Micro sample self-centering clamping device for synchrotron radiation in-situ test

Abstract

The invention relates to a micro sample self-centering clamping device for a synchrotron radiation in-situ test. Comprising a sensor transition connector, a first back tightening nut, an upper loading connecting rod, an upper in-situ clamping block, an upper clamp, a lower clamp, a lower in-situ clamping block, an auxiliary positioning tool, a lower loading connecting rod, an aligning connecting rod, a second back tightening nut, a spherical centering upper cushion block, a spherical centering lower cushion block and an aligning nut. According to the invention, stable clamping and high-precision self-centering of a small sample in a synchrotron radiation in-situ test are met, and the requirement that the small sample is combined with synchrotron radiation light source tomography to carry out a low-cycle fatigue in-situ test at a service temperature is met.

Description

Technical Field

[0001] The invention belongs to the field of design and manufacture of uniaxial in-situ tensile synchrotron radiation fatigue test fixtures for metal materials, and in particular relates to a self-centering clamping device for a micro-sample used for synchrotron radiation in-situ tests. Background Art

[0002] In engineering practice, many parts work under cyclic loads, especially key parts of aircraft engines such as blades and disks, which are in high temperature and high pressure service environment for a long time, and bear huge cyclic alternating loads such as centrifugal force, gas force and thermal stress. The main failure form is fatigue damage. At present, the fatigue fracture behavior of metal materials is mainly studied by two-dimensional characterization methods such as metallographic microscope and scanning electron microscope. However, defects, pores and inclusions introduced by the manufacturing process in the material can easily promote crack nucleation and propagation, and eventually lead to fatigue fracture. Therefore, it is necessary to analyze the damage and failure process of metal structural materials in situ, which is of great significance for a comprehensive understanding of the fracture mechanism of metal materials and improving the service safety of engineering components.

[0003] Synchrotron radiation X-ray tomography has the advantages of high spatial resolution and high temporal resolution. As a three-dimensional visualization characterization technology, it can be combined with in-situ fatigue tests to study the influence of internal structures and defects of materials on crack initiation and propagation. It has been widely used in the study of damage failure behavior of metal structural materials. However, the photon transmittance of X-rays for different metals is different, especially for powder high-temperature alloys and nickel-based high-temperature alloys commonly used in aircraft engine turbine blades and wheels. The transmittance is low, so there are more stringent requirements on the size of the in-situ test pieces and the alignment of the test section. In addition, such tiny test pieces are difficult to clamp and are easily deformed during the assembly and disassembly process, which affects the accuracy of synchrotron radiation imaging. At present, the sample clamping methods suitable for synchrotron radiation in-situ tests at home and abroad are relatively complicated. The reasonable clamping methods of tiny samples used for synchrotron radiation imaging of materials with low transmittance are not considered, and the centering mechanism is not set or the accuracy is insufficient. It is difficult to ensure the consistency of the alignment between the center of the test piece and the loading axis. Therefore, when conducting synchrotron radiation in-situ tests of tiny samples with high magnification under service conditions, it is difficult to ensure that the imaging quality meets the test requirements. Summary of the invention

