane buckling in-situ strength test sample |
| CN106248914A (en) * | 2016-08-04 | 2016-12-21 | 清华大学 | The separable concrete temperature stress testing machine vibrated of mould |
| CN108896404A (en) * | 2018-06-19 | 2018-11-27 | 中国铁路总公司 | A kind of prefabricated components are glued the experimental rig and its test method of seam tensile strength |
| CN210014910U (en) * | 2019-08-16 | 2020-02-04 | 湖北省鲲发工程检测有限公司 | Tensile test machine for connecting piece between bridge steel pieces |
| CN211927520U (en) * | 2019-12-26 | 2020-11-13 | 中国航空工业集团公司西安飞机设计研究所 | Aircraft skin transverse butt joint fatigue test fixture |
| CN112461643A (en) * | 2020-11-02 | 2021-03-09 | 燕山大学 | Plate tension and compression test auxiliary clamp based on rolling friction |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9897511B2 (en) * | 2015-03-02 | 2018-02-20 | Jacob Yefim Sheynkman | Can growth/buckling tester |
| CN205749099U (en) * | 2016-06-15 | 2016-11-30 | 武汉钢铁股份有限公司 | The anti-flexion device of flat cold-rolled sheet low cycle fatigue test |
| CN109596413A (en) * | 2018-11-29 | 2019-04-09 | 中国商用飞机有限责任公司北京民用飞机技术研究中心 | A kind of Material Stiffened Panel structure compresses test anti-bending clamping device in end |
| CN209513421U (en) * | 2018-12-04 | 2019-10-18 | 中国航空工业集团公司西安飞机设计研究所 | A kind of covering longitudinal direction opposite joint tests bending resistance fixture |
-
2021
- 2021-05-24 CN CN202110565345.1A patent/CN113203628B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000149238A (en) * | 1998-11-16 | 2000-05-30 | Fujitsu Ltd | Head strength evaluation tester |
| JP2001056275A (en) * | 1999-08-18 | 2001-02-27 | Shimadzu Corp | Electromagnetic force type minute material testing machine with microscope |
| CN104949883A (en) * | 2015-05-27 | 2015-09-30 | 中国航空工业集团公司北京航空材料研究院 | Device for testing fracture toughness of sheet center crack tensile sample |
| CN105258994A (en) * | 2015-10-20 | 2016-01-20 | 南京航空航天大学 | Device and method for preparing fiber in-plane buckling in-situ strength test sample |
| CN106248914A (en) * | 2016-08-04 | 2016-12-21 | 清华大学 | The separable concrete temperature stress testing machine vibrated of mould |
| CN108896404A (en) * | 2018-06-19 | 2018-11-27 | 中国铁路总公司 | A kind of prefabricated components are glued the experimental rig and its test method of seam tensile strength |
| CN210014910U (en) * | 2019-08-16 | 2020-02-04 | 湖北省鲲发工程检测有限公司 | Tensile test machine for connecting piece between bridge steel pieces |
| CN211927520U (en) * | 2019-12-26 | 2020-11-13 | 中国航空工业集团公司西安飞机设计研究所 | Aircraft skin transverse butt joint fatigue test fixture |
| CN112461643A (en) * | 2020-11-02 | 2021-03-09 | 燕山大学 | Plate tension and compression test auxiliary clamp based on rolling friction |
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