CN114878315A - Dynamic tensile test method for fiber bundle SHTB - Google Patents

Dynamic tensile test method for fiber bundle SHTB Download PDF

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Publication number
CN114878315A
CN114878315A CN202210297583.3A CN202210297583A CN114878315A CN 114878315 A CN114878315 A CN 114878315A CN 202210297583 A CN202210297583 A CN 202210297583A CN 114878315 A CN114878315 A CN 114878315A
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fiber bundle
test piece
shtb
reinforcing sheet
groove
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张大伟
洪嘉鑫
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Zhejiang University ZJU
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Zhejiang University ZJU
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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
    • G01N3/02—Details
    • G01N3/04—Chucks
    • 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
    • G01N3/02—Details
    • 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
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0016—Tensile or compressive
    • G01N2203/0017—Tensile
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0075—Strain-stress relations or elastic constants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/04—Chucks, fixtures, jaws, holders or anvils

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
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  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
  • Sampling And Sample Adjustment (AREA)

Abstract

The invention discloses a dynamic tensile test method for a fiber bundle SHTB, which adopts a fiber bundle test piece manufacturing device and a fiber bundle test piece clamping device. According to the invention, a fiber bundle test piece prefabricating process is adopted, so that the situation that the fiber bundle is temporarily clamped on site directly to reduce the test efficiency is avoided, through a sandwich structure formed among the first reinforcing sheet, the fiber bundle and the second reinforcing sheet, on one hand, the reinforcing sheet is utilized to bear fastening force from the outside to clamp the fiber bundle, on the other hand, the fiber bundle can be prevented from being damaged in the fastening process, and the contact area and the roughness of the interface between the fiber bundle and the reinforcing sheet are increased in a mode that the reinforcing sheet is coated with fiber impregnating glue, so that the bonding performance between the fiber bundle and the reinforcing sheet is further improved.

Description

Dynamic tensile test method for fiber bundle SHTB
Technical Field
The invention relates to the technical field of dry fiber material dynamic mechanics, in particular to a fiber bundle SHTB dynamic tensile test method.
Background
The Fiber material has the advantages of light weight, high strength, corrosion resistance and the like, and by means of the excellent characteristics of the Fiber material, the Fiber Reinforced Polymer (FRP) and the Fiber fabric Reinforced cement-based composite material (FRCM) are prepared by the Fiber material and an organic cementing material or an inorganic cement-based cementing material, and can be applied to newly building a full FRP/FRCM structure or an FRP/FRCM combined structure, or applied to repairing and reinforcing an existing structure as a reinforcing material. The existing research points out that when a building structure faces risks of extreme effects such as explosion, impact and the like, the impact resistance of the structure can be effectively improved by adopting the FRP/FRCM composite material. The dynamic mechanical property of the FRP/FRCM composite material under the action of impact load is closely related to the dynamic mechanical property of fiber bundles in the FRP/FRCM. Therefore, the research on the dynamic mechanical property, the evolution rule and the damage appearance of the fiber bundle material under the action of impact load is developed, and the research and the application of the FRP/FRCM composite material under the action of extreme load in building engineering are further promoted.
At present, the dynamic mechanical properties of materials are tested by mainly using a high-speed hydraulic servo testing machine, a drop hammer testing machine, a split Hopkinson bar and other devices. Among them, the Split Hopkinson tension Bar (SHTB for short) is the most important and reliable experimental method for studying the dynamic tensile mechanical properties of materials at high strain rates. The SHTB technology is established on the assumption of one-dimensional stress waves and the assumption of stress uniformity of a test piece, and comprises a gun barrel, an impact rod (commonly called a bullet), an incident rod, a transmission rod, an energy absorber, a corresponding air pressure device and the like, stress wave signals are acquired through strain gauges attached to the incident rod and the transmission rod through a super dynamic strain gauge and a high-speed acquisition system, and the stress-strain relation of the test piece is finally obtained on the basis of the one-dimensional stress wave propagation theory.
Generally, the test pieces for the SHTB test are generally cylindrical and lamellar. The cylindrical test piece is typically attached to the SHTB using threads or glue. The thread method is to process the test piece into a dumbbell-shaped revolving body, process external threads matched with the internal threads of the incident rod and the transmission rod at two ends, and connect the test piece with the SHTB through threads. However, for materials such as rock and concrete, the two ends of the test piece are not easy to be processed into external threads, and then the test piece is adhered to the switching clamp by using the switching clamp, and then the switching clamp is connected with the SHTB through the threads. Some test materials cannot be processed into cylindrical test pieces with the diameter meeting the requirements due to insufficient thickness, and only can be processed into sheet-shaped test pieces, and the sheet-shaped test pieces are usually connected with the SHTB by means of a switching clamp.
For the fiber material, the test piece has small diameter and soft material, so that the fiber material cannot be connected with the SHTB according to the traditional connection method of cylindrical and flaky test pieces, and the related technical standards and specifications are lacked, so that the dynamic tensile mechanical property test of the fiber material is difficult to develop. Currently, fibrous materials are often tested with an adapter fixture that is otherwise designed. Patent CN202011366933.4 discloses a clamp for a real-time fastening fiber bundle dynamic tensile test and a clamping method thereof, wherein a fiber bundle test piece is engaged with two fastening blocks with tooth-shaped surfaces to form a whole, a conical limiting shell is sleeved into the engaged whole, and a limiting block is inserted into the conical limiting shell to abut against the engaged whole, so as to complete clamping of the fiber bundle test piece. The patent CN 202011354348.2 discloses a fiber bundle dynamic tensile test fixture and an experimental use method thereof, wherein a fiber bundle test piece is placed in a fan-shaped elongated slot in a cylindrical fixture main body, a fastening block filling the fan-shaped elongated slot is placed in the cylindrical fixture main body, the two are engaged with each other to form a whole, and then a cylindrical fastening shell is sleeved in the engaged whole, so that the fastening block compresses the fiber bundle test piece. Patent CN 202110917308.2 discloses a split type clamp for hopkinson pull rod test, which is to place a metal wire test piece into two protection pieces to form a sandwich structure, the structure is clamped by two wedge-shaped clamping blocks, a sleeve with a wedge-shaped groove is sleeved in the sleeve, and then the sleeve is sleeved in a mandril, so that the mandril is connected with the wedge-shaped clamping blocks in a jacking manner, thereby realizing the stable clamping of the metal wire test piece.
