A propellant safe service life evaluation method based on characteristic parameters
By measuring the effective stabilizer content and burning rate, combined with constant temperature accelerated aging tests, characteristic parameter-time curves were established, solving the problem of accuracy in propellant safety service life assessment and realizing the safety assessment of propellants during storage and use.
Patent Information
- Application Number
- CN202510104461.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2026-05-15
- Estimated Expiration
- 2045-01-23
AI Technical Summary
The accuracy of existing propellant safety service life assessment methods needs further improvement, which may lead to incomplete combustion, insufficient engine initial speed, and safety hazards during propellant storage.
A characteristic parameter-based evaluation method was adopted. By measuring the effective stabilizer content and burning rate, combined with an isothermal accelerated aging test, characteristic parameter-time curves were established using constant-number truncation and time-time truncation. The Bethelot equation or Arrhenius equation was applied for extrapolation to evaluate the safe storage and service life of the propellant.
This improves the accuracy of propellant lifespan assessment, ensuring that propellants can be safely stored and used throughout their entire lifespan, and meeting the safety and stability requirements of weapon systems.
Smart Images
Figure CN119985845B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of propellant technology and relates to propellant performance evaluation, specifically to a method for evaluating the safe service life of propellants based on characteristic parameters. Background Technology
[0002] Propellant is the power source of solid rocket motors. During long-term storage, the performance of the propellant charge changes with the external environment and time. This degradation of propellant performance is crucial to the safe storage and normal use of the solid rocket motor throughout its lifespan. Propellant lifespan can be divided into storage lifespan and service life. During storage, certain performance parameters of the propellant change over time. Once these changes exceed a certain range, the propellant can no longer be stored or used normally. Propellant lifespan is the time during which the propellant can be safely stored and reliably used, and can be divided into safe storage lifespan and service life. Safe storage lifespan refers to the time during which the propellant can be safely stored without danger under normal storage conditions. Service life refers to the time during which the propellant can still perform its intended functions under storage conditions. Both are important indicators for the safe storage and normal use of propellants.
[0003] Different components in a propellant formulation, and the varying proportions of each component, play a crucial role in the formulation's performance, resulting in significant performance differences between various propellant formulations. During long-term engine storage, the properties of the propellant vary considerably due to changes in environmental factors such as temperature, humidity, vibration, and sedimentation. Among currently deployed propellant products, there have been instances of incomplete combustion during long-term storage, leading to insufficient initial engine velocity, affecting subsequent thrust generation, and preventing normal projectile launch. In severe cases, this can result in the projectile burning or detonating nearby. While the propellant may be able to be stored safely, it may no longer be safe for use. Some propellant products may show normal physicochemical properties, combustion properties, energy properties, mechanical properties, and sensitivity safety properties during routine performance testing during storage, but exhibit problems with stability and a continuously changing dangerous trend. These propellant products cannot continue to be stored safely. Therefore, ensuring the safe use of propellant charges requires a comprehensive consideration of both safe and stable storage requirements and the requirements for normal operation of various performance aspects. It is essential to fully meet the needs of weapon systems, necessitating a safe service life assessment that balances safety and usability. Summary of the Invention
[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a propellant safe service life assessment method based on characteristic parameters, thereby solving the technical problem that the accuracy of the existing safe service life assessment methods needs to be further improved.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0006] A method for assessing the safe service life of propellants based on characteristic parameters, wherein the effective stabilizer content and burning rate are used as characteristic parameters.
[0007] The method includes the following steps:
[0008] Step 1: Measure the raw data of the characteristic parameters:
[0009] First, the effective stabilizer content and burning rate of the propellant are measured to obtain the original effective stabilizer content data and the original burning rate data.
[0010] Step two: Conduct a constant temperature accelerated aging test.
[0011] Depending on the type of propellant, at least four constant temperature points should be selected for isothermal accelerated aging tests.
[0012] Step 3, scheduling the testing time points:
[0013] Of the four constant temperature points, 75℃ was selected for the constant temperature accelerated test pre-test. Multiple detection time points were arranged according to the change in effective stabilizer content. At each detection time point, the effective stabilizer content and the burning rate were measured respectively.
