A rapid test method for predicting the service life of rigid polyurethane foam filling materials for nuclear power new fuel transportation containers

Abstract

The invention discloses a rapid test method for predicting the service life of a polyurethane foam filling material for a new fuel transport container for nuclear power, comprising the steps of: 1, cutting a polyurethane foam sample, performing a vertical random vibration test on the sample, and collecting data; 2, performing a fast Fourier transform on the data collected in the step 1, and drawing a scatter plot; 3, performing a linear fitting on the scatter plot obtained in the step 2, and if a certain goodness of fit is not achieved, repeating the steps 1 and 2; 4, defining the end point of the service life of the polyurethane foam material based on vibration isolation theory; 5, calculating the vibration time required to reach the end point of the service life obtained in the step 4 based on the fitting straight line obtained in the step 3, and obtaining the service life of the material according to the conversion relationship; the invention creatively predicts the service life of the material according to the change of the resonance frequency, and can quickly give a life prediction conclusion; and can be used for reliability evaluation of the polyurethane foam filling material under actual service conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power equipment material detection, and in particular to a rapid test method for predicting the service life of a rigid polyurethane foam filling material for a nuclear power new fuel transportation container, and in particular to a rapid test method for predicting the service life of a rigid polyurethane foam filling material for a nuclear power new fuel transportation container under road transportation conditions. Background Art

[0002] As a clean energy, nuclear power is an inevitable choice for green development. Nuclear power safety has become the focus of current research at home and abroad. Nuclear fuel is the key to the normal operation of nuclear power plants. Nuclear fuel needs to be replaced regularly every year. Its entire life cycle includes mining, grinding, conversion, enrichment, manufacturing, transportation, loading, use, unloading, temporary storage, spent fuel reprocessing and final disposal.

[0003] Compared with other processes that are carried out at fixed locations and have standard procedures, nuclear fuel faces complex road conditions during transportation, and there is a possibility of accidents such as collisions and dumping; therefore, rigid polyurethane foam with good performance must be used as a filling material in nuclear fuel transportation containers to play the role of vibration isolation, cushioning, flame retardancy, and heat insulation;

[0004] At present, the design life of the rigid polyurethane foam products used in my country's new nuclear power fuel transportation containers is 30 years, and they have to undergo long-distance transportation every year, which places high demands on their performance stability. In order to avoid leakage of nuclear fuel during transportation, the life of the rigid polyurethane foam must be comprehensively and accurately predicted to ensure its safety and reliability.

[0005] As a polymer material, rigid polyurethane foam is easily affected by various environmental factors, such as temperature, oxygen, moisture, mechanical load, etc., which can lead to performance degradation. Therefore, it is necessary to conduct reasonable test design according to actual working conditions to predict the service life of rigid polyurethane foam.

[0006] The prior art has a traditional fatigue life prediction method, which uses the SN curve method to predict the life of rigid polyurethane foam. However, this method of the prior art requires a large number of preliminary tests, and the prediction of the life takes a long time; and it is impossible to quickly predict the service life under transportation conditions;

[0007] The existing technology also predicts the life of rigid polyurethane foam based on thermal analysis, long-term heat aging and ultraviolet aging tests. The life prediction based on thermal analysis is very sensitive to slight changes in data and has poor reproducibility; the life prediction based on long-term heat aging and ultraviolet aging tests is time-consuming and expensive; and the tests of the existing technology cannot take into account the influence of mechanical loads, especially random vibrations during transportation, and cannot accurately predict the life under transportation conditions; this is not conducive to the safety of nuclear fuel transportation.

[0008] Therefore, those skilled in the art are committed to developing a rapid test method for predicting the service life of rigid polyurethane foam filling materials for new fuel transportation containers for nuclear power plants, aiming to solve the defects in the prior art. Summary of the invention

[0009] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that in the prior art, the traditional fatigue life prediction adopts the SN curve method to predict the life of rigid polyurethane foam, which requires a large number of preliminary tests, takes a long time to predict the life, and cannot quickly predict the service life under transportation conditions; the life prediction based on thermal analysis is very sensitive to slight changes in data and has poor reproducibility; the life prediction based on long-term thermal aging and ultraviolet aging tests is time-consuming and expensive; and the tests in the prior art cannot take into account the influence of mechanical loads, especially random vibrations during transportation, and cannot easily and quickly give preliminary conclusions on life prediction under transportation conditions.

