Device, method and system for measuring damping coefficient of powder particle damper

Abstract

The invention provides a device, method and system for measuring the damping coefficient of a powder particle damper. The device comprises a cantilever beam, a laser displacement sensor, the powder particle damper, a metal block and a test weight. One end of the cantilever beam is fixedly arranged, the bottom of the other end of the cantilever beam is glued with a powder particle damper and an equal-mass metal block, and a test weight is hung at the tail end of the cantilever beam and is used for generating excitation displacement; the laser displacement sensor is arranged at the top of the other end of the cantilever beam and collects displacement data of the other end of the cantilever beam. According to the method for obtaining the damping coefficient of the additive manufacturing powder particle damper through the simple experiment table, a continuum system is converted into an equivalent single-degree-of-freedom mechanical system, the damping ratio is solved through a theoretical method and an experimental method, and economical efficiency and simplicity are achieved.

Description

Technical Field

[0001] The present invention relates to the field of damping coefficient testing, and in particular to a damping coefficient measuring device, method and system for a powder particle damper. Background Art

[0002] In the additive manufacturing process, a cavity is set inside the structure to keep the unmelted metal powder inside the structure, forming a new type of powder particle damper. The particle damper forms a coupled, closed nonlinear system through the metal powder particles and the wall surface, and relies on friction and inelastic collision to achieve energy dissipation and improve structural damping.

[0003] As a new technology, additively manufactured powder particle dampers have the advantages of not requiring additional assembly space, being small and stable, and have broad application prospects in aerospace and other fields. High-speed aircraft control surfaces are subject to complex aerodynamic loads in engineering applications and are prone to flutter during high-speed flight. Effective flutter suppression can significantly improve the comprehensive performance of high-speed aircraft. To suppress the flutter of high-speed aircraft, an effective method is to improve the damping performance of the structure without reducing the structural stiffness. Powder particle dampers are introduced into the design of aircraft control surfaces. For the design requirements of high stiffness and high damping, the necessary means is to obtain the equivalent damping coefficient c of the powder particle damper. At the same time, in order to obtain the damping coefficient of powder particle dampers with different spatial forms, the damping coefficient is applied to the optimal design of the damper position. Obtaining the damping coefficient of additively manufactured powder particle dampers has important application value.

[0004] Most of the current damping tests are based on the method adopted in the national standard GB / T 18258-2000. Vibration is applied through a vibration table, and the damping coefficient is obtained by collecting vibration data of the damping material. However, the method in the national standard is not applicable to dampers of small size and those that do not rely on internal friction of the material itself to produce damping effects. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a powder particle damper damping coefficient measurement device, method and system.

[0006] A powder particle damper damping coefficient measuring device provided by the present invention comprises: a cantilever beam, a laser displacement sensor, a powder particle damper, a metal block and a test weight.

[0007] One end of the cantilever beam is fixed, a powder particle damper and a metal block of equal mass are glued to the bottom of the other end, and a test weight is hung at the end of the cantilever beam to generate excitation displacement; the laser displacement sensor is arranged at the top of the other end of the cantilever beam to collect displacement data of the other end of the cantilever beam.

[0008] A method for measuring the damping coefficient of a powder particle damper provided by the present invention comprises:

[0009] Step S1: The cantilever beam system can be equivalent to a single-degree-of-freedom mechanical system through equivalent calculation, and a theoretical vibration curve is obtained according to the single-degree-of-freedom mechanical system;

[0010] Step S2: releasing the test weight hanging at the end of the cantilever beam, measuring the displacement time curve of the end of the cantilever beam by using a laser displacement sensor, and terminating the measurement when the measured displacement value is less than 1% of the excitation displacement value;

[0011] Step S3: Draw the displacement-time vibration curve of the equivalent single-degree-of-freedom mechanical system under given different damping coefficients, extract the vibration peak points of the vibration curve in each period and fit the curve, compare the theoretical vibration peak curve with the experimental vibration peak curve, use the root mean square error to measure the approximate correlation of discrete points, obtain the damping coefficient of the system with the powder particle damper added and the damping coefficient of the system with the metal block of equal mass added, subtract the two coefficients to obtain the damping coefficient of the powder particle damper.

[0012] Preferably, the equivalent mass M and the equivalent stiffness K of the equivalent system in step S1 are as shown in formula (1):

[0013]

[0014] Where ρ is the density of the cantilever beam, A is the cross-sectional area of ​​the cantilever beam, L is the clamping length of the cantilever beam, m is the mass of the powder granular damper, E is the elastic modulus of the cantilever beam, and I is the section moment of inertia of the cantilever beam.

[0015] Preferably, in step S1, for a single degree of freedom mechanical system, the theoretical displacement-time curve after being excited under different damping coefficients is as shown in formula (2):

[0016]

[0017] Where ζ is the system damping ratio, denoted as ω is the system vibration frequency, denoted by x0 is the initial displacement of the system, is the initial velocity of the system.

