CN107957448B

CN107957448B - Ultrasonic fatigue average stress loading device

Info

Publication number: CN107957448B
Application number: CN201711168528.XA
Authority: CN
Inventors: 张梁; 王弘
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2017-11-21
Filing date: 2017-11-21
Publication date: 2020-06-26
Anticipated expiration: 2037-11-21
Also published as: CN107957448A

Abstract

The invention relates to an ultrasonic fatigue average stress used in the field of ultrasonic fatigue testAnd (4) loading the device. The method solves the problem of average stress loading in an ultrasonic fatigue test. The technical scheme is as follows: the excircle of a positioning seat in the ultrasonic generating assembly penetrates through a through hole at the uppermost end of a vertical plate of the support, and the positioning seat and the vertical plate of the support are fastened by screws; a linear sliding sleeve a in the stress loading assembly is sleeved on the smooth straight rod in the middle of the sliding guide rod a, and a linear sliding sleeve b is sleeved on the smooth straight rod in the middle of the sliding guide rod b; a flange structure at the right end of a shell of the speed reducer in the power assembly is fastened with a vertical plate of the bracket by screws, and the left end of the ball screw is inserted into a flat key output hole of the speed reducer and can realize transmission after connection; the invention can provide +/-40 kN axial tension and pressure load application to a test piece in the ultrasonic fatigue test, can realize the 20kHz frequency fatigue test, effectively shortens the fatigue test time, and can efficiently finish 10¹⁰And (5) carrying out weekly fatigue test.

Description

Ultrasonic fatigue average stress loading device

Technical Field

The invention relates to an ultrasonic fatigue average stress loading device used in the field of ultrasonic fatigue tests.

Background

The conventional fatigue test can only complete 10⁶～10⁷Fatigue properties of materials in the range of the week, however in many industrial sectors (for example high speed trains, cars, planes, etc.) the actual service life of certain structures and parts thereof often needs to reach 10⁸～10¹⁰A high-speed aircraft turbine engine operating at 3000r/min, for example, will experience 10 weeks of service during a 20 year service period¹⁰And (4) stress cycling. Ultrasonic fatigue is an accelerated resonance type fatigue test method, and the test frequency (20kHz) of the ultrasonic fatigue test method is far higher than the conventional fatigue test frequency (less than 200 Hz). The essence of ultrasonic fatigue is to create mechanical resonance waves on the loaded pattern.

Ultrasonic fatigue test studies have shown many engineering materials up to 10¹⁰Fatigue fracture still occurs after cyclic stress cycles, therefore 10⁷The fatigue strength design of the weekly fatigue test data cannot meet the actual requirements of a plurality of projects. However, the conventional fatigue test method is utilized, the loading frequency is 100Hz, and the 10-step operation is completed once⁹The fatigue test of the cycle needs continuous movement for 115 days, obviously wastes a large amount of financial resources and manpower, and the conventional fatigue testing machine cannot continuously operate for such a long period; if the ultrasonic fatigue test technology is used, the loading frequency is 20kHz, and the same is carried out once for 10 times⁹The fatigue test of the cycle only needs to be operated for 14 hours, and a 10-bar test can be successfully established⁹S-N curves for weekly cycles.

The ultrasonic fatigue test equipment is the essential core equipment for carrying out the ultrasonic fatigue test, and a large amount of earlier researches on the method and the equipment for the ultrasonic fatigue test are carried out in a laboratory at present, so that the ultrasonic fatigue test equipment has the capability of accurately testing test pieces with different material properties. According to the related technical requirements of fatigue tests, the ultrasonic fatigue tests should perform related researches on loading average stress, however, the ultrasonic fatigue equipment used in laboratories at present does not have the function of loading average stress, and the research progress of the related tests is seriously influenced.

Based on the technical background, the invention particularly provides an ultrasonic fatigue average stress loading device which can be used for carrying out an ultrasonic fatigue average stress loading test and carrying out more complete ultrasonic fatigue test research.

Disclosure of Invention

The purpose of the invention is: in order to solve the problem of average stress loading in an ultrasonic fatigue test, the ultrasonic fatigue average stress loading device is particularly provided.

