CN112432753A - Beam structure vibration fatigue device - Google Patents
Beam structure vibration fatigue device Download PDFInfo
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- CN112432753A CN112432753A CN202011248487.7A CN202011248487A CN112432753A CN 112432753 A CN112432753 A CN 112432753A CN 202011248487 A CN202011248487 A CN 202011248487A CN 112432753 A CN112432753 A CN 112432753A
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M7/00—Vibration-testing of structures; Shock-testing of structures
- G01M7/02—Vibration-testing by means of a shake table
- G01M7/06—Multidirectional test stands
Abstract
The invention relates to a beam structure vibration fatigue device which comprises a beam test piece, a beam end clamping seat, a vibration platform, a vibration motor, a vibration isolation spring and a base, wherein one end of the beam test piece is arranged on the beam end clamping seat or two ends of the beam test piece are arranged on the beam end clamping seat, the beam end clamping seat is arranged on the vibration platform, the vibration motor is arranged on the vibration platform, an eccentric block is arranged on an output shaft of the vibration motor, the vibration isolation spring supports the vibration platform, one end of the vibration isolation spring is connected to the base, and the other end of the vibration isolation spring is connected with the vibration platform. Under the action of exciting force, the vibration platform and the accessory mounted on the vibration platform can generate forced vibration. The beam test piece and the beam end clamping seat can vibrate along with the vibration platform. Because the end part of the beam test piece is fixed, the vibration deformation part of the beam test piece is not connected with the vibration platform, the vibration deformation of the beam test piece does not influence the vibration of the vibration platform, and the distortion degree of the generated vibration waveform is small. In addition, the invention can realize the fatigue test of the cantilever beam, the simply supported beam and the fixed beams at two ends by one device.
Description
Technical Field
The invention relates to the field of fatigue testing machines, in particular to a beam structure vibration fatigue device.
Background
The beam structure is widely applied to the fields of aerospace, energy power, machinery, construction and the like, such as helicopter rotors, bridge crane main beams, elastic foundation beams, vibrating screen bearing beams and the like. Most beam structures are often subjected to alternating stresses during operation and use, and fatigue cracks are easily formed. Under the action of dynamic load interception, the cracks can continuously expand and cause fracture, so that stable operation of production is influenced slightly, and disaster accidents are induced seriously. For example, in the early 1981, the platform of the 'Kirland' number in the European North sea oil field is covered out, and the accident is caused by the fact that the bearing holes of the cross beams are cracked due to fatigue under the alternating stress of sea waves. According to data statistics, the structural failure fracture accidents caused by fatigue cracks account for more than 70-80% of the total fracture accidents. Therefore, the research on the fatigue fracture reasons of the beam structure has very important practical significance and theoretical value for accurately setting the service life and the overhaul period and reducing the generation of fatigue accidents.
The existing fatigue testing machine products mainly comprise an electro-hydraulic servo fatigue testing machine and an electromagnetic resonance type high-frequency fatigue testing machine, and the two types of fatigue testing machines cannot realize symmetrical bending periodic loading on a beam test piece. In order to perform a fatigue test on a beam test piece or a plate test piece, some scholars prepared fatigue test devices for a crack beam, a crack plate, and a crack blade. For example, a paper OF "High resolution growing quantities in vibrating beams" is published in 1997, 3.s.1997, journal OF FATIGUE & frame OF ENGINEERING MATERIALS & sturcules, volume 20, stage 7, and the paper discloses a vibration FATIGUE test device for a crack beam, which mainly comprises a sensing coil, an actuating coil, a laser sensor, a feedback control loop and a current amplifier, and drives a crack beam test piece to vibrate through electromagnetism. In the article of ' mechanical properties and tests of crack plates under dynamic environment ' published in journal of mechanical science and technology ' volume 19, supplement in 2000 and 9 months, a vibration fatigue test device containing the crack plates is disclosed, the device comprises a rotary fatigue test machine, an eccentric wheel, a pulley, a steel wire rope, a spring, a connecting piece and a test piece, in the test process, the eccentric wheel is driven to transport by the rotary fatigue test machine, and vibration load is applied to a thin plate by the spring. The thesis of Master academic thesis of Zhejiang university in 6 Yue 2006 "turbine blade vibration fatigue test and automatic control system development" discloses a vibration fatigue testing machine, which comprises an eccentric wheel, an eccentric wheel rotating shaft, a sliding column, a turbine blade and a proximity switch induction area. The eccentric wheel is driven by a driving motor to rotate, the position of the rotating shaft on the wheel surface can be changed by adjusting the upper bolt and the lower bolt of the rotating wheel, so that the rotating wheel rotates eccentrically, and the adjusting range is 0-10 mm. The sliding column is connected between the eccentric wheel and the blade, and converts the periodic motion of the eccentric wheel into the up-and-down vibration of the blade. The 2009 journal, "structural strength research" 2 nd published a paper of "fatigue test analysis of airplane horizontal tail vibration", and the test device includes a vibration exciter, a sensor, a counterweight, a horizontal tail and a rigid base, wherein a large shaft of the horizontal tail is fixed on the rigid base, and fatigue test is performed by vibration excitation of the vibration exciter. However, the vibration fatigue test time is long, and the vibration exciter is difficult to bear, so that the vibration exciter is often required to be stopped and rested regularly.
