CN116086949A - Buckling-restrained clamp for post-impact compression sheet test and test method - Google Patents

Buckling-restrained clamp for post-impact compression sheet test and test method Download PDF

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CN116086949A
CN116086949A CN202310076957.3A CN202310076957A CN116086949A CN 116086949 A CN116086949 A CN 116086949A CN 202310076957 A CN202310076957 A CN 202310076957A CN 116086949 A CN116086949 A CN 116086949A
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supports
test piece
test
plate
vertical
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鲍华强
陈振
潘直方
尹银坤
刘多猛
青亮
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Shanghai Aeronautical Materials & Structures Testing Co ltd
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Shanghai Aeronautical Materials & Structures Testing Co ltd
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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
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0076—Hardness, compressibility or resistance to crushing
    • G01N2203/0085—Compressibility
    • 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
    • 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
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0676—Force, weight, load, energy, speed or acceleration

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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)

Abstract

The invention provides a buckling restrained clamp for a post-impact compression sheet test and a test method, wherein the buckling restrained clamp comprises a base, a pair of side supports, a pair of side fixing plates and an upper pressing plate, wherein the side supports comprise vertical plates and bottom plates which are vertically connected, the side supports are fixed on the base, and two vertical edges of a test piece are clamped in the left-right direction; the side fixing plates are positioned between the side supports and fixedly connected with the vertical plates; the side fixing plate is connected with an annular simple support, a pair of transverse simple supports and a pair of vertical simple supports, the three simple supports are provided with knife edges, and the knife edges lightly lean against the front side and the rear side of the test piece; the bottom end of the upper pressing disc is connected with a pair of upper branches and is lightly placed on the top end of the test piece, so that the upper branches clamp the top edge of the test piece in the front-back direction. The test method for the compression sheet test after impact by using the buckling restrained clamp is simple in principle, the back-to-back bending percentage of the load strain curve is monitored, buckling does not occur in the loading process, and therefore accurate compression residual strength is obtained.

Description

Buckling-restrained clamp for post-impact compression sheet test and test method
Technical Field
The invention belongs to the technical field of structural strength tests of aircraft composite materials, and particularly relates to an anti-buckling clamp and a test method for a compressed sheet test after impact.
Background
Carbon fiber composites are widely used in aerospace structures due to their relatively high specific stiffness and specific strength. The composite laminates are used as basic components in aircraft structures, and the accurate measurement of their performance parameters directly influences the load carrying capacity of the aircraft structure design. The compressibility is an important component in assessing the mechanical properties of composite laminates, and the U.S. standard ASTM7137 provides a test method for measuring residual strength after impact by drop hammers, which is suitable for determining the compressive residual strength after impact of fiber reinforced resin based composites. However, the above standard has a severe limitation on the thickness of the test piece, and is only applicable to test pieces having a measured thickness in the range of 4.0 to 6.0 mm.
With the increasing demand for economic applicability of commercial aircraft, laminates with higher specific stiffness and specific strength, thinner thickness and fewer layers are being used in design and manufacturing. When the residual compressive strength of the laminate after impact is tested, the buckling load is often less than the compressive failure load, which is often not obtained during the test. Therefore, for the thin plate structure, it is necessary to design a set of buckling-preventing device for inhibiting buckling phenomenon of the laminated plate in the compression process, so as to obtain accurate compression failure strength.
Disclosure of Invention
The invention aims to solve the defects of the prior art, and provides a buckling restrained clamp and a buckling restrained testing method for a compression sheet test after impact, so as to solve the problem that the sheet is easy to buckle in the compression process after impact.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
an anti-buckling clamp for post-impact compression sheet testing, the anti-buckling clamp comprising a base, a pair of side supports, a pair of side fixing plates and an upper platen, wherein:
the base is of a rectangular plate structure and is used for supporting other components, and two rows of threaded holes are symmetrically formed in the base front and back;
the side support is of an L-shaped structure and comprises a vertical plate, a bottom plate and a vertical triangular reinforcing plate, wherein the vertical plate and the bottom plate are vertically connected, the vertical triangular reinforcing plate is connected between the vertical plate and the bottom plate, the side support is fixed on the base, and two vertical edges of the test piece are clamped in the left-right direction;
the side fixing plates are positioned between the side supports and fixedly connected with the vertical plates of the side supports; the side fixing plate is connected with an annular simple support, a pair of transverse simple supports and a pair of vertical simple supports, and knife edges are arranged on the three simple supports and lightly lean against the front side and the rear side of the test piece and are used for preventing the test piece from buckling under compression load so as to obtain accurate compression failure strength; the annular simple supports are positioned at the center of the side fixing plate, the impact damage area on the test piece is surrounded, and the pair of transverse simple supports and the pair of vertical simple supports are respectively positioned at the upper side, the lower side, the left side and the right side of the annular simple supports;
the upper pressing plate is of a rectangular plate structure, the bottom end of the upper pressing plate is fixedly connected with a pair of upper simple supports, the upper pressing plate is lightly placed at the top end of the test piece, and the upper simple supports clamp the top edge of the test piece in the front-back direction.
