CN112067466A - In-situ analysis device and method for in-plane shear matrix cracks of ceramic matrix composite - Google Patents
In-situ analysis device and method for in-plane shear matrix cracks of ceramic matrix composite Download PDFInfo
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- CN112067466A CN112067466A CN202010692870.5A CN202010692870A CN112067466A CN 112067466 A CN112067466 A CN 112067466A CN 202010692870 A CN202010692870 A CN 202010692870A CN 112067466 A CN112067466 A CN 112067466A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
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- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/14—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object using acoustic emission techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The invention relates to an in-plane shear matrix crack in-situ analysis device for a ceramic matrix composite, which comprises an in-plane shear sample and a test system; the in-plane shear test sample consists of a ceramic-based fiber bundle composite material, two reinforcing sheets and two pressing plates, wherein the front end and the rear end of the ceramic-based fiber bundle composite material are respectively placed on the lower end parts of the two reinforcing sheets, and the test system comprises an in-situ loading platform, an optical microscope, a computer, a load indicator and an acoustic emission sensor; the in-situ loading platform comprises a rocker, a gear box, a threaded rod, a left chuck, a right chuck, a base, a force sensor, a pin and a support frame; the in-situ loading platform is arranged on an object stage of the optical microscope; the acoustic emission sensor is connected with the computer through a cable. The method has the advantage of realizing the in-situ analysis of the crack propagation rule of the in-plane shear matrix of the ceramic matrix fiber bundle composite material.
Description
Technical Field
The invention belongs to the field of composite material mechanical behavior tests, and particularly relates to a device and a method for in-plane shear test of a ceramic-based fiber bundle composite material.
Background
The woven ceramic matrix composite material has low density and still has ideal mechanical properties in a high-temperature environment, and is a preferred material for a high-performance aircraft engine hot-end component. The ceramic matrix fiber bundle composite is a basic bearing unit of the woven ceramic matrix composite and is an ideal medium for researching the damage evolution mechanism of the woven ceramic matrix composite. The load born by the ceramic matrix composite material in the service process is complex, and the shear load exists besides the tensile load. The basic unit, ceramic matrix fiber bundle composite, will also be subjected to various types of loads. The anisotropy of the mechanical property of the ceramic matrix fiber bundle composite material is remarkable, the difference between the damage evolution process and the tensile load shown under the action of the shear load is large, and the damage evolution under the shear load needs to be analyzed independently.
Researches show that the damage mechanism of the ceramic matrix fiber bundle composite material under the shear load comprises various forms of matrix cracking, interface fracture, fiber/interface debonding, matrix/interface debonding, fiber fracture, fiber pulling-out and the like. Before the ultimate shear stress is reached, the in-plane shear matrix crack of the ceramic matrix fiber bundle composite is initiated and propagated throughout the damage stage, and the density thereof represents the overall damage degree of the sample. Therefore, the expansion rule of the in-plane shear matrix crack of the ceramic matrix fiber bundle composite material has important significance for the research on the damage evolution of the ceramic matrix fiber bundle composite material.
However, the ceramic matrix fiber bundle composite material is prepared by only one bundle of fibers, has small size and weak forming capability, and has high loading difficulty for realizing in-plane shearing. At the same time, shear matrix crack propagation involves an increase in the number and length of cracks, which is significantly different from the characteristics exhibited by cracks under axial or transverse tensile loads, and thus it is not easy to properly express shear matrix crack density. Since the observation of the crack propagation process requires the use of a high observation resolution, the number of observation regions of the specimen becomes very large and the test period is long.
Therefore, there is a need to provide a sample, a device and a method capable of performing in-plane shear in-situ loading and observation on a ceramic matrix fiber bundle composite material, so as to realize in-situ analysis of the crack propagation law of the in-plane shear matrix of the ceramic matrix fiber bundle composite material.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a device and a method for an in-plane shear test of a ceramic matrix fiber bundle composite material, so as to realize the in-situ analysis of the crack propagation rule of the in-plane shear matrix of the ceramic matrix fiber bundle composite material.