According to the excitation mode, the main excitation methods of the fatigue testing machine are as follows: exciter excitation, inertial excitation, and electromagnetic excitation. The fatigue test device of exciter excitation and inertia excitation belongs to mechanical excitation, in order to transmit excitation force to a test piece, a power transmission output end is connected to the test piece, and the test piece is mechanically connected with an excitation source. In order to transmit power, a mechanical transmission system is required for power transmission, and the structure of the transmission system is complex. In addition, the excitation source, the mechanical transmission system and the test piece together form a vibration system. When a test piece fatigue test is carried out, the excitation source transmits power through the mechanical transmission part, and vibration deformation of the test piece is realized. However, since the test piece belongs to the execution end of the mechanical transmission system, there is an interaction force between the test piece and the mechanical transmission system, and the vibration deformation of the test piece affects the output waveform and precision of the mechanical transmission system. At this time, the vibration of the test piece affects the power transmission, so that the waveform distortion is serious and the structure of the apparatus is complicated. The electromagnetic fatigue testing machine has the advantages that the electromagnetic force can be directly obtained, a transmission member is not needed, the vibration of a test piece does not influence the output of an excitation source, and therefore the output waveform distortion degree is small. However, the electromagnetic fatigue test system is limited by inherent magnetic saturation, is greatly influenced by a power supply voltage, is limited in the maximum excitation force of output, and is poor in low-frequency performance.
In addition, for the vibration exciter excitation and inertia type excitation beam structure fatigue test system, in order to transfer larger amplitude, a beam test piece is generally designed into a cantilever beam structure, and the mechanical transmission tail end is often directly connected with one end of the cantilever beam. The fatigue testing machine has the greatest characteristic of obtaining larger amplitude, but due to structural shape limitation, the fatigue testing machine is often designed to be only capable of completing the fatigue test of a single cantilever beam structure, cannot conveniently change a constraint mode, and is used for the fatigue test of other constraint types of beam structures, such as a simply supported beam and a beam fixed at two ends. That is to say, at present, the structural style of the existing beam structure fatigue test device can generally only complete the fatigue test of a single cantilever beam structure, and one device can not be realized to complete the vibration fatigue test of various beam structure types.
In engineering practice, beam structures can be divided into structural forms such as cantilever beams, simply supported beams and fixed beams at two ends according to the constraint types of the beams. For example, the wind turbine blade is regarded as a cantilever beam structure, the main beam of the bridge crane is regarded as a simple beam structure, and the bearing beam of the vibrating screen is regarded as a fixed beam structure at two ends. Therefore, according to the constraint mode, the beam structure is not limited to the cantilever beam structure form, and also comprises a simply supported beam, a two-end fixed beam and other structure forms. Therefore, through a fatigue test device, realize cantilever beam, simple beam and both ends fixed beam's fatigue test device simultaneously, to improve equipment function, have important practical meaning.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the beam structure vibration fatigue device which has small distortion degree of output vibration waveform and can simultaneously complete the fatigue test of a cantilever beam, a simply supported beam and a fixed beam at two ends.
In order to achieve the purpose, the invention adopts the following technical scheme: the utility model provides a beam structure vibration fatigue device, includes beam test piece, beam-ends grip slipper, vibration platform, vibrating motor, vibration isolation spring, base, the one end of beam test piece is installed on the beam-ends grip slipper or the both ends of beam test piece are installed on the beam-ends grip slipper, and the beam-ends grip slipper is installed on vibration platform, and vibrating motor installs on vibration platform, and vibrating motor's output shaft is equipped with the eccentric block, vibration isolation spring supporting vibration platform, one end are connected on the base, and the other end is connected with vibration platform, the beam-ends grip slipper has the fixed grip slipper of beam-ends and the rotatable grip slipper of beam-ends.
Furthermore, in order to test the fatigue characteristic of the hinged beam with one fixed end and the other fixed end, the top surface and the bottom surface of one end of the beam test piece are provided with arc-shaped grooves, the top surface and the bottom surface of the other end of the beam test piece are planes, one end of the beam test piece with the arc-shaped grooves is installed on the beam end rotatable clamping seat, the other end of the beam test piece is installed on the beam end fixed clamping seat, and the beam end rotatable clamping seat and the beam end fixed clamping seat are oppositely installed on the vibration platform; the beam end rotatable clamping seat comprises an upper clamping block, a lower clamping block and a support, the lower clamping block is fixedly connected with the support through screws, the upper clamping block is fixedly connected with the lower clamping block through screws, elongated protrusions are arranged on the bottom surface of the upper clamping block and the middle portion of the top surface of the lower clamping block, the tops of the protrusions are arc-shaped heads, the shapes of the arc-shaped heads are matched with those of arc-shaped grooves of a beam test piece, the elongated protrusions of the upper clamping block are pressed in the arc-shaped grooves of the top surface of the beam test piece, and the elongated protrusions of the lower clamping block are abutted against the arc-shaped grooves of the bottom; the beam end fixing and clamping seat comprises an upper chuck, a lower chuck and a supporting seat, the lower chuck and the supporting seat are connected through screws, the upper chuck and the lower chuck are connected through screws, the middle parts of the upper chuck and the lower chuck are provided with strip-shaped convex blocks, the end faces of the strip-shaped convex blocks are planes, the strip-shaped convex blocks of the upper chuck are pressed on the plane of the top end of a beam test piece, and the convex blocks of the lower chuck are pressed on the plane of the bottom end of the beam test piece.
In order to test the fatigue characteristics of the fixed beams at the two ends, the top surface and the bottom surface at one end of the beam test piece are planes, the top surface and the bottom surface at the other end of the beam test piece are also planes, the two ends of the beam test piece are both arranged on the beam end fixing clamping seats, and the two beam end fixing clamping seats are identical in structural shape and are oppositely arranged on the vibration platform; the beam end fixing and clamping seat comprises an upper chuck, a lower chuck and a supporting seat, the lower chuck and the supporting seat are connected through screws, the upper chuck and the lower chuck are connected through screws, the middle parts of the upper chuck and the lower chuck are provided with strip-shaped convex blocks, the end faces of the strip-shaped convex blocks are planes, the strip-shaped convex blocks of the upper chuck are pressed on the plane of the top end of a beam test piece, and the convex blocks of the lower chuck are pressed on the plane of the bottom end of the beam test piece.