In order to achieve the purpose, the invention adopts the following technical scheme: an ultrasonic fatigue average stress loading device comprises an ultrasonic generating assembly, a stress loading assembly, a power assembly, a linear transmission assembly, a support vertical plate, a sliding guide rod a, a locking nut, a positioning end plate, a sliding guide rod b and a test piece, wherein the ultrasonic generating assembly comprises a piezoelectric transducer, a positioning seat and a displacement amplifier; the structure is characterized in that: in the ultrasonic generating assembly, the piezoelectric transducer can convert the electric signal output by the ultrasonic frequency generator into a mechanical vibration signal for output; threaded holes are formed in two ends of the positioning seat, a circle of raised steps are arranged in the middle of the excircle of the positioning seat, and six step holes are uniformly formed in the raised steps in the circumferential direction; threaded holes are formed in the two ends of the displacement amplifier, the diameter of the section of the left end of the displacement amplifier is larger than that of the section of the right end of the displacement amplifier, and the outline of the excircle of the displacement amplifier is in smooth transition in the axial direction; the left end of the positioning seat and the output end of the piezoelectric transducer are fixed through a stud, and the right end of the positioning seat and the left end of the displacement amplifier are fixed through a stud; in the stress loading assembly, the upper part, the middle part and the lower part of a loading sliding plate are respectively provided with a through hole, the right end of the outer side of the through hole of the upper part of the loading sliding plate is circumferentially and uniformly provided with four threaded holes, the right end of the outer side of the through hole of the lower part of the loading sliding plate is circumferentially and uniformly provided with four threaded holes, and the left end of the outer side of the through hole of the middle part; the linear sliding sleeve a is embedded into a through hole in the upper part of the loading sliding plate, and the outer edge of a right bulge of the linear sliding sleeve a is fastened with the loading sliding plate through a screw; the linear sliding sleeve b is embedded into a through hole at the lower part of the loading sliding plate, and the outer edge of the right bulge of the linear sliding sleeve b is fastened with the loading sliding plate by a screw; the inner cavity of the loading support is provided with a step hole, the right end of the tension screw rod is provided with a step, the tension screw rod is arranged in the step hole of the inner cavity of the loading support, and the right end of the loading support and the left side of the upper end of the loading sliding plate are fastened by a screw; the right end of the tray is fastened with the loading sliding plate by screws, the rubber pad is placed on the bearing surface of the tray, and the tray is arranged on the lower side of the loading support; in the power assembly, a servo motor output shaft is connected with a reducer input shaft, a servo motor shell and a reducer shell are fastened by screws, the reducer output mode is a flat key hole output mode, the right end of the reducer shell is of a flange structure, and the servo motor can output stable torque and stable rotating speed according to electric signals; in the linear transmission assembly, a flat key groove is formed in the left end of a ball screw, a circle of clamping ring groove is formed in the right side of the flat key groove, the right portion of the ball screw is of a screw structure, and a threaded hole is formed in the right end of the ball screw; the transmission key is arranged in a flat key groove at the left end of the ball screw, the spring retainer ring is arranged in a retainer groove of the ball screw, the thrust bearing is arranged on the left end surface of a screw structure at the right part of the ball screw, and the anti-drop end cover is fixed with the right end of the ball screw through threads; the screw nut is sleeved on a screw structure at the right part of the ball screw, steel balls are arranged between the screw nut and the ball screw for transmission, and the screw nut can flexibly rotate on the ball screw; the left end of the screw nut is provided with a convex outer edge, and the convex outer edge at the left end of the screw nut is fastened with the left end of the sleeve by a screw; the outer circle of the sensor seat is provided with a step shaft, the steps at the left end of the sensor seat are uniformly provided with eight step holes in the circumferential direction, and the middle part of the outer circle of the sensor seat is provided with male threads; the left end of the sensor seat and the right end of the sleeve are fastened by screws, and the load sensor is fixed with the middle part of the excircle of the sensor seat through threads; the load sensor is of a spoke type structure, an inner hole of the load sensor is provided with female threads, and eight through holes are uniformly formed in the circumferential direction of the outer side of the load sensor; the lower end of the anti-rotation arm is provided with a through hole, and four threaded holes are uniformly formed in the circumferential direction of the outer side of the through hole; the linear sliding sleeve c is embedded into a through hole at the lower end of the anti-rotation arm, the outer edge of the left end of the linear sliding sleeve c is fastened with the anti-rotation arm through a screw, and the upper end of the anti-rotation arm is fastened with the outer circle of the sleeve through a screw; four through holes are sequentially arranged above and below the vertical support plate, and six threaded holes are uniformly formed in the circumferential direction of the outer side of the through hole at the uppermost end of the vertical support plate; the upper end and the lower end of the positioning end plate are respectively provided with a through hole; the sliding guide rod a is provided with a step shaft with small diameters at two ends and a large diameter in the middle, the middle part of the sliding guide rod a is provided with a smooth straight rod, and two ends of the sliding guide rod a are provided with male threads; the sliding guide rod b is provided with a step shaft with small diameters at two ends and a large diameter in the middle, the middle part of the sliding guide rod b is provided with a smooth straight rod, and two ends of the sliding guide rod b are provided with male threads; the left end of the sliding guide rod a penetrates through a second through hole from top to bottom of the vertical plate of the support, the right end of the sliding guide rod a penetrates through a through hole in the upper end of the positioning end plate, and two locking nuts are respectively fastened with male threads at two ends of the sliding guide rod a; the left end of the sliding guide rod b penetrates through a through hole at the lowest end of the vertical plate of the bracket, the right end of the sliding guide rod b penetrates through a through hole at the lower end of the positioning end plate, and the two locking nuts are respectively fastened with male threads at two ends of the sliding guide rod b; the lower end of the vertical plate of the bracket is fixedly connected with the frame, and the lower end of the positioning end plate is fixedly connected with the frame; the excircle of a positioning seat in the ultrasonic generating assembly penetrates through a through hole at the uppermost end of a vertical plate of the support, and the positioning seat and the vertical plate of the support are fastened by screws; a linear sliding sleeve a in the stress loading assembly is sleeved on the smooth straight rod in the middle of the sliding guide rod a, and a linear sliding sleeve b is sleeved on the smooth straight rod in the middle of the sliding guide rod b; a ball screw in the linear transmission assembly penetrates through a third through hole from top to bottom of a vertical support plate, a spring retainer ring is arranged on the left end face of the vertical support plate, a thrust bearing is arranged on the right end face of the vertical support plate, the right end of the excircle of a sensor seat is inserted into a through hole in the middle of a loading sliding plate, and a linear sliding sleeve c is sleeved on a smooth straight rod in the middle of a sliding guide rod b; a flange structure at the right end of a shell of the speed reducer in the power assembly is fastened with a vertical plate of the bracket by screws, and the left end of the ball screw is inserted into a flat key output hole of the speed reducer and can realize transmission after connection; threaded holes are formed in the two ends of the test piece, the middle of the test piece is of a thin neck structure, the left end of the test piece is connected with the right end of a displacement amplifier in the ultrasonic generating assembly through a screw thread, and the right end of the test piece is in threaded connection with a tension screw in the stress loading assembly; under the condition of applying axial pressure to the test piece, the loading support can directly apply the axial pressure to the right end of the test piece without connecting a tension screw rod.

