CN114689422A - Pendulum impact testing machine for impact of concrete simply supported beam and impact testing method - Google Patents

Abstract

The invention belongs to the technical field of concrete material testing, and particularly relates to a pendulum impact testing machine for concrete simply supported beam impact and an impact testing method, wherein the pendulum impact testing machine comprises a main support frame, two pendulum releases, a pendulum, a base, a test piece supporting mechanism, a load sensor and a displacement sensor; the main support frame is a T-shaped frame; the two pendulum release devices are fixed at two ends of the main support frame and release the pendulum through the electromagnet; the upper end of the pendulum bob is rotationally connected with the main support frame through a rotating shaft; the base is fixedly connected with the lower end of the main supporting frame; the test piece supporting mechanism is arranged above the base and used for bearing a test piece to be tested; the load sensor is arranged on the base and used for collecting the impact load of the piece to be tested; the displacement sensor is a non-contact displacement sensor or a contact displacement sensor and is used for acquiring the deformation of the piece to be tested. The invention can visually and quantitatively detect the impact resistance of the concrete, has reasonable structural design and accurate and effective measurement data.

Description

Pendulum impact testing machine for impact of concrete simply supported beam and impact testing method

Technical Field

The invention belongs to the technical field of concrete material testing, and particularly relates to a pendulum impact testing machine and an impact testing method for concrete simply supported beam impact.

Background

Concrete is widely used in different types of building structures, and some concrete structures, which are often subjected to impact loads such as waves, explosions or vehicles, have specific requirements on impact resistance, and in order to protect the structures from impact damage in the designed service period, the impact resistance of the concrete used must be known.

In recent years, a large amount of impact test research focuses on response analysis under high-speed impact load, such as bullet impact test, explosion test, hopkinson strut test and the like, and systematic research on impact response under low-speed impact load and characteristics after impact, such as influence of vehicles on concrete infrastructure in traffic accidents, impact response of falling objects on concrete members and the like, is lacking. There are many drawbacks to the low speed impact test specified in the U.S. ACI544 specification, especially the failure rate of the test data is too high. In the current pendulum impact test of the simply supported beam, the impact load and the absorbed energy of the pendulum can only be estimated approximately, and the load-time curve and the deflection-time curve of the test piece can not be measured directly, which are key data for analyzing impact response and characteristics, so that a test device capable of testing the impact resistance characteristics of the concrete intuitively and quantitatively is needed to be developed, and particularly, the direct and stable collection of the load-time curve and the deflection-time curve of the concrete test piece under the impact load is realized.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a pendulum impact testing machine and an impact testing method for concrete simply supported beam impact, which can visually and quantitatively detect the impact resistance characteristic of concrete, have simple structure, reasonable design and accurate and effective measured data and are particularly suitable for the pendulum impact test of the concrete simply supported beam.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a pendulum impact testing machine for concrete simply supported beam impact, comprising:

the main support frame is a T-shaped frame;

the two pendulum releasers are fixed at two ends of the main support frame and release the pendulums through electromagnets;

the upper end of the pendulum is rotationally connected with the main support frame through a rotating shaft;

the base is fixedly connected with the lower end of the main supporting frame;

the test piece supporting mechanism is arranged above the base and used for bearing a test piece to be tested;

the load sensor is arranged on the base and used for collecting the impact load of the piece to be tested;

and the displacement sensor is a non-contact displacement sensor or a contact displacement sensor and is used for acquiring the deformation of the piece to be tested.

Further, the pendulum bob comprises a pendulum bob arm and a hammer head, the upper end of the pendulum bob arm is fixedly connected with the rotating shaft, the lower end of the pendulum bob arm is fixedly connected with the hammer head through a bolt, and when the hammer head rotates to the lowest point, the impact force of the pendulum bob is perpendicular to the to-be-tested part.

Furthermore, the pendulum bob type mechanical hand further comprises a circular dial fixed on the rotating shaft, and a pointer synchronously rotating with the pendulum bob arm is arranged on the circular dial.

Furthermore, the test piece supporting mechanism is a raised bearing platform, the raised bearing platform is fixed on the base, and the test piece to be tested is placed on the raised bearing platform.