[0014] Step 4, scheduled testing time:
[0015] The remaining three of the four constant temperature points are scheduled for testing, and the distribution interval of the scheduled testing time points is the same as the distribution interval of the multiple testing time points obtained in step three; at each testing time point, the effective stabilizer content and the burning rate are measured respectively.
[0016] Step 5: Experiment and record the data:
[0017] In the constant-temperature accelerated aging test at each temperature point, the sampling time at each test time point was recorded, and the measurement data of effective stabilizer content and burning rate were recorded.
[0018] Step 6, truncate:
[0019] The truncation method for the isothermal accelerated aging test process of effective stabilizer content adopts constant truncation, and the critical point of truncation is 50% effective stabilizer content.
[0020] When the burning rate is below an unacceptable value, the truncation method for the isothermal accelerated aging test of the burning rate adopts constant truncation, and the critical point of truncation is an unacceptable value.
[0021] When the burning rate does not reach an unacceptable value but the effective stabilizer content reaches the critical point first, the truncation method for the isothermal accelerated aging test process of the effective stabilizer content is timed truncation.
[0022] Step 7, Create the feature parameter-time curve:
[0023] Effective stabilizer content-time curves and burning rate-time curves were established at four constant temperature points.
[0024] Step 8: Lifetime prediction using effective stabilizer content as a characteristic parameter:
[0025] Based on the effective stabilizer content-time curve obtained in step seven, the safe period of the propellant at different temperatures, the safe storage life of the propellant at room temperature, and the aging decomposition temperature coefficient of the propellant are calculated.
[0026] Step 9, Lifetime prediction using burning rate as a characteristic parameter:
[0027] Based on the burning rate-time curve obtained in step seven, the burning rate failure period of the propellant at different temperatures, the service life of the propellant at room temperature, and the temperature coefficient of burning rate decline of the propellant are calculated, and the burning rate is noted as the characteristic parameter.
[0028] The present invention also has the following technical features:
[0029] In step two, the temperature interval between any two adjacent temperature points among the four constant temperature points is 10℃.
[0030] In step three, the range of multiple detection time points is set from the original effective stabilizer content to an effective stabilizer content of less than or equal to 50%.
[0031] In step three, the multiple detection time points refer to six to seven detection time points.
[0032] In step eight, the method for calculating the safe period of the propellant at different temperatures is as follows: Using 50% effective stabilizer content as the critical point for propellant safety storage life failure, draw a line parallel to the horizontal axis through this point and intersect it with the effective stabilizer degradation curve at different temperatures. The time corresponding to each intersection point is the safe period τ of the propellant at different temperatures. i .
[0033] In step eight, the method for calculating the safe storage life of the propellant at room temperature is as follows:
[0034]
[0035] In the formula:
[0036] τ 30This refers to the safe storage life of the propellant at 30°C.
[0037] Both A and B are coefficients.
[0038] In step eight, the method for calculating the aging decomposition temperature coefficient of the propellant is as follows:
[0039]
[0040] In the formula:
[0041] γ 10 The aging decomposition temperature coefficient of the propellant is the rate of change of the decomposition rate for every 10°C increase or decrease in temperature.
[0042] B is a coefficient.
[0043] In step nine, the calculation method for the propellant burn-up rate failure period at different temperatures is as follows:
[0044] The propellant burning rate failure critical point is obtained. A line parallel to the horizontal axis of the burning rate-time curve obtained in step seven is drawn to intersect the burning rate-time curves at different temperatures. The time corresponding to each intersection point is calculated, which is the burning rate failure period of the propellant at different temperatures.
[0045] In step nine, the calculation method for the propellant's service life at room temperature is as follows:
[0046] Based on the burning rate failure period of the propellant at different temperatures, the service life of the propellant at room temperature is calculated by extrapolation according to the Bethelot equation or the Arrhenius equation, and the characteristic parameter is noted as the burning rate.
[0047] In step nine, the method for calculating the propellant burning rate reduction temperature coefficient is as follows:
[0048]
[0049] In the formula:
[0050] γ′ 10 The temperature coefficient of the propellant burning rate decrease is the rate of change of the decomposition rate for every 10°C increase or decrease in temperature.
[0051] B′ is a coefficient.