[0004] In order to overcome the shortcomings of the sample clamping method adopted in the existing synchrotron radiation in-situ test, the present invention provides a micro-sample self-centering clamping device for synchrotron radiation in-situ test, which can achieve high-precision self-centering of the center of the in-situ test piece and the loading axis of the test machine through a centering device, so that the off-plane displacement of the in-situ sample center during the test loading process does not exceed 0.2mm, thereby ensuring the imaging accuracy of synchrotron radiation X-ray tomography and avoiding repeated adjustment of the sample center position before imaging.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A self-centering clamping device for a micro-sample used for a synchrotron radiation in-situ test comprises a sensor transition connector, a first backing nut, an upper loading connecting rod, an upper in-situ clamping block, an upper clamp, a lower clamp, a lower in-situ clamping block, an auxiliary positioning tool, a lower loading connecting rod, a self-aligning connecting rod, a second backing nut, a spherical centering upper pad, a spherical centering lower pad, and a self-aligning nut; the top of the sensor transition connector is connected to a force sensor and a driving device on the upper part of a fatigue testing machine for transmitting load; the upper loading connecting rod is connected to the sensor transition connector by threads, and the first backing nut is used to ensure that the upper loading connecting rod and the sensor transition connector are firmly connected; the upper in-situ clamping block is located at the bottom end of the upper loading connecting rod, and the lower in-situ clamping block is located at the upper end of the lower loading connecting rod; the in-situ sample used in the test and The upper clamp and the lower clamp are connected by two bolts, and a certain pre-tightening force is applied to the bolts to make them stably connected without relative displacement; the upper clamp is connected to the groove of the upper original-situ clamp block by surface contact; before the fatigue testing machine applies the load, the auxiliary positioning tool is inserted into the gap between the upper clamp and the upper original-situ clamp block and then removed to ensure that the upper clamp is in the center of the groove of the upper original-situ clamp block; when the tensile load is applied, the lower clamp and the lower original-situ clamp block have surface contact, thereby realizing the clamping of the specimen; the lower loading connecting rod is connected to the self-aligning connecting rod by threads, and the second back-tightening nut is used to ensure that the lower loading connecting rod is firmly connected to the self-aligning connecting rod; the spherical centering upper pad and the spherical centering lower pad are spherically superimposed on the lower end of the self-aligning connecting rod, and then tightened by the self-aligning nut on the self-aligning connecting rod and contacting with the lower end of the fatigue testing machine.

[0007] Preferably, the upper in-situ clamping block and the lower in-situ clamping block are externally connected to a temperature loading module and a heat preservation device of a fatigue testing machine, so as to quickly heat and keep warm the clamped in-situ specimens.

[0008] Preferably, the auxiliary positioning tool ensures that the upper fixture is located at the center of the groove of the upper in-situ clamp block, thereby improving the centering of the in-situ sample and the center of the light source.

[0009] Preferably, when a tensile load is applied to the lower loading connecting rod, the load is transmitted to the self-aligning connecting rod, and the horizontal plane of the spherical centering upper pad fixed to the bottom of the self-aligning connecting rod is tightly fitted with the horizontal plane of the bottom of the fatigue testing machine. By pre-adjusting the tightness of the self-aligning nut, the spherical centering upper pad and the spherical centering lower pad cooperate through the spherical surface during the gradual tightening process to achieve high-precision self-centering.

[0010] Preferably, the in-situ sample used is of micro-size, and the micro-sample self-centering clamping device achieves stable clamping and high-precision imaging of the micro-size in-situ sample with a cross-sectional size of 0.4mm×0.4mm in the test section.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] (1) The present invention utilizes close surface contact under tensile load to ensure the clamping of the in-situ sample, and is provided with an auxiliary positioning tool to ensure the clamping position. It has a simple structure, a stable connection, and is easy to align. The in-situ sample used can be of a tiny size, and can stably clamp a tiny sample with a cross-sectional size of 0.4×0.4 (mm) in the test section, and can perform high-precision synchrotron radiation X-ray tomography imaging;

[0013] (2) The present invention is provided with a self-aligning device, and the distance between the self-aligning device and the clamping end is increased by a self-aligning connecting rod, thereby improving the centering effect. Before applying the pre-tightening tensile load, the tightness of the self-aligning nut is adjusted, and during the tensioning process, the center of the in-situ specimen and the loading axis are aligned in accordance with each other through the cooperation between the spherical pads, thereby achieving high-precision self-centering without the need for repeated adjustments before each loading;

[0014] The present invention is different from the clamping method and centering method of the synchrotron radiation in-situ sample fixture in the literature. It has a simple structure and is easy to assemble and disassemble. The clamping method is simple and effective. It is combined with a centering device to achieve high-precision self-centering, which solves the problem of insufficient centering between the synchrotron radiation in-situ sample and the loading axis. The present invention can be used for synchrotron radiation X-ray tomography in-situ imaging of tiny samples with a cross-sectional size of 0.4mm×0.4mm, thereby enhancing the test stability and ensuring the imaging accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the overall structure of a self-centering clamping device for a micro-sample used in a synchrotron radiation in-situ test proposed by the present invention;

[0016] Figure 2 This is a schematic diagram of the structure of the synchrotron radiation in-situ sample clamping device;

[0017] Figure 3 This is a schematic diagram of the working mode of the auxiliary positioning tool;

[0018] Figure 4 This is the rear side view of the synchrotron radiation in-situ sample clamping device;

[0019] Figure 5 Schematic diagram of the assembly structure of the synchrotron radiation in-situ test centering device.