Furthermore, a stress steel arm is placed on the raised bearing platform, the rear end of the stress steel arm is fixedly connected with a load sensor through a bolt, the load sensor is horizontally fixed on a load sensor supporting platform through a bolt, the load sensor supporting platform is fixed on the base through a bolt, and the front end of the stress steel arm is an impact-resistant stress blade of a to-be-tested piece.

Furthermore, the non-contact displacement sensor is erected right above the piece to be tested through an external support.

Further, test piece supporting mechanism is including preventing subassembly, preceding object platform and the back bearing platform of kick-backing, preceding object platform and back bearing platform are all fixed on the base, form a recess that can hold the piece of waiting to test jointly, prevent that the subassembly of kick-backing is fixed on the upper portion of preceding object platform of holding.

Furthermore, the anti-rebound assembly comprises a positioning bolt, a bolt knob, a front top plate and a rear top plate, a spring is arranged between the front top plate and the rear top plate, the positioning bolt is fixedly connected with the front top plate, a screw hole is formed in the front object bearing table, and the positioning bolt penetrates through the screw hole and then is fastened through the bolt knob.

Furthermore, a pore channel for allowing a blade at the front end of the U-shaped stress steel arm to penetrate through is arranged on the rear bearing platform, the U-shaped stress steel arm is placed on the rear bearing platform, the rear end of the U-shaped stress steel arm is fixedly connected with a load sensor through a bolt, the load sensor is horizontally fixed on a load sensor supporting platform through a bolt, and the load sensor supporting platform is fixed on the base through a bolt; the contact type displacement sensor is arranged on the inner side of the rear bearing platform.

The invention also provides an impact test method based on the pendulum impact tester for the concrete simply supported beam impact, which comprises the following steps:

step 1, fixing a pendulum at an initial height through a pendulum releaser;

step 2, placing the to-be-tested piece on the raised bearing platform, aligning the middle part of the to-be-tested piece with the blade of the stressed steel arm, and adjusting the position of an impact point; or the to-be-tested piece is placed in a groove formed by the front object bearing table and the rear bearing table, the position of the impact point is adjusted, the to-be-tested piece is respectively contacted with the rear top plate and the cutting edge at the front end of the U-shaped stress steel arm, and the to-be-tested piece is placed completely;

step 3, debugging and calibrating the displacement sensor and the load sensor, and confirming the normal operation of the signal acquisition instrument and the control computer;

and 4, releasing the pendulum bob by the pendulum bob releaser, impacting the piece to be tested, recording the swing angle of the pendulum bob, calculating the impact energy consumption of the piece to be tested, and simultaneously recording the change curves of the impact load and the deflection of the test piece along with time, thereby completing the test.

Compared with the prior art, the invention has the following advantages:

1. the load sensor can directly and stably acquire the load-time curve of the piece to be tested in the instantaneous impact process, and the method is different from the qualitative analysis and load estimation of the concrete impact resistance by the predecessors.

2. The displacement sensor can intuitively and real-timely acquire the deformation deflection-time curve of the piece to be tested under the action of the impact load, and is different from the traditional test method, the traditional test method only focuses on the form after impact damage, and ignores the dynamic response change of the concrete material, so that the invention can more clearly represent the impact response characteristic of the concrete.

3. The pendulum release releases the pendulum through the electromagnet, so that the pendulum is released without initial speed, and test errors are reduced.

4. The pendulum arm is fixedly connected with the hammer head through the bolt, the hammer head is various in form, and the hammer head can be replaced by disassembling the bolt, so that the pendulum arm is suitable for pieces to be tested with different sizes, and the impact response test under different impulses is realized.

5. The pendulum impact testing machine for concrete simply supported beam impact has the advantages of simple structure, reasonable design and high testing accuracy, and greatly improves the testing efficiency.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic structural view of a pendulum impact tester for impact of a concrete simply supported beam according to a first embodiment of the present invention;

FIG. 2 is a schematic structural view of a pendulum impact tester for impact of a concrete simply supported beam according to a second embodiment of the present invention;

fig. 3 is a schematic structural view of an antirebound assembly according to a second embodiment of the present invention.