In order to test the fatigue characteristics of the hinged beams at the two ends, the top surface and the bottom surface of one end of the beam test piece are provided with arc-shaped grooves, the top surface and the bottom surface of the other end of the beam test piece are also provided with arc-shaped grooves, the two ends of the beam test piece are both arranged on the beam end rotatable clamping seats, the two beam ends of the two beam ends have the same rotatable structural shape and are oppositely arranged on the vibration platform; the rotatable grip slipper of beam-ends includes clamp splice, clamp splice and support down, and clamp splice and support pass through screw fixed connection down, go up the clamp splice and pass through screw fixed connection with clamp splice down, and the bottom surface of going up the clamp splice and the top surface middle part of clamp splice down are equipped with rectangular shape arch, and protruding top is the arc head, and the arc head shape matches with the arc wall of beam test piece, goes up the rectangular shape arch of clamp splice and presses in the arc wall of beam test piece top surface, and the rectangular shape arch top of lower clamp splice is in the arc wall of beam test piece bottom surface.
In order to test the fatigue property of the cantilever beam, the top surface and the bottom surface of the fixed end part of the beam test piece are planes, the top surface and the bottom surface of the other end of the beam test piece are also planes, one end of the beam test piece is installed on the beam end fixing clamping seat, and the other end of the beam test piece is not fixed and can freely vibrate. The beam end fixing and clamping seat is arranged on the vibration platform; the beam end fixing and clamping seat comprises an upper chuck, a lower chuck and a supporting seat, the lower chuck and the supporting seat are connected through screws, the upper chuck and the lower chuck are connected through screws, the middle parts of the upper chuck and the lower chuck are provided with strip-shaped convex blocks, the end faces of the strip-shaped convex blocks are planes, the strip-shaped convex blocks of the upper chuck are pressed on the plane of the top end of a beam test piece, and the convex blocks of the lower chuck are pressed on the plane of the bottom end of the beam test piece.
Preferably, the vibration platform is provided with a side wall protruding out of the platform, the beam end fixing and clamping seat is a pressing plate, one end or two ends of the beam test piece are arranged between the pressing plate and the side wall, and the pressing plate is directly and fixedly arranged on the side wall through screws.
Furthermore, the vibration motor is a variable frequency speed regulation motor, and the variable frequency speed regulation motor is electrically connected with the frequency converter.
Preferably, the vibration motor is a single-phase series motor, and the single-phase series motor is electrically connected with a single-phase voltage regulator.
The beam test piece is provided with a balancing weight, the balancing weight comprises an upper balancing weight and a lower balancing weight, the structural shapes and the sizes of the upper balancing weight and the lower balancing weight are consistent, the upper balancing weight is arranged above the beam test piece, the lower balancing weight is arranged below the beam test piece, and the upper balancing weight and the lower balancing weight are connected through a bolt.
And a notch is arranged on the beam test piece.
The invention has the beneficial effects that: the beam structure vibration fatigue device has small distortion degree of output vibration waveform and can simultaneously complete fatigue tests of a cantilever beam, a simply supported beam and two end fixed beams. Because the beam structure vibration fatigue device includes beam test piece, beam-ends grip slipper, vibration platform, vibrating motor, vibration isolation spring, base. The vibrating motor is arranged on the vibrating platform, and an eccentric block is arranged on an output shaft of the vibrating motor. When the vibration motor is in transit, the eccentric block generates eccentric excitation force. Under the action of the exciting force, the vibration platform and the accessory mounted on the vibration platform can generate forced vibration. The beam test piece and the beam clamping seat can vibrate along with the vibration platform.
Because the beam test piece has weight, the beam test piece is under the action of reciprocating inertia excitation force when moving along with the vibration platform. The rotating speed of the vibration motor is adjusted, so that the rotating frequency of the vibration motor is close to or equal to the natural frequency of the beam test piece, the beam test piece can resonate, large amplitude is generated, the working efficiency of a fatigue test is improved, and the energy consumption is reduced. In the fatigue device, the end part of the beam test piece is fixed, the vibration deformation part of the beam test piece is not connected with the vibration platform, and the vibration deformation of the beam test piece does not influence the vibration of the vibration platform. That is, no transmission member is required to be arranged between the vibration deformation of the beam test piece and the vibration platform. Thus, the vibration of the beam test piece has very little effect on the vibration platform. Thus, the vibration platform output vibration waveform is stabilized. The beam test piece is excited by a stable waveform, and the generated vibration waveform has small distortion degree.
In addition, because the beam structure vibration fatigue device includes the beam-ends grip slipper, the beam-ends grip slipper has fixed grip slipper of beam-ends and rotatable grip slipper of beam-ends. Like this, the optional beam-ends grip slipper in one end or both ends of roof beam test piece to constitute the beam structure of different restraint types, can carry out the fatigue test of cantilever beam, simple beam, both ends fixed beam. For example, when one end of the beam test piece is clamped on the beam end fixing and clamping seat, and the other end is free, a cantilever beam structure is formed. When the two ends of the beam test piece are clamped on the beam end rotatable clamping seat, a simply supported beam structure is formed. When the two ends of the beam test piece are clamped on the beam end fixing and clamping seat, a two-fixing beam structure is formed. Therefore, the invention can realize the fatigue test of the cantilever beam, the simply supported beam and the fixed beams at two ends by one device.