The three patents adopt the switching clamp to realize the connection of the fiber material and the SHTB, the switching clamp comprises various different parts, the shape is complex, and the processing difficulty of the clamp is high and the manufacturing cost is high. Meanwhile, as the number of the parts of the switching clamp is large, the clamping step of the fiber bundle test piece is complicated during the test, and the clamping effect and precision can be inevitably influenced. In addition, each test needs to unscrew the switching clamp from the SHTB, complete clamping of the fiber bundle test piece and then assemble the fiber bundle test piece, so that on one hand, the test efficiency is reduced, and on the other hand, the fiber bundle test piece may generate twisting effect due to rotation of two ends, so that the appearance of the fiber bundle is changed, and the real dynamic tensile mechanical property of the fiber material cannot be reflected.
Disclosure of Invention
The invention provides a fiber bundle SHTB dynamic tensile test method, which can meet the fastening requirement of a fiber bundle test piece in an SHTB test through a clamp main body and a clamp pressing block to ensure the reliability and accuracy of a test result, and has the advantages of simple structure, quickness in assembly, reusability and batch manufacturing of the test piece.
A dynamic tensile test method of a fiber bundle SHTB adopts a fiber bundle test piece manufacturing device and a fiber bundle test piece clamping device;
the fiber bundle test piece manufacturing device comprises a fiber bundle test piece lower die and a fiber bundle test piece upper die which can be matched and clamped with each other; a plurality of first grooves for placing first reinforcing sheets are formed in the lower die of the fiber bundle test piece; a plurality of grooves II for placing second reinforcing sheets are formed in the upper die of the fiber bundle test piece;
the fiber bundle test piece clamping device comprises a clamp main body and a clamp pressing block which can be matched with each other to clamp; grooves for placing the reinforcing sheets are formed in the clamp main body and the clamp pressing block;
the method for testing the SHTB dynamic tensile test of the fiber bundle comprises the following steps:
s1, placing lower dies of the fiber bundle test pieces at two ends according to the gauge length required by the SHTB test of the fiber bundles, and placing a first reinforcing sheet in the first groove;
s2, uniformly coating fiber impregnating adhesive on the surfaces, which are used for being in contact with the fiber bundles, of the first reinforcing sheets, drawing the fiber bundles to be centered and horizontally placed on the central lines of the first reinforcing sheets on the two sides, uniformly coating the fiber impregnating adhesive on the contact surfaces of the first reinforcing sheets and the fiber bundles again, and fully infiltrating the fiber impregnating adhesive in the fiber bundles;
s3, placing a second reinforcing sheet on the first reinforcing sheet in an aligned mode according to the surface, in contact with the fiber bundle, of the second reinforcing sheet, then aligning the second groove with the second reinforcing sheet, placing an upper die of the fiber bundle test piece on a lower die of the fiber bundle test piece, and clamping the upper die of the fiber bundle test piece and the lower die of the fiber bundle test piece together;
s4, curing until the fiber impregnating adhesive is cured, demolding, and cutting the exposed end of the fiber bundle to obtain a fiber bundle test piece for the SHTB test, wherein both sides of the fiber bundle test piece are cured and clamped with the first reinforcing sheet and the second reinforcing sheet together to form a whole;
s5, fixedly connecting an incident rod and a projection rod of the SHTB with one end of the clamp body respectively;
s6, adjusting an incident rod and a projection rod of the SHTB provided with the clamp main body to keep the surface of one side of the clamp main body, which is provided with the groove III, on the same horizontal plane;
s7, placing the reinforcing sheet of the fiber bundle test piece for the SHTB test into the third groove, aligning the fourth groove of the clamp pressing block with the reinforcing sheet of the fiber bundle test piece for the SHTB test, and placing the clamp pressing block on the clamp main body to form firm clamping among the clamp pressing block, the fiber bundle test piece for the SHTB test and the clamp main body;
and S8, carrying out a dynamic tensile test of the fiber bundle SHTB.
According to the invention, a fiber bundle test piece prefabricating process is adopted, so that the situation that the fiber bundle is temporarily clamped on site directly to reduce the test efficiency is avoided, through a sandwich structure formed among the first reinforcing sheet, the fiber bundle and the second reinforcing sheet, on one hand, the reinforcing sheet is utilized to bear fastening force from the outside to clamp the fiber bundle, on the other hand, the fiber bundle can be prevented from being damaged in the fastening process, and the contact area and the roughness of the interface between the fiber bundle and the reinforcing sheet are increased in a mode that the reinforcing sheet is coated with fiber impregnating glue, so that the bonding performance between the fiber bundle and the reinforcing sheet is further improved.
In a preferred embodiment, the surfaces of the first reinforcing sheet and the second reinforcing sheet which are used for contacting with the grooves, and the bottom surfaces of the first groove, the second groove, the third groove and the fourth groove are mutually engaged sawtooth surfaces.
In a preferred embodiment, the tooth form angle of the sawtooth surface is 42-46 degrees, and the tooth height is 0.2-0.5 mm.