In the ultrasonic fatigue average stress loading device, the inherent frequencies of the positioning seat, the displacement amplifier, the test piece and the loading support are the same as the vibration frequency output by the piezoelectric transducer, the axial lengths of the positioning seat, the displacement amplifier and the test piece are all half resonant wave wavelength, the axial length of the loading support is (2n +1)/4 resonant wave wavelengths, wherein n is a natural number; the positions of all the connecting surfaces among the piezoelectric transducer, the positioning seat, the displacement amplifier, the test piece and the loading support are positions with the maximum amplitude of the resonant wave, and the stress at the positions is zero; the amplitude of the resonant wave is zero at the position of the connecting surface of the positioning seat and the vertical plate of the bracket; the amplitude of the resonance wave is zero at the position of the connecting surface of the loading support and the loading sliding plate; the amplitude of the resonant wave of the middle section of the test piece is zero, the internal stress is maximum, and the test piece is a fatigue fracture surface.

The invention has the beneficial effects that: (1) the invention can realize the average stress loading in the ultrasonic fatigue test, so that the ultrasonic fatigue test is more complete, and the test range of the ultrasonic fatigue test is further widened; (2) the invention designs the natural frequency and length size of the ultrasonic generating assembly, the test piece and the loading support, ensures the resonance requirement of the test piece, and effectively avoids the resonance damage of other parts; (3) the invention adopts electric signal control, compared with the traditional electrohydraulic servo fatigue testing machine, the power consumption is small, and the control precision is high; (4) the invention can realize the fatigue test of 20kHz frequency, effectively shorten the fatigue test time and efficiently finish 10 kHz frequency¹⁰Carrying out weekly fatigue test; (5) the invention can provide +/-40 kN axial tension and pressure for the test piece, and effectively complete the ultrasonic fatigue average stress loading test.

