Conversion method and system for actual excitation and accelerated life experiment excitation of clamp

Abstract

The invention belongs to the technical field of mechanical analysis, and relates to a conversion method and system for actual excitation and accelerated life experiment excitation of a hoop, and the method comprises the steps: calculating the mass of an additional mass rod of actual excitation and the excitation duration of a vibration table; carrying out a resonance excitation experiment on the clamp-mass rod system; obtaining the inherent frequency after the excitation duration of 30 minutes; after the resonance experiment is finished, the frequency sweeping test is carried out again, and the inherent frequency and the dynamic transmissibility peak value after the fixed-frequency excitation test are determined according to the frequency sweeping result; the resonance experiment with the duration of 30 * n min is repeatedly carried out; taking the inherent frequency after the fixed-frequency excitation test as a fixed-frequency excitation frequency; and ending the dynamic transmission performance degradation characteristic test until a preset time length is reached or the hoop is damaged, and extracting data for mechanical analysis. The method has the beneficial effects that the parameters such as vibration time, vibration frequency and vibration amplitude in the accelerated life test are determined, and the method has research significance on the accelerated life test and mechanical property degradation of the single-connection hoop.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical analysis, and in particular to a method and system for converting actual excitation of a clamp and excitation of an accelerated life experiment. Background Art

[0002] The single-joint metal felt clamp, referred to as the single-joint clamp, is an important connecting component of the aircraft engine pipeline system, mainly used to connect the pipeline support to the casing. The single-joint clamp can provide support stiffness to achieve the frequency modulation effect of the entire pipeline system. At the same time, the single-joint clamp is a component for mutual transmission of casing vibration and pipeline vibration. Under the joint action of the two structural vibrations, the degradation of the mechanical properties of the clamp is inevitable. The degradation of the support stiffness performance of the single-joint clamp will cause the clamp to loosen prematurely, crack or break the joint, and even cause the inherent characteristics of the pipeline system to deviate from the design value, causing serious vibration problems and affecting the reliability of the pipeline system. Therefore, it is of great engineering practical significance to systematically carry out research on the degradation of the mechanical properties of the single-joint clamp. How to propose a solution that can simulate the law of performance changes of the clamp during long-term service has become a technical problem that needs to be solved urgently. Summary of the invention

[0003] Technical issues to be solved

[0004] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method and system for converting actual excitation of a clamp and accelerated life test excitation, which solves the technical problem of how to simulate the performance change law of a clamp during long-term service.

[0005] Technical Solution

[0006] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0007] In a first aspect, the present invention provides a method for converting actual excitation of a clamp to excitation of an accelerated life test, comprising:

[0008] S1, use 2g amplitude sweep test to obtain the natural frequency of the "clamp-mass rod" system, obtain the order with the largest deformation of the clamp or the order with the largest response amplitude, and determine the initial dynamic transmission rate peak of the clamp, where g is the acceleration excitation and 1g is 9.8m / s 2 ;

[0009] S2, based on the theory of accelerated life test, under the natural frequency and 10g excitation in S1, calculate the excitation duration of the vibration table, and convert the actual working conditions by the mass of the mass bar;

[0010] S3, using the natural frequency obtained in S1 as the fixed-frequency excitation frequency, a resonance excitation experiment was carried out on the "clamp-mass rod" system for 30 minutes with an acceleration excitation of 10g;

[0011] S4, conduct a frequency sweep test with an amplitude of 2g and obtain the natural frequency of the "clamp-mass rod" system after 30 minutes of excitation. After the resonance experiment is completed, conduct a frequency sweep test on the "clamp-mass rod" system again, and determine and record the natural frequency and dynamic transmission rate peak of the "clamp-mass rod" system after 30 minutes of fixed-frequency excitation test based on the frequency sweep results.