In a preferred embodiment, a first platform higher than a bottom surface of the groove is arranged at two ends of the groove close to the edge of the lower die of the fiber bundle test piece, and a surface of the first platform is lower than the surface of the lower die of the fiber bundle test piece.
In a preferred embodiment, two ends of the second groove are provided with a second platform which is corresponding to the first platform and is higher than the bottom surface of the second groove near the edge of the upper die of the fiber bundle test piece, and the surface of the second platform is lower than the surface of the upper die of the fiber bundle test piece; the space formed by the first platform and the second platform can provide a penetrating movable space for the fiber bundle.
In a preferred embodiment, the clamp main body comprises a threaded connecting piece and a connecting block which is fixedly connected with the threaded connecting piece through a bearing block and used for placing a clamp pressing block; the threaded connector is positioned at the end part of the clamp main body and is used for being fixedly connected with an incident rod or a projection rod of the SHTB; the third groove is formed in the connecting block, a third platform higher than the third bottom surface of the third groove is arranged at the edge, close to the connecting block, of one end, far away from the bearing block, of the third groove, and the third surface of the third platform is lower than the surface of the connecting block.
In a preferred embodiment, one end of the four grooves close to the edge of the clamp pressing block is provided with a platform four which is corresponding to the platform three and is higher than the bottom surface of the four grooves, and the surface of the platform four is lower than the surface of the clamp pressing block; the space formed by the third platform and the fourth platform can provide a penetrating movable space for the fiber bundle.
In a preferred example, the central axis of the surface of one side of the connecting block with the groove III, the central axis of the bearing block and the central axis of the threaded connector are aligned with the central axis of the SHTB.
In a preferred embodiment, the lower die of the fiber bundle test piece is provided with a positioning rod, and the upper die of the fiber bundle test piece is provided with a positioning hole which can be matched with the positioning rod.
In a preferred example, the clamping pressing block, the fiber bundle test piece for the SHTB test and the clamp main body are clamped by fastening bolts between the upper die and the lower die of the fiber bundle test piece.
Compared with the prior art, the invention has the main advantages that:
1. the invention realizes the prefabrication of the fiber bundle test piece for the SHTB test, avoids the direct temporary clamping of the fiber bundle on the site to reduce the test efficiency and saves the time cost in the test process.
2. The invention adopts the fiber bundle test piece prefabricating process, utilizes the lower fiber bundle test piece die, the upper fiber bundle test piece die, the first reinforcing sheet and the second reinforcing sheet, and has the advantages of simple process, convenient disassembly, assembly line work, batch manufacture and regular and uniform overall shape and size of the test piece.
3. According to the invention, through the sandwich structure formed among the first reinforcing sheet, the fiber bundle and the second reinforcing sheet, on one hand, the reinforcing sheet is utilized to bear fastening force from the outside so as to clamp the fiber bundle, and on the other hand, damage to the fiber bundle in the fastening process can be avoided.
4. According to the invention, the contact area and the roughness of the interface between the fiber bundle and the reinforcing sheet are increased by coating the reinforcing sheet with the fiber dipping glue, and the bonding performance between the fiber bundle and the reinforcing sheet is further improved.
5. The clamping device adopts an assembly design, each part of the clamping device is an independent device, and when any part in the clamping device is damaged, the damaged part can be replaced without discarding other devices fixedly connected with the damaged part, so that the economic cost in the test process is saved.
6. The clamping device has the advantages of fewer components, simple shape, convenience in processing, low manufacturing cost and convenience in installation, clamping steps of the fiber bundle test piece are simple and convenient during testing, the fastening requirement of the fiber bundle test piece in an SHTB test is met through the clamp main body and the clamp pressing block, the first heavy clamping fastening is realized, and the reliability and the accuracy of a test result are ensured.
7. The toothed surfaces which are meshed with each other are arranged on the contact surfaces of the reinforcing sheet and the groove, so that the contact area and the roughness of the reinforcing sheet and the groove of the clamping device are increased, the reinforcing sheet and the fiber bundle are solidified and clamped to form an integral fiber bundle test piece after the clamping device is clamped, the sliding is avoided, the dual fastening effect is realized, the specifications of the reinforcing sheet and the groove are unified, the coaxiality of the fiber bundle test piece, the clamping device and the SHTB is further ensured after the fastening force is applied, and the precision and the accuracy of the test are ensured.
8. The invention meets the instantaneity of the clamping device, and the test can be carried out after clamping and fastening the fiber bundle test piece, thereby improving the test efficiency.
9. The invention can realize that the strain rate of a fiber bundle test piece on the SHTB is 100s -1 -1000s -1 Dynamic tensile mechanical properties under conditionsCan be tested.
Drawings
FIG. 1 is a diagram of the assembled fiber bundle test piece manufacturing apparatus;
FIG. 2 is a schematic structural view of each component in the fiber bundle test piece manufacturing device;
FIG. 3 is a side view of a lower die shaft of a fiber bundle test piece;
FIG. 4 is a side view of a mold shaft on a fiber bundle test piece;
FIG. 5 is an axial side view of the first reinforcing sheet;
FIG. 6 is an axial side view of a second reinforcing sheet;
FIG. 7 is a side view of the shaft of a fiber bundle specimen;
FIG. 8 is a block diagram of the assembled fiber bundle specimen holding device;
FIG. 9 is a schematic structural view of each component of the fiber bundle specimen clamping device;
FIG. 10 is a side view of the clamp body shaft;
FIG. 11 is a side view of the clamp press block shaft;
reference numerals:
1. a fiber bundle test piece lower die; 1-1, a first groove; 1-1-1, a sawtooth surface I; 1-2, a first platform; 1-3, a positioning rod; 1-4, bolt hole I;
2. a fiber bundle test piece upper die; 2-1, a second groove; 2-1-1 and a sawtooth surface II; 2-2, a second platform; 2-3, positioning holes; 2-4, bolt hole II;
3. a first reinforcing sheet; 3-1, a sawtooth surface III;
4. a second reinforcing sheet; 4-1, saw-tooth surface four;
5. a fiber bundle;
6. a clamp body; 6-1, a threaded connector; 6-2, a bearing block; 6-3, connecting blocks; 6-3-1 and a third groove; 6-3-1-1, saw-tooth surface five; 6-3-2 and a third platform; 6-3-3, bolt hole III;
7. pressing a block by the clamp; 7-1, and a groove IV; 7-1-1 and six sawtooth surfaces; 7-2, and a platform IV; 7-3, bolt hole four;
8. and fastening the bolt.