Drawings
FIG. 1 is a schematic structural diagram of a first embodiment of the beam structure vibration fatigue device of the present invention, when the device is used for a fatigue test of a beam with one end fixed and one end hinged;
FIG. 2 is a schematic structural view of the support joint of FIG. 1;
FIG. 3 is a schematic view of the vibration motor shown in FIG. 1 with a protective cover removed from one end;
FIG. 4 is a schematic diagram of the eccentric block structure of FIG. 3
FIG. 5 is a schematic structural view of the beam specimen of FIG. 1 mounted on the beam-end rotatable supporting seat and the beam-end fixed clamping seat;
FIG. 6 is a cross-sectional structural schematic view of the beam specimen of FIG. 5;
FIG. 7 is a schematic view of the inertial excitation of the vibration motor of FIG. 1;
FIG. 8 is a schematic structural view of a second embodiment of the beam structure vibration fatigue device of the present invention when used in a fatigue test of a fixed beam at both ends;
FIG. 9 is a schematic structural view of the beam specimen of FIG. 8 mounted on two beam-end fixing clamps;
FIG. 10 is a cross-sectional view of the beam specimen of FIG. 9;
FIG. 11 is a schematic structural view of a beam specimen mounted on two beam-end rotatable clamping seats in a third embodiment when the beam structure vibration fatigue device of the present invention is used in a fatigue test of a two-end hinged beam;
FIG. 12 is a cross-sectional structural schematic view of the beam specimen of FIG. 11;
FIG. 13 is a schematic structural view of a fourth embodiment of the beam structure vibration fatigue device of the present invention when used in a cantilever fatigue test;
FIG. 14 is a schematic view of the beam end fixture for mounting the beam specimen of FIG. 13;
FIG. 15 is a top view of the beam specimen of FIG. 14;
FIG. 16 is a schematic structural view of a fifth embodiment of the beam structure vibration fatigue device of the present invention when used in a notched cantilever fatigue test;
FIG. 17 is a schematic structural view of the cantilever test piece with a notch in FIG. 16 mounted on a beam-end holder;
FIG. 18 is a top view of the notched cantilever test piece of FIG. 17;
FIG. 19 is a schematic structural view of a sixth embodiment of the beam structure vibration fatigue device of the present invention, when used in a fatigue test of a fixed beam at both ends;
FIG. 20 is a top view of the beam trial of FIG. 19;
Detailed Description
The first embodiment is as follows:
as can be seen from fig. 1, the beam structure vibration fatigue device shown in the first embodiment includes a base 1, a support column 11, a vibration isolation spring 2, a vibration platform 3, a support joint 31, a beam end clamping seat 4, a beam test piece 5, and a vibration motor 6. Four T-shaped supporting columns 11 are welded at four corners of the base 1, the vibration isolation springs 2 are metal spiral column compression springs, the supporting columns 11 are welded with bottom end spring coils of the vibration isolation springs 2, and top end spring coils of the vibration isolation springs 2 are welded with the supporting joints 31. As can be seen from fig. 2, the supporting joint 31 includes three parts, a disk 312 is provided in the middle, a spring guide column 311 and a supporting cylinder 313 are provided at the two ends, the top coil of the supporting spring 2 is welded to the bottom surface of the disk 312 through the spring guide column 311, and the top surface of the supporting cylinder 313 is welded to the bottom surface of the vibration platform 3, so that the four vibration isolation springs 2 are used to support the vibration platform 3. The middle of the vibration platform 3 is flat, and the periphery is provided with a side wall 32 which is square. Two vibration motors 6 are arranged on the bottom surface of the vibration platform 3, the vibration motors 6 are variable-frequency speed-regulating motors, and the two variable-frequency speed-regulating motors are arranged side by side to form a two-shaft type inertia vibration exciter. In order to adjust the running frequency of the vibration motor, the variable-frequency speed-regulating motor is electrically connected with the frequency converter. Referring to fig. 3 and 4, an eccentric block 61 is mounted on the output shaft of the variable frequency adjustable speed motor, and the eccentric block 61 is made of Q235. The eccentric block 61 comprises a semicircular block 611 and a semicircular ring-shaped latch 612, one end of the latch 612 is integrally formed with the semicircular block 611, the other end is provided with a protruding boss 613, and a through hole is formed in the protruding boss 613. The semicircular block 611 and the latch 612 are formed with a latch hole 614 in the surrounding area, and the motor output shaft is installed in the latch hole 614. A screw hole is formed at a position corresponding to the semicircular block 611 of the latch 612 below the through hole of the protrusion boss 613, and a fastening screw 615 passes through the through hole and is coupled to the screw hole to fix the eccentric block 61 to the output shaft of the vibration motor. In order to prevent dust and ensure safety, a protective cover 62 is also arranged on the variable frequency speed regulating motor. In order to adjust the rotating speed of the vibration motor, the variable-frequency speed-regulating motor is electrically connected with the frequency converter, so that the beam test piece generates resonance in the test.
Referring to fig. 5, the beam specimen of this embodiment has one fixed end and one rotatable end. Referring to fig. 6, the top and bottom surfaces of one end of the beam specimen are provided with arc-shaped grooves 51, and the top and bottom surfaces of the other end are flat surfaces. The beam end holder comprises a beam end rotatable holder 41 and a beam end fixed holder 42. The beam end rotatable clamping seat 41 and the beam end fixed clamping seat 42 are oppositely arranged on the vibration platform 3.
The beam-end rotatable clamp 41 includes an upper clamp block 411, a lower clamp block 412 and a support 413. The lower clamping block 412 and the support 413 are fixedly connected by four lower countersunk screws 416. The upper clamping block 411 and the lower clamping block 412 are fixedly connected through four upper countersunk head screws 417. The upper and lower clamping blocks 411, 412 can be separated by loosening the four upper countersunk screws 417. The middle of the bottom surface of the upper clamping block 411 and the middle of the top surface of the lower clamping block 412 are provided with elongated protrusions 414, the top of each elongated protrusion 414 is an arc-shaped head 415, the shape of each arc-shaped head 415 is matched with the corresponding arc-shaped groove 51, the elongated protrusions 414 of the upper clamping block are pressed in the arc-shaped grooves 51 on the top surface of the beam test piece 5, and the elongated protrusions of the lower clamping block 412 are pressed in the arc-shaped grooves on the bottom surface of the beam test piece. Thus, the end of the beam specimen 5 can rotate due to the matching of the elongated projections and the arc-shaped grooves. The beam specimen 5 is rotatably connected with the beam end rotatable clamp 41.