[0010] To achieve the above object, the present invention provides a rapid test method for predicting the service life of a rigid polyurethane foam filling material for a nuclear power new fuel transport container, comprising the following steps:

[0011] Step 1, cutting a rigid polyurethane foam sample, performing a vertical random vibration test on the sample, and collecting data;

[0012] Step 2: Perform fast Fourier transform on the data collected in step 1 and draw a scatter plot;

[0013] Step 3: Perform linear fitting on the scatter plot obtained in step 2. If a certain goodness of fit is not achieved, repeat steps 1 and 2.

[0014] Step 4: Based on vibration isolation theory, define the end of the life of the rigid polyurethane foam material;

[0015] Step 5: Based on the fitting straight line obtained in step 3, the vibration time required to reach the end of the life obtained in step 4 is calculated, and the service life of the material is obtained according to the conversion relationship;

[0016] The rigid polyurethane foam sample intercepted in step 1 is a cuboid;

[0017] The test atmosphere of the vertical random vibration test in step 1 is air, and the test temperature is room temperature;

[0018] The duration of the random vibration test in step 1 is 24 hours, and the PSD curve adopts the general transportation random vibration PSD curve;

[0019] In step 1, during the vibration process of the random vibration test, data sampling needs to be performed at a constant interval, and the duration of each sampling needs to be consistent;

[0020] The data collected in step 1 is a time domain signal of acceleration;

[0021] Step 2, performing fast Fourier transform on the data collected in step 1, and drawing a scatter plot of the resonance frequency and the corresponding vibration time;

[0022] The step 2 uses fast Fourier transform to transform the time domain signal of acceleration collected in step 1 into a frequency domain signal of acceleration;

[0023] In step 2, the frequency when the recording material reaches the maximum acceleration amplitude is used as the resonance frequency at the corresponding sampling time point, and a scatter plot of the resonance frequency and the corresponding vibration time is drawn;

[0024] Step 3: Perform linear fitting on the scatter plot obtained in step 2. If a certain goodness of fit is not achieved, repeat steps 1 and 2.

[0025] The step 3 is to perform linear fitting on the data points in the scatter plot obtained in the step 2, and the goodness of fit specified in the step 3 is 0.8;

[0026] The fitting straight line obtained in step 3, the abscissa of the fitting straight line is the vibration time, and the ordinate is the frequency;

[0027] In step 3, if the goodness of fit does not reach 0.8 after linear fitting, steps 1 and 2 need to be repeated until the goodness of fit can reach 0.8;

[0028] Step 4: Based on vibration isolation theory, define the end of the life of the rigid polyurethane foam material;

[0029] The step 4 is based on the classic formula of vibration isolation theory:

[0030]

[0031] In the above formula, η is the vibration transfer coefficient. When η is less than 1, it indicates that the material has a vibration isolation effect; β is the damping ratio, and λ is the ratio of the external excitation frequency to the material resonance frequency;

[0032] In step 4, it can be seen from the above formula that when the external excitation frequency is the resonant frequency of the material, times, the material can play a vibration isolation role; on the contrary, when the resonant frequency of the material When the frequency is greater than the cutoff frequency of the road surface, the material loses its vibration isolation function;

[0033] Step 5: Based on the fitting straight line obtained in step 3, the vibration time required to reach the end of the life obtained in step 4 is calculated, and the service life of the material is obtained according to the conversion relationship;

[0034] The end point of the material life defined in step 4 is the frequency; when the frequency defined in step 4 is substituted into the fitting straight line obtained in step 3, the vibration time required to reach the end point of the life obtained in step 4 can be calculated;

[0035] In step 5, according to the empirical formula In the empirical formula, K is the test time estimation constant, in km / min; t is the time, in min; S is the distance, in km;

[0036] In step 5, the constant K can be estimated according to the test time; thereby the actual transportation distance corresponding to the vibration time can be calculated, and the vibration time can be converted into the service life of the material in combination with the transportation mileage per unit time in actual use of the material;

[0037] Furthermore, the length and width of the rigid polyurethane foam sample cut in step 1 are (100±1) mm, and the height is (50±1) mm;

[0038] Furthermore, the PSD curve in step 1 adopts the general transport random vibration PSD curve in GB / T 4857.23-2021;