The invention further provides that the front side and the rear side of the test piece are symmetrically stuck with the strain gauges through glue, and the number of the strain gauges is preferably 4 or 8.
The invention is further arranged that the U-shaped grooves are formed in the two sides of the triangular reinforcing plate on the bottom plate, the side supports are fixed on the base through bolts, and the distance between the side supports is adjusted through the U-shaped grooves in the bottom plate for test pieces with different widths, so that compression loading of the test pieces with different widths is realized.
The invention is further characterized in that the left and right sides of the side fixing plate are respectively provided with a threaded mounting hole, the two sides of the vertical plate, which are positioned on the triangular reinforcing plate, are respectively provided with a U-shaped groove corresponding to the threaded mounting holes, and the side fixing plate is fixed between the side supports through bolts.
The invention is further arranged that the side fixing plate is provided with a first mounting hole, a second mounting hole and a third mounting hole which are respectively corresponding to the positions of the transverse simple branch, the vertical simple branch and the annular simple branch, one side of the three simple branches connected with the side fixing plate is provided with a threaded hole, the three simple branches are fixed on the side fixing plate through bolts, the three mounting holes are all U-shaped grooves, and the position adjustment of the transverse simple branches in the up-down direction and the vertical simple branches in the left-right direction in a small range can be respectively realized or the fixed position can be adjusted according to the size of the annular simple branches.
The invention is further arranged that the transverse simple supports are positioned between the vertical simple supports, the length of the vertical simple supports is 80% -90% of the height of the test piece, and the length of the transverse simple supports is 65% -80% of the width of the test piece, so that the buckling preventing effect of the clamp is optimal.
The invention is further characterized in that a pair of bottom brackets are arranged on the base between the pair of side fixing plates and used for clamping the bottom edge of the test piece in the front-back direction.
The invention is further arranged that the side fixing plate is provided with a plurality of first observation holes and a second observation hole positioned in the center of the side fixing plate, and the first observation holes and the second observation holes are used for observing the performances of different positions and impact damage areas of the test piece in the compression process.
The invention is further characterized in that the transverse simple support is provided with two first openings for avoiding the positions of the strain gauges on the test piece.
The invention is further arranged that the upper edge and the lower edge of the side fixing plate are respectively provided with a second notch for guiding out a wire connected with the strain gauge on the test piece.
The invention is further characterized in that U-shaped grooves are symmetrically formed in the front and back of the upper pressing plate, threaded holes are formed in the upper simple supports, the upper simple supports are fixedly connected to the bottom end of the upper pressing plate through bolts, and the distance between the upper simple supports is adjusted through the U-shaped grooves of the upper pressing plate during test.
The invention also provides a test method for the post-impact compression sheet test, which comprises the test piece, the buckling-restrained clamp, test equipment, a strain gauge and a data acquisition instrument, and specifically comprises the following steps:
(1) The strain gauges are respectively connected to a data acquisition instrument after being stuck to the front side and the rear side of the test piece;
(2) The side supports are fixedly connected to the base, and the positions of the side supports are adjusted according to the width of the test piece so that the side supports clamp two sides of the test piece in the left-right direction;
(3) The annular simple supports, the transverse simple supports and the vertical simple supports are respectively installed and fixed on the side fixing plates, and the side fixing plates on one side are connected and fixed with the vertical plates on the side supports; centering through adjusting the front and back positions of the side fixing plates, so that the centering line of the test piece coincides with the centering line of the side support, and then installing the side fixing plates on the other side, so that the knife edges of the three simple supports are lightly leaned against the test piece;
(4) The bottom end of the upper pressing plate is fixedly connected with the upper simple support and then is lightly placed at the top end of the test piece, and the distance between the upper simple supports is adjusted so that the top edge of the test piece is clamped by the upper simple support;
(5) Placing the buckling restrained clamp fixed with the test piece on a supporting table of the test equipment, enabling a pressure head of the test equipment to move downwards to act on the upper pressure plate, and enabling the upper pressure plate to transmit load to the test piece for compression residual strength test; and simultaneously, the back-to-back bending percentage of the compressive strain curve is monitored, so that the accurate compressive strength is ensured.