In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:
the in-plane shear matrix crack in-situ analysis device for the ceramic matrix composite is characterized in that: the in-plane shear test device comprises an in-plane shear test sample and a test system; the in-plane shear test sample is composed of a ceramic-based fiber bundle composite material, two reinforcing sheets and two press plates, wherein one corner of each reinforcing sheet extends outwards, a concave ladder is formed at the outer end of each extending part, the extending parts of the reinforcing sheets form a high-end part and a low-end part, the two reinforcing sheets are oppositely arranged left and right, the extending parts of the two reinforcing sheets are arranged between the two reinforcing sheets in tandem, the front end and the rear end of the ceramic-based fiber bundle composite material are respectively arranged on the low-end parts of the two reinforcing sheets, the press plates are pressed on the low-end parts, the front end and the rear end of the ceramic-based fiber bundle composite material are fixedly pressed on the extending parts of the reinforcing sheets, fiber monofilaments in the ceramic-based fiber bundle composite material extend along the front-back direction of the ceramic-based fiber bundle composite material, and the lower surfaces at the two ends of the ceramic-based fiber, the upper surfaces of two ends of the ceramic-based fiber bundle composite material are fixedly adhered to the pressure plate through epoxy resin glue, and a plurality of first through holes are formed in the middle of the reinforcing sheet; the test system comprises an in-situ loading platform, an optical microscope, a computer, a load indicator and an acoustic emission sensor; the in-situ loading platform comprises a rocker, a gear box, a threaded rod, a left chuck, a right chuck, a base, a force sensor, a pin and a support frame; the base is of a C-shaped structure with a horizontal bottom plate and two vertically raised ends, the left end of the base is provided with a third threaded hole, and the right end of the base is provided with a second through hole at a position opposite to the third threaded hole; the left chuck and the right chuck are of a C-shaped structure with the same structure and a fixed through hole in the center, the left end of the left chuck is provided with a first threaded hole, the right end of the right chuck is provided with a second threaded hole, a force sensor is positioned between the left chuck and the left end of the base, two ends of the force sensor are respectively and fixedly connected with the third threaded hole and the first threaded hole of the left chuck through threaded heads, a gear box is fixed on the right side of the right end of the base, a threaded rod passes through the second through hole, the left end of the threaded rod is hinged with the second threaded hole of the right chuck, the right end is in transmission connection with the gear box, threads are arranged in the second through hole, the threaded rod can rotate in the second through hole so as to drive the right chuck to move left and right together, the rocker is connected with the gear box, when the rocker shakes, the gear box can drive the, the pin penetrates through the fixing through hole and the first through hole simultaneously to fixedly connect the two reinforcing sheets with the left chuck and the right chuck respectively, two ends of the support frame are detachably fixed at the left end and the right end of the base respectively and used for providing supporting force for two ends of the base, and the in-situ loading platform is installed on an objective table of the optical microscope; the optical microscope is provided with a knob for controlling the in-plane movement of the objective table, so that the optical microscope is opposite to the part, which is not fixed by the reinforcing sheet, in the middle of the reinforcing sheet, and the computer is connected with the optical microscope and is used for displaying and measuring the in-plane shear matrix cracks; the load indicator is connected with the force sensor; the acoustic emission sensor is arranged at the upper end of the left chuck; the acoustic emission sensor is connected with the computer through a cable.
In order to optimize the structural form, the specific measures adopted further comprise:
the ceramic matrix fiber bundle composite is of a sheet-shaped structure.
A plurality of third through holes are formed around the second through holes; the base passes through the third through hole through the bolt and is connected with the gear box.
The bottom of the base is of a hollow structure; fourth threaded holes are formed in the two sides of the hollow structure; the objective table is arranged in the hollow structure, and the objective table and the base are fixed to each other through the locking bolt penetrating through the fourth threaded hole.
The top of both ends respectively is equipped with two fifth screw holes about the base, and both ends are equipped with two second through-holes respectively about the support frame, and the support frame bolt passes fifth screw hole and second through-hole simultaneously and fixes the support frame on the base.
The middle part of the support frame is provided with a circular ring structure, a ceramic-based fiber bundle composite material is arranged right below the circular ring structure, and the optical microscope can be fixed on the circular ring structure.
The fixed through hole is arranged at the upper ends of the left chuck and the right chuck, the lower ends of the left chuck and the right chuck are provided with positioning through holes aligned with the fixed through hole, the lower end of the pin penetrates into the positioning through holes in sequence after penetrating through the fixed through hole and the first through hole for limiting, and the upper end of the pin is positioned at the upper part of the fixed through hole.
The left chuck is made of ferromagnetic materials, and the shell of the acoustic emission sensor is magnetically adsorbed on the left chuck;
vaseline is smeared between the acoustic emission sensor and the left chuck, between the left chuck and the pin, and between the pin and the first through hole of the reinforcing sheet to serve as an acoustic coupling agent, so that the attenuation of acoustic emission signals is reduced.
