CN110132739B - Micro fatigue test normal load loading device and method - Google Patents

Micro fatigue test normal load loading device and method Download PDF

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Publication number
CN110132739B
CN110132739B CN201910443359.9A CN201910443359A CN110132739B CN 110132739 B CN110132739 B CN 110132739B CN 201910443359 A CN201910443359 A CN 201910443359A CN 110132739 B CN110132739 B CN 110132739B
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clamping plate
fixing
plate
screw rod
load
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CN110132739A (en
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胡殿印
毛建兴
倪卓慧
曲震
王荣桥
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Beihang University
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Beihang University
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02Details
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058Kind of property studied
    • G01N2203/0069Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0073Fatigue

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

The invention relates to a normal load loading device and method for a fretting fatigue test. The loading device consists of two parts: a fixed portion and a load-carrying portion. The method specifically comprises the following steps: the clamp comprises a micro-motion pad, a first clamping plate, a second clamping plate, a force measuring sensor, a load adjusting screw, a locknut, a limiting screw rod, a positioning nut, a limiting nut, a bushing, a fixing plate, a fixing bolt, an inner side fixing block and an outer side fixing block. The invention realizes the micro-motion fatigue test on a common fatigue testing machine.

Description

Micro fatigue test normal load loading device and method
Technical Field
The invention relates to the field of fretting fatigue tests, in particular to a normal load loading device and method for a standard test piece in a fretting fatigue test in a laboratory.
Background
Tenon joint structures are widely adopted in the axial-flow compressor, turbine and other power machines of the aircraft engine. Fretting fatigue accelerates crack initiation and propagation at the dovetail joint and accelerates component failure. Disks and blades of the compressor of an aircraft engine are widely made of titanium alloy, which is sensitive to fretting fatigue.
In order to study the fretting fatigue properties of materials, fretting fatigue tests need to be carried out in laboratories. The ordinary uniaxial fatigue testing machine cannot apply normal load to the standard test piece, so that the ordinary uniaxial fatigue testing machine cannot be directly used for fretting fatigue testing. At present, the fretting fatigue test is carried out by a multi-axis fatigue testing machine or a device is added on a single-axis fatigue testing machine to apply normal load to a test piece to carry out the test. At present, most devices for applying normal force in the fretting fatigue test are loaded through hydraulic loading and loading rings, the normal load which can be applied by the hydraulic loading is larger, but the normal loads on the left side and the right side are simultaneously loaded, and the normal loads on the left side and the right side are difficult to ensure to be consistent even if a control program is used, so that a test piece can be influenced by extra bending moment to influence the test precision; although the loading ring can overcome the problem, the loading ring has a simple structure, cannot apply a large normal load, and is generally not axially fixed, so that the axial rigidity is low.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the defects in the background art are overcome, the normal load loading device and the normal load loading method for the fretting fatigue test are provided, and the purpose of carrying out the fretting fatigue test on a common fatigue testing machine is achieved. The invention integrates the advantages of the two devices, can apply larger normal load to the test piece, and simultaneously realizes unilateral loading through a mechanical structure, thereby avoiding additional bending moment caused by asymmetrical loading.
The technical scheme of the invention is as follows: a fretting fatigue test normal load loading device comprises: the device comprises a test piece (1), a micro-motion pad (2), a first clamping plate (3), a second clamping plate (4), a force measuring sensor (5), a load adjusting screw (6), a fixing plate (7), a limiting screw rod (8), a limiting nut (9), an outer side fixing block (10), an inner side fixing block (11), a check nut (12), a shaft sleeve (13), a fixing screw rod (14) and a positioning nut (15). The outer side fixing block (10) and the inner side fixing block (11) fix the whole normal load loading device on the upright posts at two sides of the fatigue testing machine under the action of bolts, the inner side fixing block (11) is connected with a fixing screw rod (14), and a threaded hole is formed in the corresponding position of the fixing plate (7) and used for being connected with the fixing screw rod (14). The fixing plates (7) on two sides are connected through the limiting screw rod (8), the positioning nut (15) is installed on the limiting screw rod (8), a through hole is formed in the corresponding position of the fixing plate (7), the positioning nut (15) is used for positioning the fixing plate (7) on the right side, and the limiting nut (9) and the positioning nut (15) clamp the fixing plate (7) on the right side together, so that the fixing effect is achieved. The right side of the second clamping plate (4) is provided with a threaded hole, and the force measuring sensor (5) is installed on the second clamping plate (4) through a screw. After the load adjusting screw (6) passes through a threaded hole in the right side plate of the first clamping plate (3), a loose nut (12) is installed and then abuts against the force measuring sensor (5). Open at the corresponding position of first grip block (3) and second grip block (4) has the through-hole for stop screw (8) pass, thereby, whole device just can be fixed on the stand of fatigue testing machine both sides. Rectangular grooves for installing the micromotion pads (2) are formed in the left side plate of the first clamping plate (3) and the second clamping plate (4) in advance; in the test, the fretting fatigue normal load is applied through the load adjusting screw (6). And a shaft sleeve (13) is additionally arranged among the first clamping plate (3), the second clamping plate (4) and the limiting screw (8) to play a role in reducing abrasion.
The micro fatigue normal load loading device can realize different micro pair forms by changing the geometry and the size of the micro pad according to different specific requirements.
The micro fatigue normal load loading device can be installed on fatigue testing machines of different models by replacing fixing screws with different lengths.
The invention discloses a normal load loading method for a fretting fatigue test, which comprises the following steps of:
the test method comprises the steps that firstly, in the test process, a micro fatigue normal force is applied through a load adjusting screw (6), a load cell (5) is fixed on a second clamping plate (4), the load adjusting screw (6) is screwed down, the load adjusting screw (6) can be firstly propped against the load cell (5), under the action of a limiting screw rod (8), the load cell (5) and the second clamping plate (4) move leftwards together until a micro pad (2) on the second clamping plate (4) is contacted with a test piece (1), and the positioning effect is achieved. After which the second clamping plate (4) is not in motion.