The beam-end fixing holder 42 includes an upper jaw 421, a lower jaw 422, and a support seat 423. The lower jaw 422 and the support base 423 are connected by a lower countersunk head screw. The upper and lower chucks 421 and 422 are connected by an upper countersunk screw. The middle parts of the upper clamping head 421 and the lower clamping head 422 are provided with elongated lugs 424, and the end surfaces of the elongated lugs are planes. The elongated tab 424 of the upper clamp rests on the top plane of the beam specimen and the tab of the lower clamp rests on the bottom plane of the beam specimen. Thus, the beam test piece is fixed on the beam end fixing clamp 42 by the pretightening force of the upper countersunk head screw.
In the fatigue test of the present embodiment, which is used for the one-end-fixed one-end-hinged beam, the four countersunk head screws 417 on the beam-end rotatable clamping seat 41 and the beam-end fixing seat 42 are firstly loosened, and the upper clamping block 411 and the upper clamping head 421 are loosened. After the beam test piece 5 is mounted at a predetermined position, the upper countersunk screw 417 is screwed. Then, the two vibration motors are started to operate, and the two vibration motors are controlled to synchronously and reversely rotate. Referring to fig. 7, the two vibration motors are driven and arranged in parallel to form two-axis inertial vibration exciters, and when the two vibration motors are controlled to rotate synchronously and reversely, the exciting forces generated by the eccentric blocks are mutually offset in the horizontal direction, and a resultant force is superposed in the vertical direction, so that the motion trail of the vibration table is a straight line along the vertical direction. When the semi-circular disc eccentric blocks of the two vibration motor belts rotate, the centrifugal force F generated by the two eccentric blocks always offsets the component force Fx along the horizontal direction, the component force Fy along the vertical direction is always mutually superposed, and the generated resultant exciting force 2Fy forces the vibration table to do reciprocating vibration similar to a straight line along the vertical direction. When the centrifugal forces are completely superposed, the exciting force is the maximum, and the centrifugal forces are completely offset, the exciting force is zero.
The vibration motor rotates circularly to generate circular exciting force along the vertical direction. Under the action of the exciting force, the vibration platform and the parts mounted on the vibration platform can generate forced vibration. The beam test piece firstly moves in a rigid body along with the vibration platform, and the beam test piece generates a rigid body inertia exciting force due to the weight of the beam test piece. When the rotating speed of the vibrating motor is adjusted, the rotating speed frequency is close to or equal to the natural frequency of the beam test piece, the beam test piece can generate strong resonance, and large amplitude is generated. Through resonance excitation, the beam test piece can generate large vibration deformation. Therefore, the working efficiency of the fatigue test can be improved, and the energy consumption can be reduced. Because the two ends of the beam test piece are fixed, the vibration deformation part is arranged in the middle and is not connected with the vibration platform, and the vibration deformation of the beam test piece does not influence the vibration of the vibration platform. That is, there is no direct contact between the vibrating portion of the beam specimen and the vibrating platform. Thus, the vibration of the beam test piece has very little effect on the vibration platform. Thus, the vibration platform output vibration waveform is stabilized. The beam test piece is excited by a stable waveform, and the generated vibration waveform has small distortion degree.
Through the operation, the fatigue test of the hinged beam with one end fixed is completed. Based on similar theory, the test result of the structure that one end is fixed with one end hinge supported beam can provide reference for the design of the prototype beam structure.
Of course, the vibration motor of this embodiment may also have an eccentric mass mounted on each output shaft, wherein one eccentric mass may be fixed and the other eccentric mass may be adjustable, and adjusting the included angle between the adjustable eccentric mass and the fixed eccentric mass may change the magnitude of the exciting force. When leaving the factory, the included angle between the adjustable eccentric block and the fixed eccentric block is 0 degree. The vibration motor can be directly purchased from outsourcing, such as a YZS type vibration motor of Henan Tongtai machinery Co.
Example two:
as shown in fig. 8, the difference between the second example and the first example is the structural shape and the clamping manner of the beam specimen, and the additional arrangement of the counterweight 7. As can be seen from fig. 9, the top and bottom surfaces of one end of the beam specimen are flat surfaces, and the top and bottom surfaces of the other end are also flat surfaces. Referring to fig. 10, a central through hole 52 is formed in the middle of the beam specimen 5. In order to increase the inertia exciting force, a balancing weight 7 is arranged on the beam test piece, the balancing weight comprises an upper balancing weight 71 and a lower balancing weight 72, the structural shapes and the sizes of the upper balancing weight 71 and the lower balancing weight 72 are consistent, five through holes are formed in the upper balancing weight 71 and the lower balancing weight 72, four of the through holes are located at four corners, and one of the through holes is located at a middle position. The upper balancing weight 71 is arranged above the beam test piece 5, the lower balancing weight 72 is arranged below the beam test piece, and the upper balancing weight 71 and the lower balancing weight 72 are connected through five bolts. Wherein, the bolt of central position passes through the through-hole of upper balance weight 71, roof beam test piece and lower balance weight 72 in proper order. In this embodiment, both ends of the beam test piece are mounted on the beam-end fixing clamping seat 42, and the beam-end fixing clamping seat 42 of this embodiment has the same structural shape as the beam-end fixing clamping seat of the first embodiment, and is not described herein again. Through the clamping mode, the beam test piece becomes the two-end fixed beam, and the fatigue test of the two-end fixed beam test piece can be completed. Fixed beams at two ends are common in engineering, such as bearing beams of vibrating screens. Based on a similar theory, the test result of the structural form of the beam with two fixed ends can provide reference for the design of the engineering prototype beam structure.
