KR101864590B1 - Impact shear test apparatus. - Google Patents

Impact shear test apparatus. Download PDF

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KR101864590B1
KR101864590B1 KR1020160182390A KR20160182390A KR101864590B1 KR 101864590 B1 KR101864590 B1 KR 101864590B1 KR 1020160182390 A KR1020160182390 A KR 1020160182390A KR 20160182390 A KR20160182390 A KR 20160182390A KR 101864590 B1 KR101864590 B1 KR 101864590B1
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specimen
weight
load
impact
load transmission
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KR1020160182390A
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Korean (ko)
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김동주
지 투엉 노
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세종대학교산학협력단
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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
    • 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
    • G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
    • G01N3/303—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight generated only by free-falling weight
    • 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
    • G01N2203/0025—Shearing
    • 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

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

Abstract

The present invention relates to an impact shearing test apparatus and, more specifically, relates to an impact shearing test apparatus which performs an impact test with respect to a specimen by generating a free fall load with a specimen fixing bar and a strain rate measurement device. As stated above, the impact shearing test apparatus is added to a system testing shearing resistance of ultra high performance fiber reinforced concretes (UHPFRCs) to provide a system for measuring a shearing load experienced by a test body by measuring a strain rate with a strain rate gauge based on potential energy. Therefore, a shearing test progress with respect to materials having a plurality of cracks such as ultra high performance fiber reinforced concretes and a shearing load experienced by an accurate test body can be measured.

Description

Impact Shear Test System. {Impact shear test apparatus.}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact shear testing apparatus, and more particularly, to an apparatus for generating a free fall load using a specimen fixing bar and a strain measuring apparatus to perform an impact test on a specimen.

UHPFRCs (Ultra High Performance Fiber Reinforced Concrete) have excellent mechanical properties such as high compressive strength, tensile strength, and energy absorption capacity, and are widely used in infrastructure and military facilities to resist impact and explosion loads. .

Under impact loading conditions such as a missile impact on a concrete wall or an airplane collision in a high-rise building, shear failure predominates over compression or tensile failure.

However, understanding the shear behavior of UHPFRCs at the high strain rate corresponding to the current impact load is still limited by the absence of standard shear tests and the absence of systems that produce high impact loads.

Test methods for investigating the shear resistance of FRC (fiber reinforced concrete) s and UHPFRCs (ultrahigh strength concrete) still provide limited information.

The general principle of this shear test method is that it is not suitable for materials with many cracks like UHPFRCs because the test is conducted by setting the shear front end of the test specimen in advance.

As a result, the strain hardening behavior inherent in UHPFRCs can not be measured by conventional methods.

KR 2008-0087290

The present invention relates to a system for measuring the shear resistance of a UHPFRCs and a system for measuring the shear load experienced by a specimen by measuring the strain using a strain gauge based on potential energy, And it is an object of the present invention to provide a shock shear testing apparatus.

In order to achieve the above object, according to an embodiment of the present invention, there is provided a method for testing an impact shear test apparatus, comprising: a base provided at the bottom of a floor or work space with a predetermined weight, A vertical bar arranged at regular intervals and extending in a vertical direction, an upper plate spaced apart from the base by a predetermined distance and fixed to one end of the vertical bar, A load transfer member which is provided at one side of the guide rail and transfers a load generated by dropping the weight to the test specimen, Respectively, and fixing the ends of the specimen and vertically extending upward A support frame having one side fixed to the upper surface of the base and vertically extending upwardly and the other side connected to one end of the specimen fixing bar, and a strain measuring device attached to one side of the specimen fixing bar to measure a strain of the specimen fixing bar It is possible to provide an impact shear testing apparatus including the apparatus.

In this case, when the weight is dropped, the load transmission portion is in contact with the lower portion of the weight, and the first load transmission portion and the first load transmission portion, which receive the load of the falling weight, It is possible to include a second load transmission part provided to be spaced apart from the first specimen and to transmit the load and impact to the specimen in direct contact with the specimen.

The electromagnet may further include an electromagnet provided on the upper plate to fix the weight to the lower surface of the upper plate.

In this case, it is possible to further include a lifting cable passing through the upper plate and connected to one side of the weight to raise the weight upwardly to contact the lower surface of the upper plate.

The apparatus may further include at least one control rod spaced a predetermined distance from both sides of the guide rail and extending vertically downwardly from the upper plate, the control rod passing through the weight.

It is also possible to further include a horizontal beam positioned between the first load transmission portion and the second load transmission portion and restricting the downward travel of the first load transmission portion.