The invention further provides that when the centering is adjusted in the step (3), the bottom brackets are respectively arranged on the front side and the rear side of the test piece on the base, so that the bottom edges of the test piece are clamped by the bottom brackets after the front side fixing plate and the rear side fixing plate are installed.
Compared with the prior art, the invention has the following beneficial effects:
the buckling restrained clamp and the testing method for the compression sheet test after impact disclosed by the invention are simple in principle and clear in thought, the buckling restrained clamp is designed, the back-to-back bending percentage of a load strain curve is monitored, the sheet laminated board is ensured not to buckle in the loading process, and therefore, the accurate compression residual strength is obtained, and the method is accurate and efficient.
Drawings
FIG. 1 is a schematic structural view of a buckling restrained brace for post impact compression sheet testing;
FIG. 2 is an exploded view of the buckling restrained brace of the compression sheet test after impact (the rear side panel structure in the exploded view is omitted);
FIG. 3 is a schematic view of the structure of a side fixing plate;
FIG. 4 is a schematic view of a simple support structure and a test piece on a side fixing plate;
FIG. 5 is a schematic structural view of a simply supported structure on a side fixing plate;
FIG. 6 is a schematic view of a test piece;
FIG. 7 is a schematic illustration of the attachment of strain gauges to test pieces in example 2;
fig. 8 is a graph of compressive strain during compression in example 2.
Detailed Description
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.
In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Example 1
According to fig. 1 and 2, there is shown a buckling restrained clamp for post-impact compression sheet test according to the present invention, the buckling restrained clamp comprises a base 2, a pair of side supports 3, a pair of side fixing plates 4 and an upper platen 6, wherein:
the base 2 is of a rectangular plate structure and provides support for other components, and two rows of threaded holes are symmetrically formed in the base 2 front and back;
the side supports 3 are of L-shaped structures and are used for clamping two vertical edges of the test piece 1 in the left-right direction, the side supports 3 comprise vertical plates 3-1 and bottom plates 3-3 which are vertically connected, the vertical plates 3-1 and the bottom plates 3-3 are further fixedly connected through a vertical triangular reinforcing plate 3-2, U-shaped grooves are formed in the two sides of the triangular reinforcing plate 3-2 on the bottom plates 3-3, the side supports 3 are fixed on the base 2 through bolts, and for test pieces with different widths, the distance between the side supports 3 is adjusted through the U-shaped grooves in the bottom plates 3-3, so that compression loading of the test pieces with different widths is realized;
as shown in connection with fig. 3-5, the side fixing plates 4 are located between the side supports 3 and are fixed by being connected with the risers 3-1 of the side supports 3; the side fixing plate 4 is connected with an annular simple branch 5-3, a pair of transverse simple branches 5-1 and a pair of vertical simple branches 5-2, threaded holes are formed in one side, connected with the side fixing plate 4, of the annular simple branch 5-3, the transverse simple branch 5-1 and the vertical simple branch 5-2, and knife edges are formed in the side, opposite to the side fixing plate 4, of the side fixing plate, and are lightly abutted to the front side and the rear side of the test piece 1 and used for preventing buckling of the test piece 1 under compression load so as to obtain accurate compression failure strength; the annular simple supports 5-3 are positioned at the center of the side fixing plate 4, an impact damage area on the test piece 1 is surrounded, the pair of transverse simple supports 5-1 are respectively positioned at the upper side and the lower side of the annular simple supports 5-3, and the pair of vertical simple supports 5-2 are respectively positioned at the left side and the right side of the annular simple supports 5-3;
the upper pressing plate 6 is of a rectangular plate structure, U-shaped grooves are formed in the front-back symmetry mode, a pair of upper simple supports 7 are arranged at the bottom end of the upper pressing plate 6, threaded holes are formed in the upper simple supports 7, the upper simple supports 7 are fixedly connected to the bottom end of the upper pressing plate 6 through bolts, the upper pressing plate 6 is lightly placed at the top end of the test piece 1 during test, the distance between the upper simple supports 7 is adjusted through the U-shaped grooves of the upper pressing plate 6, and the upper simple supports 7 clamp the top edge of the test piece 1 in the front-back direction.