[0039] Furthermore, in step 1, during the vibration process of the random vibration test, data sampling is performed every 10 minutes, each sampling lasts for 2.34 seconds, and a total of 10,000 data points are collected;

[0040] Furthermore, the linear fitting in step 3 mainly utilizes the principle of least squares method;

[0041] Furthermore, in step 4, the cut-off frequency of the road surface vibration of 250 Hz may be times, that is, 176.8Hz is defined as the end of the material's life;

[0042] By adopting the above scheme, the rapid test method for predicting the service life of the rigid polyurethane foam filling material for nuclear power new fuel transportation container disclosed in the present invention has the following advantages:

[0043] (1) The rapid test method for predicting the service life of rigid polyurethane foam filling materials for nuclear power new fuel transportation containers of the present invention creatively predicts the service life of materials based on changes in resonance frequency, avoiding a large number of preliminary tests required by the traditional fatigue life prediction SN curve method, and can conveniently and quickly provide a preliminary conclusion on life prediction;

[0044] (2) The rapid test method for predicting the service life of rigid polyurethane foam filling materials for nuclear power new fuel transportation containers of the present invention can complete all tests using only a vibration test bench, and the test time is less than that of the prior art, and the test cost is also lower; the test of the prior art cannot take into account the influence of mechanical loads, especially random vibrations during transportation, while the method of the present invention can conveniently and quickly predict the service life of rigid polyurethane foam under transportation conditions; it can be used for reliability evaluation of rigid polyurethane foam filling materials under actual service conditions; it has good scientific significance and engineering value.

[0045] In summary, the rapid test method for predicting the service life of rigid polyurethane foam filling materials for nuclear power new fuel transportation containers disclosed in the present invention creatively predicts the service life of the material based on the change in resonance frequency, and can quickly and easily give a preliminary conclusion on the life prediction; all tests can be completed using only a vibration test bench, and the test time is less than that of the prior art, and the test cost is also lower; the method of the present invention can conveniently and quickly predict the service life of rigid polyurethane foam under transportation conditions; it can be used for reliability evaluation of rigid polyurethane foam filling materials under actual service conditions; it has good scientific significance and engineering value.

[0046] The concept, specific technical scheme and technical effects of the present invention will be further described below in conjunction with specific implementation methods to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic flow diagram of a rapid test method for predicting the service life of a rigid polyurethane foam filling material for a nuclear power new fuel transport container according to the present invention;

[0048] Figure 2 is the waveform of the acceleration signal of the non-vibrated sample in the frequency domain in Example 1 of the present invention;

[0049] Figure 3 is a scatter plot of the experimental data of the resonance frequency and the vibration time in Example 1 of the present invention;

[0050] Figure 4 1 and 2 are the experimental data and the fitting straight line of the resonant frequency and the vibration time in Example 1 of the present invention. DETAILED DESCRIPTION

[0051] The following describes the preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the embodiments in the text are exemplary descriptions, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0052] Example 1: The method of the present invention is used to predict the service life of a rigid polyurethane foam used in a large advanced pressurized water reactor nuclear power plant.

[0053] As shown in the figure, Figure 1 It is a schematic flow diagram of a rapid test method for predicting the service life of a rigid polyurethane foam filling material for a nuclear power new fuel transport container according to the present invention;

[0054] In this embodiment 1, step 1 is first performed, a rigid polyurethane foam sample is cut, a vertical random vibration test is performed on the sample, and data is collected;

[0055] In specific implementation, the rigid polyurethane foam sample intercepted in Example 1 of the present invention is a mature rigid polyurethane foam product used in a large advanced pressurized water reactor nuclear power plant;

[0056] The rigid polyurethane foam sample cut in step 1 is a rectangular parallelepiped; the length and width of the sample are (100±1) mm, and the height is (50±1) mm;

[0057] In specific implementation, in Example 1 of the present invention, the test atmosphere of the vertical random vibration test in step 1 is air, and the test temperature is room temperature; the duration of the random vibration test is 24 hours, and the PSD curve adopts the general transportation random vibration PSD curve in GB / T4857.23-2021;

[0058] In step 1, during the vibration process of the random vibration test, data sampling needs to be performed at a constant interval, and the duration of each sampling needs to be consistent; the data collected in step 1 is a time domain signal of acceleration;

[0059] In specific implementation, in Example 1 of the present invention, during the vibration process of the random vibration test, data sampling is performed every 10 minutes, the duration of each sampling is 2.34 seconds, and a total of 10,000 data points are collected;