And secondly, continuously tightening the load adjusting screw (6) to enable the first clamping plate (3) to move rightwards integrally, and enabling the micro-motion pad (2) on the left side of the test piece (1) to be pressed on the test piece.
And thirdly, continuously screwing the load adjusting screws (6), so that the micro-motion pads (2) on the two sides can be tightly pressed on the two sides of the test piece (1) with a certain load, and the purpose of applying normal load is achieved. After the expected normal load is reached, the locknut (12) is tightened, and the reduction of the normal load caused by the loosening of the threads in the test process can be prevented. The force measuring sensor (5) can be externally connected with a number display, so that the size change of the normal force can be continuously monitored in the experimental process.
Compared with the prior art, the invention has the advantages that:
(1) because the test piece is fixed on the upper clamp and the lower clamp of the fatigue testing machine firstly, the test piece cannot be guaranteed to be positioned at the symmetric centers of the two micro-motion pads, and the test piece is bent under asymmetric load. The invention can avoid the situation, and the micro-pads can be automatically and symmetrically positioned at the two sides of the test piece in the process of applying normal load by using the load adjusting screws.
(2) The invention has simple structure and can apply larger normal load. Can be fixed on a fatigue testing machine, and has large axial rigidity. Has wide applicability and can be used for fatigue testing machines of different models.
Drawings
FIG. 1 is a front view of the overall structure of the loading device of the present invention;
FIG. 2 is an isometric view of the overall structure of the loading device of the present invention;
fig. 3 is an isometric view of a first clamping plate in the loading device of the present invention.
Detailed Description
The invention is described in detail below with reference to the accompanying drawings and examples.
Firstly, the whole device needs to be fixed with the fatigue testing machine through the upright posts on the two sides of the fatigue testing machine.
As shown in FIGS. 1-3, the entire fretting fatigue normal load loading device of the present invention is divided into two parts: a fixed portion and a load-applying portion;
the load loading part comprises a micro-motion pad 2, a first clamping plate 3, a second clamping plate 4, a load cell 5, a load adjusting screw 6, a locknut 12 and a shaft sleeve 13. The micro-motion pad 2 can be replaced according to different needs of tests. The first clamping plate 3 is formed by connecting a left flat plate and a right flat plate through four rods, a groove is formed in the right side of the left flat plate and used for placing the micro-motion pad 2, a threaded through hole is formed in the right flat plate and used for installing a load adjusting screw 6, the load adjusting screw 6 penetrates through the threaded through hole and then abuts against the force measuring sensor 5, the force measuring sensor 5 is fixed on the right side of the second clamping plate 4 through screws, and a groove is also formed in the left side of the second clamping plate 4 and used for installing the micro-motion pad 2. Through holes are formed at corresponding positions of the first clamping plate 3 and the second clamping plate 4, and limit screws 8 are fixed on the fixing plates 7 at both sides through the through holes, so that the displacement of the load loading part is limited, and only the load loading part is allowed to move in the normal direction, i.e., the x direction in fig. 1.
The fixing part consists of a fixing plate 7, a limit screw 8, a limit nut 9, an outer side fixing block 10, an inner side fixing block 11, a fixing screw 14 and a positioning nut 15. Two sides of the bracket are respectively provided with a fixing plate 7, and the fixing plates 7 are used for supporting a limiting screw 8. The load loading part is supported by means of a limit screw 8. The check screw is subjected primarily to the force of gravity of the load-bearing part and the frictional forces caused in the contact area by the normal load in the test, both forces being in the vertical direction, i.e. in the y-direction in fig. 1. So the strength of the limit screw 8 when being bent needs to be checked. The positioning nut 15 is used for positioning the right fixing plate 7, and the limiting nut 9 and the positioning nut 15 clamp the right fixing plate 7, so that the right fixing plate 7 is fixed. Threaded through holes are formed in the corresponding positions of the fixing plates 7 on the left side and the right side, stepped holes are formed in the corresponding positions of the inner fixing blocks 11 and used for installing fixing screws 14, and the fixing screws 14 penetrate through the stepped holes and are assembled in the threaded through holes in the fixing plates 7. And finally, fixing the whole normal load loading device on the upright columns at two sides of the fatigue testing machine by the outer side fixing blocks 10 and the inner side fixing blocks 11 at two sides under the action of bolts.
In the test process, the test piece 1 is firstly clamped on the upper clamp and the lower clamp of the fatigue testing machine. Load is applied by screwing the load adjusting screw 6, the load adjusting screw 6 can be firstly propped against the force measuring sensor 5 to drive the second clamping plate 4 to move leftwards, and the second clamping plate 4 does not move any more until the micro-motion pad 2 on the right side is contacted with the test piece 1, so that the positioning effect is achieved. Then continue to tighten load adjusting screw 6, under the effect of screw thread, first grip block 3 can move to the right, and until left fine motion pad 2 also compresses tightly on test piece 1, continue to tighten load adjusting nut 6, the fine motion pad 2 of both sides just can compress tightly at test piece both sides with the normal load of a certain numerical value. After the normal load reaches the magnitude required for the test, the locknut 12 is tightened. The load cell 5 is externally connected with a display, so that the size of the normal load can be monitored. The locknut 12 can ensure that the reduction of the normal load caused by the loosening of the thread can not be caused in the test process.
In order to reduce the abrasion among the first clamping plate 3, the second clamping plate 4 and the limiting screw 8, a shaft sleeve 13 is additionally arranged between the through holes of the first clamping plate 3 and the second clamping plate 4 and the limiting screw 8.
After the test is finished, the locknut 12 is loosened, the load adjusting screw 6 is loosened, the display reading of the external force sensor 5 is reduced to 0, the load adjusting screw 6 is continuously loosened, the first clamping plate 3 moves leftwards, and after the first clamping plate 3 moves leftwards for a certain distance, enough space is provided for taking out the test piece.
The invention has not been described in detail and is within the skill of the art.
The above description is only a part of the embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims (1)