The reference numbers in the figures denote:

1. the test device comprises a main support frame, 2 parts of a pendulum release, 301 parts of a pendulum arm, 302 parts of a hammer head, 4 parts of a base, 5 parts of a load sensor, 6 parts of a non-contact displacement sensor, 7 parts of a contact displacement sensor, 8 parts of a circular dial, 9 parts of a raised bearing platform, 10 parts of a to-be-tested piece, 11 parts of a stressed steel arm, 12 parts of a load sensor support platform, 13 parts of a front bearing platform, 14 parts of a rear bearing platform, 15 parts of a positioning bolt, 16 parts of a bolt knob, 17 parts of a front top plate, 18 parts of a rear top plate, 19 parts of a spring, 20 parts of a U-shaped stressed steel arm, 21 parts of a signal acquisition instrument and 22 parts of a control computer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

As shown in fig. 1, the pendulum impact testing machine for concrete simply supported beam impact of the embodiment comprises a main support frame 1, two pendulum releasers 2, a pendulum, a base 4, a test piece supporting mechanism, a load sensor 5 and a displacement sensor; the main support frame 1 is a T-shaped frame; the two pendulum releasers 2 are fixed at two ends of the main support frame 1 through bolts, the pendulum releasers 2 are used for fixing and releasing pendulum weights, generally, the pendulum releasers 2 adopt electromagnets to release pendulum weights, the initial speed is zero when releasing is guaranteed, and the test error is reduced; the upper end of the pendulum bob is rotationally connected with the main support frame 1 through a rotating shaft, and the pendulum bob and the rotating shaft rotate together; the base 4 is fixedly connected with the lower end of the main support frame 1 and can be fixed by welding; the test piece supporting mechanism is arranged above the base 4 and used for bearing a test piece 10 to be tested; the load sensor 5 is arranged on the base 4 and used for collecting the impact load of the piece to be tested 10; the displacement sensor is used for acquiring the deformation of the piece to be tested 10; the load sensor 5 and the displacement sensor are connected with a control computer 22 through a signal acquisition instrument 21, and the change curves of the load and the deflection along with the time can be displayed on the control computer 22.

The pendulum bob comprises a pendulum bob arm 301 and a hammer head 302, the hammer head 302 is made of steel with enough rigidity, the upper end of the pendulum bob arm 301 is fixedly connected with a rotating shaft, the rotating shaft is connected with the main support frame 1 through a bearing, the lower end of the pendulum bob arm 301 is fixedly connected with the hammer head 302 through a bolt, and when the hammer head 302 rotates to the lowest point, the impact force of the pendulum bob is vertical to the to-be-tested piece 10; the replacement of different models of hammers 302 can be performed by disassembling the bolts to be suitable for different sizes of the to-be-tested pieces 10.

Pendulum impact tester still includes the circular dial 8 of fixing in the axis of rotation, be equipped with the pointer with pendulum arm 301 synchronous rotation on the circular dial 8, conveniently show turned angle.

The test piece supporting mechanism is a convex bearing platform 9, the convex bearing platform 9 is fixed on the base 4, the piece to be tested 10 is placed on the convex bearing platform 9, the convex bearing platform 9 is used for correctly placing the piece to be tested 10, and the normal damage form of the test piece cannot be influenced in the impact process.

The stress steel arm 11 is placed on the protruding cushion cap 9, the rear end of the stress steel arm 11 is fixedly connected with the load sensor 5 through a bolt, the load sensor 5 is horizontally fixed on the load sensor supporting table 12 through a bolt, the load sensor supporting table 12 is fixed on the base 4 through a bolt, and the front end of the stress steel arm 11 is an impact-resistant stress blade of the to-be-tested piece 10. The impact load data of the piece to be tested 10 is collected by the signal collector 21 and the control computer 22.

The displacement sensor adopts a non-contact displacement sensor 6, is erected right above the piece to be tested 10 through an external bracket so as to accurately acquire the deformation of the piece to be tested 10, and acquires the deformation data of the piece to be tested 10 through a signal acquisition instrument 21 and a control computer 22.

The embodiment also provides an impact test method based on the pendulum impact tester for the impact of the concrete simply supported beam, which comprises the following steps:

in step S101, the bob is fixed at the initial height by the bob releaser 2.

Step S102, placing the piece to be tested 10 on the raised bearing platform 9, aligning the middle part of the piece to be tested 10 with the blade of the stressed steel arm 11, adjusting the position of the impact point, and finishing placing the piece to be tested 10.