Detailed Description
The invention is further described with reference to the following drawings and specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The following examples are conducted under conditions not specified, usually according to conventional conditions, or according to conditions recommended by the manufacturer.
As shown in fig. 1 to 7, the device for manufacturing a fiber bundle test piece includes a fiber bundle test piece lower mold 1, a fiber bundle test piece upper mold 2, a first reinforcing sheet 3, a second reinforcing sheet 4, and a fiber bundle 5.
The lower die 1 of the fiber bundle test piece comprises a plurality of grooves I1-1 which are identical in shape and size and are arranged in parallel, a platform I1-2, positioning rods 1-3 and bolt holes I1-4. The bottom surface of the first groove 1-1 is provided with a sawtooth surface 1-1-1, the length of the long side of the first groove 1-1 is smaller than the width of the lower die 1 of the fiber bundle test piece, and the short side of the first groove 1-1 and the outer surface of the lower die 1 of the fiber bundle test piece are provided with a first platform 1-2. The surface of the first platform 1-2 is 0.5mm lower than the surface of the lower die 1 of the fiber bundle test piece. The positioning rods 1-3 are symmetrically arranged at two ends of the lower die 1 of the fiber bundle test piece. The first bolt holes 1-4 are symmetrically arranged at four corners of the lower die 1 of the fiber bundle test piece, and when the first grooves 1-1 arranged on the lower die 1 of the fiber bundle test piece are more, in order to prevent the lower die 1 of the fiber bundle test piece from being deformed due to overlong length, a pair of first bolt holes 1-4 can be additionally arranged in the middle of the lower die 1 of the fiber bundle test piece.
The upper die 2 of the fiber bundle test piece comprises a plurality of grooves II 2-1, platforms II 2-2, positioning holes 2-3 and bolt holes II 2-4 which are identical in shape and size and are arranged in parallel. The bottom surface of the second groove 2-1 is provided with a sawtooth surface 2-1-1, the length of the long side of the second groove 2-1 is smaller than the width of the upper die 2 of the fiber bundle test piece, and the short side of the second groove 2-1 and the outer surface of the upper die 2 of the fiber bundle test piece are provided with a second platform 2-2. The surface of the second platform 2-2 is 0.5mm lower than the surface of the die 2 on the fiber bundle test piece. The positioning holes 2-3 are symmetrically arranged at two ends of the mould 2 on the fiber bundle test piece. The bolt holes II 2-4 are symmetrically arranged at four corners of the fiber bundle test piece upper die 2, and when the number of the grooves II 2-1 arranged on the fiber bundle test piece upper die 2 is large, in order to prevent the fiber bundle test piece upper die 2 from being deformed due to overlong length, a pair of bolt holes II 2-4 can be additionally arranged in the middle of the fiber bundle test piece upper die 2.
The structural size of the upper die 2 of the fiber bundle test piece is the same as that of the lower die 1 of the fiber bundle test piece, the structural sizes of the groove II 2-1 and the platform II 2-2 of the upper die 2 of the fiber bundle test piece are the same as those of the groove I1-1 and the platform I1-2 of the lower die 1 of the fiber bundle test piece, and the positions of the groove II 2-1, the platform II 2-2, the positioning hole 2-3 and the bolt hole II 2-4 of the upper die 2 of the fiber bundle test piece are matched with those of the groove I1-1, the platform I1-2, the positioning rod 1-3 and the bolt hole I1-4 of the lower die 1 of the fiber bundle test piece.
The space formed by the first platform 1-2 and the second platform 2-2 can provide a penetrating movable space for the fiber bundle 5, and the fiber bundle 5 is prevented from being extruded to generate shearing damage after the lower die 1 of the fiber bundle test piece and the upper die 2 of the fiber bundle test piece are clamped together through the fastening bolt 8.
The number of the first grooves 1-1 in the lower die 1 of the fiber bundle test piece and the number of the second grooves 2-1 in the upper die 2 of the fiber bundle test piece are 3-6, the distance is 15-20 mm, a plurality of fiber bundles can be manufactured simultaneously to meet the requirement of batch production, a proper operation space is provided for manufacturing, and the length of the lower die 1 of the fiber bundle test piece and the length of the upper die 2 of the fiber bundle test piece are not too long to deform.
One side of the first reinforcing sheet 3, which is contacted with the first groove 1-1, is provided with a sawtooth surface three 3-1, and the sawtooth surface three 3-1 of the first reinforcing sheet 3 is meshed with the sawtooth surface one 1-1-1 of the first groove 1-1. One side of the second reinforcing sheet 4, which is in contact with the groove II 2-1, is provided with a sawtooth surface IV 4-1, and the sawtooth surface IV 4-1 of the second reinforcing sheet 4 is meshed with the sawtooth surface II 2-1-1 of the groove II 2-1.
The structural dimensions of the first reinforcing sheet 3 and the second reinforcing sheet 4 are the same as those of the first groove 1-1 of the lower die 1 of the fiber bundle test piece and those of the second groove 2-1 of the upper die 2 of the fiber bundle test piece, so that the positions of the first reinforcing sheet 3 and the second reinforcing sheet 4 are matched with each other when the die is supported, laid and assembled, and the overall shapes formed by the reinforcing sheets and the fiber bundles through curing and clamping are regular and uniform in size.