Drawings

FIG. 1 is a schematic structural diagram of an ultrasonic fatigue average stress loading device according to the present invention in an average stress state;

FIG. 2 is a schematic structural diagram of the ultrasonic fatigue average stress loading device according to the present invention in a state of no average stress applied;

FIG. 3 is a schematic three-dimensional structure diagram of an ultrasonic fatigue average stress loading device according to the present invention;

in the figure: 01. the ultrasonic testing device comprises an ultrasonic generating assembly, 011 piezoelectric transducers, 012, a positioning seat, 013, a displacement amplifier, 02, a stress loading assembly, 021, a tension screw, 022, a loading support, 023, a loading sliding plate, 024, a linear sliding sleeve a, 025, a linear sliding sleeve b, 026, a tray, 027, a rubber pad, 03, a power assembly, 031, a servo motor, 032, a speed reducer, 04, a linear transmission assembly, 041, a transmission key, 042, a spring collar, 043, a thrust bearing, 044, a ball screw, 045, a screw nut, 046, a sleeve, 047, a linear sliding sleeve c, 048, an anti-rotation arm, 049, an anti-dropping end cover, 0410, a sensor seat, 0411, a load sensor, 05, a support vertical plate, 06, a sliding guide rod a, 07, a locking nut, 08, a positioning end plate, 09, a sliding guide rod b and a test piece.