Step S103, debugging and calibrating the non-contact displacement sensor 6 and the load sensor 5, and confirming the normal operation of the signal acquisition instrument 21 and the control computer 22.

And step S104, the pendulum release 2 releases the pendulum to impact the piece to be tested 10, the swing angle of the pendulum is recorded, the energy absorbed by the piece to be tested 10 is accurately calculated according to the potential energy conversion principle, and the change curves of the impact load and the deflection of the test piece along with time are recorded, so that the test is completed.

Example two

This embodiment is substantially the same as the first embodiment, and the same parts are not described again, but the differences are as follows:

as shown in fig. 2, the test piece supporting mechanism includes a rebound prevention assembly, a front object bearing table 13 and a rear object bearing table 14, the front object bearing table 13 and the rear object bearing table 14 are both fixed on the base 4 and jointly form a groove capable of accommodating the test piece 10 to be tested, the rebound prevention assembly is fixed on the upper portion of the front object bearing table 13, the rebound prevention assembly prevents the test piece 10 to be tested from generating large displacement under the impact action, and the rebound prevention assembly plays a role in buffering; as shown in fig. 3, the rebound prevention assembly comprises a positioning bolt 15, a bolt knob 16, a front top plate 17 and a rear top plate 18, a spring 19 is arranged between the front top plate 17 and the rear top plate 18, the positioning bolt 15 is fixedly connected with the front top plate 17, a screw hole is formed in the front object bearing table 13, and the positioning bolt 15 penetrates through the screw hole and then is fastened by the bolt knob 16; the rear bearing platform 14 is provided with a hole for enabling a blade at the front end of the U-shaped stress steel arm 20 to penetrate through, the U-shaped stress steel arm 20 is placed on the rear bearing platform 14, the rear end of the U-shaped stress steel arm 20 is fixedly connected with the load sensor 5 through a bolt, the load sensor 5 is horizontally fixed on the load sensor supporting platform 12 through a bolt, and the load sensor supporting platform 12 is fixed on the base 4 through a bolt. The displacement sensor is a contact displacement sensor 7, is arranged on the inner side of the rear bearing platform 14, and acquires deformation data of the piece to be tested 10 under the impact action through a signal acquisition instrument 21 and a control computer 22. It should be noted that enough specimen damage space should be left between the main support frame 1 and the front and rear object-bearing tables 13, 14 so as not to affect the test effect.

The embodiment also provides an impact test method based on the pendulum impact tester for the impact of the concrete simply supported beam, which comprises the following steps:

in step S101, the bob is fixed at the initial height by the bob releaser 2.

Step S102, placing the piece to be tested 10 in a groove formed by the front object bearing table 13 and the rear bearing table 14, adjusting the position of an impact point, and enabling the piece to be tested 10 to be respectively contacted with the rear top plate 18 and the front end blade of the U-shaped stress steel arm 20, wherein the piece to be tested 10 is placed completely.

Step S103, debugging and calibrating the non-contact displacement sensor 6 and the load sensor 5, and confirming the normal operation of the signal acquisition instrument 21 and the control computer 22.

And step S104, the pendulum release 2 releases the pendulum to impact the piece to be tested 10, the swing angle of the pendulum is recorded, the impact energy consumption of the piece to be tested 10 is accurately calculated according to the potential energy conversion principle, and simultaneously, the change curves of the impact load and the deflection of the test piece along with time are recorded, so that the test is completed.

In a word, the impact testing machine is reasonable in structural design, and a load-time curve and a deflection-time curve of the piece to be tested 10 under the impact action can be directly measured through the impact testing machine, so that the impact testing result of the concrete simply supported beam is more accurate.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Finally, it is to be noted that: the above description is only a preferred embodiment of the present invention, and is only used to illustrate the technical solutions of the present invention, and not to limit the protection scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. The utility model provides a concrete simple beam strikes and uses pendulum impact tester which characterized in that includes:

the main support frame is a T-shaped frame;

the two pendulum releasers are fixed at two ends of the main support frame and release the pendulums through electromagnets;

the upper end of the pendulum is rotationally connected with the main support frame through a rotating shaft;

the base is fixedly connected with the lower end of the main supporting frame;

the test piece supporting mechanism is arranged above the base and used for bearing a test piece to be tested;

the load sensor is arranged on the base and used for collecting the impact load of the piece to be tested;

and the displacement sensor is a non-contact displacement sensor or a contact displacement sensor and is used for acquiring the deformation of the piece to be tested.