In this case, it is also possible to further include a plurality of shock absorbers provided under the control rod to absorb the residual impact of the weight.

According to the above-mentioned problem solving means of the present invention, in the system for investigating the shear resistance of UHPFRCs, in addition to this, the shear load experienced by the test body is measured by measuring the strain using a strain gauge based on the potential energy The object of the present invention is to provide a shock shear test apparatus provided with a system capable of performing a shear test on a material accompanied by a plurality of cracks such as ultrahigh strength concrete and measuring a shear load experienced by an accurate test body Possible effects exist.

1 is a front view of an impact shear testing apparatus according to an embodiment of the present invention.
2 is a perspective view of an impact shear testing apparatus according to an embodiment of the present invention.
FIG. 3 is a block diagram showing elements necessary for measuring a deformation amount of a specimen according to an embodiment of the present invention.
4 is an enlarged perspective view of the impact shear testing apparatus according to an embodiment of the present invention.
5 is a perspective enlarged view of an apparatus for testing an impact shear according to an embodiment of the present invention.
6 is an enlarged perspective view of an apparatus for testing an impact shear according to an embodiment of the present invention.
7 is an enlarged perspective view of an apparatus for testing an impact shear according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the difference that the embodiments of the present invention are not conclusive.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

1 is a front view of an impact shear testing apparatus according to an embodiment of the present invention.

2 is a perspective view of an impact shear testing apparatus according to an embodiment of the present invention.

Referring to Figs. 1 and 2, it is possible to confirm the configuration of the impact shear testing apparatus including the weight and the specimen.

Specifically, a base 1 is provided at the bottom of the floor or work space with a predetermined weight and is installed at the lower portion of the impact shear tester. The base 1 is arranged at regular intervals in the circumferential direction on the edge of the base 1, A top plate 3 connected to one end of the vertical bar 2 and spaced a certain distance from the base 1 and fixed to one end of the vertical bar 2 and vertically downward from the center of the top plate 3; A weight 5 capable of moving up and down along the guide rail 4 provided at a center of the guide rail 4 so as to extend in a predetermined length and one side of the guide rail 4; A load transfer portion 6 provided at the both ends of the specimen to transmit the load generated by dropping of the weight 5 to the specimen, a specimen fixing bar 8 positioned at both ends of the specimen and vertically extending upward, , One side A support frame 7 provided on the upper surface of the specimen fixing bar 8 and vertically extending upwardly and the other side connected to one end of the specimen fixing bar 8 and a specimen fixing bar 8 attached to one side of the specimen fixing bar 8, It is possible to provide an impact shear testing apparatus including a strain measuring device 13 for measuring the strain of the test piece 8.

In this case, when the weight drops down from the upper portion to the lower portion due to free fall, a certain amount of load can be applied to the specimen through the load transmission portion. Based on the amount of deformation of the specimen and the amount of strain gauge change, It is possible to measure the shear load experienced by the specimen of high strength concrete.

FIG. 3 is a block diagram showing elements necessary for measuring a deformation amount of a specimen according to an embodiment of the present invention.

Referring to FIG. 3, it is possible to confirm the length (B) and the section (60 mm) of the entire specimen and the load applied thereto.

Specifically, both ends of the specimen are completely fixed by the specimen fixing bar, and the specimen fixing bar is connected to the support frame.

Two strain gauges are attached to the surface of the specimen clamping bar and indirectly obtain the stress applied to the specimen after measuring the strain.

In addition, when a load is applied to the second load transmission part (62, FIG. 5) which is in contact with the upper part of the specimen while the weight is falling, a load is transmitted to the specimen at the same time so that the specimen is deformed or broken.

Then, the load applied to the specimen is calculated by the elastic strain obtained from the strain measuring device transmitted through the specimen fixing bar, and the pure shear stress of the specimen is calculated based on the calculated load.

The graph below shows the shear stress-strain curve of UHPFRCs reinforced with 1.5% of steel fiber in the same form of test specimen as this patent at static speed.

[graph]

Figure 112016129098785-pat00001

In this case, the shear stress calculation of the specimen

Figure 112016129098785-pat00002
It is possible to calculate using the formula

here,

Figure 112016129098785-pat00003
Is the shear strength (MPa), P is the working load (kN), b is the width of the specimen and d is the depth of the specimen (mm).

In this case, the working load, ie the shear load experienced by the test body, is obtained by multiplying the strain of the specimen fixing bar measured by the strain gauge by the modulus of elasticity of the steel and then multiplying by the cross-sectional area of the specimen fixing bar.