[0052] Compared with the prior art, the present invention has the following technical effects:
[0053] (I) The method of the present invention provides a more accurate assessment of service life, and the propellant can meet the requirements for safe use throughout its entire life cycle, thus ensuring that the propellant can be safely stored and its service life is guaranteed.
[0054] (II) The method of the present invention conducts an accelerated aging test on the propellant product at a constant temperature. In the test, two characteristic parameters, effective stabilizer content and burning rate, are selected for detection. The test truncation adopts a combination of fixed-number truncation and timed truncation to effectively evaluate the safe service life of the propellant.
[0055] (III) The evaluation method of the present invention selects the effective stabilizer content and burning rate as characteristic parameters to characterize the stability and combustion performance respectively, adopts the four-temperature level high temperature constant temperature accelerated test as the means to accelerate performance degradation, selects the critical point of effective stabilizer content and burning rate as the criterion for safe use, and then uses the Bethelot equation or Arrhenius equation to extrapolate to room temperature to obtain the safe service life. Attached Figure Description
[0056] Figure 1 Photograph of the newly prepared sample.
[0057] Figure 2 To accelerate the process of taking photos of the sample tube.
[0058] Figure 3 Photos of the sample and the safety oven.
[0059] Figure 4 The curves show the changes in effective stabilizer content at 55℃ and 65℃.
[0060] Figure 5 The curves show the changes in effective stabilizer content at 75℃ and 85℃.
[0061] Figure 6 The curves show the changes in combustion rate at 55℃ and 65℃.
[0062] Figure 7 The curves show the changes in combustion rate at 75℃ and 85℃.
[0063] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation
[0064] It should be noted that, unless otherwise specified, all materials and equipment used in this invention are those known in the prior art.
[0065] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.
[0066] Example:
[0067] This embodiment presents a method for assessing the safe service life of propellants based on characteristic parameters, which uses the effective stabilizer content and burning rate as characteristic parameters.
[0068] The method includes the following steps:
[0069] Step 1: Measure the raw data of the characteristic parameters:
[0070] First, the effective stabilizer content and burning rate of the propellant are measured to obtain the original effective stabilizer content data and the original burning rate data.
[0071] Step two: Conduct a constant temperature accelerated aging test.
[0072] Depending on the type of propellant, at least four constant temperature points should be selected for isothermal accelerated aging tests.
[0073] In step two, the temperature interval between any two adjacent temperature points among the four constant temperature points is 10℃.
[0074] Specifically, in this step, under the premise of ensuring that the propellant aging mechanism is the same at each temperature point, four suitable constant temperature points are selected for testing. Then, regression analysis is performed according to the Bethelot equation or the Arrhenius equation, and the service life at room temperature is obtained by extrapolation to room temperature.
[0075] Step 3, scheduling the testing time points:
[0076] Of the four constant temperature points, 75℃ was selected for the constant temperature accelerated test pre-test. Multiple detection time points were arranged according to the change in effective stabilizer content. At each detection time point, the effective stabilizer content and the burning rate were measured respectively.
[0077] In step three, the range for setting multiple detection time points is from the original effective stabilizer content to the effective stabilizer content being less than or equal to 50%.
[0078] In step three, there are six to seven detection time points. This ensures that the effective stabilizer content at each detection time point is evenly distributed throughout the entire range.
[0079] In this step, the detection time points are divided into the effective stabilizer content detection time point and the burning rate detection time point. The burning rate detection time point is set synchronously with the effective stabilizer content detection time point.
[0080] Step 4, scheduled testing time:
[0081] The remaining three of the four constant temperature points are scheduled for testing, and the distribution interval of the scheduled testing time points is the same as the distribution interval of the multiple testing time points obtained in step three; at each testing time point, the effective stabilizer content and the burning rate are measured respectively.
[0082] In this specific embodiment, based on the 75°C pre-test, when the detection time intervals for the three temperatures of 55°C, 65°C, and 85°C are expected, the effective stabilizer content is calculated at approximately 3 times the amount for each 10°C temperature interval.
[0083] Furthermore, in this step, since extensive empirical data shows that the change in burning rate during propellant isothermal accelerated testing does not have a multiple relationship similar to that of effective stabilizer content, and each propellant product has different burning rate requirements, there is no uniform failure threshold for burning rate in propellant isothermal accelerated testing. Instead, the range of burning rate variation is determined based on the specific requirements of the product or test object. The burning rate detection time points are initially set synchronously with the effective stabilizer content detection time points, and then subsequent detection time points are predicted based on the degree of change in the actual measured burning rate data.