2. The pendulum impact testing machine for concrete simply supported beam impact according to claim 1, wherein the pendulum comprises a pendulum arm and a hammer head, the upper end of the pendulum arm is fixedly connected with the rotating shaft, the lower end of the pendulum arm is fixedly connected with the hammer head through a bolt, and when the hammer head rotates to the lowest point, the pendulum impact force is perpendicular to the to-be-tested member.

3. The pendulum impact tester for concrete simply supported beam impact according to claim 2, further comprising a circular scale fixed on the rotation shaft, wherein the circular scale is provided with a pointer rotating synchronously with the pendulum arm.

4. The pendulum impact tester for concrete simply supported beam impact according to claim 1, wherein the test piece supporting mechanism is a raised platform, the raised platform is fixed on the base, and the test piece to be tested is placed on the raised platform.

5. The pendulum impact testing machine for concrete simply supported beam impact according to claim 4, characterized in that a stressed steel arm is placed on the raised bearing platform, the rear end of the stressed steel arm is fixedly connected with a load sensor through a bolt, the load sensor is horizontally fixed on a load sensor supporting platform through a bolt, the load sensor supporting platform is fixed on a base through a bolt, and the front end of the stressed steel arm is an impact-resistant stressed blade of a to-be-tested piece.

6. The pendulum impact tester for concrete simply supported beam impact according to claim 5, wherein the non-contact displacement sensor is erected directly above a test piece through an external bracket.

7. The pendulum impact tester for concrete simply supported beam impact according to claim 1, wherein the test piece supporting mechanism comprises an anti-rebound assembly, a front object bearing table and a rear object bearing table, the front object bearing table and the rear object bearing table are fixed on the base and jointly form a groove capable of accommodating a test piece to be tested, and the anti-rebound assembly is fixed on the upper portion of the front object bearing table.

8. The pendulum impact testing machine for concrete simply supported beam impact according to claim 7, wherein the rebound prevention assembly comprises a positioning bolt, a bolt knob, a front top plate and a rear top plate, a spring is arranged between the front top plate and the rear top plate, the positioning bolt is fixedly connected with the front top plate, a screw hole is formed in the front object bearing platform, and the positioning bolt is fastened by the bolt knob after passing through the screw hole.

9. The pendulum impact testing machine for concrete simply supported beam impact according to claim 8, wherein the rear bearing platform is provided with a hole for a blade at the front end of a U-shaped stressed steel arm to pass through, the U-shaped stressed steel arm is placed on the rear bearing platform, the rear end of the U-shaped stressed steel arm is fixedly connected with a load sensor through a bolt, the load sensor is horizontally fixed on a load sensor supporting platform through a bolt, and the load sensor supporting platform is fixed on a base through a bolt; the contact type displacement sensor is arranged on the inner side of the rear bearing platform.

10. An impact test method based on a pendulum impact tester for impact of concrete simple-supported beams according to any one of claims 1 to 9, characterized by comprising the steps of:

step 1, fixing a pendulum at an initial height through a pendulum releaser;

step 2, placing the to-be-tested piece on the raised bearing platform, aligning the middle part of the to-be-tested piece with the blade of the stressed steel arm, and adjusting the position of an impact point; or the to-be-tested piece is placed in a groove formed by the front object bearing table and the rear bearing table, the position of the impact point is adjusted, the to-be-tested piece is respectively contacted with the rear top plate and the cutting edge at the front end of the U-shaped stress steel arm, and the to-be-tested piece is placed completely;

step 3, debugging and calibrating the displacement sensor and the load sensor, and confirming the normal operation of the signal acquisition instrument and the control computer;

and 4, releasing the pendulum bob by the pendulum bob releaser, impacting the piece to be tested, recording the swing angle of the pendulum bob, calculating the impact energy consumption of the piece to be tested, and simultaneously recording the change curves of the impact load and the deflection of the test piece along with time, thereby completing the test.

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