CN204925041U - Contain convex supersound fatigue testing specimen of uniform section section - Google Patents

Abstract

The utility model provides a fatigue test sample, including two centre gripping sections and load section, two centre gripping sections and load section are cylindrical, two centre gripping sections respectively fixed connection in the both sides of load section, the fatigue test sample is axis symmetry and central symmetrical structure, and the coupling part of two centre gripping sections and load section is the arc, the utility model discloses richen the tired experiment machine's of supersound sample type, promoted its range of application. The great number expense of the system control software upgrade of producer production has been avoided. Standard formulation and upgrading for supersound fatigue test are laid a good foundation.

Description

Circular-arc ultrasonic fatigue sample containing uniform-section segment

Technical Field

The utility model relates to a metal material supersound fatigue performance test field especially indicates a contain convex supersound fatigue sample of uniform cross section.

Background

The ultrasonic fatigue test is a new technology for testing the fatigue performance of materials, and adopts a piezoelectric ceramic transducer to convert an electric signal supplied by a high-frequency power supply into mechanical vibration with the same frequency, and then the mechanical vibration is amplified by a vibration displacement amplifier. One end of the sample is connected with the displacement amplifier, and the other end is free. The resonance occurs under the excitation of the displacement amplifier, resonance waves are generated in the sample, a pull-press symmetrical cyclic load is formed along the axial direction of the sample, and a longitudinal displacement and stress strain field is established.

Compared with the traditional fatigue test technology, the fatigue test device has the advantages that the test device is obvious in advantages, the test working frequency is extremely high, the efficiency of the fatigue test can be greatly improved, and the fatigue test device is mainly used for testing the ultrahigh cycle fatigue performance of high-strength steel. The working frequency of the traditional high-frequency fatigue test is 100-200 Hz, and the working frequency of the ultrasonic fatigue test can reach 2.0 multiplied by 10⁴Hz, testing a fatigue life of 1 x 10⁹The traditional high-frequency fatigue test needs about 100 days to be carried out continuously, and the ultrasonic fatigue test can be completed only about one day. The ultrasonic fatigue test technology is a revolution in the field of fatigue test, and greatly improves the test efficiency and the research and development efficiency.

At present, the high-end market of steel has great demand on ultra-high cycle fatigue test, and the steel 1 for major engineering can be obtained by utilizing the ultrasonic fatigue test technology0⁷The fatigue performance of the product is very high for more than a week, and the product is provided for users, provides reference for designing safer fatigue criteria for the users, and has important significance for popularizing the application range of the product and developing the market space.

System control software on an ultrasonic fatigue tester apparatus is typically provided with two sample types: the circular arc-shaped test piece and the notch-shaped test piece are shown in fig. 1 and 2, and the maximum stress is at the section with the smallest diameter in the tests of the two test pieces. When the influence of surface treatment on the fatigue performance of a material needs to be researched, a section of equal-stress cross section area is required in the middle of a sample, and the existing arc-shaped sample and the existing notch-shaped sample cannot meet the test requirements. This greatly limits the application of ultrasonic fatigue testing machines.

SUMMERY OF THE UTILITY MODEL

In order to solve the problem, the utility model provides a contain convex supersound fatigue sample of uniform cross section, a serial communication port, including two clamping sections and load section, two clamping sections and load section are cylindrical, two clamping sections respectively fixed connection in the both sides of load section, the fatigue test sample is axis symmetry and central symmetrical structure, and two clamping sections are the arc with the connecting portion of load section, curved radius of curvature R and variable cross section length L₂Load section radius R₁Radius R of the clamping section₂In a relationship of $R=\frac{L_2^2+{(R_2-R_1)}^2}{2(R_2-R_1)}.$

Length of clamping section $L_3=\frac{1}{k}\arctan \[\frac{1+\frac{\mathrm{\β}}{k}tan\left({\mathrm{kL}}_1\right)\tanh \left({\mathrm{\βL}}_2\right)}{\tan \left({\mathrm{kL}}_1\right)+\frac{k}{\mathrm{\β}}\tanh \left({\mathrm{\βL}}_2\right)}-\frac{\mathrm{\α}}{k}\tanh \left({\mathrm{\αL}}_2\right)\],$ Wherein, $k=\frac{2\mathrm{\π}f}{c},$ f is the vibration frequency, c is the propagation speed of the resonant wave in the material,

the two clamping sections and the load section are integrally formed.