[0012] S5, repeat S3 and S4 to carry out a repeatability test with a duration of 30×n min; use the natural frequency of the "clamp-mass rod" system obtained in S4 after a fixed-frequency excitation test with a duration of 30×n min as the fixed-frequency excitation frequency to achieve resonance retention; repeat S3 to S4, record the natural frequency and state transfer rate peak obtained after each resonance test, until the preset duration is reached or the clamp is damaged, end the dynamic transfer performance degradation characteristics test, and extract relevant data for mechanical analysis.

[0013] Optionally, before S1, it also includes:

[0014] The initial hysteresis curve of the clamp is obtained through static mechanical testing, and the static mechanical properties of the clamp in the initial state are calibrated.

[0015] Optionally, after S5, the following steps are further included:

[0016] After the dynamic transmission performance degradation characteristics test is completed, the clamp on the "clamp-mass rod" system is removed, a static mechanical test is performed, and the hysteresis curve of the clamp is recorded to obtain the static mechanical characteristics of the clamp after the accelerated life test.

[0017] Optionally, the actual working condition is converted by the mass of the mass bar according to the following formula:

[0018]

[0019] Where a is the acceleration under actual working conditions; a p The acceleration provided by the vibration table in the equivalent actual working condition; m p is the mass of the pipeline; m k is the mass of the clamp; m b is the mass of the mass rod; f is the actual working condition excitation frequency, f p is the equivalent actual working condition excitation frequency.

[0020] Optionally, the vibration table excitation duration is calculated according to the following formula:

[0021] N p =t p ·f p

[0022] Nb =t b ·f b

[0023] Among them, N p and N b are the number of clamp cycles in equivalent actual service conditions and accelerated life test, t p and t b The equivalent vibration table excitation duration in actual service conditions and accelerated life test, f b is the vibration frequency in the accelerated life test.

[0024] Optionally, a is calculated according to the following formula p :

[0025]

[0026] Among them, a b It is the vibration acceleration in the accelerated life test.

[0027] Optionally, the preset duration is 300 minutes.

[0028] In a second aspect, the present invention provides a system for converting actual excitation of a clamp to excitation of an accelerated life test, comprising:

[0029] Vibration table;

[0030] The fixture support is fixed on the vibration table;

[0031] A single-joint metal felt clamp fixedly connected to the upper end of the clamp support;

[0032] The mass rod is fixed by clamping it to a single-joint metal felt clamp;

[0033] A plurality of acceleration sensors are arranged on the fixture support to collect input signals of the basic vibration excitation, and are arranged on one side of the mass rod to collect response outputs of the mass rod;

[0034] A workstation is connected to a plurality of acceleration sensors, and is used for processing data of the collected input signals of the basic vibration excitation and the response output of the cylindrical bar material, so as to complete the conversion between the actual excitation of the clamp and the excitation of the accelerated life test.

[0035] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements a method for converting actual excitation of a clamp and accelerated life test excitation as described in any one of the first aspects above.

[0036] In a fourth aspect, the present invention provides a storage device comprising a storage medium and a processor, wherein the storage medium stores a computer program, and when the program is executed by the processor, the method for converting actual excitation of a clamp and accelerated life test excitation as described in any one of the first aspects above is implemented.

[0037] Beneficial Effects

[0038] The beneficial effects of the present invention are as follows: a method for converting actual excitation of a clamp and excitation of an accelerated life test of the present invention, through the conversion of actual excitation of the clamp and excitation of the accelerated life test, converts the high-frequency large excitation in the actual service condition into the mass bar and excitation amplitude and resonance residence time under laboratory conditions through equal work and accelerated life, realizes the equivalent of a clamp-pipeline system in the actual engine to a clamp-mass bar system for accelerated life test, and gives the equivalent relationship between the mass of the mass bar and the actual pipeline mass. And the vibration excitation in the actual working condition is equivalently converted to the experimental excitation to obtain the vibration parameters and vibration duration of the accelerated life test; thereby, the combination of the clamp and the pipe with large excitation and high frequency under the actual working condition is equivalent to the combination of the clamp and the mass bar with small excitation and low frequency under the actual working condition. It has certain significance for the accelerated life test and mechanical property degradation research of the single clamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of force analysis of a clamp-mass bar system under equivalent actual working conditions provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of force analysis of a clamp-pipeline system under actual working conditions provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the SN curve in a double logarithmic coordinate system of the 1Cr18Ni9Ti material provided in an embodiment of the present invention;