[0060] Then proceed to step 2, perform fast Fourier transform on the data collected in step 1, and draw a scatter plot of the resonance frequency and the corresponding vibration time;

[0061] The step 2 uses fast Fourier transform to transform the time domain signal of acceleration collected in step 1 into a frequency domain signal of acceleration;

[0062] In step 2, the frequency at which the recording material reaches the maximum acceleration amplitude is used as the resonance frequency at the corresponding sampling time point;

[0063] As shown in the figure, Figure 2 is the waveform of the acceleration signal of the non-vibrated sample in the frequency domain in Example 1 of the present invention;

[0064] based on Figure 2 , draw a scatter plot of the resonance frequency and the corresponding vibration time; as shown in the figure, Figure 3 is a scatter plot of the experimental data of the resonance frequency and the vibration time in Example 1 of the present invention;

[0065] Then, step 3 is performed to perform linear fitting on the scatter plot obtained in step 2. If a certain goodness of fit is not achieved, steps 1 and 2 are repeated;

[0066] The step 3 is to perform linear fitting on the data points in the scatter plot obtained in the step 2, and the goodness of fit specified in the step 3 is 0.8;

[0067] The fitting straight line obtained in step 3, the abscissa of the fitting straight line is the vibration time, and the ordinate is the frequency;

[0068] In step 3, if the goodness of fit does not reach 0.8 after linear fitting, steps 1 and 2 need to be repeated until the goodness of fit can reach 0.8;

[0069] The linear fitting in step 3 mainly utilizes the principle of least squares method;

[0070] In specific implementation, this embodiment 1 uses the built-in method of Origin software to perform linear fitting;

[0071] As shown in the figure, Figure 4 The experimental data and the fitting straight line of the resonance frequency and the vibration time in Example 1 of the present invention;

[0072] Said Figure 4 The goodness of fit is 0.808; there is no need to repeat steps 1 and 2, and the next step 4 can be directly performed to define the end point of the life of the rigid polyurethane foam material based on the vibration isolation theory;

[0073] The step 4 is based on the classic formula of vibration isolation theory:

[0074]

[0075] In the above formula, η is the vibration transfer coefficient. When η is less than 1, it indicates that the material has a vibration isolation effect; β is the damping ratio, and λ is the ratio of the external excitation frequency to the material resonance frequency;

[0076] In step 4, it can be seen from the above formula that when the external excitation frequency, in this embodiment 1, is the road vibration frequency; is the resonant frequency of the material times, the material can play a vibration isolation role; on the contrary, when the resonant frequency of the material When the frequency is greater than the cutoff frequency of the road surface, the material loses its vibration isolation function;

[0077] In specific implementation, this embodiment 1 sets the cut-off frequency of the road surface vibration to 250 Hz. times, that is, 176.8Hz is defined as the end of the material's life;

[0078] Finally, step 5 is performed to calculate the vibration time required to reach the end of life obtained in step 4 based on the fitting straight line obtained in step 3, and the service life of the material is obtained according to the conversion relationship;

[0079] The material life endpoint defined in step 4 is a frequency, which is 176.8 Hz in this embodiment 1. When the frequency defined in step 4 is substituted into the fitting line obtained in step 3, the vibration time required to reach the life endpoint obtained in step 4 can be calculated. In this embodiment 1, after the substitution, it can be obtained that the rigid polyurethane foam fails after 372 hours of random vibration.

[0080] In step 5, according to the empirical formula

[0081] In the above empirical formula, K is the test time estimation constant, in km / min; t is time, in min; S is distance, in km;

[0082] In specific implementation, in this embodiment 1, the test time estimation constant k is 6 km / min; substituting it into the empirical formula, it can be obtained that 372 hours of random vibration is equivalent to the actual transportation distance of 133920 km experienced by the material;

[0083] In specific implementation, according to the information provided by the manufacturer, the actual transportation mileage of the rigid polyurethane foam in one year is about 4400 km, and it can be concluded that the service life of the material is about 30.44 years.