The utility model has the advantages that:

and in the resonance process of the circular arc-shaped sample with the equal section, the stress of the equal section area of the sample is equal. Before testing, the area may be surface treated to investigate the effect of different surface treatments on the fatigue properties of the material. Or for materials with obvious defects (such as inclusion and shrinkage), the material can be designed into a circular arc sample with a constant section, so that the material defects can be conveniently searched in a larger area in the test process, and a safer fatigue test result can be obtained. The utility model discloses richen the sample type of ultrasonic fatigue experiment machine, promoted its range of application. The high cost caused by upgrading the system control software of the manufacturer is avoided. And a foundation is laid for standard formulation and upgrading of the ultrasonic fatigue test.

Drawings

FIG. 1 and FIG. 2 are two circular arc-shaped samples provided by the original equipment;

FIG. 3 is a schematic structural diagram of a circular arc fatigue specimen with a constant section;

FIG. 4 is a schematic diagram of a test of a circular arc ultrasonic fatigue sample with a constant section;

in the figure: 1. the ultrasonic fatigue testing device comprises a clamping section, 2, a loading section, 3, a transducer, 4, a displacement amplifier, 5, a plate-shaped ultrasonic fatigue test sample, 6 and a cooling air nozzle.

Detailed Description

The invention will be described in further detail with reference to the following figures and specific embodiments:

as shown in fig. 3, the circular arc ultrasonic fatigue test sample with the uniform cross section comprises two clamping sections 1 and a load section 2, wherein the two clamping sections 1 and the load section 2 are cylindrical, the two clamping sections 1 are respectively and fixedly connected to two sides of the load section 2, the fatigue test sample is of an axial symmetry and central symmetry structure, and the connecting part of the two clamping sections 1 and the load section 2 is arc-shaped.

Taking spring steel as an example, the material parameters E, rho and E are 206GPa and 7850kg/m respectively obtained by measuring or consulting a material manual³Selecting a dimension parameter L according to design requirements₁＝10mm，L₂＝5mm，R₁＝1.5mm，

R₂After 5mm, the resonance length L of the obtained sample is calculated₃＝10.12mm，R＝5.32mm。

The sample is screwed into the displacement amplifier and, as shown in FIG. 4, the sample is locked with a torque wrench, and the torque is usually adjusted to 3.5 to 4.5 N.m. When the spanner makes a 'click' sound, the spanner stops rotating immediately, and the test sample is locked. And adjusting a cooling air nozzle to align the stress concentration part of the sample, and opening a valve to start cooling the sample.

Opening the control software of the ultrasonic fatigue system, selecting the type of the arc-shaped sample, and giving the type at will $R_1^0=1.5mm,R_2^0=5mm,$ Can obtain a sampleResonant length of $L_2^0=9.85mm.$

Knowing the dimensional parameters of circular-arc shaped specimensAnd the size parameter L of the circular arc sample with the equal section₁，L₂，L₃，R₁，R₂And (6) finally. Stress amplitude sigma for supposing that a sample containing a constant section needs to be loaded_maxThe stress amplitude value to be loaded of the corresponding circular arc-shaped sample is obtained by a stress conversion formula under the condition of 400MPa Namely the stress amplitude corresponding to the circular arc-shaped sample which needs to be input in the system control software.

After other test parameters are set in the control system software, the TestStart is clicked, and the ultrasonic fatigue test of the arc-shaped test sample with the equal section is started.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (2)

1. The utility model provides a contain convex supersound fatigue sample of constant cross section, its characterized in that includes two clamping sections (1) and load section (2), two clamping sections (1) and load section (2) are cylindrical, two clamping sections (1) respectively fixed connection in the both sides of load section (2), the fatigue test sample is axis symmetry and central symmetrical structure, and the connecting portion of two clamping sections (1) and load section (2) is the arc.

2. The ultrasonic fatigue test specimen containing the circular arc with the constant cross-section as claimed in claim 1, wherein the two clamping sections (1) and the loading section (2) are integrally formed.