[0042] Figure 4 Cloud diagram of the finite element model of the clamp 1Gr18Ni9Ti provided in the embodiment of the present invention under a load of 1500N;

[0043] Figure 5 Cloud diagram of the finite element model of the clamp 1Gr18Ni9Ti provided in the embodiment of the present invention under a load of 2000N;

[0044] Figure 6 Cloud diagram of the finite element model of the clamp 1Gr18Ni9Ti provided in the embodiment of the present invention under a load of 2500N;

[0045] Figure 7 SN curve of the finite element model of the clamp 1Gr18Ni9Ti provided in the embodiment of the present invention in a double logarithmic coordinate system;

[0046] Figure 8 A conversion diagram between an accelerated life test and actual operating conditions provided by an embodiment of the present invention;

[0047] Fig. 9 A site diagram of bolt orientation for a clamp dynamic transmission degradation performance test provided by an embodiment of the present invention;

[0048] Fig.10 The X-direction transverse static stiffness of the DK8 clamp provided in the embodiment of the present invention varies with time;

[0049] Fig.11 The variation trend of the transverse dynamic stiffness in the X direction of the DK8 clamp provided in the embodiment of the present invention over time;

[0050] Fig.12 A schematic diagram of the microscopic morphology of the DK8 clamp metal felt after the accelerated life test provided in an embodiment of the present invention;

[0051] Fig.13 A connection diagram of a conversion system provided by an embodiment of the present invention;

[0052] Fig.14 A site diagram of the opening direction of the dynamic transmission degradation performance test of the clamp provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0054] In actual experimental tests, it is common to apply excitation to the system through a vibration table to simulate the excitation transmitted from the casing to the clamp pipe system in actual working conditions to conduct an accelerated life test. This embodiment proposes a conversion theory between the actual excitation of the clamp and the excitation of the accelerated life test to determine parameters such as vibration time, vibration frequency, and vibration amplitude in the accelerated life test.

[0055] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0056] In a first aspect, this embodiment provides a method for converting actual excitation of a clamp to excitation of an accelerated life test, including:

[0057] S1, use 2g amplitude sweep test to obtain the natural frequency of the "clamp-mass rod" system, obtain the order with the largest deformation of the clamp or the order with the largest response amplitude, and determine the initial dynamic transmission rate peak of the clamp, where g is the acceleration excitation and 1g is 9.8m / s 2 ;

[0058] S2, based on the theory of accelerated life test, under the natural frequency and 10g excitation in S1, calculate the excitation duration of the vibration table, and convert the actual working conditions by the mass of the mass bar;

[0059] S3, using the natural frequency obtained in S1 as the fixed-frequency excitation frequency, a resonance excitation experiment was carried out on the "clamp-mass rod" system for 30 minutes with an acceleration excitation of 10g;

[0060] S4, conduct a frequency sweep test with an amplitude of 2g and obtain the natural frequency of the "clamp-mass rod" system after 30 minutes of excitation. After the resonance experiment is completed, conduct a frequency sweep test on the "clamp-mass rod" system again, and determine and record the natural frequency and dynamic transmission rate peak of the "clamp-mass rod" system after 30 minutes of fixed-frequency excitation test based on the frequency sweep results.