The in-plane shear matrix crack in-situ analysis method of the ceramic matrix composite comprises the following steps:
step 1: coating a layer of epoxy resin adhesive on the surface of the lower end part of each reinforcing sheet, and then adhering the lower surface of the ceramic-based fiber bundle composite material to the lower end parts of the two reinforcing sheets;
step 2: coating a layer of epoxy resin adhesive on the upper surface of the ceramic-based fiber bundle composite material, and then covering a pressing plate and pressing tightly;
and step 3: starting an optical microscope and a computer;
and 4, step 4: calibrating a scale of the optical microscope by using a micrometer;
and 5: after the epoxy resin glue in the sample prepared in the step 2 is solidified, placing the epoxy resin glue between a left chuck and a right chuck of the in-situ loading platform, and then placing a pin coated with a vaseline acoustic coupling agent to fix the sample;
step 6: starting the load indicator, and rotating a rocker of the original position loading platform to enable the reading F =0N of the load indicator;
and 7: adsorbing an acoustic emission sensor on the upper surface of the left chuck coated with the Vaseline acoustic coupling agent;
and 8: adjusting the position of an in-situ loading platform on the objective table through a knob to enable the sample to be positioned in the observation field of the optical microscope;
and step 9: adjusting the magnification and the focal length of the optical microscope to obtain a proper observation visual field;
step 10: rotating a rocker of the in-situ loading platform to load the sample, sensing whether an acoustic emission signal is generated in the sample through an acoustic emission sensor, recording the load F at the moment if the acoustic emission signal is generated, and executing the step 11; if no acoustic emission signal is generated, continuing loading until an acoustic emission signal appears;
step 11: judging whether the sample fails, if so, executing the step 20, and if not, continuing to execute the step 12;
step 12: moving the objective table through a knob of the optical microscope, positioning an observation visual field to the upper left corner of the sample, marking the scanning times n =0 of the crack column at the moment, and marking the total length L =0mm of the crack;
step 13: measuring the length delta L of the in-plane shear matrix crack in a visual field, and calculating the total length L = L + delta L of the crack under the load F;
step 14: moving the objective table downwards by 1 observation visual field through a knob of the optical microscope, then measuring the length delta L of the in-plane shear matrix crack in the visual field, and calculating the total length L = L + delta L of the crack under the load F;
step 15: judging whether the observation visual field reaches the lower boundary of the sample, if not, returning to the step 14 until the observation visual field reaches the lower boundary of the sample, and if so, executing the step 16;
step 16: moving the objective table through a knob of the optical microscope to return the observation visual field to the upper left corner of the sample and marking the scanning times of the crack columns at the moment, wherein n = n + 1;
and step 17: moving the object stage to the right by a knob of the optical microscope for 1 observation visual field range;
step 18: judging whether the sample reaches the right boundary of the sample, if the observation visual field does not reach the right boundary, returning to execute the step 13, and if the observation visual field reaches the right boundary of the sample, executing the step 19;
step 19: rotating a rocker of the in-situ loading platform to load the sample, and stopping loading when the reading F = F + delta F of the load indicator;
step 20: completing an in-situ observation test of the in-plane shear matrix crack, and inputting an in-situ loading load F and the crack length L measured under the load into a computer;
step 21: the expansion of the shear matrix crack comprises the increase of the number and the length of the matrix crack, the density of the shear matrix crack is defined according to the total length of the shear matrix crack in a unit area, the shear stress is obtained by dividing the load F by the cross section area of the sample, the density of the shear matrix crack is obtained by dividing the length L of the shear matrix crack by the area of the observation area, and a change diagram of the in-plane shear stress and the density of the matrix crack is drawn to obtain the expansion rule of the in-plane shear matrix crack of the ceramic matrix fiber bundle composite material.
The invention has the beneficial effects that:
1. the method realizes the in-situ test analysis of the crack density of the in-plane shear matrix of the fiber bundle grade ceramic matrix composite material, and can obtain the change relation of the crack density of the shear matrix along with the shear stress.
2. The method judges the crack initiation of the matrix through the acoustic emission technology, and observes the cracks of the sheared matrix after the acoustic emission signal indicates that the cracks of the sheared matrix occur, thereby reducing the workload of unnecessary observation tests and improving the test efficiency.
3. The method defines the crack density of the in-plane shear matrix, gives a clear measurement standard of the crack propagation process of the in-plane shear matrix, and avoids generating ambiguity.