The first reinforcing sheet 3, the fiber bundle 5 and the second reinforcing sheet 4 form a sandwich structure. The reinforcing sheet can not only bear the fastening force from the external mold to clamp the fiber bundle, but also avoid damage to the fiber bundle during the fastening process.
The first reinforcing sheet 3 and the second reinforcing sheet 4 may be made of a metal material such as aluminum or a non-metal material such as acryl.
The contact surfaces of the first reinforcing sheet 3 and the second reinforcing sheet 4 with the fiber bundles 5 are coated with fiber-impregnated glue (e.g., epoxy-impregnated glue). The contact area and the roughness of the interface between the fiber bundle and the reinforcing sheet are increased by coating the fiber impregnated glue on the contact surface between the reinforcing sheet and the fiber bundle, and the bonding performance between the fiber bundle and the reinforcing sheet is further improved.
The tooth form angle of the first sawtooth surface 1-1-1, the second sawtooth surface 2-1-1, the third sawtooth surface 3-1 and the fourth sawtooth surface 4-1 is 42 degrees to 46 degrees, and the tooth height is 0.2mm to 0.5 mm. The mode that sets up the sawtooth surface in the contact surface department of reinforcing piece and mould recess increases the area of contact and the roughness of reinforcing piece and mould recess, guarantees that the inside reinforcing piece can not appear sliding after the mould presss from both sides tightly about, makes reinforcing piece and tow can closely bond, further ensures to be unified by reinforcing piece and tow solidification clamp whole shape rule size of forming.
The material of the fiber bundle material includes, but is not limited to, alkali-resistant glass fiber, carbon fiber, aramid fiber, basalt fiber, polyphenylene benzobisoxazole fiber, and natural fiber such as sisal, ramie, etc.
The specific manufacturing process flow of the fiber bundle test piece for the SHTB test is as follows:
1) and (3) formwork support:
according to a gauge length required by a fiber bundle SHTB test, symmetrically placing fiber bundle test piece lower dies 1 at two ends, placing a first reinforcing sheet 3 in a groove I1-1 of the fiber bundle test piece lower die, and mutually meshing a sawtooth surface III 3-1 of the first reinforcing sheet 3 and a sawtooth surface I1-1-1 of the groove I1-1;
2) laying:
uniformly coating fiber impregnating glue on the contact surfaces of the first reinforcing sheets 3 and the fiber bundles 5, tensioning and centering the fiber bundles 5, flatly placing the fiber bundles on the central lines of the first reinforcing sheets 3 at two sides, and uniformly coating the fiber impregnating glue on the contact surfaces of the first reinforcing sheets 3 and the fiber bundles 5 again to fully infiltrate the fiber impregnating glue into the fiber bundles 5. Because the contact surface of the reinforcing sheet and the fiber bundle is coated with the fiber impregnating adhesive, the contact area and the roughness of the interface of the fiber bundle and the reinforcing sheet are increased, and the bonding performance between the fiber bundle and the reinforcing sheet is further improved. In order to ensure that the fiber bundle is not loosened due to retraction in the process of manufacturing the fiber bundle test piece, so that the actual gauge length does not meet the gauge length required by the test, the exposed ends at the two sides of the fiber bundle can be hung with heavy objects and the like, and the flatness of the fiber bundle and the coaxiality of the fiber bundle and a reinforcing sheet are ensured;
3) assembling:
the one side of contacting with second reinforcing sheet 4 and tow 5 aligns and places on first reinforcing sheet 3, makes and forms sandwich structure between first reinforcing sheet 3, tow 5, the 4 three of second reinforcing sheet, and the reinforcing sheet not only can undertake the fastening force that comes from outside mould in order to press from both sides tight tow, can avoid again simultaneously causing the damage to the tow in fastening process. Then, a groove II 2-1 of the upper die 2 of the fiber bundle test piece is aligned with a second reinforcing sheet 4, the upper die 2 of the fiber bundle test piece is placed on the lower die 1 of the fiber bundle test piece along a positioning rod 1-3 of the lower die 1 of the fiber bundle test piece through a positioning hole 2-3, a serrated surface IV 4-1 of the second reinforcing sheet 4 is meshed with a serrated surface II 2-1-1 of the groove II 2-1, a fastening bolt 8 penetrates through bolt holes II 2-4 and bolt holes I1-4 of the upper die 2 of the fiber bundle test piece and the lower die 1 of the fiber bundle test piece, and the upper die 2 of the fiber bundle test piece and the lower die 1 of the fiber bundle test piece are clamped together by applying a fastening force. The sawtooth surface is arranged on the contact surface of the reinforcing sheet and the die groove, so that the contact area and the roughness of the reinforcing sheet and the die groove are increased, the inner reinforcing sheet clamped by the upper die and the lower die cannot slide, the reinforcing sheet and the fiber bundle can be tightly bonded, the regular size of the integral shape formed by the reinforcing sheet and the fiber bundle through curing and clamping is further ensured to be uniform, and the coaxiality of the fiber bundle and the reinforcing sheet is further ensured after the fastening force is applied;
4) maintaining and removing the mold:
and curing at a certain temperature and humidity until the fiber impregnating adhesive is cured, removing the fastening bolt 8, taking down the upper fiber bundle test piece mold 2, taking out the fiber bundle 5 with two sides cured and clamped together with the first reinforcing sheet 3 and the second reinforcing sheet 4 into a whole from the lower fiber bundle test piece mold 1, and shearing the exposed ends of the two sides of the fiber bundle 5 to obtain the fiber bundle test piece for the SHTB test.