[0061] S5, repeat S3 and S4 to carry out a repeatability test with a duration of 30×n min; use the natural frequency of the "clamp-mass rod" system obtained in S4 after a fixed-frequency excitation test with a duration of 30×n min as the fixed-frequency excitation frequency to achieve resonance retention; repeat S3 to S4, record the natural frequency and state transfer rate peak obtained after each resonance test, until the preset duration is reached or the clamp is damaged, end the dynamic transfer performance degradation characteristics test, and extract relevant data for mechanical analysis.

[0062] Where n is the number of experimental groups. The total experimental duration is determined according to the experimental duration of the laboratory accelerated experimental condition in theory, and n is further determined; however, if the clamp is damaged prematurely during the experiment, the experiment is terminated.

[0063] Optionally, before S1, it also includes:

[0064] The initial hysteresis curve of the clamp is obtained through static mechanical testing, and the static mechanical properties of the clamp in the initial state are calibrated.

[0065] Optionally, after S5, the following steps are further included:

[0066] After the dynamic transmission performance degradation characteristics test is completed, the clamp on the "clamp-mass rod" system is removed, a static mechanical test is performed, and the hysteresis curve of the clamp is recorded to obtain the static mechanical characteristics of the clamp after the accelerated life test.

[0067] Optionally, the actual working condition is converted by the mass of the mass bar according to the following formula:

[0068]

[0069] Where a is the acceleration under actual working conditions; a p The acceleration provided by the vibration table in the equivalent actual working condition; m p is the mass of the pipeline; m k is the mass of the clamp; m b is the mass of the mass rod; f is the actual working condition excitation frequency, f p is the equivalent actual working condition excitation frequency.

[0070] Optionally, the vibration table excitation duration is calculated according to the following formula:

[0071] N p =t p ·f p

[0072] N b =t b ·f b

[0073] Among them, N p and N b are the number of clamp cycles in equivalent actual service conditions and accelerated life test, t p and t b The equivalent vibration table excitation duration in actual service conditions and accelerated life test, f b is the vibration frequency in the accelerated life test.

[0074] Optionally, a is calculated according to the following formula p :

[0075]

[0076] Among them, a b It is the vibration acceleration in the accelerated life test.

[0077] Optionally, the preset duration is 300 minutes.

[0078] After the metal felt clamp is installed on the equipment, it needs to go through a long period of service, and can only be inspected and maintained after it reaches the maintenance period. During this long service process, the pipeline-clamp system is installed on the casing and is subjected to various excitations from the engine. The excitations are continuous and complex. As a clamp connecting the supporting structure, the bolt connection will loosen, the clamp will break, the metal felt will wear, etc., which will cause the clamp performance to change. In order to study the performance change law of the clamp during long-term service, a single-unit clamp-mass bar system is used to carry out accelerated life tests to achieve the degradation of the clamp performance under laboratory conditions. The force analysis is carried out on the "clamp-pipeline" system under actual working conditions and the "clamp-mass bar" system in equivalent actual working conditions (accelerated test model under actual working conditions). The specific situations are as follows. Figure 1 and Figure 2 shown.

[0079] Equivalent working condition: F1-(m k +m b )g=(m k +m b ) p .

[0080] Actual working conditions: F0-(m k +m p )g=(m k +m p )a.

[0081] Where F1 is the exciting force provided by the vibration table in the equivalent actual working condition; F0 is the exciting force under the actual working condition; a is the acceleration under the actual working condition; a p The acceleration provided by the vibration table in the equivalent actual working condition; m p is the mass of the tube; m k is the mass of the clamp; m b For the quality of the quality stick.

[0082] To ensure that the excitation of the clamp-mass bar system in the equivalent actual working condition is the same as the work done by the clamp-pipeline system in the actual working condition, we have:

[0083] (m k +m b ) p X p =(m k +m p )aX

[0084] a=Xω 2

[0085] ω=2πf

[0086] Where, X pis the vibration displacement amplitude of the clamp-mass bar system in the equivalent actual working condition; X is the vibration displacement of the clamp-pipeline system in the actual working condition; ω is the excitation circular frequency.