[0020] The figures are marked as follows: sensor transition connector 1, first back-tightening nut 2, upper loading connecting rod 3, upper in-situ clamp 4, upper clamp 5, lower clamp 6, lower in-situ clamp 7, auxiliary positioning tool 8, lower loading connecting rod 9, self-aligning connecting rod 10, second back-tightening nut 11, spherical centering upper pad 12, spherical centering lower pad 13, and self-aligning nut 14. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figure 1 As shown, a micro-sample self-centering clamping device for synchrotron radiation in-situ testing of the present invention comprises: a sensor transition connector 1, a first back-tightening nut 2, an upper loading connecting rod 3, an upper in-situ clamping block 4, an upper clamp 5, a lower clamp 6, a lower in-situ clamping block 7, an auxiliary positioning tool 8, a lower loading connecting rod 9, an aligning connecting rod 10, a second back-tightening nut 11, a spherical centering upper pad 12, a spherical centering lower pad 13, and an aligning nut 14.

[0023] The top of the sensor transition connector 1 is connected to the force sensor and the driving device on the upper part of the fatigue machine, the upper loading connecting rod 3 is connected to the sensor transition connector 1 by threads, and the first back-tightening nut 2 is used to ensure that the upper loading connecting rod 3 is firmly connected to the sensor transition connector 1, to ensure a rigid connection and to transmit tensile load; the upper in-situ clamp 4 is located at the bottom end of the upper loading connecting rod 3, and the lower in-situ clamp 7 is located at the upper end of the lower loading connecting rod 9; the in-situ specimen is connected to the upper fixture 5 and the lower fixture 6 by two bolts, and a certain pre-tightening force is applied to the bolts to make them stably connected without relative displacement; the upper fixture 5 is connected to the groove of the upper in-situ clamp 4 by surface contact; the fatigue test Before the testing machine applies load, the auxiliary positioning tool 8 is inserted into the gap between the upper clamp 5 and the upper in-situ clamp block 4 and then removed to ensure that the upper clamp 5 is in the center of the groove of the upper in-situ clamp block 4; when the fatigue machine applies a certain tensile load, the lower clamp 6 and the lower in-situ clamp block 7 are in surface contact, thereby realizing the clamping of the specimen; the lower loading connecting rod 9 is connected to the self-aligning connecting rod 10 by threads, and the second back-tightening nut 11 is used to ensure that the lower loading connecting rod 9 is firmly connected to the self-aligning connecting rod 10; the spherical centering upper pad 12 and the spherical centering lower pad 13 are spherically superimposed on the lower end of the self-aligning connecting rod 10, and then pressed by the self-aligning nut 14 on the self-aligning connecting rod 10 and contacted with the lower end of the fatigue machine.

[0024] Preferably, the upper in-situ clamping block 4 and the lower in-situ clamping block 6 are externally connected to a temperature loading module and a heat preservation device of a fatigue testing machine, so as to quickly heat and keep the in-situ specimens warm.

[0025] Preferably, the auxiliary positioning tool 8 is used to ensure that the upper clamp 5 is located at the center of the groove of the upper in-situ clamp block 4, thereby improving the centering of the in-situ sample.

[0026] Preferably, when a certain tensile load is applied to the lower loading connecting rod 9, the load is transmitted to the self-aligning connecting rod 10, and the horizontal plane of the spherical centering upper pad 12 fixed to the bottom of the self-aligning connecting rod 10 is tightly fitted with the horizontal plane of the bottom of the fatigue testing machine. By pre-adjusting the tightness of the self-aligning nut 14, the spherical centering upper pad 12 and the spherical centering lower pad 13 are spherically matched during the gradual tightening process to achieve high-precision self-centering.