As shown in fig. 8 to 11, the fiber bundle test piece clamping device includes a clamp main body 6, a clamp press block 7, and a fastening bolt 8, where the clamp main body 6 includes a threaded connector 6-1 (specifically, an external thread in this embodiment), a receiving block 6-2, and a connecting block 6-3, and the clamp press block 7 corresponds to the connecting block 6-3 of the clamp main body 6.
The external thread 6-1 of the clamp body 6 is used to connect with the internal thread of the incident rod or the projection rod of the SHTB, and the central axis of the external thread 6-1 of the clamp body 6 is aligned with the central axis of the SHTB. One end of the bearing block 6-2 of the clamp body 6 bears the external thread 6-1 of the clamp body 6, and the other end bears the connecting block 6-3 of the clamp body 6. The height of the receiving block 6-2 of the jig main body 6 is the same as the diameter of the external thread 6-1 of the jig main body 6, and the central axis of the receiving block 6-2 of the jig main body 6 is aligned with the central axis of the external thread 6-1 of the jig main body 6. The connecting block 6-3 of the clamp body 6 comprises a groove III 6-3-1, a platform III 6-3-2 and a bolt hole III 6-3-3, the height of the connecting block 6-3 of the clamp body 6 is half of the height of the bearing block 6-2 of the clamp body 6, and the central axis of the surface of one side, provided with the groove, of the connecting block 6-3 of the clamp body 6 is aligned with the central axis of the external thread 6-1 of the clamp body 6. The bottom surface of the groove III 6-3-1 is provided with a sawtooth surface V6-3-1-1, the sawtooth surface V6-3-1-1 of the groove III 6-3-1 is meshed with the sawtooth surface III 3-1 of the first reinforcing sheet 3, the length of the long side of the groove III 6-3-1 is smaller than the width of the connecting block 6-3 of the clamp body 6, one side of the short side of the groove III 6-3-1 is flush with the surface of the bearing block 6-2 of the clamp body 6, and the other side of the short side of the groove III 6-3-1 and the outer surface of the connecting block 6-3 of the clamp body 6 are provided with a platform III 6-3-2. The surface of the platform III 6-3-2 is 0.5mm lower than the surface of the connecting block 6-3 of the clamp body 6. The bolt holes III 6-3-3 are symmetrically arranged at two ends of the connecting block 6-3 of the clamp body 6, which are parallel to the central axis.
The clamp pressing block 7 comprises a groove four 7-1, a platform four 7-2 and a bolt hole four 7-3. The bottom surface of the groove IV 7-1 is provided with a sawtooth surface VI 7-1-1, the sawtooth surface VI 7-1-1 of the groove IV 7-1 is meshed with the sawtooth surface IV 4-1 of the second reinforcing sheet 4, the length of the long side of the groove IV 7-1 is smaller than the width of the clamp pressing block 7, one side of the short side of the groove IV 7-1 is flush with the surface of the clamp pressing block 7, and the other side of the short side of the groove IV 7-1 and the outer surface of the clamp pressing block 7 are provided with a platform IV 7-2. The surface of the platform four 7-2 is 0.5mm lower than the surface of the clamp pressing block 7. And the four bolt holes 7-3 are symmetrically arranged at two ends of the clamp pressing block 7 parallel to the central axis.
The structural size of the clamp pressing block 7 is the same as that of the connecting block 6-3 of the clamp main body 6, the structural sizes of the groove four 7-1 and the platform four 7-2 of the clamp pressing block 7 are the same as those of the groove three 6-3-1 and the platform three 6-3-2 of the connecting block 6-3 of the clamp main body 6, the positions of the groove four 7-1, the platform four 7-2 and the bolt hole four 7-3 of the clamp pressing block 7 are matched with those of the groove three 6-3-1, the platform three 6-3-2 and the bolt hole three 6-3-3 of the connecting block 6-3 of the clamp main body 6, and the structural sizes of the groove four 7-1 of the clamp pressing block 7 are matched with those of the first reinforcing sheet 3, the groove three 6-3-1 of the connecting block 6-3 of the clamp main body 6 and the first reinforcing sheet 3, The second reinforcing plate 4 has the same structural size, so that the reinforcing plate and the fiber bundle are solidified and clamped to form an integral fiber bundle test piece in the test, the clamp main body 6 and the clamp pressing block 7 are matched with each other, the fiber bundle test piece can form a clamping through the connecting block 6-3 of the clamp main body 6 and the clamp pressing block 7 through the fastening bolt 8, the first clamping and fastening are realized, the coaxiality of the fiber bundle test piece, the clamping device and the SHTB is ensured, and the test precision and accuracy are ensured.
The space formed by the third platform 6-3-2 and the fourth platform 7-2 can provide a penetrating movable space for the fiber bundle, and the fiber bundle is prevented from being extruded to generate shearing damage after the connecting block 6-3 of the clamp body 6 and the clamp pressing block 7 are clamped together through the fastening bolt 8.
The tooth form angle of the third sawtooth surface 3-1, the fourth sawtooth surface 4-1, the fifth sawtooth surface 6-3-1-1 and the sixth sawtooth surface 7-1-1 is 42 degrees to 46 degrees, and the tooth height is 0.2mm to 0.5 mm. The contact area and the roughness of the reinforcing sheet and the clamping device groove are increased by arranging the serrated surface at the contact surface of the reinforcing sheet and the clamping device groove, so that the clamping device is ensured to clamp the whole fiber bundle test piece formed by the reinforcing sheet and the fiber bundle solidification clamping after clamping, and the dual fastening effect is realized.