[0087] Substituting the amplitude expression into the above formula, the conversion relationship of the mass rod in the equivalent actual working condition can be obtained as follows:

[0088]

[0089]

[0090] Where f is the actual working condition excitation frequency, f p is the equivalent excitation frequency of the actual working condition. Through this formula, the combination of the clamp and the pipe with large excitation and high frequency under the actual working condition can be equivalent to the combination of the clamp and the mass rod with small excitation and low frequency under the actual working condition. The mass of the mass rod used under the equivalent actual working condition can be further obtained. The mass of the mass rod must be at least greater than 0 to have physical meaning. At the same time, it is necessary to ensure that the mass of the real mass rod is at least greater than the mass of the pipeline. Therefore, the maximum value of the acceleration excitation required in the equivalent actual working condition can be obtained as:

[0091]

[0092] In the accelerated test under laboratory conditions, the vibration amplitude is increased to shorten the test period. The equivalent relationship of the accelerated vibration test is based on the principle of producing equal fatigue damage, that is, from the SN fatigue curve of the material:

[0093]

[0094] In the formula, a p and a b They are the vibration acceleration amplitudes of the clamp-mass bar system in equivalent actual service conditions and the clamp-mass bar system in the enhanced test, in m / s 2 ; N p and N b are the vibration cycles in equivalent actual service conditions and in enhanced tests respectively; C D is the deformation energy, unit is J; the index K is the material constant, which is obtained according to the slope of the fatigue curve (SN curve) after logarithmization of the material used for the metal felt. K is a positive value, K=m.

[0095] According to the SN curve expression:

[0096] S m N=C

[0097] In the formula, S is the stress amplitude; N is the number of cycles; m and C are material constants. After logarithmization:

[0098]

[0099] Let b = -1 / m, a = C (1 / m) , the above formula can be simplified to:

[0100] log S=b·log N+log a

[0101] Use logarithmic coordinates to fit the curve to get the first fitting formula:

[0102] log S=(-0.1345)·log N+log(1.6598×10 9 )

[0103] Therefore, b = -0.1345, a = 1.6598 × 10 9 , so m=-1 / b=7.345.

[0104] Transforming the formula log S = b·log N + log a gives the power function formula:

[0105] S=aN b

[0106] Therefore, if Figure 3 As shown, the SN curve formula of 1Gr18Ni9Ti material is:

[0107] S=(1.6598×10 9 )N (-0.1345)

[0108] like Figure 4 , Figure 5 and Figure 6 Shown are cloud diagrams of the finite element model of the clamp 1Gr18Ni9Ti under loads of 1500N, 2000N and 2500N. The different alternating stresses / maximum number of cycles corresponding to the finite element model of the clamp 1Gr18Ni9Ti under different loads are shown in Table 1.

[0109] Table 1

[0110]

[0111] Substitute the material parameters of 1Gr18Ni9Ti into the existing clamp finite element model to obtain the overall SN curve of the model. The principle is the same as above. The next fitting formula in the logarithmic coordinate system is:

[0112] logS=(-0.1423)·logN+log(1.9429×10 9 )

[0113] Therefore, if Figure 7 As shown in the figure, the SN curve formula of the metal rubber clamp structure with 1Gr18Ni9Ti as the material is:

[0114] S=(1.9429×10 9 )N (-0.1423)

[0115] Table 2 shows the fatigue curve slopes of 1Gr18Ni9Ti material and its finite element model.

[0116] Table 2

[0117]

[0118] Considering the slopes of the two fatigue curves, K=7 is taken.

[0119] The number of vibration cycles N is equal to the product of the vibration time t and the vibration frequency f, so the number of cycles in the equivalent actual service condition and the accelerated test can be expressed as:

[0120] N p =t p ·f p

[0121] N b =t b ·f b

[0122] Where N p and N b are the number of clamp cycles in equivalent actual service conditions and accelerated life test, respectively; f p and f b are the vibration frequencies in equivalent actual service conditions and accelerated life tests respectively; t p and t b They are equivalent to the vibration time in actual service conditions and accelerated life tests respectively.