Detailed Description

As shown in fig. 1, 2 and 3, the ultrasonic fatigue average stress loading device of the present invention is composed of an ultrasonic generating component 01, a stress loading assembly 02, a power assembly 03, a linear transmission assembly 04, a support vertical plate 05, a sliding guide rod a06, a lock nut 07, a positioning end plate 08, a sliding guide rod b09 and a test piece 10, wherein the ultrasonic generating component 01 includes a piezoelectric transducer 011, a positioning seat 012 and a displacement amplifier 013, the stress loading assembly 02 includes a tension screw 021, a loading support 022, a loading sliding plate 023, a linear sliding sleeve a024, a linear sliding sleeve b025, a tray 026 and a rubber pad 032, the power assembly 03 includes a servo motor 031 and a reducer 032, the linear transmission assembly 04 comprises a transmission key 041, a spring retainer ring 042, a thrust bearing 043, a ball screw 044, a screw nut 045, a sleeve 046, a linear sliding sleeve c047, an anti-rotation arm 048, an anti-drop end cover 049, a sensor seat 0410 and a load sensor 0411; the structure is characterized in that: in the ultrasonic generating component 01, the piezoelectric transducer 011 can convert the electric signal output by the ultrasonic frequency generator into a mechanical vibration signal for output; threaded holes are formed in two ends of the positioning seat 012, a circle of raised steps are arranged in the middle of the excircle of the positioning seat 012, and six step holes are uniformly formed in the raised steps in the circumferential direction; threaded holes are formed in two ends of the displacement amplifier 013, the diameter of the section of the left end of the displacement amplifier 013 is larger than that of the section of the right end of the displacement amplifier 013, and the outline of the outer circle of the displacement amplifier 013 is in smooth transition in the axial direction; the left end of the positioning seat 012 and the output end of the piezoelectric transducer 011 are fixed by a stud, and the right end of the positioning seat 012 and the left end of the displacement amplifier 013 are fixed by a stud; in the stress loading assembly 02, a through hole is respectively arranged at the upper part, the middle part and the lower part of a loading sliding plate 023, four threaded holes are uniformly arranged at the right end of the outer side of the through hole at the upper part of the loading sliding plate 023 in the circumferential direction, four threaded holes are uniformly arranged at the right end of the outer side of the through hole at the lower part of the loading sliding plate 023 in the circumferential direction, and eight threaded holes are uniformly arranged at the left end of the outer; the linear sliding sleeve a024 is embedded into a through hole at the upper part of the loading sliding plate 023, and the outer edge of a right bulge of the linear sliding sleeve a024 is fastened with the loading sliding plate 023 by screws; the linear sliding sleeve b025 is embedded into a through hole at the lower part of the loading sliding plate 023, and the outer edge of the right protrusion of the linear sliding sleeve b025 is fastened with the loading sliding plate 023 by screws; the inner cavity of the loading support 022 is provided with a step hole, the right end of the tension screw 021 is provided with a step, the tension screw 021 is arranged in the step hole of the inner cavity of the loading support 022, and the right end of the loading support 022 and the left side of the upper end of the loading sliding plate 023 are fastened by screws; the right end of a tray 026 and a loading sliding plate 023 are fastened by screws, a rubber pad 027 is placed on a bearing surface of the tray 026, and the tray 026 is installed at the lower side of a loading bearing 022; in the power assembly 03, an output shaft of a servo motor 031 is connected with an input shaft of a speed reducer 032, a housing of the servo motor 031 is fastened with a housing of the speed reducer 032 by screws, the output mode of the speed reducer 032 is a flat keyhole output mode, the right end of the housing of the speed reducer 032 is of a flange structure, and the servo motor 031 can output stable torque and rotation speed according to electric signals; in the linear transmission assembly 04, a flat key groove is arranged at the left end of a ball screw 044, a circle of clamping ring grooves are arranged on the right side of the flat key groove, the right part of the ball screw 044 is provided with a screw structure, and a threaded hole is arranged at the right end of the ball screw 044; the transmission key 041 is arranged in a flat key groove at the left end of the ball screw 044, the spring retainer ring 042 is arranged in a retainer groove of the ball screw 044, the thrust bearing 043 is arranged on the left end surface of the right screw structure of the ball screw 044, and the anti-dropping end cover 049 is fixed with the right end thread of the ball screw 044; the screw nut 045 is sleeved on a screw structure at the right part of the ball screw 044, steel balls are arranged between the screw nut 045 and the ball screw 044 for transmission, and the screw nut 045 can flexibly rotate on the ball screw 044; the left end of the lead screw nut 045 is provided with a convex outer edge, and the convex outer edge at the left end of the lead screw nut 045 is fastened with the left end of the sleeve 046 by a screw; the excircle of the sensor seat 0410 is provided with a step shaft, eight step holes are uniformly arranged on the left end step of the sensor seat 0410 in the circumferential direction, and the middle part of the excircle of the sensor seat 0410 is provided with a male thread; the left end of the sensor seat 0410 and the right end of the sleeve 046 are fastened by screws, and the load sensor 0411 and the middle part of the excircle of the sensor seat 0410 are fixed by threads; the load sensor 0411 is of a spoke type structure and can bear tension and compression bidirectional loads, an inner hole of the load sensor 0411 is provided with female threads, and eight through holes are uniformly formed in the circumferential direction of the outer side of the load sensor 0411; the lower end of the anti-rotation arm 048 is provided with a through hole, and four threaded holes are uniformly formed in the circumferential direction of the outer side of the through hole; a linear sliding sleeve c047 is embedded into a through hole at the lower end of the anti-rotation arm 048, the outer edge of the left end of the linear sliding sleeve c047 is fastened with the anti-rotation arm 048 through a screw, and the upper end of the anti-rotation arm 048 is fastened with the outer circle of the sleeve 046 through a screw; four through holes are sequentially arranged above and below the support vertical plate 05, and six threaded holes are uniformly formed in the circumferential direction of the outer side of the through hole at the uppermost end of the support vertical plate 05; the upper end and the lower end of the positioning end plate 08 are respectively provided with a through hole; the sliding guide rod a06 is a step shaft with small diameters at two ends and large diameter in the middle, the middle of the sliding guide rod a06 is a smooth straight rod, and the two ends of the sliding guide rod a06 are male threads; the sliding guide rod b09 is a step shaft with small diameters at two ends and large diameter in the middle, the middle of the sliding guide rod b09 is a smooth straight rod, and the two ends of the sliding guide rod b09 are male threads; the left end of a sliding guide rod a06 penetrates through a second through hole from top to bottom of the support vertical plate 05, the right end of a sliding guide rod a06 penetrates through a through hole at the upper end of the positioning end plate 08, and two locking nuts 07 are respectively fastened with male threads at two ends of a sliding guide rod a 06; the left end of a sliding guide rod b09 penetrates through a through hole at the lowest end of a support vertical plate 05, the right end of a sliding guide rod b09 penetrates through a through hole at the lower end of a positioning end plate 08, and two locking nuts 07 are respectively fastened with male threads at two ends of a sliding guide rod b 09; the lower end of the support vertical plate 05 is fixedly connected with the rack, and the lower end of the positioning end plate 08 is fixedly connected with the rack; the excircle of a positioning seat 012 in the ultrasonic generating assembly 01 passes through a through hole at the uppermost end of a support vertical plate 05, and the positioning seat 012 and the support vertical plate 05 are fastened by screws; a linear sliding sleeve a024 in the stress loading assembly 02 is sleeved on the smooth straight rod in the middle of the sliding guide rod a06, and a linear sliding sleeve b025 is sleeved on the smooth straight rod in the middle of the sliding guide rod b 09; a ball screw 044 in the linear transmission assembly 04 penetrates through a third through hole from top to bottom of a support vertical plate 05, a spring clamping ring 042 is installed on the left end face of the support vertical plate 05, a thrust bearing 043 is installed on the right end face of the support vertical plate 05, the right end of the excircle of a sensor seat 0410 is inserted into a through hole in the middle of a loading sliding plate 023, the outer side of a load sensor 0411 is fastened with the loading sliding plate 023 by screws, and a linear sliding sleeve c047 is sleeved on a smooth straight rod in the middle of a sliding guide rod b; a flange structure at the right end of a shell of a speed reducer 032 in a power assembly 03 is fastened with a vertical plate 05 of a bracket by screws, and the left end of a ball screw 044 is inserted into a flat key output hole of the speed reducer 032 and can realize transmission after connection; threaded holes are formed in two ends of a test piece 10, the middle of the test piece 10 is of a thin-neck structure, the left end of the test piece 10 is connected with the right end of a displacement amplifier 013 in the ultrasonic generating assembly 01 through a stud, and the right end of the test piece 10 is in threaded connection with a tension screw 021 in the stress loading assembly 02; under the condition of applying axial pressure to the test piece 10, the loading support 022 directly applies axial pressure to the right end of the test piece 10 without connecting the tension screw 021.