The experimental use method of the fiber bundle test piece clamping device comprises the following steps:
the method comprises the following steps: the incident rod and the projection rod of the SHTB are respectively connected with the external thread 6-1 of the clamp body 6 through threads;
step two: adjusting an incident rod and a projection rod of the SHTB provided with the clamp main body 6 to keep the surface of one side, provided with the groove, of the connecting block 6-3 of the clamp main body 6 on the same horizontal plane so as to ensure the flatness of the fiber bundle after the fiber bundle test piece is placed, prevent twisting effect caused by changing the appearance of the fiber bundle due to rotation of two ends and ensure the real dynamic tensile mechanical property of the fiber material;
step three: a first reinforcing sheet 3, a fiber bundle 5 and a second reinforcing sheet 4 are placed in a groove III 6-3-1 of a connecting block 6-3 of a clamp main body 6 to be solidified and clamped together to form an integral fiber bundle test piece for the SHTB test, a serrated face III 3-1 of the first reinforcing sheet 3 is meshed with a serrated face V6-3-1-1 of the groove III 6-3-1, a clamp pressing block 7 is placed on the clamp main body 6 after a groove IV 7-1 of the clamp pressing block 7 is aligned with a fiber bundle test piece reinforcing sheet, and a serrated face IV 4-1 of the second reinforcing sheet 4 is meshed with a serrated face VI 7-1-1 of the groove IV 7-1;
step four: and (3) passing a fastening bolt 8 through a bolt hole IV 7-3 and a bolt hole III 6-3-3 of the clamp pressing block 7 and the clamp main body 6, and applying fastening force to form fastening clamping among the clamp pressing block 7, the clamp main body 6 and the fiber bundle test piece so as to realize first heavy clamping and fastening. Because the sawtooth surface is arranged at the contact surface of the reinforcing sheet and the groove of the clamping device, the contact area and the roughness of the reinforcing sheet and the groove of the clamping device are increased, the phenomenon that the reinforcing sheet and a fiber bundle solidifying and clamping integrated fiber bundle test piece cannot slide after the clamping device clamps the fiber bundle test piece is guaranteed, the dual fastening effect is realized, meanwhile, the coaxiality of the fiber bundle test piece, the clamping device and the SHTB three is further guaranteed after the fastening force is applied, and the test precision and accuracy are guaranteed.
Step five: a dynamic tensile test of the fiber bundle SHTB was performed.
According to the invention, the fiber bundle test piece for the SHTB test is prefabricated by the steps of formwork erecting, laying, assembling, maintaining and formwork stripping and by the aid of the lower fiber bundle test piece die 1, the upper fiber bundle test piece die 2, the first reinforcing sheet 3, the second reinforcing sheet 4 and the fastening bolts 8, and the method has the advantages of simple process, convenience in disassembly, capability of pipeline work, batch manufacture, regular shape and uniform size of the whole test piece and the like.
According to the invention, the fiber bundle is prevented from being damaged in the fastening process by the sandwich structure formed among the first reinforcing sheet 3, the fiber bundle 5 and the second reinforcing sheet 4, and the bonding performance between the fiber bundle and the reinforcing sheets is further improved by the way of coating the reinforcing sheets with fiber impregnating glue.
The clamping device adopting the assembly design has the advantages of fewer parts, simple shape, convenience in processing, lower manufacturing cost, convenience in installation, easiness in replacement, simplicity and convenience in clamping steps and the like, meets the fastening requirement of a fiber bundle test piece in an SHTB test by the clamp main body 6, the clamp pressing block 7 and the fastening bolt 8, realizes first-time clamping and fastening, and ensures the reliability and accuracy of a test result.
According to the invention, the serrated surfaces which are meshed with each other are arranged on the contact surfaces of the reinforcing sheet and the groove of the clamping device, so that the reinforcing sheet and the fiber bundle are solidified and clamped to form an integral fiber bundle test piece which cannot slide after the clamping device is clamped, the dual fastening effect is realized, the specifications of the reinforcing sheet and the groove of the clamping device are unified, the coaxiality of the fiber bundle test piece, the clamping device and the SHTB is further ensured after fastening force is applied, and the precision and the accuracy of the test are ensured.
The invention meets the instantaneity of the clamping device, can carry out the test after clamping and fastening the fiber bundle test piece, improves the test efficiency, and simultaneously can realize that the strain rate of the fiber bundle test piece on the SHTB is 100s -1 -1000s -1 And (3) testing the dynamic tensile mechanical property under the condition.
Furthermore, it should be understood that various changes and modifications can be made by one skilled in the art after reading the above description of the present invention, and equivalents also fall within the scope of the invention as defined by the appended claims.