4. The method has the advantages of strong programming, no omission and repeated statistics of observation areas and high reliability of results. Meanwhile, the programmed mode reduces the implementation difficulty of testers and ensures the stability of test results.
Drawings
FIG. 1 is a schematic view of an in-plane shear matrix crack observation specimen of the present invention;
FIG. 2 is a schematic view of a reinforcing sheet of the present invention;
FIG. 3 is a schematic illustration of a platelet-shaped ceramic matrix fiber bundle composite material used in the present invention;
FIG. 4 is a schematic view of an in-plane shear matrix crack observation system of the present invention;
FIG. 5 is a schematic view of the in situ load station of the present invention;
FIG. 6 is a schematic view of a base of the present invention;
FIG. 7 is a schematic view of the chuck of the present invention;
FIG. 8 is a schematic view of a support stand according to the present invention;
FIG. 9 is a flow chart of an in-plane shear matrix crack test observation of the present invention;
wherein the reference numerals are: the ceramic matrix fiber bundle composite material 1, the fiber monofilaments 101, the reinforcing sheet 2, the first through hole 201, the low end portion 202, the high end portion 203, the epoxy glue 3, the pressing plate 4, the in-situ loading platform 5, the rocker 501, the gear box 502, the threaded rod 503, the left chuck 504, the first threaded hole 504a, the right chuck 505, the second threaded hole 505a, the fixing through hole 505b, the positioning through hole 505c, the base 506, the third threaded hole 506a, the second through hole 506b, the third through hole 506c, the hollowed-out structure 506d, the fourth threaded hole 506e, the fifth threaded hole 506f, the force sensor 507, the threaded head 507a, the pin 508, the bolt 509, the support frame 510, the second through hole 510a, the annular structure 510b, the support frame bolt 511, the locking bolt 512, the optical microscope 6, the stage 601, the knob 602, the computer 7, the load indicator 8 and the acoustic emission sensor 9.
Detailed Description
Embodiments of the present invention are described in further detail below with reference to the accompanying drawings.
As shown in FIG. 1, the present invention provides a sample for in-plane shear matrix cracking of a ceramic matrix fiber bundle composite, comprising: a ceramic matrix fiber bundle composite 1 and a reinforcing sheet 2. As shown in fig. 2, the reinforcing sheet 2 is a stepped flat plate; two through holes 201 are formed in the middle of the reinforcing sheet 2; the lower end portion 202 of the reinforcing sheet 2 is shorter than the upper end portion 203; as shown in fig. 3, the ceramic matrix fiber bundle composite 1 is in a shape of a thin sheet, and the axial direction of the fiber monofilament 101 in the ceramic matrix fiber bundle composite 1 is the same as the length direction of the ceramic matrix fiber bundle composite 1; the lower surface of the ceramic-based fiber bundle composite material 1 is stuck to the lower end part 202 of the reinforcing sheet 2 through a layer of epoxy resin glue 3; and coating a layer of epoxy resin glue 3 on the upper surface of the ceramic-based fiber bundle composite material 1 again and reinforcing the ceramic-based fiber bundle composite material in a mode of pressing a pressing plate 4.
As shown in FIG. 4, a test system for in-plane shear matrix crack observation of a ceramic matrix fiber bundle composite is provided, which is characterized by comprising: a home position loading station 5 (fig. 5), an optical microscope 6, a computer 7, a load indicator 8, and an acoustic emission sensor 9; the in-situ loading platform 5 comprises a rocker 501, a gear box 502, a threaded rod 503, a left chuck 504, a right chuck 505, a base 506, a force sensor 507, a pin 508, a bolt 509, a support frame 510, a support frame bolt 511 and a locking bolt 512; the base 506 is a C-shaped structure with a horizontal bottom plate and two vertically tilted ends, one end of the base 506 is provided with a third threaded hole 506a, and the other end of the base 506 is provided with a second through hole 506b at a position opposite to the third threaded hole 506 a; a plurality of third through holes 506c are formed around the second through hole 506 b; the base 506 is connected with the gear box 502 through a bolt 509, and the bolt 509 passes through a third through hole 506c on the base; the bottom of the base 506 is a hollow structure 506 d; fourth threaded holes 506e are formed in the two sides of the hollow-out structure 506 d; the top of the base 506 is provided with four fifth threaded holes 506 f; the left chuck 504 and the right chuck 505 are C-shaped structures with completely identical structures and two through holes in the centers; the ends of the left and right collets 504 and 505 each have a second threaded hole 505a, taking the right collet 505 as an example (fig. 7), and the end of the right collet 505 has a second threaded hole 505 a; two fixing through holes 505b at the upper end of the right chuck 505 are counter bores and are used for matching with the pins 