In the ultrasonic fatigue average stress loading device, the natural frequencies of the positioning seat 012, the displacement amplifier 013, the test piece 10 and the loading support 022 are the same as the vibration frequency output by the piezoelectric transducer 011, the axial lengths of the positioning seat 012, the displacement amplifier 013 and the test piece 10 are all half resonant wave wavelength, the axial length of the loading support 022 is (2n +1)/4 resonant wave wavelengths, wherein n is a natural number; the positions of the connecting surfaces between the piezoelectric transducer 011, the positioning seat 012, the displacement amplifier 013, the test piece 10 and the loading support 022 are positions with the maximum amplitude of the resonance wave, and the stress at the positions is zero; the resonance wave amplitude is zero at the position of the connecting surface of the positioning seat 012 and the support vertical plate 05; the amplitude of the resonant wave is zero at the position of the connecting surface of the loading support 022 and the loading sliding plate 023; the amplitude of the resonant wave at the middle section of the test piece 10 is zero, the internal stress is the largest, and the test piece is a fatigue fracture surface.

The working principle of the ultrasonic fatigue average stress loading device is as follows: the ultrasonic frequency generator transmits an electric signal to a piezoelectric transducer 011 in the ultrasonic generating assembly 01, the piezoelectric transducer 011 converts the electric signal into a mechanical vibration signal and outputs the mechanical vibration signal to a positioner 012, and the amplitude of the mechanical vibration signal is amplified by a displacement amplifier 013 and then transmitted to a test piece 10; the output torque of the servo motor 031 is controlled, amplified by the speed reducer 032 and transmitted to the ball screw 044 in the linear transmission assembly 04, converted into the linear motion of the screw nut 045 through the transmission effect of the ball screw nut pair, and transmitted to the stress loading assembly 02 through the sleeve 046, the sensor seat 0410 and the load sensor 0411, and at this time, the stress loading assembly 02 can apply an axial average tension-compression load to the test piece 10.