[0123] Substitute the vibration cycle number into the formula:

[0124]

[0125] The relationship between vibration time t, vibration frequency f and excitation amplitude a can be obtained:

[0126]

[0127] When the service time of the clamp-mass bar system in the equivalent service condition is t p =500h, f p = 1000Hz, while in the laboratory, in order to reach the fatigue limit of the material, the number of cycles must not be less than 1.0×10 7 , that is, N b ≥1.0×10 7 , if in f b=1000Hz, t b >2.8h≈3h, so:

[0128]

[0129] According to the experience of clamp fatigue test, the excitation acceleration amplitude is usually selected as a in the laboratory acceleration test. b = 10g, therefore, the equivalent of 10 / 2.077 = 4.81g excitation in actual service conditions produces fatigue damage to the clamp-pipeline system. Based on the equivalent actual working conditions and laboratory accelerated test conditions, the mass of the mass bar is calculated as follows:

[0130]

[0131] At this time, the excitation frequency in the equivalent working condition is the same as the excitation frequency in the accelerated test, so the excitation time in the accelerated test can be calculated according to the formula Calculation also needs to meet the minimum number of cycles of fatigue life. Therefore, when the mass of the mass bar cannot meet the requirement and the acceleration under the equivalent actual working conditions needs to be changed, resulting in the calculated excitation time being less than 2.8h, the excitation time of the accelerated test takes the minimum value of 3h.

[0132] The actual engine service conditions are converted twice, from the actual service conditions to the equivalent conditions and then to the accelerated test conditions. The high-frequency, large-amplitude and long-duration excitation of the actual pipeline-clamp system in the engine is converted to the low-frequency, medium-duration and short-duration excitation in the laboratory to ensure that the clamp system works and has the same fatigue damage. The specific conversion relationship between the conditions is as follows: Figure 8 shown.

[0133] Taking a certain actual working condition as an example, combined with the above test theory and method, a laboratory accelerated life test was carried out. The experimental working condition was the clamp opening downward working condition. Fig. 9 The actual working condition vibration frequency f is 3790Hz and the acceleration excitation a is 43.3g.

[0134] The service time of the clamp-mass bar system in the equivalent service condition is t p =500h, f p =1000Hz, the initial resonance frequency of the laboratory accelerated test condition is 956Hz, and f is taken approximately b =1000Hz according to the number of fatigue cycles N b ≥1.0×10 7 , take t b =3h, acceleration test acceleration excitation a b =10g, according to the formula Get ap =4.81g. have to:

[0135]

[0136] Table 3 shows the conversion results under different working conditions.

[0137] Table 3

[0138] Condition Name Acceleration excitation / g Vibration frequency / Hz Conversion mass / Kg Actual working conditions 43.3 3790 - Equivalent actual working conditions 4.81 1000 0.213 Laboratory Accelerated Conditions 10 1000 0.213

[0139] The initial new clamp was subjected to two static tests in the opening direction. After each accelerated test, the clamp was retested in the opening direction twice. The test results are shown in Table 4, which are the loading force and deformation / mm of the DK8 clamp under the laboratory accelerated life condition with a tightening torque of 7N.

[0140] Table 4

[0141]

[0142]

[0143] Further calculations were performed to obtain the average stiffness of the clamp in its initial state and after degradation, as shown in Table 5. The static stiffness of the DK8 clamp was plotted as Fig.10 shown.

[0144] In order to realize the accelerated degradation experimental analysis, the resonance of the clamp-mass bar system was stopped and swept every 30 minutes on the vibration table to obtain the natural frequency. The dynamic stiffness was obtained by calculation. Table 5 shows the inherent characteristics and mechanical parameters of the DK8 clamp under the laboratory accelerated life condition. The dynamic stiffness of the DK8 clamp is plotted as shown in Fig.11 .