508; two positioning through holes 505c at the lower end of the right clamping head 505 are common holes; a second threaded hole 505a of the right clamping head 505 is connected with the threaded rod 503 and then passes through a second through hole 506b on the base 506 to be connected with the gear box 502; the force sensor 507 is connected with the first threaded hole 504a of the left clamping head 504 and the threaded hole 506b of the base 506 through the threaded heads 507a on the force sensor 507; four pins 508 respectively penetrate through the left chuck 504, the right chuck 505 and the reinforcing sheet 2 and are used for fixing and loading the sample; the rocker 501 is connected with the gear box 502, and the gear box 502 can be driven to work through the rotation of the rocker 501, so that the right chuck 505 is driven to move horizontally; the support 510 is i-shaped (fig. 8) to reduce deformation of the base 506; two ends of the supporting frame 510 are provided with four second through holes 510 a; the support frame bolt 511 passes through the second through hole 510a and then fixes the support frame 510 and the base 506 together through the fifth threaded hole 506 f; the middle of the supporting frame 510 is provided with a circular ring structure 510 b; the ceramic matrix fiber bundle composite material 1 is arranged right below the circular ring structure 510 b; the in-situ loading platform 5 is arranged on the object stage 601 of the optical microscope 6; the objective table 601 is arranged in the hollow-out structure 506d, and the objective table and the hollow-out structure are fixed through a locking bolt 512; the optical microscope 6 is provided with a knob 602 which can control the in-plane movement of the object stage 601; the computer 7 is connected with the optical microscope 6 and is used for displaying and measuring the in-plane shear matrix cracks; the load indicator 8 is connected with the force sensor 507; the acoustic emission sensor 9 is disposed at the upper end of the left collet 504; the acoustic emission sensor 9 is connected with the computer 7 through a cable;
the left chuck 504 is made of 45# steel, and the shell of the acoustic emission sensor 9 is magnetically adsorbed on the left chuck 504;
vaseline serving as an acoustic coupling agent is coated between the acoustic emission sensor 9 and the left chuck 504, between the left chuck 504 and the pin 508, and between the pin 508 and the first through hole 201 of the reinforcing sheet 2, so that the attenuation of acoustic emission signals is reduced.
An in-situ test method for matrix crack propagation rules by adopting the sample and the device is characterized by comprising the following steps:
step 1: coating a layer of epoxy resin glue 3 on the surface of the lower end part 202 of the reinforcing sheet 2, and then adhering the lower surface of the ceramic matrix fiber bundle composite material 1 to the lower end parts 202 of the two reinforcing sheets 2;
step 2: coating a layer of epoxy resin glue 3 on the upper surface of the ceramic-based fiber bundle composite material 1, and then covering and pressing a pressing plate 4;
and step 3: starting the optical microscope 6 and the computer 7;
and 4, step 4: calibrating the scale of the optical microscope 6 using a micrometer;
and 5: after the epoxy resin glue in the sample prepared in the step 2 is solidified, placing the sample between a left chuck 504 and a right chuck 505 of the in-situ loading table 5, and then placing a pin 508 coated with Vaseline acoustic coupling agent to fix the sample and the clamp;
step 6: starting the load indicator 8, rotating the rocker 501 of the home position loading platform 5 to make the reading F =0N of the load indicator 8;
and 7: adsorbing the acoustic emission sensor 9 on the upper surface of the left cartridge 504 coated with the Vaseline acoustic coupling agent;
and 8: the position of the in-situ loading platform 5 on the object stage 601 is adjusted through the knob 602, so that the sample is positioned in the observation field of the optical microscope 6;
and step 9: adjusting the magnification and the focal length of the optical microscope 6 to obtain a proper observation visual field;
step 10: the rocker 501 of the in-situ loading table 5 is rotated to load the sample, and whether the acoustic emission signal is generated in the sample is sensed through the acoustic emission sensor 9. If an acoustic emission signal is present, the load F at this point is recorded and step 11 is performed. If no acoustic emission signal is generated, continuing loading until an acoustic emission signal appears;
step 11: and judging whether the sample fails or not. If the sample fails, executing step 20, and if the sample does not fail, continuing to execute step 12;
step 12: the stage 601 is moved by the knob 602 of the optical microscope 6 to position the observation field to the upper left corner of the specimen. Marking the scanning times n =0 of the crack columns at the moment, and marking the total length L =0mm of the cracks;
step 13: measuring the length delta L of the in-plane shear matrix crack in a visual field, and calculating the total length L = L + delta L of the crack under the load F;