Claims

1. The utility model provides an ultrasonic fatigue average stress loading device, generate subassembly (01) by the supersound, stress loading assembly (02), power assembly (03), linear transmission assembly (04), support riser (05), slip guide arm a (06), lock nut (07), location end plate (08), slip guide arm b (09) and test piece (10) constitute, supersound generates subassembly (01) including piezoelectric transducer (011), positioning seat (012) and displacement amplifier (013), stress loading assembly (02) include tension screw (021), loading support (022), loading slide plate (023), linear sliding sleeve a (024), linear sliding sleeve b (025), tray (026) and rubber pad (027), power assembly (03) include servo motor (031) and reduction gear (032), linear transmission assembly (04) include transmission key (041), spring (042) rand, The device comprises a thrust bearing (043), a ball screw (044), a screw nut (045), a sleeve (046), a linear sliding sleeve c (047), an anti-rotation arm (048), an anti-falling end cover (049), a sensor seat (0410) and a load sensor (0411); the method is characterized in that: in the ultrasonic generating assembly (01), the piezoelectric transducer (011) can convert the electric signal output by the ultrasonic frequency generator into a mechanical vibration signal and output the mechanical vibration signal; threaded holes are formed in two ends of the positioning seat (012), a circle of raised steps are arranged in the middle of the excircle of the positioning seat (012), and six step holes are uniformly formed in the raised steps in the circumferential direction; threaded holes are formed in two ends of the displacement amplifier (013), the diameter of the section of the left end of the displacement amplifier (013) is larger than that of the section of the right end of the displacement amplifier, and the outline of the outer circle of the displacement amplifier (013) is in smooth transition in the axial direction; the left end of the positioning seat (012) is fixed with the output end of the piezoelectric transducer (011) by a stud, and the right end of the positioning seat (012) is fixed with the left end of the displacement amplifier (013) by a stud; in the stress loading assembly (02), a through hole is respectively arranged at the upper part, the middle part and the lower part of a loading sliding plate (023), four threaded holes are uniformly arranged at the right end of the outer side of the through hole at the upper part of the loading sliding plate (023) in the circumferential direction, four threaded holes are uniformly arranged at the right end of the outer side of the through hole at the lower part of the loading sliding plate (023) in the circumferential direction, and eight threaded holes are uniformly arranged at the left end of the outer side of the through hole; the linear sliding sleeve a (024) is embedded into a through hole at the upper part of the loading sliding plate (023), and the outer edge of the right bulge of the linear sliding sleeve a (024) is fastened with the loading sliding plate (023) by a screw; the linear sliding sleeve b (025) is embedded into a through hole at the lower part of the loading sliding plate (023), and the outer edge of the right side bulge of the linear sliding sleeve b (025) is fastened with the loading sliding plate (023) by screws; the inner cavity of the loading support (022) is provided with a step hole, the right end of the tension screw (021) is provided with a step, the tension screw (021) is placed in the step hole of the inner cavity of the loading support (022), and the right end of the loading support (022) and the left side of the upper end of the loading sliding plate (023) are fastened by screws; the right end of a tray (026) is fastened with a loading sliding plate (023) by screws, a rubber pad (027) is placed on the bearing surface of the tray (026), and the tray (026) is installed at the lower side of a loading bearing (022); in the power assembly (03), an output shaft of a servo motor (031) is connected with an input shaft of a speed reducer (032); in the linear transmission assembly (04), a flat key groove is formed in the left end of a ball screw (044), a circle of clamping ring groove is formed in the right side of the flat key groove, the right portion of the ball screw (044) is of a screw structure, and a threaded hole is formed in the right end of the ball screw (044); the transmission key (041) is arranged in a flat key groove at the left end of the ball screw (044), the spring collar (042) is arranged in a collar groove of the ball screw (044), the thrust bearing (043) is arranged on the left end surface of a right screw structure of the ball screw (044), and the anti-drop end cover (049) and the right end of the ball screw (044) are fixed by threads; the screw nut (045) is sleeved on a screw structure at the right part of the ball screw (044), steel balls are arranged between the screw nut (045) and the ball screw (044) for transmission, and the screw nut (045) can flexibly rotate on the ball screw (044); the left end of the screw nut (045) is provided with a convex outer edge, and the convex outer edge of the left end of the screw nut (045) and the left end of the sleeve (046) are fastened by a screw; the excircle of the sensor seat (0410) is provided with a step shaft, the step at the left end of the sensor seat (0410) is uniformly provided with eight step holes along the circumferential direction, and the middle part of the excircle of the sensor seat (0410) is provided with male threads; the left end of the sensor seat (0410) and the right end of the sleeve (046) are fastened by screws, and the load sensor (0411) and the middle part of the excircle of the sensor seat (0410) are fixed by threads; the lower end of the anti-rotation arm (048) is provided with a through hole, and four threaded holes are uniformly formed in the circumferential direction of the outer side of the through hole; the linear sliding sleeve c (047) is embedded into a through hole at the lower end of the anti-rotation arm (048), the outer edge of the left end of the linear sliding sleeve c (047) is fastened with the anti-rotation arm (048) by a screw, and the upper end of the anti-rotation arm (048) is fastened with the excircle of the sleeve (046) by a screw; four through holes are sequentially arranged on the vertical support plate (05) from top to bottom, and six threaded holes are uniformly formed in the circumferential direction of the outer side of the through hole at the uppermost end of the vertical support plate (05); the upper end and the lower end of the positioning end plate (08) are respectively provided with a through hole; the sliding guide rod a (06) is provided with a step shaft with small diameters at two ends and large diameter in the middle, the middle part of the sliding guide rod a (06) is provided with a smooth straight rod, and two ends of the sliding guide rod a (06) are provided with male threads; the sliding guide rod b (09) is provided with a step shaft with small diameters at two ends and large diameter in the middle, the middle part of the sliding guide rod b (09) is provided with a smooth straight rod, and two ends of the sliding guide rod b (09) are provided with male threads; the left end of the sliding guide rod a (06) penetrates through a second through hole of the support vertical plate (05) from top to bottom, the right end of the sliding guide rod a (06) penetrates through a through hole in the upper end of the positioning end plate (08), and two locking nuts (07) are respectively fastened with male threads at two ends of the sliding guide rod a (06); the left end of a sliding guide rod b (09) penetrates through a through hole at the lowest end of a support vertical plate (05), the right end of the sliding guide rod b (09) penetrates through a through hole at the lower end of a positioning end plate (08), and two locking nuts (07) are respectively fastened with male threads at two ends of the sliding guide rod b (09); the lower end of the support vertical plate (05) is fixedly connected with the rack, and the lower end of the positioning end plate (08) is fixedly connected with the rack; the excircle of a positioning seat (012) in the ultrasonic generating assembly (01) penetrates through a through hole at the uppermost end of a support vertical plate (05), and the positioning seat (012) and the support vertical plate (05) are fastened by screws; a linear sliding sleeve a (024) in the stress loading assembly (02) is sleeved on the smooth straight rod in the middle of the sliding guide rod a (06), and a linear sliding sleeve b (025) is sleeved on the smooth straight rod in the middle of the sliding guide rod b (09); a ball screw (044) in the linear transmission assembly (04) penetrates through a third through hole from top to bottom of a support vertical plate (05), a spring collar (042) is installed on the left end face of the support vertical plate (05), a thrust bearing (043) is installed on the right end face of the support vertical plate (05), the right end of the excircle of a sensor seat (0410) is inserted into a through hole in the middle of a loading sliding plate (023), the outer side of a load sensor (0411) is fastened with the loading sliding plate (023) through a screw, and a linear sliding sleeve c (047) is sleeved on a smooth straight rod in the middle of a sliding guide rod b (09); a flange structure at the right end of a shell of a speed reducer (032) in a power assembly (03) is fastened with a vertical plate (05) of a bracket by screws, and the left end of a ball screw (044) is inserted into a flat key output hole of the speed reducer (032) and can realize transmission after connection; threaded holes are formed in two ends of a test piece (10), the middle of the test piece (10) is of a thin neck structure, the left end of the test piece (10) is connected with the right end of a displacement amplifier (013) in the ultrasonic generation assembly (01) through a stud, and the right end of the test piece (10) is connected with a tension screw (021) in the stress loading assembly (02) in a threaded mode.