[0145] Table 5

[0146]

[0147]

[0148] from Fig.10 and Fig.11 It can be seen from the figure that the mechanical properties of the DK8 clamp significantly decreased after the accelerated life test. In order to further study the damage of the metal felt of the DK8 clamp in the accelerated life test, the degraded clamp was taken and photographed by scanning electron microscope to obtain the microscopic morphology of the degraded clamp, see Fig.12 .

[0149] It can be observed from the figure that the metal felt is severely worn, a large amount of metal debris appears, and the metal wire is broken, and the system stiffness is weakened.

[0150] In a second aspect, this embodiment provides a system for converting actual excitation of a clamp to an excitation of an accelerated life test, the system comprising:

[0151] Vibration table;

[0152] The fixture support is fixed on the vibration table;

[0153] A single-joint metal felt clamp fixedly connected to the upper end of the clamp support;

[0154] The mass rod is fixed by clamping it to a single-joint metal felt clamp;

[0155] A plurality of acceleration sensors are arranged on the fixture support to collect input signals of the basic vibration excitation, and are arranged on one side of the mass rod to collect response outputs of the mass rod;

[0156] A workstation is connected to a plurality of acceleration sensors, and is used for processing data of the collected input signals of the basic vibration excitation and the response output of the cylindrical bar material, so as to complete the conversion between the actual excitation of the clamp and the excitation of the accelerated life test.

[0157] like Fig.13 The figure shows the connection relationship diagram of the test system established in this embodiment. The cylindrical bar is fixed on the vibration table of the vibration table through the metal felt clamp and the fixture support. Acceleration sensors are arranged on the fixture support and the cylindrical bar respectively. The former is used to collect the input signal of the basic vibration excitation, and the latter is used to collect the response output of the cylindrical bar. Fig. 9 and Fig.14 The site diagram of the clamp dynamic transmission degradation characteristic test is given. The experimental instruments are shown in Table 6.

[0158] Table 6

[0159] Instrument Name model Sensitivity Remark Data Acquisition System 16-channel LMS - - Dongling vibration table ES-6-230 - - Accelerometer PCB 356A01 0.5223mV / m / s2 Mass 3g

[0160] According to the system for converting the actual excitation of a clamp into the excitation of an accelerated life experiment provided in this embodiment, since it is used to implement the steps of a method for converting the actual excitation of a clamp into the excitation of an accelerated life experiment provided in the first aspect of the present invention, the system for converting the actual excitation of a clamp into the excitation of an accelerated life experiment has all the technical effects of the method for converting the actual excitation of a clamp into the excitation of an accelerated life experiment, and will not be repeated here.

[0161] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements a method for converting actual excitation of a clamp and accelerated life test excitation as described in any one of the first aspects above.

[0162] In a fourth aspect, an embodiment of the present invention provides a storage device, including a storage medium and a processor, wherein the storage medium stores a computer program, and when the program is executed by the processor, a method for converting actual excitation of a clamp and accelerated life test excitation as described in any one of the first aspects above is implemented.

[0163] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0164] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention should also include these modifications and variations.