[0018] Preferably, the theoretical vibration peak curve is obtained by extracting the vibration peak point of the vibration curve in each cycle, fitting it through a cubic polynomial, and multiplying it with a sinusoidal function consistent with the vibration frequency ω to obtain approximate data.

[0019] A powder particle damper damping coefficient measurement system provided by the present invention comprises:

[0020] Module M1: Through equivalent calculation, the cantilever beam system can be equivalent to a single-degree-of-freedom mechanical system, and the theoretical vibration curve can be obtained according to the single-degree-of-freedom mechanical system;

[0021] Module M2: Release the test weight hanging at the end of the cantilever beam, measure the displacement time curve of the end of the cantilever beam by using the laser displacement sensor, and terminate the measurement when the measured displacement value is less than 1% of the excitation displacement value;

[0022] Module M3: Draw the displacement-time vibration curve of the equivalent single-degree-of-freedom mechanical system under given different damping coefficients. By extracting the vibration peak points of the vibration curve in each period and fitting the curve, the theoretical vibration peak curve is compared with the experimental vibration peak curve. The root mean square error is used to measure the approximate correlation of discrete points. The damping coefficient of the system with added powder particle damper and the damping coefficient of the system with added metal blocks of equal mass are obtained. The two coefficients are subtracted to obtain the damping coefficient of the powder particle damper.

[0023] Preferably, the equivalent mass M and equivalent stiffness K of the equivalent system in the module M1 are as shown in formula (1):

[0024]

[0025] Where ρ is the density of the cantilever beam, A is the cross-sectional area of ​​the cantilever beam, L is the clamping length of the cantilever beam, m is the mass of the powder granular damper, E is the elastic modulus of the cantilever beam, and I is the section moment of inertia of the cantilever beam.

[0026] Preferably, for a single-degree-of-freedom mechanical system in the module M1, the theoretical displacement-time curve after being excited under different damping coefficients is as shown in formula (2):

[0027]

[0028] Where ζ is the system damping ratio, denoted as ω is the system vibration frequency, denoted by x0 is the initial displacement of the system, is the initial velocity of the system.

[0029] Preferably, the theoretical vibration peak curve is obtained by extracting the vibration peak point of the vibration curve in each cycle, fitting it through a cubic polynomial, and multiplying it with a sinusoidal function consistent with the vibration frequency ω to obtain approximate data.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention proposes a method for obtaining the damping coefficient of an additively manufactured powder particle damper using a simple test bench, a method for converting a continuum system into an equivalent single-degree-of-freedom mechanical system, and solving the damping ratio through theoretical and experimental methods, which is economical and simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0033] Figure 1 It is a schematic diagram of a damping coefficient measuring device for an additively manufactured powder particle damper disclosed in the present invention;

[0034] Figure 2 It is a schematic diagram of the theoretical vibration curve in the present invention;

[0035] Figure 3 It is a schematic diagram before and after curve fitting in the present invention. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0037] The present invention proposes a device for measuring the damping coefficient of an additively manufactured powder particle damper through experiments, comprising a cantilever beam, a laser displacement sensor, a powder particle damper and a test weight.

[0038] One end of the cantilever beam is fixed, a powder particle damper and a metal block of equal mass are glued to the bottom of the other end, and a test weight is hung at the end of the cantilever beam to generate excitation displacement. The laser displacement sensor is set at the top of the other end of the cantilever beam to collect displacement data of the other end of the cantilever beam.

[0039] The test equipment measures the displacement-time curve of the end of the cantilever beam through a laser displacement sensor, and then compares the measured test curve with the standard displacement-time curve of the equivalent single-degree-of-freedom equivalent system to obtain the damping coefficient of the corresponding powder particle damper.

[0040] Specifically, the following steps are included:

[0041] Step S1: obtaining theoretical vibration curve;

[0042] Through equivalent calculation, the cantilever beam system can be equivalent to a single-degree-of-freedom mechanical system. The equivalent mass M and equivalent stiffness K of the equivalent system are shown in formula (1):

[0043]

[0044] Where ρ is the density of the cantilever beam, A is the cross-sectional area of ​​the cantilever beam, L is the clamping length of the cantilever beam, m is the mass of the powder granular damper, E is the elastic modulus of the cantilever beam, and I is the section moment of inertia of the cantilever beam.

[0045] For a single degree of freedom mechanical system, the theoretical displacement-time curve after being excited under different damping coefficients is shown in formula (2):

[0046]

[0047] Where ζ is the system damping ratio, denoted as ω is the system vibration frequency, denoted by x0 is the initial displacement of the system, is the initial velocity of the system.