In the fatigue test for the beam with two fixed ends, the upper countersunk head screw on the upper chuck 421 is firstly loosened, the beam test piece 5 is installed at a predetermined position, and then the upper countersunk head screw is screwed. Then, the two vibration motors are started to operate, and the two vibration motors are controlled to synchronously and reversely rotate. The eccentric mass 61 follows the rotation of the motor by the belt of the vibration motor. The exciting forces generated by the eccentric blocks are mutually offset in the horizontal direction, a resultant force is superposed in the vertical direction, and the exciting force is generated along the vertical direction of the vibration platform. The vibration motor rotates circularly to generate circular exciting force along the vertical direction. Under the action of the exciting force, the vibration platform and the parts mounted on the vibration platform can generate forced vibration. The beam test piece can move as a rigid body along with the vibration platform and is subjected to the inertial excitation force of the beam test piece and the inertial excitation of the balancing weight. After having added the balancing weight, the exciting force of multiplicable roof beam test piece, the vibration deformation of increase roof beam test piece. Through adjusting the rotating speed of the vibrating motor, the rotating speed frequency is close to or equal to the natural frequency of the beam test piece, and the beam test piece can generate strong resonance to generate large amplitude. Through resonance excitation, the beam test piece can generate large vibration deformation. Therefore, the working efficiency of the fatigue test can be improved, and the energy consumption can be reduced. Since the two fixed ends of the beam specimen 5 do not laterally deform, the vibration deformation portion is in the middle. The elastic deformation of the beam specimen 5 does not interfere with the vibration of the vibration table. That is, the elastic vibration of the beam specimen has little influence on the vibration of the vibration table. Therefore, the vibration platform has good stability of output vibration waveform, the vibration waveform of the beam test piece is very stable under the excitation of the stable waveform, and the waveform distortion degree is small.
Example three:
the difference between the third example and the first example is the structural shape and the clamping mode of the beam test piece. As shown in fig. 11 and 12, the top and bottom surfaces of both ends of the beam specimen are provided with arc-shaped grooves 51. The two ends of the beam specimen are respectively arranged on the two beam end rotatable clamping seats 41. The structure of the beam end rotatable clamping seat 41 in this embodiment is the same as the beam end rotatable clamping seat in the first embodiment, and is not described herein again. The beam test piece is in such a way that two ends of the beam test piece can rotate slightly, and the beam test piece also moves slightly in the horizontal direction, which is similar to the restraint of a simply supported beam structure. The simple beam structure is common in engineering, and for example, a main beam of a bridge crane is regarded as the simple beam structure. Based on a similar theory, the test result of the structural form of the beam with two rotatable ends can provide reference for the design of the engineering prototype beam structure.
Example four:
the difference between the fourth example and the first example is the structural shape and the clamping mode of the beam test piece and the connection mode of the vibration platform and the base. As shown in fig. 13, the present embodiment includes a base 1, a vibration isolation spring 2, a vibration platform 3, a beam specimen 5, and a vibration motor 6. The top end spring coil of the vibration isolation spring 2 is directly welded with the bottom surface of the vibration platform 3, and the bottom end spring coil of the vibration isolation spring 2 is welded with the base 1. The structural shapes of the vibration motor, the base and the vibration platform are the same as those of the first embodiment. The beam end fixing clamp 42 has the same structure as the beam end fixing clamp in the first embodiment, and is not described herein again. The beam end fixing clamping seat 42 is installed on the side wall of the vibration platform, one end of the beam test piece is installed on the beam end fixing clamping seat, and the other end of the beam test piece is free and free. Referring to fig. 14, the free end of the beam test piece is further provided with a mass block 8, the mass block 8 includes an upper mass block 81 and a lower mass block 82, the upper mass block 81 and the lower mass block 82 have the same structural shape and size, and the upper mass block 81 and the lower mass block 82 are both provided with two through holes. Referring to fig. 15 again, the beam test piece is also provided with two through holes, and the two through holes are arranged along the axial direction of the beam test piece. The upper mass block 81 is arranged above the beam test piece, the lower mass block 82 is arranged below the beam test piece, and the upper mass block 81 and the lower mass block 82 are connected through two bolts. The bolts pass through the through holes of the upper mass block 81, the beam test piece and the lower mass block 82 in sequence. Through this kind of mode, the one end of roof beam test piece is fixed, and one end is free, forms the cantilever beam structure. Cantilever beam structures are common in engineering, such as turbine blades, wind turbine blades, and helicopter rotors. In design analysis, these structures are often simplified to cantilever beam structure analysis. Based on a similar theory, the fatigue test result of the cantilever beam structure form can provide reference for the design of the engineering prototype beam structure.
Example five:
as can be seen from fig. 16, 17 and 18, the difference between the fifth example and the fourth example is the structural shape of the beam specimen, the middle of the beam specimen of the present embodiment is provided with a notch 54, and the other structural shapes and fixing manners are the same as those of the fourth example. In this manner, the present embodiment may complete a crack propagation test of the cantilever beam. The test results provide data support for designing cantilever beam structures based on damage tolerance.