[0084] Step 5: Experiment and record the data:
[0085] In the constant-temperature accelerated aging test at each temperature point, the sampling time at each test time point was recorded, and the measurement data of effective stabilizer content and burning rate were recorded.
[0086] Step 6, truncate:
[0087] The truncation method for the isothermal accelerated aging test process of effective stabilizer content adopts constant truncation, and the critical point of truncation is 50% effective stabilizer content.
[0088] When the burning rate is below an unacceptable value, the truncation method for the isothermal accelerated aging test of the burning rate adopts constant truncation, and the critical point of truncation is an unacceptable value.
[0089] When the burning rate does not reach an unacceptable value but the effective stabilizer content reaches the critical point first, the truncation method for the isothermal accelerated aging test process of the effective stabilizer content is timed truncation.
[0090] Further in step six, there is a unified failure criterion threshold for the effective stabilizer content of propellant products or test subjects, namely 50% effective stabilizer content. Therefore, the isothermal accelerated test for effective stabilizer content is truncated at a constant value when the effective stabilizer content reaches 50%. There is no unified failure criterion threshold for the burning rate of propellant products or test subjects. If the product or test subject has an unacceptable value, the isothermal accelerated test for burning rate is truncated at a constant value when the unacceptable value is reached. If the product or test subject does not have an unacceptable value, the failure criterion threshold for effective stabilizer content is used for timed truncation.
[0091] Step 7, Create the feature parameter-time curve:
[0092] Effective stabilizer content-time curves and burning rate-time curves were established at four constant temperature points.
[0093] Further in step seven, when performing curve fitting using data processing software, a unified curve model should be selected for each temperature point curve, and a model with the highest possible correlation coefficient should be chosen for fitting. R0 is recommended. 2 The value is not less than 0.99.
[0094] Step 8: Lifetime prediction using effective stabilizer content as a characteristic parameter:
[0095] Based on the effective stabilizer content-time curve obtained in step seven, the safe period of the propellant at different temperatures, the safe storage life of the propellant at room temperature, and the aging decomposition temperature coefficient of the propellant are calculated.
[0096] In step eight, the method for calculating the safe period of the propellant at different temperatures is as follows: Using 50% effective stabilizer content as the critical point for propellant safety storage life failure, draw a line parallel to the horizontal axis through this point and intersect it with the effective stabilizer degradation curve at different temperatures. The time corresponding to each intersection point is the safe period τ of the propellant at different temperatures. i .
[0097] In step eight, the method for calculating the safe storage life of the propellant at room temperature is as follows:
[0098]
[0099] In the formula:
[0100] τ 30 This refers to the safe storage life of the propellant at 30°C.
[0101] Both A and B are coefficients.
[0102] In step eight, the method for calculating the aging decomposition temperature coefficient of the propellant is as follows:
[0103]
[0104] In the formula:
[0105] γ 10 The aging decomposition temperature coefficient of the propellant is the rate of change of the decomposition rate for every 10°C increase or decrease in temperature.
[0106] B is a coefficient.
[0107] Step 9, Lifetime prediction using burning rate as a characteristic parameter:
[0108] Based on the burning rate-time curve obtained in step seven, the burning rate failure period of the propellant at different temperatures, the service life of the propellant at room temperature, and the temperature coefficient of burning rate decline of the propellant are calculated, and the burning rate is noted as the characteristic parameter.
[0109] In step nine, the calculation method for the propellant burn-up rate failure period at different temperatures is as follows:
[0110] The propellant burning rate failure critical point is obtained. A line parallel to the horizontal axis of the burning rate-time curve obtained in step seven is drawn to intersect the burning rate-time curves at different temperatures. The time corresponding to each intersection point is calculated, which is the burning rate failure period of the propellant at different temperatures.
[0111] In step nine, the calculation method for the propellant's service life at room temperature is as follows:
[0112] Based on the burning rate failure period of the propellant at different temperatures, the service life of the propellant at room temperature is calculated by extrapolation according to the Bethelot equation or the Arrhenius equation, and the characteristic parameter is noted as the burning rate.