Further, as shown in fig. 6, the front and rear sides of the test piece 1 are symmetrically adhered with strain gauges 1-1 by glue, and the number of the strain gauges 1-1 is preferably 4 or 8.
Further, threaded mounting holes 4-7 are respectively formed in the left and right sides of the side fixing plate 4, U-shaped grooves corresponding to the threaded mounting holes 4-7 are formed in the two sides of the triangular reinforcing plate 3-2 on the vertical plate 3-1 of the side support 3, and the side fixing plate 4 is fixed between the side supports 3 through bolts.
Further, the side fixing plate 4 is provided with a first mounting hole 4-1 corresponding to the position of the transverse simple branch 5-1, a second mounting hole 4-2 corresponding to the position of the vertical simple branch 5-2 and a third mounting hole 4-3 corresponding to the position of the annular simple branch 5-3, the three simple branches are fixed on the side fixing plate 4 through bolts, and the three mounting holes 4-1, 4-2 and 4-3 are U-shaped grooves, so that the position adjustment of the transverse simple branch 5-1 in the up-down direction and the position adjustment of the vertical simple branch 5-2 in the left-right direction by a small amplitude can be respectively realized or the fixed position can be adjusted according to the size of the annular simple branch 5-3.
Preferably, the transverse simple supports 5-1 are located between the vertical simple supports 5-2, the length of the vertical simple supports 5-2 is 80% -90% of the height of the test piece 1, and the length of the transverse simple supports 5-2 is 65% -80% of the width of the test piece 1, so that the buckling prevention effect of the clamp is optimal.
Further, a pair of bottom brackets 8 for holding the bottom edge of the test piece 1 in the front-rear direction are provided on the base 2 between the pair of side fixing plates 4.
Further, the side fixing plate 4 is provided with a plurality of first observation holes 4-4 and second observation holes 4-5 positioned in the center of the side fixing plate 4, which are used for observing the performances of different positions and impact damage areas of the test piece 1 in the compression process.
Further, two first openings 5-1-1 are formed in the transverse simple support 5-1 and used for avoiding the position of the strain gauge on the test piece 1.
Further, the upper edge and the lower edge of the side fixing plate 4 are respectively provided with a second notch 4-6 for guiding out a wire connected with the strain gauge on the test piece 1.
The test method of the post-impact compression sheet test using the buckling restrained clamp comprises the test piece 1, the buckling restrained clamp, test equipment, a strain gauge 1-1 and a data acquisition instrument (the test equipment and the data acquisition instrument are not shown in the drawings), wherein:
the test piece is a laminated board formed by paving unidirectional tapes in different directions;
the buckling restrained clamp comprises a tool for fixing the test piece to test equipment and a tool for loading load to the test piece;
the test equipment is an electronic universal tester, the loading precision of the tester is less than 1%, and the coaxiality is less than 8%;
and the strain gauge is connected with the data acquisition instrument after being stuck to the test piece and is used for acquiring strain data and force value data in the test loading process.