[0048] Step S2: experimental data measurement;

[0049] At the beginning of the experiment, the thin wire at the end of the cantilever beam was cut, and the cantilever beam system began to vibrate. The displacement-time curve of the end of the cantilever beam was measured by a laser displacement sensor. The measurement was terminated when the measured displacement value was less than one percent of the excitation displacement value.

[0050] Step S3: experimental data analysis;

[0051] Given different damping coefficients, the displacement-time vibration curve of the equivalent single-degree-of-freedom mechanical system can be plotted. By extracting the vibration peak points of the vibration curve in each period and fitting the curve through the cubic spline interpolation method, the theoretical vibration peak curve is compared with the experimental vibration peak curve. The root mean square error is used to measure the approximate correlation of discrete points. The damping coefficient of the additively manufactured powder particle damper system and the damping coefficient of the metal block system with equal mass can be obtained. The subtraction of the two coefficients is the damping coefficient of the additively manufactured powder particle damper.

[0052] After the above design steps, the damping coefficient of the additively manufactured powder particle damper is obtained.

[0053] The present invention is further described below in conjunction with a specific case.

[0054] Figure 1 The figure shows the schematic diagram of the test bench. The cantilever beam size is L = 188 mm and the density is 7.85 g / cm 3 , the elastic modulus is 205GPa, the rectangular cross-section size is 15mm*2mm, and the mass m of the additively manufactured powder particle damper is 3.45g.

[0055] Adjust the weight of the weight to make the end of the cantilever beam produce an excitation displacement of 1mm. At this time, the cantilever beam starts to vibrate after the thin rope is cut, and the displacement time curve of the end of the cantilever beam is measured. The theoretical vibration frequency of the measured system is 40.56Hz, which is close to the experimental measurement value of 39.7Hz. The cantilever beam system can be equivalent to a single degree of freedom mechanical system for calculation, and the experimental data are obtained as follows Figure 2 shown.

[0056] The given damping coefficient range is set to 0 to 0.03, 2000 sampling points are set, and the root mean square error is used to measure the fitting effect of the two curves. The data before and after fitting are compared. Figure 3 As shown in the figure, the damping coefficient of the system with particle damper is 0.0165N·s / m, and the damping coefficient of the metal block system with equal mass is 0.0098N·s / m. The damping coefficient provided by the powder particle damper is the difference between the two, which is 0.00685N·s / m.

[0057] The equivalent damping coefficient of the powder particle damper is obtained through experimental design and data processing, which can be used in the optimization design. The application example fully illustrates the effectiveness of the analysis process of the present invention.

[0058] The present invention also provides a powder particle damper damping coefficient measurement system, which can be implemented by executing the process steps of the powder particle damper damping coefficient measurement method, that is, those skilled in the art can understand the powder particle damper damping coefficient measurement method as a preferred implementation of the powder particle damper damping coefficient measurement system.

[0059] A powder particle damper damping coefficient measurement system, comprising:

[0060] Module M1: Through equivalent calculation, the cantilever beam system can be equivalent to a single-degree-of-freedom mechanical system, and the theoretical vibration curve can be obtained according to the single-degree-of-freedom mechanical system;

[0061] The equivalent mass M and equivalent stiffness K of the equivalent system are shown as follows:

[0062] M=0.236ρAL+m

[0063]

[0064] Where ρ is the density of the cantilever beam, A is the cross-sectional area of ​​the cantilever beam, L is the clamping length of the cantilever beam, m is the mass of the powder granular damper, E is the elastic modulus of the cantilever beam, and I is the section moment of inertia of the cantilever beam.

[0065] For a single degree of freedom mechanical system, the theoretical displacement-time curve after being excited under different damping coefficients is shown as follows

[0066]

[0067] Where ζ is the system damping ratio, denoted as ω is the system vibration frequency, denoted by x0 is the initial displacement of the system, is the initial velocity of the system.

[0068] Module M2: Release the test weight hanging at the end of the cantilever beam, measure the displacement time curve of the end of the cantilever beam by using the laser displacement sensor, and terminate the measurement when the measured displacement value is less than 1% of the excitation displacement value;

[0069] Module M3: Draw the displacement-time vibration curve of the equivalent single-degree-of-freedom mechanical system under given different damping coefficients. By extracting the vibration peak points of the vibration curve in each cycle, the theoretical vibration peak curve is compared with the experimental vibration peak curve through a cubic polynomial fitting curve. The root mean square error is used to measure the approximate correlation of discrete points, and the damping coefficient of the system with added powder particle damper and the damping coefficient of the system with added metal blocks of equal mass are obtained. The two coefficients are subtracted to obtain the damping coefficient of the powder particle damper.