The crack propagation test process is divided into two parts, firstly, cracks are prefabricated, the rotating speed frequency is close to or equal to the natural frequency of the beam test piece by adjusting the rotating speed of the vibration motor, and the beam test piece can generate strong resonance so as to generate large amplitude. Because of the stress concentration at the notches, fatigue cracks can form at the notches after a period of time. During the test, the crack length was observed by an industrial inspection video microscope (AOSVI AF216C) and the motor was stopped after the crack length reached approximately the pre-set requirement. And measuring the crack length off line by an industrial video microscope to finish the fatigue crack prefabrication. And secondly, restarting the vibration motor, and controlling the rotating speed of the motor to enable the beam test piece to vibrate circularly under the specified stress. In the test process, the crack length is measured on line through an industrial detection video microscope, and the whole crack propagation test time is recorded simultaneously after the crack is unstably propagated or is propagated to a preset size. Thus, the crack propagation test was completed.
Example six:
as shown in fig. 19, the difference between the sixth embodiment and the first embodiment lies in the structure of the beam specimen and the structure of the beam end clamping seat, the top and bottom surfaces of the two ends of the beam specimen are flat surfaces, the vibration platform 3 is provided with the side wall 32 protruding out of the platform, the beam end fixing clamping seat is a pressing plate 43, the two pressing plates are provided with two through holes, the two ends of the beam specimen are also provided with two holes, and the corresponding position on each side wall is provided with a threaded hole. Two ends of the beam test piece are arranged between the pressing plate 43 and the side wall 32, and the screws sequentially penetrate through the pressing plate through holes and the beam test piece through holes and then are in threaded connection with the side wall threaded holes. And directly and fixedly mounting the beam test piece on the side wall. Like this, the roof beam test piece both ends snap-on is on the vibration platform lateral wall, forms both ends fixed beam structure. Of course, this embodiment can also be used for the cantilever beam structure, and when fixing, only one end of the beam test piece needs to be fixed, and the cantilever beam structure is formed.
According to the beam structure vibration fatigue device disclosed by the embodiment of the invention, the beam end fixing clamping seat or/and the beam end rotatable clamping seat is/are selected from one end or two ends of the beam test piece, so that beam structures with different constraint types are formed. Therefore, the fatigue test of beam structure types such as cantilever beams, simply supported beams, fixed beams at two ends and the like can be carried out.
The beam structure vibration fatigue device of the present invention is not limited to the first embodiment, the second embodiment, the third embodiment, the fourth embodiment and the fifth embodiment, and for example, the vibration motors are not limited to two, and may be one or four vibration motors. A vibration motor drives the vibration platform to vibrate in horizontal and vertical directions to form a single-shaft vibration exciter, and when a shaft with an eccentric block rotates, an exciting force in a circumferential direction is usually generated. If the eccentric blocks at the two ends of the shaft have different installation phases, an excitation couple which changes along the circumferential direction can be generated, so that the multi-axial fatigue test of the beam test piece can be performed. When four vibration motors are used, a four-axis inertial vibration exciter is formed, and usually, exciting forces of two frequencies are generated. The vibration motor is not limited to a variable frequency speed regulation motor, and can also be a single-phase series motor, and the single-phase series motor is electrically connected with a single-phase voltage regulator and can also be used for a vibration fatigue test.
The present invention is not limited to the above-described embodiments, and various changes and modifications of the present invention are intended to be included within the scope of the claims and the equivalent technology of the present invention if they do not depart from the spirit and scope of the present invention.
Claims (10)
1. The utility model provides a beam structure vibration fatigue device which characterized in that: including roof beam test piece, beam-ends grip slipper, vibration platform, vibrating motor, vibration isolation spring, base, the one end of roof beam test piece is installed on the beam-ends grip slipper or the both ends of roof beam test piece are installed on the beam-ends grip slipper, and the beam-ends grip slipper is installed on vibration platform, and vibrating motor installs on vibration platform, and vibrating motor's output shaft is equipped with the eccentric block, vibration isolation spring supporting vibration platform, one end are connected on the base, and the other end is connected with vibration platform, the beam-ends grip slipper has the fixed grip slipper of beam-ends and the rotatable grip slipper of beam-ends.
2. The beam structure vibration fatigue device according to claim 1, wherein the top surface and the bottom surface of one end of the beam test piece are provided with arc-shaped grooves, the top surface and the bottom surface of the other end are planes, one end of the beam test piece with the arc-shaped grooves is mounted on the beam end rotatable clamping seat, the other end of the beam test piece is mounted on the beam end fixed clamping seat, and the beam end rotatable clamping seat and the beam end fixed clamping seat are mounted on the vibration platform oppositely; the beam end rotatable clamping seat comprises an upper clamping block, a lower clamping block and a support, the lower clamping block is fixedly connected with the support through screws, the upper clamping block is fixedly connected with the lower clamping block through screws, elongated protrusions are arranged on the bottom surface of the upper clamping block and the middle portion of the top surface of the lower clamping block, the tops of the protrusions are arc-shaped heads, the shapes of the arc-shaped heads are matched with those of arc-shaped grooves of a beam test piece, the elongated protrusions of the upper clamping block are pressed in the arc-shaped grooves of the top surface of the beam test piece, and the elongated protrusions of the lower clamping block are abutted against the arc-shaped grooves of the bottom; the beam end fixing and clamping seat comprises an upper chuck, a lower chuck and a supporting seat, the lower chuck and the supporting seat are connected through screws, the upper chuck and the lower chuck are connected through screws, the middle parts of the upper chuck and the lower chuck are provided with strip-shaped convex blocks, the end faces of the strip-shaped convex blocks are planes, the strip-shaped convex blocks of the upper chuck are pressed on the plane of the top end of a beam test piece, and the convex blocks of the lower chuck are pressed on the plane of the bottom end of the beam test piece.