Specifically, the test method for the post-impact compression sheet test comprises the following steps:
(1) The strain gauge 1-1 is adhered to the front side and the rear side of the test piece 1 and then respectively connected to a data acquisition instrument;
(2) The side supports 3 are fixedly connected to the base 2, and the positions of the side supports 3 are adjusted according to the width of the test piece 1 so that the side supports 3 clamp two sides of the test piece 1 in the left-right direction;
(3) The annular simple supports 5-3, the transverse simple supports 5-1 and the vertical simple supports 5-2 are respectively installed and fixed on the side fixing plates 4, and the side fixing plates 4 on one side are connected and fixed with the vertical plates 3-1 on the side supports 3; drawing centering lines on the base 2, the side supports 3 and the test piece 1 respectively, adjusting the front and rear positions of the side fixing plates 4 to enable the centering lines of the test piece 1 to coincide with the centering lines of the side supports 3, arranging the bottom briefs 8 on the base 2 on the front and rear sides of the test piece 1 respectively, and installing the side fixing plates 4 on the other side to enable knife edges of the three briefs to lightly lean against the test piece 1, and simultaneously enabling the bottom edges of the test piece 1 to be clamped by the bottom briefs 8;
(4) Fixedly connecting the upper simple supports 7 to the bottom end of the upper pressing plate 6, and lightly placing the upper pressing plate 6 on the top end of the test piece 1, and adjusting the distance between the upper simple supports 7 to enable the top edge of the test piece 1 to be clamped by the upper simple supports 7;
(5) Placing the buckling restrained clamp fixed with the test piece 1 on a supporting table of the test equipment, enabling a pressure head of the test equipment to move downwards to act on the upper pressure plate 6, and enabling the upper pressure plate 6 to transmit load to the test piece 1 to perform a compression residual strength test to obtain compression residual strength; and simultaneously, the back-to-back bending percentage of the compressive strain curve is monitored, so that the accurate compressive strength is ensured.
Specifically, the bending percentage is calculated by the strain values acquired by two strain gauges 1-1 back to back in the compression process, epsilon 1 And epsilon 2 The indicated strain on the back-to-back strain gage, respectively, is calculated by:
Figure BDA0004066647700000071
compared with the prior art, the test method provided by the invention has the advantages that the principle is simple, the thought is clear, the buckling phenomenon is avoided in the loading process by designing the buckling restrained clamp and monitoring the back-to-back bending percentage of the load strain curve, so that the accurate compressive residual strength is obtained, and the method is accurate and efficient.
Example 2
The buckling restrained brace and the test method of the post-impact compression sheet test described in example 1 were used for the compression residual strength test, and the test piece in this example was a laminated board structure made of a carbon fiber composite material, and the configuration size of the test piece was 150mm x 100mm x 3mm.
Before the test, firstly, the compression buckling load of the laminated board in a four-side simply supported state is obtained through simulation analysis or theoretical calculation, and the compression buckling load and the estimated breaking load are compared, so that whether the buckling-restrained clamp is needed or not is judged. In this embodiment, the estimated breaking load is greater than the compressive buckling load of the test piece, so that the compressive residual strength test is performed using the buckling restrained brace described above. The size of the impact damage area is obtained through an ultrasonic nondestructive C-scanning detection method, a clamp covering the impact damage area is designed, and the size of the annular simple support is ensured to encircle the impact damage area on the test piece.
In the test process, a compressive strain curve is obtained through the strain gauge, and the back-to-back bending percentage of the strain gauge is monitored, 4 strain gauges are stuck on the test piece in the embodiment, as shown in fig. 7-8, which are respectively a strain gauge sticking schematic diagram and a compressive strain curve in the compression process, the strain value is continuously increased along with the increase of the load, the bending percentages of the front surface and the back surface are not increased along with the increase of the load (the maximum value of the bending percentages is 4.45%), the bending percentages are always kept within 5%, and the requirement that the bending percentage of test control is less than 10% is met. Through the buckling restrained clamp, buckling phenomenon is avoided in the compression loading process, and more accurate compression residual strength is obtained.
The above description of the specific embodiments of the present invention has been given by way of example only, and the present invention is not limited to the above described specific embodiments. Accordingly, equivalent changes and modifications are intended to be included within the scope of the present invention without departing from the spirit and scope thereof.

Claims (10)

1. The utility model provides a compression sheet test's buckling restrained anchor clamps after striking which characterized in that, buckling restrained anchor clamps include base, a pair of side stay, a pair of side fixed plate and last pressure disk, wherein:
the side support is of an L-shaped structure and comprises a vertical plate, a bottom plate and a vertical triangular reinforcing plate, wherein the vertical plate and the bottom plate are vertically connected, the vertical triangular reinforcing plate is connected between the vertical plate and the bottom plate, the side support is fixed on the base, and two vertical edges of a test piece are clamped in the left-right direction;
the side fixing plates are positioned between the side supports and fixedly connected with the vertical plates of the side supports; the side fixing plate is connected with an annular simple support, a pair of transverse simple supports and a pair of vertical simple supports, and knife edges are arranged on the three simple supports and lean against the front side and the rear side of the test piece; the annular simple supports encircle an impact damage area on the test piece, and the pair of transverse simple supports and the pair of vertical simple supports are respectively positioned on the upper side, the lower side, the left side and the right side of the annular simple supports;
the upper pressing plate is fixedly connected with a pair of upper branches, the upper pressing plate is placed at the top end of the test piece, and the upper branches clamp the top edge of the test piece in the front-back direction.