[0027] Preferably, the in-situ sample used may be of a tiny size, enabling stable clamping and high-precision imaging of a tiny sample with a cross-sectional size of 0.4 mm×0.4 mm in the test section.

[0028] Preferably, the upper loading connecting rod 3, the upper in-situ clamping block 4 and the upper fixture 5 are connected to form an upper loading axis of the fatigue testing machine, and the lower fixture 6, the lower in-situ clamping block 7 and the lower loading connecting rod 8 are connected to form a lower loading axis of the fatigue testing machine. The upper and lower loading axes and the in-situ specimen together constitute the loading axis of the fatigue testing machine;

[0029] Preferably, the self-aligning connecting rod 10, the second backing nut 11, the spherical centering upper pad 12, the spherical centering lower pad 13, and the self-aligning nut 14 constitute a centering device for ensuring that the center of the in-situ sample is consistent with the loading axis, and realizing high-precision self-centering through the cooperation of the spherical pad.

[0030] like Figure 2 As shown, the clamping process of the in-situ specimen includes: the upper in-situ clamp block 4 is located at the bottom end of the upper loading link 3, and the lower in-situ clamp block 7 is located at the top end of the lower loading link 9; the in-situ specimen is connected to the upper clamp 5 and the lower clamp 6 by two bolts, and a certain pre-tightening force is applied to the bolts to ensure that the in-situ specimen is stably connected to the upper clamp 5 and the lower clamp 6 without relative displacement; the parallel surface of the upper clamp 5 contacts the parallel surface of the groove of the upper in-situ clamp block 4, and is suspended in the groove; as shown in FIG. Figure 3 As shown, the auxiliary positioning tool 8 is used to adjust the relative position of the upper fixture 5 and the inner surface of the groove of the upper in-situ clamping block 4 so that it is located at the center of the groove;

[0031] The upper clamp 5 and the upper in-situ clamp block 4 transmit the load through direct surface contact. When the fatigue machine slowly applies a certain tensile load, the lower clamp 6 and the lower in-situ clamp block 7 gradually come into surface contact until they fit tightly, thereby achieving stable clamping of the in-situ sample.

[0032] Among them, Figure 4 As shown, the upper in-situ clamping block 5 and the lower in-situ clamping block 7 have semicircular grooves on their backs to prevent the bolts connecting the in-situ specimen from interfering with the in-situ clamping blocks;

[0033] The upper in-situ clamp block 4, the lower in-situ clamp block 7, the upper fixture 5, the lower fixture 6 and their connecting bolts and the auxiliary positioning tool 8 constitute a sample clamping module, and an insulation layer and a temperature loading device are installed on the outer surface of the module to achieve rapid heating and stable heat preservation of the in-situ sample, and then conduct synchrotron radiation in-situ experiments under high temperature conditions;

[0034] The total length of the in-situ sample ranges from 30mm to 45mm, and the minimum cross-sectional size of the test section can reach 0.4mm×0.4mm, which can achieve stable clamping and high-precision imaging of tiny samples;

[0035] The process of achieving high-precision self-centering of the in-situ specimen is as follows:

[0036] like Figure 5 As shown, the lower loading connecting rod 9 is connected to the self-aligning connecting rod 10 by threads, and the second back-tightening nut 11 is used to ensure that the lower loading connecting rod 9 is firmly connected to the self-aligning connecting rod 10; the spherical centering upper pad 12 and the spherical centering lower pad 13 are spherically superimposed and mounted on the lower end of the self-aligning connecting rod 10 to form a shaft hole clearance fit with the lower end of the self-aligning connecting rod 10, and then the overall relative position is adjusted by the self-aligning nut 14 on the self-aligning connecting rod 10;

[0037] The lower end of the self-aligning connecting rod 10, the spherical centering upper pad 12, the spherical centering lower pad 13 and the self-aligning nut 14 constitute a self-aligning device, which is located outside the lower shell of the fatigue testing machine.

[0038] When conducting the synchrotron radiation in-situ fatigue test, the tightness of the self-aligning nut 14 is appropriately adjusted, and a certain tensile load is slowly applied to drive the lower clamp 6 to gradually fit with the inner surface of the groove of the lower in-situ clamp 7. At the same time, the spherical centering upper pad 12 is closely fitted with the horizontal surface of the bottom of the fatigue testing machine. In the process of gradual tightening, the spherical centering upper pad 12 and the spherical centering lower pad 13 form a spherical fit to achieve high-precision self-centering. At this point, the installation of the entire device is completed.