[0070] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0071] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A powder particle damper damping coefficient measuring device, characterized in that: include: Cantilever beam, laser displacement sensor, powder particle damper, metal block and test weight. One end of the cantilever beam is fixed, a powder particle damper and a metal block of equal mass are glued to the bottom of the other end, and a test weight is hung at the end of the cantilever beam to generate excitation displacement; the laser displacement sensor is arranged at the top of the other end of the cantilever beam to collect displacement data of the other end of the cantilever beam.

2. A method for measuring the damping coefficient of a powder particle damper, based on the damping coefficient measuring device of the powder particle damper according to claim 1, characterized in that: include: Step S1: The cantilever beam system can be equivalent to a single-degree-of-freedom mechanical system through equivalent calculation, and a theoretical vibration curve is obtained according to the single-degree-of-freedom mechanical system; Step S2: releasing the test weight hanging at the end of the cantilever beam, measuring the displacement time curve of the end of the cantilever beam by using a laser displacement sensor, and terminating the measurement when the measured displacement value is less than 1% of the excitation displacement value; Step S3: Draw the displacement-time vibration curve of the equivalent single-degree-of-freedom mechanical system under given different damping coefficients, extract the vibration peak points of the vibration curve in each period and fit the curve, compare the theoretical vibration peak curve with the experimental vibration peak curve, use the root mean square error to measure the approximate correlation of discrete points, obtain the damping coefficient of the system with the powder particle damper added and the damping coefficient of the system with the metal block of equal mass added, subtract the two coefficients to obtain the damping coefficient of the powder particle damper.

3. The method for measuring the damping coefficient of a powder particle damper according to claim 2, characterized in that: The equivalent mass M and equivalent stiffness K of the equivalent system in step S1 are shown in formula (1): Where ρ is the density of the cantilever beam, A is the cross-sectional area of ​​the cantilever beam, L is the clamping length of the cantilever beam, m is the mass of the powder granular damper, E is the elastic modulus of the cantilever beam, and I is the section moment of inertia of the cantilever beam.

4. The method for measuring the damping coefficient of a powder particle damper according to claim 2, characterized in that: In step S1, for a single degree of freedom mechanical system, the theoretical displacement-time curve after being excited under different damping coefficients is as shown in formula (6): Where ζ is the system damping ratio, denoted as ω is the system vibration frequency, denoted by x0 is the initial displacement of the system, is the initial velocity of the system.

5. The method for measuring the damping coefficient of a powder particle damper according to claim 2, characterized in that: The theoretical vibration peak curve is obtained by extracting the vibration peak point of the vibration curve in each cycle, fitting it through a cubic polynomial, and multiplying it with a sinusoidal function consistent with the vibration frequency ω to obtain approximate data.

6. A powder particle damper damping coefficient measurement system, comprising: Module M1: Through equivalent calculation, the cantilever beam system can be equivalent to a single-degree-of-freedom mechanical system, and the theoretical vibration curve can be obtained according to the single-degree-of-freedom mechanical system; Module M2: Release the test weight hanging at the end of the cantilever beam, measure the displacement time curve of the end of the cantilever beam by using the laser displacement sensor, and terminate the measurement when the measured displacement value is less than 1% of the excitation displacement value; Module M3: Draw the displacement-time vibration curve of the equivalent single-degree-of-freedom mechanical system under given different damping coefficients. By extracting the vibration peak points of the vibration curve in each period and fitting the curve, the theoretical vibration peak curve is compared with the experimental vibration peak curve. The root mean square error is used to measure the approximate correlation of discrete points. The damping coefficient of the system with added powder particle damper and the damping coefficient of the system with added metal blocks of equal mass are obtained. The two coefficients are subtracted to obtain the damping coefficient of the powder particle damper.

7. The damping coefficient measurement system of the powder particle damper according to claim 6, characterized in that: The equivalent mass M and equivalent stiffness K of the equivalent system in the module M1 are shown in formula (1): Where ρ is the density of the cantilever beam, A is the cross-sectional area of ​​the cantilever beam, L is the clamping length of the cantilever beam, m is the mass of the powder granular damper, E is the elastic modulus of the cantilever beam, and I is the section moment of inertia of the cantilever beam.

8. The powder particle damper damping coefficient measurement system according to claim 6, characterized in that: For the single-degree-of-freedom mechanical system in the module M1, the theoretical displacement-time curve after being excited under different damping coefficients is shown in formula (6): Where ζ is the system damping ratio, denoted as ω is the system vibration frequency, denoted by x0 is the initial displacement of the system, is the initial velocity of the system.

9. The damping coefficient measurement system of the powder particle damper according to claim 6, characterized in that: The theoretical vibration peak curve is obtained by extracting the vibration peak point of the vibration curve in each cycle, fitting it through a cubic polynomial, and multiplying it with a sinusoidal function consistent with the vibration frequency ω to obtain approximate data.

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