Claims (8)

1. A dynamic tensile test method of a fiber bundle SHTB is characterized in that a fiber bundle test piece manufacturing device and a fiber bundle test piece clamping device are adopted;
the fiber bundle test piece manufacturing device comprises a fiber bundle test piece lower die (1) and a fiber bundle test piece upper die (2) which can be matched and clamped with each other; a plurality of first grooves (1-1) for placing first reinforcing sheets (3) are formed in the lower fiber bundle test piece die (1); a plurality of grooves II (2-1) for placing second reinforcing sheets (4) are formed in the upper die (2) of the fiber bundle test piece;
the fiber bundle test piece clamping device comprises a clamp main body (6) and a clamp pressing block (7) which can be matched and clamped with each other; grooves for placing the reinforcing sheets are formed in the clamp main body (6) and the clamp pressing block (7);
the method for testing the SHTB dynamic tensile test of the fiber bundle comprises the following steps:
s1, placing lower molds (1) of the fiber bundle test pieces at two ends according to the gauge length required by the SHTB test of the fiber bundles, and placing first reinforcing sheets (3) in the first grooves (1-1);
s2, uniformly coating fiber impregnating adhesive on the surface, used for being in contact with the fiber bundle (5), of the first reinforcing sheet (3), tensioning, centering and horizontally placing the fiber bundle (5) on the central line of the first reinforcing sheets (3) on two sides, uniformly coating the fiber impregnating adhesive on the contact surface of the first reinforcing sheet (3) and the fiber bundle (5) again, and fully soaking the fiber impregnating adhesive in the fiber bundle (5);
s3, placing a second reinforcing sheet (4) on a first reinforcing sheet (3) in an aligned mode according to the face, in contact with the fiber bundle (5), of the second reinforcing sheet, then aligning a second groove (2-1) with the second reinforcing sheet (4), placing an upper fiber bundle test piece die (2) on a lower fiber bundle test piece die (1), and clamping the upper fiber bundle test piece die (2) and the lower fiber bundle test piece die (1) together;
s4, curing until the fiber impregnating adhesive is cured, demolding, and cutting the exposed end of the fiber bundle to obtain a fiber bundle test piece for the SHTB test, wherein both sides of the fiber bundle test piece are cured and clamped together with the first reinforcing sheet (3) and the second reinforcing sheet (4) to form a whole;
s5, fixedly connecting an incident rod and a projection rod of the SHTB with one end of the clamp main body (6) respectively;
s6, adjusting an incident rod and a projection rod of the SHTB provided with the clamp main body (6) to ensure that the surface of one side of the clamp main body (6) provided with the groove III (6-3-1) is kept on the same horizontal plane;
s7, placing the reinforcing sheet of the fiber bundle test piece for the SHTB test into a groove III (6-3-1), aligning a groove IV (7-1) of a clamp pressing block (7) with the reinforcing sheet of the fiber bundle test piece for the SHTB test, and placing the clamp pressing block (7) on a clamp main body (6) to form firm clamping among the clamp pressing block (7), the fiber bundle test piece for the SHTB test and the clamp main body (6);
and S8, carrying out a dynamic tensile test of the fiber bundle SHTB.
2. The dynamic tensile test method of the fiber bundle SHTB according to claim 1, wherein the surfaces of the first reinforcing sheet (3) and the second reinforcing sheet (4) which are in contact with the grooves, and the bottom surfaces of the first groove (1-1), the second groove (2-1), the third groove (6-3-1) and the fourth groove (7-1) are serrated surfaces which are engaged with each other.
3. The method of claim 2 wherein the serrated face has a profile angle of 42 ° to 46 ° and a tooth height of 0.2mm to 0.5 mm.
4. The dynamic tensile test method for the fiber bundle SHTB according to claim 1, wherein a first platform (1-2) higher than the bottom surface of the first groove (1-1) is arranged at the two ends of the first groove (1-1) close to the edge of the lower die (1) of the fiber bundle test piece, and the surface of the first platform (1-2) is lower than the surface of the lower die (1) of the fiber bundle test piece;
a second platform (2-2) which corresponds to the first platform (1-2) and is higher than the bottom surface of the second groove (2-1) is arranged at the two ends of the second groove (2-1) and close to the edge of the upper mold (2) of the fiber bundle test piece, and the surface of the second platform (2-2) is lower than the surface of the upper mold (2) of the fiber bundle test piece; the space formed by the first platform (1-2) and the second platform (2-2) can provide a penetrating movable space for the fiber bundle (5).
5. The dynamic tensile test method of the fiber bundle SHTB according to claim 1, wherein the clamp body (6) comprises a threaded connector (6-1) and a connecting block (6-3) fixedly connected with the threaded connector (6-1) through a receiving block (6-2) and used for placing a clamp pressing block (7); the threaded connector (6-1) is positioned at the end part of the clamp body (6) and is used for being fixedly connected with an incident rod or a projection rod of the SHTB; the groove III (6-3-1) is arranged on the connecting block (6-3), a platform III (6-3-2) higher than the bottom surface of the groove III (6-3-1) is arranged at one end, far away from the bearing block (6-2), of the groove III (6-3-1) and close to the edge of the connecting block (6-3), and the surface of the platform III (6-3-2) is lower than that of the connecting block (6-3);
one end of the groove IV (7-1), which is close to the edge of the clamp pressing block (7), is provided with a platform IV (7-2) which corresponds to the platform III (6-3-2) and is higher than the bottom surface of the groove IV (7-1), and the surface of the platform IV (7-2) is lower than the surface of the clamp pressing block (7); the space formed by the third platform (6-3-2) and the fourth platform (7-2) can provide a penetrating movable space for the fiber bundle (5).
6. The dynamic tensile test method of the fiber bundle SHTB of claim 5, wherein the connecting block (6-3) has a surface central axis of one side of the groove three (6-3-1), a central axis of the receiving block (6-2), and a central axis of the threaded connection member (6-1) aligned with a central axis of the SHTB.
7. The dynamic tensile test method of the fiber bundle SHTB according to claim 1, wherein the lower die (1) of the fiber bundle test piece is provided with a positioning rod (1-3), and the upper die (2) of the fiber bundle test piece is provided with a positioning hole (2-3) which can be matched with the positioning rod (1-3).
8. The dynamic tensile test method of the fiber bundle SHTB according to claim 1, wherein the clamping pressure block (7) between the upper die (2) and the lower die (1) of the fiber bundle test piece, the fiber bundle test piece for the SHTB test and the clamp body (6) are clamped by the fastening bolt (8).
CN202210297583.3A 2022-03-24 2022-03-24 Dynamic tensile test method for fiber bundle SHTB Pending CN114878315A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117589604A (en) * 2024-01-19 2024-02-23 南京航空航天大学 Yarn dynamic stretching device based on Hopkinson pull rod and mechanical testing method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117589604A (en) * 2024-01-19 2024-02-23 南京航空航天大学 Yarn dynamic stretching device based on Hopkinson pull rod and mechanical testing method

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