step 14: moving the stage 601 downward by a knob 602 of the optical microscope 6 for 1 observation field, measuring the length Δ L of the in-plane shear matrix crack in the field of view, and calculating the total length L = L + Δ L of the crack under the load F;
step 15: it is determined whether the observation field of view reaches the lower boundary of the sample. If the lower boundary of the specimen is not reached, the process returns to step 14 until the observation field reaches the lower boundary of the specimen. If the observation field of view has reached the lower boundary then step 16 is performed;
step 16: moving the stage 601 by the knob 602 of the optical microscope 6 returns the observation field to the upper left corner of the specimen and marks the number of crack row scans n = n +1 at that time;
and step 17: the stage 601 is moved rightward by the knob 602 of the optical microscope 6 by 1 observation visual field range;
step 18: and judging whether the sample reaches the right boundary of the sample. If the observation field of view does not reach the right boundary, the process returns to step 13. If the observation field of view has reached the right boundary of the specimen, step 19 is performed;
step 19: rotating a rocker 501 of the in-situ loading table 5 to load the sample, and stopping loading when the reading F = F + Δ F of the load indicator 8;
step 20: and (4) completing an in-situ observation test of the in-plane shear matrix crack, and inputting the in-situ loading load F and the crack length L measured under the load into a computer.
Step 21: propagation of shear matrix cracks involves an increase in the number and length of matrix cracks, with shear matrix crack density being defined as the total length of shear matrix cracks per unit area. And dividing the load F by the cross section area of the sample to obtain the shear stress, dividing the shear matrix crack length L by the area of the observation area to obtain the shear matrix crack density, and drawing a change diagram of the in-plane shear stress and the matrix crack density to obtain the in-plane shear matrix crack propagation rule of the ceramic matrix fiber bundle composite material.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to those skilled in the art may occur to one skilled in the art without departing from the scope and spirit of the present invention.
Claims (10)
1. The in-plane shear matrix crack in-situ analysis device for the ceramic matrix composite is characterized in that: the in-plane shear test device comprises an in-plane shear test sample and a test system; the in-plane shear test sample comprises a ceramic-based fiber bundle composite material (1), two reinforcing sheets (2) and two press plates (4), one corner of each reinforcing sheet (2) extends outwards, the outer end of each extending part forms a concave ladder, so that the extending part of each reinforcing sheet (2) forms a high end part (203) and a low end part (202), the two reinforcing sheets (2) are oppositely arranged on the left and right sides, the extending parts of the two reinforcing sheets (2) are arranged between the two reinforcing sheets (2) in a front-back mode, the front end and the rear end of the ceramic-based fiber bundle composite material (1) are respectively arranged on the low end parts (202) of the two reinforcing sheets (2), the press plates (4) are pressed on the low end parts (202), the front end and the rear end of the ceramic-based fiber bundle composite material (1) are fixedly pressed on the extending parts of the reinforcing sheets (2), and fiber monofilaments (101) in the ceramic-based fiber bundle composite material (1) are fixedly arranged on the front and the rear of the ceramic-based fiber bundle composite material (1) The direction is extended, the lower surfaces of two ends of the ceramic-based fiber bundle composite material (1) are fixedly adhered to the lower end part (202) through epoxy resin glue (3), the upper surfaces of two ends of the ceramic-based fiber bundle composite material (1) are fixedly adhered to the pressing plate (4) through the epoxy resin glue (3), and a plurality of first through holes (201) are formed in the middle of the reinforcing sheet (2); the testing system comprises an in-situ loading platform (5), an optical microscope (6), a computer (7), a load indicator (8) and an acoustic emission sensor (9); the in-situ loading platform (5) comprises a rocker (501), a gear box (502), a threaded rod (503), a left chuck (504), a right chuck (505), a base (506), a force sensor (507), a pin (508) and a support frame (510); the base (506) is of a C-shaped structure with a horizontal bottom plate and two vertically tilted ends, the left end of the base (506) is provided with a third threaded hole (506a), and the right end of the base (506) is provided with a second through hole (506b) at a position opposite to the third threaded hole (506 a); the left chuck (504) and the right chuck (505) are of a C-shaped structure with the same structure and a fixed through hole (505b) formed in the center, the left end of the left chuck (504) is provided with a first threaded hole (504a), the right end of the right chuck (505) is provided with a second threaded hole (505a), a force sensor (507) is positioned between the left chuck (504) and the left end of a base (506), two ends of the force sensor (507) are respectively and fixedly connected with a third threaded hole (506a) and the first threaded hole (504a) of the left chuck (504) through threaded heads (507a), the gear box (502) is fixed on the right side of the right end of the base (506), a threaded rod (503) penetrates through a second through hole (506b), the left end of the threaded rod (503) is hinged with the second threaded hole (505a) of the right chuck (505), the right end is in transmission connection with the gear box (502), and threads are arranged in the second through hole (506b), the threaded rod (503) can rotate in the second through hole (506b) so as to drive the right chuck (505) to move left and right together, the rocker (501) is connected with the gear box (502), when the rocker (501) is rocked, the gear box (502) can drive the threaded rod (503) to rotate, the two reinforcing sheets (2) can be respectively placed into the C-shaped openings of the left chuck (504) and the right chuck (505), meanwhile, the fixing through hole (505b) is aligned with the first through hole (201), the pin (508) penetrates through the fixing through hole (505b) and the first through hole (201) simultaneously to fixedly connect the two reinforcing sheets (2) with the left chuck (504) and the right chuck (505) respectively, two ends of the supporting frame (510) are respectively and detachably fixed at the left end and the right end of the base (506), the in-situ loading platform (5) is arranged on an object stage (601) of the optical microscope (6); the optical microscope (6) is provided with a knob (602) for controlling the in-plane movement of the object stage (601), so that the optical microscope (6) is opposite to the part which is not fixed by the reinforcing sheet (2) in the middle of the reinforcing sheet (2), and the computer (7) is connected with the optical microscope (6) and is used for displaying and measuring the in-plane shear matrix cracks; the load indicator (8) is connected with the force sensor (507); the acoustic emission sensor (9) is arranged at the upper end of the left chuck (504); and the acoustic emission sensor (9) is connected with the computer (7) through a cable.
2. The in-plane shear matrix crack in-situ analysis device for the ceramic matrix composite according to claim 1, wherein: the ceramic matrix fiber bundle composite material (1) is of a sheet-shaped structure.
3. The in-plane shear matrix crack in-situ analysis device of the ceramic matrix composite according to claim 2, wherein: a plurality of third through holes (506c) are formed around the second through hole (506 b); the base (506) is connected with the gear box (502) through a third through hole (506c) by a bolt (509).
4. The in-plane shear matrix crack in-situ analysis device for the ceramic matrix composite of claim 3, wherein: the bottom of the base (506) is a hollow structure (506 d); fourth threaded holes (506e) are formed in two sides of the hollow structure (506 d); the object stage (601) is arranged in the hollow-out structure (506d), and the object stage (601) and the base (506) are fixed with each other through the locking bolt (512) penetrating through the fourth threaded hole (506 e).
5. The in-plane shear matrix crack in-situ analysis device for the ceramic matrix composite according to claim 4, wherein: the top of the left end and the right end of the base (506) are respectively provided with two fifth threaded holes (506f), the left end and the right end of the support frame (510) are respectively provided with two second through holes (510a), and a support frame bolt (511) penetrates through the fifth threaded holes (506f) and the second through holes (510a) to fix the support frame (510) on the base (506).
6. The in-plane shear matrix crack in-situ analysis device for the ceramic matrix composite of claim 5, wherein: the middle part of support frame (510) be provided with ring structure (510b), be ceramic matrix fiber bundle composite (1) under ring structure (510b), optical microscope (6) can fix on ring structure (510 b).
7. The in-plane shear matrix crack in-situ analysis device of the ceramic matrix composite of claim 6, wherein: the fixed through hole (505b) is arranged at the upper ends of the left chuck (504) and the right chuck (505), the lower ends of the left chuck (504) and the right chuck (505) are provided with a positioning through hole (505c) aligned with the fixed through hole (505b), the lower end of the pin (508) penetrates through the fixed through hole (505b) and the first through hole (201) in sequence and then is limited in the positioning through hole (505c), and the upper end of the pin (508) is positioned at the upper part of the fixed through hole (505 b).
8. The in-plane shear matrix crack in-situ analysis device of the ceramic matrix composite of claim 7, wherein: the left chuck (504) is made of ferromagnetic materials, and the shell of the acoustic emission sensor (9) is magnetically adsorbed on the left chuck (504).