3. The beam structure vibration fatigue device according to claim 1, wherein the top and bottom surfaces of one end of the beam test piece are flat surfaces, the top and bottom surfaces of the other end are also flat surfaces, both ends of the beam test piece are mounted on the beam end fixing clamping seats, and the two beam end fixing clamping seats have the same structural shape and are oppositely mounted on the vibration platform; the beam end fixing and clamping seat comprises an upper chuck, a lower chuck and a supporting seat, the lower chuck and the supporting seat are connected through screws, the upper chuck and the lower chuck are connected through screws, the middle parts of the upper chuck and the lower chuck are provided with strip-shaped convex blocks, the end faces of the strip-shaped convex blocks are planes, the strip-shaped convex blocks of the upper chuck are pressed on the plane of the top end of a beam test piece, and the convex blocks of the lower chuck are pressed on the plane of the bottom end of the beam test piece.
4. The beam structure vibration fatigue device according to claim 1, wherein the top surface and the bottom surface of one end of the beam test piece are provided with arc-shaped grooves, the top surface and the bottom surface of the other end of the beam test piece are also provided with arc-shaped grooves, both ends of the beam test piece are both mounted on the beam end rotatable clamping seats, and the two beam end rotatable structures have the same shape and are oppositely mounted on the vibration platform; the rotatable grip slipper of beam-ends includes clamp splice, clamp splice and support down, and clamp splice and support pass through screw fixed connection down, go up the clamp splice and pass through screw fixed connection with clamp splice down, and the bottom surface of going up the clamp splice and the top surface middle part of clamp splice down are equipped with rectangular shape arch, and protruding top is the arc head, and the arc head shape matches with the arc wall of beam test piece, goes up the rectangular shape arch of clamp splice and presses in the arc wall of beam test piece top surface, and the rectangular shape arch top of lower clamp splice is in the arc wall of beam test piece bottom surface.
5. The beam structure vibration fatigue device according to claim 1, wherein the fixed end portion top and bottom surfaces of the beam specimen are flat surfaces, and the other end portion top and bottom surfaces are also flat surfaces, and one end of the beam specimen is mounted on the beam end fixing holder, and the other end is not fixed and can freely vibrate. The beam end fixing and clamping seat is arranged on the vibration platform; the beam end fixing and clamping seat comprises an upper chuck, a lower chuck and a supporting seat, the lower chuck and the supporting seat are connected through screws, the upper chuck and the lower chuck are connected through screws, the middle parts of the upper chuck and the lower chuck are provided with strip-shaped convex blocks, the end faces of the strip-shaped convex blocks are planes, the strip-shaped convex blocks of the upper chuck are pressed on the plane of the top end of a beam test piece, and the convex blocks of the lower chuck are pressed on the plane of the bottom end of the beam test piece.
6. The beam structure vibration fatigue device of claim 1, wherein the vibration platform is provided with a side wall protruding out of the platform, the beam end fixing holder is a pressing plate, one end or both ends of the beam test piece are installed between the pressing plate and the side wall, and the pressing plate is directly and fixedly installed on the side wall through screws.
7. The beam structure vibration fatigue device of claim 1, wherein the vibration motor is a variable frequency adjustable speed motor, and the variable frequency adjustable speed motor is electrically connected with a frequency converter.
8. The beam structure vibration fatigue device of claim 1, wherein the vibration motor is a single phase series motor, the single phase series motor being electrically connected to a single phase voltage regulator.
9. The beam structure vibration fatigue device of claim 1, characterized in that the beam test piece is provided with a weight block, the weight block comprises an upper weight block and a lower weight block, the upper weight block and the lower weight block have the same structural shape and size, the upper weight block is arranged above the beam test piece, the lower weight block is arranged below the beam test piece, and the upper weight block and the lower weight block are connected through a bolt.
10. The beam structure vibration fatigue device of claim 1, wherein the beam specimen is provided with a notch.
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| CN202011248487.7A CN112432753A (en) | 2020-11-10 | 2020-11-10 | Beam structure vibration fatigue device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113188740A (en) * | 2021-04-28 | 2021-07-30 | 天津理工大学 | Elastic beam nonlinear vibration testing platform |
| CN114112264A (en) * | 2021-11-19 | 2022-03-01 | 中国直升机设计研究所 | Helicopter control lever system support vibration fatigue test verification method and device |
| CN114323523A (en) * | 2021-12-30 | 2022-04-12 | 天津大学 | Vibrating screen crossbeam fatigue testing machine |
| CN114608964A (en) * | 2022-03-11 | 2022-06-10 | 电子科技大学 | Small-diameter wire transmission bending fatigue life testing device |
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2020
- 2020-11-10 CN CN202011248487.7A patent/CN112432753A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113188740A (en) * | 2021-04-28 | 2021-07-30 | 天津理工大学 | Elastic beam nonlinear vibration testing platform |
| CN113188740B (en) * | 2021-04-28 | 2022-07-22 | 天津理工大学 | Elastic beam nonlinear vibration testing platform |
| CN114112264A (en) * | 2021-11-19 | 2022-03-01 | 中国直升机设计研究所 | Helicopter control lever system support vibration fatigue test verification method and device |
| CN114112264B (en) * | 2021-11-19 | 2024-01-02 | 中国直升机设计研究所 | Helicopter control lever system support vibration fatigue test verification method and device |
| CN114323523A (en) * | 2021-12-30 | 2022-04-12 | 天津大学 | Vibrating screen crossbeam fatigue testing machine |
| CN114323523B (en) * | 2021-12-30 | 2023-02-24 | 天津大学 | Vibrating screen crossbeam fatigue testing machine |
| CN114608964A (en) * | 2022-03-11 | 2022-06-10 | 电子科技大学 | Small-diameter wire transmission bending fatigue life testing device |
| CN114608964B (en) * | 2022-03-11 | 2023-06-06 | 电子科技大学 | Small-diameter wire transmission bending fatigue life test device |
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