1. A fretting fatigue test normal load loading device is characterized by comprising: the device comprises a test piece (1), a micro-motion pad (2), a first clamping plate (3), a second clamping plate (4), a force measuring sensor (5), a load adjusting screw (6), a fixing plate (7), a limiting screw rod (8), a limiting nut (9), an outer side fixing block (10), an inner side fixing block (11), a check nut (12), a shaft sleeve (13), a fixing screw rod (14) and a positioning nut (15); the outer side fixing block (10) and the inner side fixing block (11) fix the whole normal load loading device on the upright columns at two sides of the fatigue testing machine under the action of bolts, the inner side fixing block (11) is connected with a fixing screw rod (14), a threaded hole is formed in the corresponding position of the fixing plate (7) and used for being connected with the fixing screw rod (14), the fixing screw rod (14) with proper length can be determined according to the specific type of the fatigue testing machine, and the purpose of adapting to different fatigue testing machines is achieved; the fixing plates (7) on the two sides are connected through a limiting screw rod (8), a positioning nut (15) is installed on the limiting screw rod (8), a through hole is formed in the corresponding position of the fixing plate (7), the positioning nut (15) is used for positioning the fixing plate (7) on the right side, and the limiting nut (9) and the positioning nut (15) clamp the fixing plate (7) on the right side together, so that the fixing effect is achieved; a threaded hole is formed in the right side of the second clamping plate (4), and the force measuring sensor (5) is installed on the second clamping plate (4) through a screw; after the load adjusting screw (6) passes through a threaded hole in the right side plate of the first clamping plate (3), a locknut (12) is installed and then propped against the force measuring sensor (5); through holes are formed in the corresponding positions of the first clamping plate (3) and the second clamping plate (4) so that a limiting screw (8) can penetrate through the through holes, and therefore the whole device can be fixed on the stand columns on the two sides of the fatigue testing machine; rectangular grooves for mounting the micromotion pad (2) are formed in the left side plate of the first clamping plate (3) and the second clamping plate (4) in advance, and the micromotion fatigue tests in different micromotion pair forms are carried out by modifying the geometric dimension of the micromotion pad (2); in the test, the fretting fatigue normal load is applied through the load adjusting screw (6), and the shaft sleeve (13) is additionally arranged among the first clamping plate (3), the second clamping plate (4) and the limiting screw rod (8) to play a role in reducing abrasion.
CN201910443359.9A 2019-05-24 2019-05-24 Micro fatigue test normal load loading device and method Active CN110132739B (en)