[0039] The centering device can realize the high-precision self-centering function of the sample center and the loading axis, can ensure the neutrality and load transfer stability of the two, and improve the imaging accuracy of synchrotron radiation in-situ experiments on tiny samples.

[0040] The parts not described in detail in the present invention belong to the well-known technology in the art.

[0041] The scope of the present invention is defined by the appended claims, and all equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A self-centering clamping device for micro-samples used in synchrotron radiation in-situ tests, characterized in that: It includes a sensor transition connector, a first back-tightening nut, an upper loading connecting rod, an upper in-situ clamp, an upper fixture, a lower fixture, a lower in-situ clamp, an auxiliary positioning tool, a lower loading connecting rod, a self-aligning connecting rod, a second back-tightening nut, a spherical centering upper pad, a spherical centering lower pad, and a self-aligning nut; the top of the sensor transition connector is connected to the force sensor and the drive device on the upper part of the fatigue testing machine to transfer the load; the upper loading connecting rod and the sensor transition connector are connected by threads, and the first back-tightening nut is used to ensure that the upper loading connecting rod and the sensor transition connector are firmly connected; the upper in-situ clamp is located at the bottom end of the upper loading connecting rod, and the lower in-situ clamp is located at the upper end of the lower loading connecting rod; the in-situ specimen used in the test is connected to the upper fixture and the lower fixture by two bolts The upper clamp and the upper original-situ clamp block are connected and a certain pre-tightening force is applied to the bolts to make them stably connected without relative displacement; the groove of the upper clamp and the upper original-situ clamp block are connected through surface contact; before the fatigue testing machine applies the load, the auxiliary positioning tool is inserted into the gap between the upper clamp and the upper original-situ clamp block and then removed to ensure that the upper clamp is in the center of the groove of the upper original-situ clamp block; when the tensile load is applied, the lower clamp and the lower original-situ clamp block have surface contact, thereby realizing the clamping of the specimen; the lower loading connecting rod and the self-aligning connecting rod are connected by threads, and the second back-tightening nut is used to ensure that the lower loading connecting rod and the self-aligning connecting rod are firmly connected; the spherical centering upper pad and the spherical centering lower pad are spherically superimposed on the lower end of the self-aligning connecting rod, and then tightened by the self-aligning nut on the self-aligning connecting rod and contacting with the lower end of the fatigue testing machine.

2. The self-centering clamping device for micro-samples used in synchrotron radiation in-situ tests according to claim 1, characterized in that: The upper in-situ clamping block and the lower in-situ clamping block are externally connected to the temperature loading module and the heat preservation device of the fatigue testing machine, and are used for quickly heating and heat preservation of the clamped in-situ sample.

3. The self-centering clamping device for micro-samples used in synchrotron radiation in-situ testing according to claim 1 is characterized in that: The auxiliary positioning tool ensures that the upper fixture is located at the center of the groove of the upper in-situ clamping block, thereby improving the centering of the in-situ sample and the center of the light source.

4. The self-centering clamping device for micro-samples used in synchrotron radiation in-situ testing according to claim 1 is characterized in that: When a tensile load is applied to the lower loading connecting rod, the load is transmitted to the self-aligning connecting rod, and the horizontal plane of the spherical centering upper pad fixed to the bottom of the self-aligning connecting rod is tightly fitted with the horizontal plane of the bottom of the fatigue testing machine. By pre-adjusting the tightness of the self-aligning nut, the spherical centering upper pad and the spherical centering lower pad cooperate through the spherical surface during the gradual tightening process to achieve high-precision self-centering.

5. The self-centering clamping device for micro-samples used in synchrotron radiation in-situ testing according to claim 1, characterized in that: The in-situ sample used is of micro-size, and the micro-sample self-centering clamping device realizes stable clamping and high-precision imaging of the micro-size in-situ sample with a cross-sectional size of 0.4mm×0.4mm in the test section.

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