[0165] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for converting actual excitation of a clamp to excitation of an accelerated life test, characterized in that: include: S1, use 2g amplitude sweep test to obtain the natural frequency of the "clamp-mass rod" system, obtain the order with the largest deformation of the clamp or the order with the largest response amplitude, and determine the initial dynamic transfer rate peak of the clamp, where g is the acceleration excitation and 1g is 9.8m / s 2 ; S2, based on the theory of accelerated life test, under the natural frequency and 10g excitation in S1, calculate the excitation duration of the vibration table, and convert the actual working conditions by the mass of the mass bar; S3, using the natural frequency obtained in S1 as the fixed-frequency excitation frequency, a resonance excitation experiment was carried out on the "clamp-mass rod" system for 30 minutes with an acceleration excitation of 10g; S4, conduct a frequency sweep test with an amplitude of 2g and obtain the natural frequency of the "clamp-mass rod" system after 30 minutes of excitation. After the resonance experiment is completed, conduct a frequency sweep test on the "clamp-mass rod" system again, and determine and record the natural frequency and dynamic transmission rate peak of the "clamp-mass rod" system after 30 minutes of fixed-frequency excitation test based on the frequency sweep results. S5, repeat S3 and S4 to carry out a repeatability test with a duration of 30×nmin; use the natural frequency of the "clamp-mass rod" system obtained in S4 after a fixed-frequency excitation test with a duration of 30×nmin as the fixed-frequency excitation frequency to achieve resonance retention; repeat S3 to S4, record the natural frequency and state transfer rate peak obtained after each resonance test, until the preset duration is reached or the clamp is damaged, end the dynamic transfer performance degradation characteristics test, and extract relevant data for mechanical analysis.

2. The method for converting actual excitation of a clamp to an accelerated life test excitation according to claim 1, characterized in that: Prior to S1, it also included: The initial hysteresis curve of the clamp is obtained through static mechanical testing, and the static mechanical properties of the clamp in the initial state are calibrated.

3. The method for converting actual excitation of a clamp to an accelerated life test excitation according to claim 2, characterized in that: After S5, it also includes: After the dynamic transmission performance degradation test is completed, the clamp on the "clamp-mass rod" system is removed, a static mechanical test is performed, and the hysteresis curve of the clamp is recorded to obtain the static mechanical properties of the clamp after the accelerated life test.

4. The method for converting actual excitation of a clamp to an accelerated life test excitation according to claim 3, characterized in that: The actual working conditions are converted by the mass of the mass bar according to the following formula: Where a is the acceleration under actual working conditions; a p The acceleration provided by the vibration table in the equivalent actual working condition; m p is the mass of the pipeline; m k is the mass of the clamp; m b is the mass of the mass rod; f is the actual working condition excitation frequency, f p is the equivalent actual working condition excitation frequency.

5. The method for converting actual excitation of a clamp to excitation of an accelerated life test according to claim 4, characterized in that: The excitation duration of the vibration table is calculated according to the following formula: N p =t p ·f p N b =t b ·f b Among them, N p and N b are the number of clamp cycles in equivalent actual service conditions and accelerated life test, t p and t b The equivalent vibration table excitation duration in actual service conditions and accelerated life test, f b is the vibration frequency in the accelerated life test.

6. The method for converting actual excitation of a clamp to an excitation of an accelerated life test according to claim 5, characterized in that: Calculate a according to the following formula p : Among them, a b It is the vibration acceleration in the accelerated life test.

7. The method for converting actual excitation of a clamp to excitation of an accelerated life test according to claim 6, characterized in that: The preset duration is 300 minutes.

8. A conversion system for actual excitation of a clamp and excitation of an accelerated life test, characterized in that: include: Vibration table; The fixture support is fixed on the vibration table; A single-joint metal felt clamp fixedly connected to the upper end of the clamp support; The mass rod is fixed by clamping it to a single-joint metal felt clamp; A plurality of acceleration sensors are arranged on the fixture support to collect input signals of the basic vibration excitation, and are arranged on one side of the mass rod to collect response outputs of the mass rod; A workstation is connected to a plurality of acceleration sensors, and is used for processing data of the collected input signals of the basic vibration excitation and the response output of the cylindrical bar material, so as to complete the conversion between the actual excitation of the clamp and the excitation of the accelerated life test.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for converting actual excitation of a clamp and excitation of an accelerated life test as described in any one of claims 1 to 7 is implemented.

10. A storage device comprising a storage medium and a processor, wherein the storage medium stores a computer program, wherein: When the processor executes the computer program, the method for converting actual excitation of a clamp and accelerated life test excitation as described in any one of claims 1 to 7 is implemented.

Images