[0084] In summary, the technical solution of this patent creatively predicts the service life of the material based on the change of the resonant frequency, avoiding the large number of preliminary tests required by the traditional fatigue life prediction SN curve method, and can easily and quickly give a preliminary conclusion of the life prediction; all tests can be completed using only a vibration test bench, and the test time is less than that of the existing technology, and the test cost is also lower; the tests of the existing technology cannot take into account the influence of mechanical loads, especially random vibrations during transportation, while the method of the present invention can conveniently and quickly predict the service life of rigid polyurethane foam under transportation conditions; it can be used for the reliability evaluation of rigid polyurethane foam filling materials under actual service conditions; it has good scientific significance and engineering value.

[0085] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A rapid test method for predicting the service life of rigid polyurethane foam filling materials for nuclear power new fuel transportation containers, It is characterized in that The steps include: Step 1, cutting a rigid polyurethane foam sample, performing a vertical random vibration test on the sample, and collecting data; Step 2: Perform fast Fourier transform on the data collected in step 1 and draw a scatter plot; Step 3: Perform linear fitting on the scatter plot obtained in step 2. If a certain goodness of fit is not achieved, repeat steps 1 and 2. Step 4: Based on vibration isolation theory, define the end of the service life of the rigid polyurethane foam material; The step 4 is based on the classic formula of vibration isolation theory: ; In the above formula, η is the vibration transfer coefficient. When η is less than 1, it indicates that the material has a vibration isolation effect; β is the damping ratio, and λ is the ratio of the external excitation frequency to the material resonance frequency; In step 4, it can be seen from the above formula that when the external excitation frequency is the resonant frequency of the material, times, the material plays a vibration isolation role; conversely, when the resonant frequency of the material When the frequency is greater than the cutoff frequency of the road surface, the material loses its vibration isolation function; Step 5: Based on the fitting straight line obtained in step 3, the vibration time required to reach the end of the life obtained in step 4 is calculated, and the service life of the material is obtained according to the conversion relationship; The end point of the material life defined in step 4 is the frequency; when the frequency defined in step 4 is substituted into the fitting straight line obtained in step 3, the vibration time required to reach the end point of the life obtained in step 4 is calculated; In step 5, according to the empirical formula ; In the empirical formula, K is the test time estimation constant, in km / min; t is the time, in min; S is the distance, in km; In step 5, the constant K is estimated according to the test time; thereby, the actual transportation distance corresponding to the vibration time is calculated, and the vibration time is converted into the service life of the material in combination with the transportation mileage per unit time in actual use of the material.

2. The rapid test method according to claim 1, It is characterized in that The rigid polyurethane foam sample intercepted in step 1 is a cuboid; The test atmosphere of the vertical random vibration test in step 1 is air, and the test temperature is room temperature; The duration of the random vibration test in step 1 is 24 hours, and the PSD curve adopts the general transportation random vibration PSD curve; In step 1, during the vibration process of the random vibration test, data sampling needs to be performed at a constant interval, and the duration of each sampling needs to be consistent; The data collected in step 1 is a time domain signal of acceleration.

3. The rapid test method according to claim 1, It is characterized in that The step 2 uses fast Fourier transform to transform the time domain signal of acceleration collected in step 1 into a frequency domain signal of acceleration; In step 2, the frequency at which the recording material reaches the maximum acceleration amplitude is used as the resonance frequency at the corresponding sampling time point, and a scatter plot of the resonance frequency and the corresponding vibration time is drawn.

4. The rapid test method according to claim 1, It is characterized in that Step 3 is to perform linear fitting on the data points in the scatter plot obtained in step 2, and the goodness of fit specified in step 3 is 0.8; The fitting straight line obtained in step 3, the abscissa of the fitting straight line is the vibration time, and the ordinate is the frequency; In step 3, if the goodness of fit does not reach 0.8 after linear fitting, steps 1 and 2 need to be repeated until the goodness of fit reaches 0.

8.

5. The rapid test method according to claim 1, It is characterized in that The PSD curve in step 1 adopts the general transport random vibration PSD curve in GB / T 4857.23-2021.

6. The rapid test method according to claim 1, It is characterized in that In the step 1, during the vibration process of the random vibration test, data sampling is performed every 10 minutes, each sampling lasts for 2.34 seconds, and a total of 10,000 data points are collected.

7. The rapid test method according to claim 1, It is characterized in that The linear fitting in step 3 mainly utilizes the principle of least squares method.

8. The rapid test method according to claim 1, It is characterized in that In step 4, the cut-off frequency of the road surface vibration is 250 Hz (1 / ) times, that is, 176.8 Hz is defined as the end of the material's life.

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