In addition, the shear strain is defined as the angle change between AB and AD in Fig.

The following equation (1) represents the shear strain.

here

Figure 112016129098785-pat00004
Is the shear strain, ax is the angle of AB and A'B ', and ay is the angle between AD and y axis.

Figure 112016129098785-pat00005

Based on the above equation, the shear strain can be calculated by obtaining a vertical displacement d with a high-speed camera or the like.

The above-mentioned strain measuring apparatus and shear stress calculation formula as described above can be used to determine the working load (P) of the weight acting on the apparatus, and also to accurately grasp the shear stress and the shear strain in the case of a member having many cracks It is possible.

4 is an enlarged perspective view of the impact shear testing apparatus according to an embodiment of the present invention.

Referring to FIG. 4, it is possible to confirm the configuration of the impact shear test apparatus of the present invention including a control rod.

Specifically, it is possible to further include an electromagnet 9 provided on the upper plate 3 to fix the weight 5 in contact with the lower surface of the upper plate 3.

The electromagnet may be attached to the lower part of the upper plate by fixing the weight to the electromagnet.

In this case, it is possible that the potential energy possessed by the weight is transmitted to the specimen as impact energy due to the power-off of the electromagnet.

The lifting cable further passes through the upper plate 3 and is connected to one side of the weight 5 so as to raise the weight 5 upwardly so as to contact the lower surface of the upper plate 3 .

It is possible to move the weight close to the lower portion of the top plate by the lifting cable or the like before fixing through the electromagnet.

In addition, at least one control rod (10), which is spaced apart from both sides of the guide rail (4) by a predetermined distance and extends vertically downward from the upper plate (3) It will be appreciated that it would be possible to further include

The control rod prevents the weight from rotating when the weight moves downward along the guide rail and allows the weight to stably transmit impact energy to the specimen through the load transmission unit .

5 to 7 are enlarged views of an impact shear testing apparatus according to an embodiment of the present invention.

5 to 7, it is possible to confirm the concrete construction of the present invention including the first load transmission portion, the second load transmission portion and the horizontal beam.

More specifically, the apparatus further includes a horizontal beam 11 positioned between the first load transmission portion 61 and the second load transmission portion 62 and restricting the downward travel of the first load transmission portion 61 It is possible.

The energy of the weight is transferred to the first load transmission part and the second load transmission part connected to the guide rail is moved at the same time It is possible to deliver the impact to the specimen.

In this case, it is possible to provide a horizontal beam for controlling the first load transmitting portion so that the first load transmitting portion does not go unduly when the deformation amount of the specimen is excessive or the specimen is broken.

It is also possible to provide an impact absorbing plate for absorbing additional residual impact of the weight and reflecting only the initial impact shear test result.

To this end, it is preferable to further include a plurality of impact absorption plates 12 provided below the control rod 10 to absorb the residual impact of the weight 5.

Additionally, the stress signal history is measured with two strain gauges attached to two specimen bars.

In order to measure the pure stress value, the specimen fixing bar should be designed so that it is not affected by the stress wave reflected from the end portion of the specimen fixing bar in contact with the support frame, that is, You will need a sufficient length.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

1: Base
2: vertical bar
3: Top plate
4: Guide rail
5: Weight
6:
7: Support frame
8: Specimen fixing bar
9: Electromagnet
10: Control Load
11: Horizontal beam
12: Shock absorber plate
13: strain measuring device
61: first load transmission portion
62: a second load transmission portion

Claims (7)