2. The buckling restrained clamp according to claim 1, wherein two rows of threaded holes are symmetrically formed on the base front and back; the U-shaped grooves are formed in two sides of the triangular reinforcing plate on the bottom plate, the side supports are fixed on the base through bolts, and the distance between the side supports is adjusted through the U-shaped grooves in the bottom plate for test pieces with different widths, so that compression loading of the test pieces with different widths is achieved.
3. The buckling restrained clamp according to claim 1, wherein threaded mounting holes are formed in the left side and the right side of the side fixing plate respectively, U-shaped grooves corresponding to the threaded mounting holes are formed in the two sides of the triangular reinforcing plate on the vertical plate, and the side fixing plate is fixed between the side supports through bolts.
4. The buckling restrained clamp according to claim 1, wherein the side fixing plate is provided with a first mounting hole, a second mounting hole and a third mounting hole which correspond to the positions of the transverse simple branch, the vertical simple branch and the annular simple branch respectively, one side of the three simple branches connected with the side fixing plate is provided with a threaded hole, and the three simple branches are fixed on the side fixing plate through bolts.
5. The buckling restrained brace of claim 4, wherein the first mounting hole, the second mounting hole and the third mounting hole are all U-shaped grooves, and the position adjustment of the transverse simply support in the up-down direction and the vertical simply support in the left-right direction and the fixed position adjustment according to the size of the annular simply support are respectively realized.
6. The buckling restrained clamp of claim 1, wherein the cross beam is located between the vertical beams, the length of the vertical beams is 80% -90% of the height of the test piece, and the length of the cross beam is 65% -80% of the width of the test piece 。
7. The buckling restrained clamp according to claim 1, wherein the transverse simple support is provided with two first notches for avoiding the positions of the strain gauges on the test piece; the upper edge and the lower edge of the side fixing plate are respectively provided with a second opening for guiding out a wire connected with the strain gauge on the test piece.
8. The buckling restrained clamp according to claim 1, wherein the upper pressing plate is provided with U-shaped grooves symmetrically in the front-back direction, the upper jambs are provided with threaded holes, the upper jambs are fixedly connected to the bottom ends of the upper pressing plate through bolts, and the distance between the upper jambs is adjusted through the U-shaped grooves of the upper pressing plate during testing.
9. A test method for a post-impact compression sheet test using the buckling restrained brace according to any of claims 1 to 8, characterized by comprising the steps of:
(1) The strain gauges are respectively connected to a data acquisition instrument after being stuck to the front side and the rear side of the test piece;
(2) The side supports are fixedly connected to the base, and the positions of the side supports are adjusted according to the width of the test piece so that the side supports clamp two sides of the test piece in the left-right direction;
(3) The annular simple supports, the transverse simple supports and the vertical simple supports are respectively installed and fixed on the side fixing plates, and the side fixing plates on one side are connected and fixed with the vertical plates on the side supports; centering through adjusting the front and back positions of the side fixing plates, so that the centering line of the test piece coincides with the centering line of the side support, and then installing the side fixing plates on the other side, so that the knife edges of the three simple supports are lightly leaned against the test piece;
(4) The bottom end of the upper pressing plate is fixedly connected with the upper simple support and then is lightly placed at the top end of the test piece, and the distance between the upper simple supports is adjusted so that the top edge of the test piece is clamped by the upper simple support;
(5) The buckling restrained clamp is placed on a supporting table of test equipment, a pressure head of the test equipment moves downwards to act on the upper pressure plate, and the upper pressure plate transmits load to a test piece to carry out a compression residual strength test; while the back-to-back bending percentage of the compressive strain curve is monitored.
10. The test method according to claim 9, wherein in the step (3), bottom brackets are respectively provided on the front and rear sides of the test piece on the base when the centering is adjusted, so that the bottom edges of the test piece are clamped by the bottom brackets after the front and rear side fixing plates are mounted.
CN202310076957.3A 2023-01-19 2023-01-19 Buckling-restrained clamp for post-impact compression sheet test and test method Pending CN116086949A (en)

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