[0113] In step nine, the method for calculating the propellant burning rate reduction temperature coefficient is as follows:
[0114]
[0115] In the formula:
[0116] γ′ 10 The temperature coefficient of the propellant burning rate decrease is the rate of change of the decomposition rate for every 10°C increase or decrease in temperature.
[0117] B′ is a coefficient.
[0118] This invention assesses the safe service life of propellants based on a combination of effective stabilizer content and burning rate, prioritizing safe use and using the safe storage life assessment based on the effective stabilizer content parameter as the primary foundation. If the service life characterized by burning rate is shorter than the safe storage life, then that service life is considered the safe service life. Conversely, if the service life characterized by burning rate is longer than the safe storage life, then the safe storage life is the same as the safe service life. In other words, the shortest service life for safe use is equivalent to the safe storage life; beyond this period, the propellant can no longer be guaranteed safe use.
[0119] Application example:
[0120] This application example provides a propellant safe service life assessment method based on characteristic parameters, according to the above embodiments. The method uses the effective stabilizer content and burning rate as characteristic parameters.
[0121] First, propellant selection:
[0122] In this application example, the known modified double-base GOQ propellant was selected as the test subject.
[0123] This application example assesses the safe service life of a modified double-base propellant used as a launch charge. In this example, the modified double-base propellant, after being ignited by a flame, generates high-temperature, high-pressure gas. This gas flows through the nozzle, is accelerated, and converts thermal energy into kinetic energy, generating thrust to propel the projectile out of the launch tube. The modified double-base propellant in this application example has high energy, a low pressure index, a low temperature sensitivity coefficient, and a high density, thus ensuring the engine's operating time and total stroke requirements.
[0124] Second, the test subjects:
[0125] The test samples were newly manufactured propellant burning rate strips with dimensions of Φ5mm × 150mm. The accelerated storage test consisted of four accelerated temperature stress levels, with eight detection time points at each temperature. Five samples were introduced at each detection time point, requiring a total of 160 samples. Sample photos are available below. Figure 1 and Figure 2 .
[0126] Third, the experimental items:
[0127] The test items include: effective stabilizer content measurement test, burning rate test, and constant temperature accelerated aging test. The effective stabilizer content measurement test is carried out according to the stabilizer bromination method in Method 210.1 of GJB770B-2005 "Test Methods for Gunpowder". The burning rate test is carried out according to the burning rate target line method in Method 7.6.1 of GJB770B-2005 "Test Methods for Gunpowder". The constant temperature accelerated aging test is carried out according to the thermal accelerated aging method for estimated safe storage life in Method 506.1 of GJB770B-2005 "Test Methods for Gunpowder".
[0128] Fourth, the method and steps:
[0129] The method includes the following steps:
[0130] Step 1: Measure the raw data of the characteristic parameters:
[0131] Step one in the embodiments is adopted.
[0132] Step two: Conduct a constant temperature accelerated aging test.
[0133] Step two in the examples is adopted. In this application example, accelerated aging tests are conducted at four temperature levels: 55℃, 65℃, 75℃, and 85℃, based on the characteristics of the modified double-base GOQ propellant formulation.
[0134] Step 3, scheduling the testing time points:
[0135] Step three in the embodiment is adopted. In this application example, as... Figure 3 As shown, the sample placed inside ensures that the freshly prepared burning rate strip sample does not come into contact with the oven wall.
[0136] Step 4, scheduled testing time:
[0137] Step four in the example is adopted. In this application example, based on the test results at 75°C, test time points of 55°C, 65°C, and 85°C are scheduled. Similarly, 6-7 test time points are set for each temperature point, and the effective stabilizer content and burning rate are measured at each test time point.
[0138] Step 5: Experiment and record the data:
[0139] Step five in the embodiment is adopted.
[0140] Step 6, truncate:
[0141] Step six in the examples is adopted. In this application example, the effective stabilizer content tracking and monitoring is truncated at a critical point of 50%, i.e., an effective stabilizer content of 0.71%. The modified double-base GOQ propellant in this application example does not have a failure critical point requirement for burning rate, so the truncated time is based on the effective stabilizer content.