A base 1 provided at the bottom of the floor or work space with a predetermined weight and installed at the bottom of the impact shear testing apparatus;
A vertical bar 2 arranged at an edge of the base 1 at regular intervals in a circumferential direction and extending in a vertical direction;
An upper plate 3 spaced apart from the base 1 by a predetermined distance and fixed to one end of the vertical bar 2;
A guide rail 4 extending vertically downward from the center of the upper plate 3 by a predetermined length;
A weight 5 disposed at the center of the guide rail 4 and vertically movable along the guide rail 4;
A load transfer part 6 provided at one side of the guide rail 4 for transferring a load generated by dropping of the weight 5 to a specimen;
A specimen fixing bar 8 positioned at both ends of the specimen and vertically extending upward with fixing the end portion of the specimen;
A support frame (7) provided on one side of the base (1) and vertically extended upwardly, the other side of which is connected to one end of the specimen fixing bar (8);
A strain measuring device (13) attached to one side of the specimen fixing bar (8) and measuring the strain of the specimen fixing bar (8);
At least one control rod (10) spaced a predetermined distance from both sides of the guide rail (4) and extending vertically downwardly from the upper plate (3) by a predetermined length, the control rod being installed through the weight (5); And
A horizontal beam 11 positioned between the first load transmission portion 61 and the second load transmission portion 62 and restricting the downward travel of the first load transmission portion 61;
≪ / RTI >
The load transmitting portion (6)
A first load transmission part (61) directly contacting with the lower part of the weight (5) when the weight (5) drops, and receiving a load of the weight (5) falling first; And
A second load transmission part (62) spaced apart from the first load transmission part (61) by a predetermined distance, the second load transmission part (62) being in contact with the specimen and transmitting a load and an impact to the specimen;
/ RTI >
A plurality of shock absorbers (12) provided below the control rod (10) to absorb the residual impact of the weight (5);
Further comprising an impact shear testing device
delete The method according to claim 1,
An electromagnet 9 provided on the upper plate 3 to fix the weight 5 in contact with the lower surface of the upper plate 3;
Further comprising: an impact shear testing device.
The method according to claim 1,
A lifting cable passing through the upper plate 3 and connected to one side of the weight 5 so as to raise the weight 5 upwards so as to come into contact with the lower surface of the upper plate 3;
Further comprising: an impact shear testing device.
delete The method according to claim 1,
A horizontal beam 11 positioned between the first load transmission portion 61 and the second load transmission portion 62 and restricting the downward travel of the first load transmission portion 61;
Further comprising: an impact shear testing device. delete
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109580385A (en) * 2018-11-16 2019-04-05 北京东方雨虹防水技术股份有限公司 Waterproof layer resists the test equipment and its test method of underground engineering valve pit subsidence
CN112146996A (en) * 2020-08-13 2020-12-29 武汉理工大学 Experimental device for normal disturbance induces rock mass shear fracture
CN113075034A (en) * 2021-03-12 2021-07-06 建华建材（安徽）有限公司 Assembled precast concrete pier tensile strength detection experimental apparatus
CN115219351A (en) * 2022-07-07 2022-10-21 武汉科技大学 Blasting vibration simulation device for shear rheological test
KR102534938B1 (en) * 2021-11-30 2023-05-26 국방과학연구소 Shock drop table test device for simulating dynamic shear force on jointed rocks
CN116952705A (en) * 2023-09-19 2023-10-27 中铁十七局集团第五工程有限公司 Structural bionic basalt fiber reinforced composite material impact resistance detection device

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KR20040093760A (en) * 2003-04-30 2004-11-09 주식회사 만도 Impact tester use in a shock absorber
KR20080087290A (en) 2007-03-26 2008-10-01 양성모 Shear stress-strain evaluation method for solder joint by micro mechanics test method
KR20120125792A (en) * 2011-05-09 2012-11-19 세종대학교산학협력단 Impact test system using energy frame

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KR20080087290A (en) 2007-03-26 2008-10-01 양성모 Shear stress-strain evaluation method for solder joint by micro mechanics test method
KR20120125792A (en) * 2011-05-09 2012-11-19 세종대학교산학협력단 Impact test system using energy frame

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109580385A (en) * 2018-11-16 2019-04-05 北京东方雨虹防水技术股份有限公司 Waterproof layer resists the test equipment and its test method of underground engineering valve pit subsidence
CN109580385B (en) * 2018-11-16 2022-03-18 北京东方雨虹防水技术股份有限公司 Test equipment and test method for resisting underground engineering settlement damage of waterproof layer
CN112146996A (en) * 2020-08-13 2020-12-29 武汉理工大学 Experimental device for normal disturbance induces rock mass shear fracture
CN112146996B (en) * 2020-08-13 2024-03-08 武汉理工大学 Experimental device for normal disturbance induces rock mass shear fracture
CN113075034A (en) * 2021-03-12 2021-07-06 建华建材（安徽）有限公司 Assembled precast concrete pier tensile strength detection experimental apparatus
KR102534938B1 (en) * 2021-11-30 2023-05-26 국방과학연구소 Shock drop table test device for simulating dynamic shear force on jointed rocks
CN115219351A (en) * 2022-07-07 2022-10-21 武汉科技大学 Blasting vibration simulation device for shear rheological test
CN116952705A (en) * 2023-09-19 2023-10-27 中铁十七局集团第五工程有限公司 Structural bionic basalt fiber reinforced composite material impact resistance detection device
CN116952705B (en) * 2023-09-19 2024-02-20 中铁十七局集团第五工程有限公司 Structural bionic basalt fiber reinforced composite material impact resistance detection device

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