9. The in-plane shear matrix crack in-situ analysis device of the ceramic matrix composite of claim 8, wherein: vaseline serving as an acoustic coupling agent is smeared between the acoustic emission sensor (9) and the left chuck (504), between the left chuck (504) and the pin (508), and between the pin (508) and the first through hole (201) of the reinforcing sheet (2), so that the attenuation of acoustic emission signals is reduced.
10. The method for crack in-situ analysis of an in-plane shear matrix crack in-situ analysis device of ceramic matrix composites of claim 9, wherein: the method comprises the following steps:
step 1: coating a layer of epoxy resin glue (3) on the surface of the lower end part (202) of the reinforcing sheet (2), and then adhering the lower surface of the ceramic-based fiber bundle composite material (1) to the lower end parts (202) of the two reinforcing sheets (2);
step 2: coating a layer of epoxy resin glue (3) on the upper surface of the ceramic-based fiber bundle composite material (1), and then covering a pressing plate (4) and pressing tightly;
and step 3: starting the optical microscope (6) and the computer (7);
and 4, step 4: -calibrating the scale of the optical microscope (6) using a micrometer;
and 5: after the epoxy resin glue in the sample prepared in the step 2 is solidified, placing the sample between a left chuck (504) and a right chuck (505) of an in-situ loading platform (5), and then placing a pin (508) coated with Vaseline acoustic coupling agent to fix the sample;
step 6: starting the load indicator (8), and rotating a rocker (501) of the home position loading platform (5) to enable the load indicator (8) to indicate F = 0N;
and 7: adsorbing an acoustic emission sensor (9) on the upper surface of a left chuck (504) coated with Vaseline acoustic coupling agent;
and 8: the position of an in-situ loading platform (5) on the objective table (601) is adjusted through a knob (602), so that the sample is positioned in the observation field of the optical microscope (6);
and step 9: adjusting the magnification and the focal length of the optical microscope (6) to obtain a proper observation visual field;
step 10: loading the sample by rotating a rocker (501) of the in-situ loading platform (5), sensing whether an acoustic emission signal is generated in the sample by an acoustic emission sensor (9), recording the load F at the moment and executing the step 11 if the acoustic emission signal is generated; if no acoustic emission signal is generated, continuing loading until an acoustic emission signal appears;
step 11: judging whether the sample fails, if so, executing the step 20, and if not, continuing to execute the step 12;
step 12: moving the objective table (601) through a knob (602) of the optical microscope (6), positioning an observation visual field to the upper left corner of the sample, marking the scanning times n =0 of the crack column at the moment, and marking the total length L =0mm of the crack;
step 13: measuring the length delta L of the in-plane shear matrix crack in a visual field, and calculating the total length L = L + delta L of the crack under the load F;
step 14: moving the objective table (601) downwards by a knob (602) of the optical microscope (6) for 1 observation visual field, then measuring the length delta L of the in-plane shear matrix crack in the visual field, and calculating the total length L = L + delta L of the crack under the load F;
step 15: judging whether the observation visual field reaches the lower boundary of the sample, if not, returning to the step 14 until the observation visual field reaches the lower boundary of the sample, and if so, executing the step 16;
step 16: moving the stage (601) by a knob (602) of the optical microscope (6) to return the observation field to the upper left corner of the sample and mark the number of crack column scans n = n +1 at that time;
and step 17: moving the object stage (601) by a knob (602) of the optical microscope (6) to move 1 observation visual field range to the right;
step 18: judging whether the sample reaches the right boundary of the sample, if the observation visual field does not reach the right boundary, returning to execute the step 13, and if the observation visual field reaches the right boundary of the sample, executing the step 19;
step 19: rotating a rocker (501) of the home position loading platform (5) to load the sample, and stopping loading when the reading F = F + delta F of the load indicator (8);
step 20: completing an in-situ observation test of the in-plane shear matrix crack, and inputting an in-situ loading load F and the crack length L measured under the load into a computer;
step 21: the expansion of the shear matrix crack comprises the increase of the number and the length of the matrix crack, the density of the shear matrix crack is defined according to the total length of the shear matrix crack in a unit area, the shear stress is obtained by dividing the load F by the cross section area of the sample, the density of the shear matrix crack is obtained by dividing the length L of the shear matrix crack by the area of the observation area, and a change diagram of the in-plane shear stress and the density of the matrix crack is drawn to obtain the expansion rule of the in-plane shear matrix crack of the ceramic matrix fiber bundle composite material.
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