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Publication number Priority date Publication date Assignee Title
CN110702544B (en) * 2019-10-15 2022-03-11 常州达姆斯检测技术有限公司 Fatigue detection device with reinforcing rib parts on surface
CN111650063A (en) * 2020-07-02 2020-09-11 天津科技大学 Normal load loading device based on single-shaft fatigue testing machine
CN113092290B (en) * 2021-03-26 2022-05-20 太原理工大学 External prestress reinforced concrete beam fatigue test device and method
CN114199487A (en) * 2021-12-07 2022-03-18 中国第一汽车股份有限公司 Motor shell vibration fatigue test device and test method
CN115076205A (en) * 2022-06-22 2022-09-20 东方电气风电股份有限公司 Novel bolt anti-loosening method applied to oil immersion environment of wind generating set
CN115266312A (en) * 2022-09-14 2022-11-01 浙江工业大学 Micro-motion fatigue transverse loading device based on different testing machine types

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CN201622210U (en) * 2010-03-16 2010-11-03 陈跃良 Adjustable fretting fatigue tester
CN103196766A (en) * 2013-03-26 2013-07-10 深圳市特种设备安全检验研究院 Steel wire micro-kinetic-friction abrasion testing machine
CN106442182A (en) * 2016-09-20 2017-02-22 四川大学 High-temperature micro-motion fatigue experiment clamping and loading device

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CN101178345A (en) * 2007-12-05 2008-05-14 西南交通大学 Twisting or micro-moving frictional wear test method and device thereof
CN201622210U (en) * 2010-03-16 2010-11-03 陈跃良 Adjustable fretting fatigue tester
CN103196766A (en) * 2013-03-26 2013-07-10 深圳市特种设备安全检验研究院 Steel wire micro-kinetic-friction abrasion testing machine
CN106442182A (en) * 2016-09-20 2017-02-22 四川大学 High-temperature micro-motion fatigue experiment clamping and loading device

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