2. The ultrasonic fatigue mean stress loading device of claim 1, wherein: the natural frequency of the positioning seat (012), the displacement amplifier (013), the test piece (10) and the loading support (022) is the same as the vibration frequency output by the piezoelectric transducer (011), the axial lengths of the positioning seat (012), the displacement amplifier (013) and the test piece (10) are all half resonant wave wavelength, the axial length of the loading support (022) is (2n +1)/4 resonant wave wavelengths, and n is a natural number.

3. The ultrasonic fatigue mean stress loading device of claim 1, wherein: the positions of the connecting surfaces among the piezoelectric transducer (011), the positioning seat (012), the displacement amplifier (013), the test piece (10) and the loading support (022) are positions with the maximum amplitude of the resonant wave, and the stress at the positions is zero; the amplitude of the resonance wave is zero at the position of the connecting surface of the positioning seat (012) and the vertical plate (05) of the bracket; the amplitude of the resonant wave is zero at the position of the connecting surface of the loading support (022) and the loading sliding plate (023); the amplitude of the resonance wave of the middle section of the test piece (10) is zero, the internal stress is maximum, and the test piece is a fatigue fracture surface.

4. The ultrasonic fatigue mean stress loading device of claim 1, wherein: the load sensor (0411) is of a spoke type structure and can bear tension and compression bidirectional loads, an inner hole of the load sensor (0411) is provided with female threads, and eight through holes are uniformly formed in the circumferential direction of the outer side of the load sensor (0411).

5. The ultrasonic fatigue mean stress loading device of claim 1, wherein: under the condition that the test piece (10) only bears the axial pressure load, the tension screw (021) is not connected, and the loading support (022) directly applies the axial pressure to the right end of the test piece (10).

6. The ultrasonic fatigue mean stress loading device of claim 1, wherein: servo motor (031) shell and reduction gear (032) for the shell screw fasten, reduction gear (032) output mode is flat keyhole output form, reduction gear (032) shell right-hand member is the flange structure, servo motor (031) can be according to stable moment of torsion and the rotational speed of signal of telecommunication output.