[0142] Step 7, Create the feature parameter-time curve:
[0143] Step seven of the embodiments is adopted. In this application example, Origin software is used to plot the effective stabilizer content and burning rate on the ordinate and the aging time on the abscissa to obtain the effective stabilizer content-time curve and the burning rate-time curve of the sample at a certain constant temperature. There are four curves in total at four temperatures. When performing curve fitting, a unified curve model should be selected for the curves at each temperature point, see [link to documentation]. Figures 4 to 7 .
[0144] Step 8: Lifetime prediction using burning rate as a characteristic parameter based on effective stabilizer content:
[0145] Step eight in the examples is used. The results of the index calculation based on the effective stabilizer content in this application example are shown in Tables 3 and 4.
[0146] Step 9, Lifetime prediction using burning rate as a characteristic parameter:
[0147] Step nine in the embodiments is adopted. In this application example, the modified double-base GOQ propellant has no critical point requirement for burning rate failure. The lower limit of its product burning rate technical specification requirement is used as the critical point. The burning rate degradation temperature coefficient and the safe service life with burning rate as a parameter at different temperatures are obtained through calculation.
[0148] Fifth, the test results:
[0149] In step five, the results of the effective stabilizer content measurement test are shown in Table 1.
[0150] Table 1 Results of the test for measuring the effective stabilizer content
[0151]
[0152]
[0153] The results of the burning rate test in step five are shown in Table 2.
[0154] Table 2 Results of the Burn Rate Test
[0155]
[0156] Sixth, life expectancy:
[0157] In step eight, lifetime prediction is performed using the effective stabilizer content as a characteristic parameter:
[0158] Plot the data in Table 1 against aging time using the effective stabilizer content. Figure 4 and Figure 5 The aging time corresponding to 50% consumption of effective stabilizer at each aging temperature was determined from the curve, which is the critical point of safe storage life at different aging temperatures, as shown in Table 3.
[0159] Table 3 Critical points for safe storage life at different aging temperatures
[0160]
[0161]
[0162] Substituting the data from Table 3 into the Bethelot equation and performing regression, the experimental form of the Bethelot equation is obtained as follows:
[0163] T = A + B · log10τ
[0164] T = 363.43 - 17.3880 logτ
[0165] R 2 =0.9876
[0166] Extrapolating to 30℃, 25℃, and 20℃, the safe storage life of the propellant at different temperatures was obtained (see Table 4). The aging decomposition temperature coefficient γ of the propellant was also calculated. 10 It is 3.70.
[0167] Table 4 Safe storage life at different temperatures
[0168] Storage temperature / °C 20 25 30 Safe storage life / year 31 16 8
[0169] In step nine, lifetime prediction is performed using burning rate as a characteristic parameter:
[0170] Plot the data in Table 2 against aging time using combustion rate, see... Figure 6 and Figure 7The aging time corresponding to the lower limit of the burning rate (product burning rate index requirement) of 27.5 mm / s at each aging temperature was obtained from the curve, which is the critical point of burning rate degradation at different aging temperatures, as shown in Table 5.
[0171] Table 5 Critical points of burn rate degradation life under different aging temperatures
[0172] Aging temperature / ℃ 55 65 75 85 Burn rate degradation critical point / d 95 23 4.2 6.1
[0173] The burning rate data after aging at 85℃ is generally too high, which is due to systematic bias during measurement and should be removed. Substituting the data of 55℃, 65℃ and 75℃ in Table 8 into the Bethelott equation and performing regression, the experimental formula of the Bethelott equation is as follows, which shows good correlation.
[0174] T = A + B · log10τ
[0175] T = 357.05 - 14.5400 logτ
[0176] R 2 =0.9960
[0177] Extrapolating to 30℃, 25℃, and 20℃, the safe service life of the propellant at different temperatures is obtained (see Table 6). The temperature coefficient γ′ of the propellant's burning rate decrease is also obtained. 10 It is 4.87.
[0178] Table 6 Burn-rate degradation life at different temperatures
[0179] Storage temperature / °C 20 25 30 Safe service life / year 70 31 14
Claims
1. A method for assessing the safe service life of propellants based on characteristic parameters, characterized in that, This method uses the effective stabilizer content and burning rate as characteristic parameters; The method includes the following steps: Step 1: Measure the raw data of the characteristic parameters: First, the effective stabilizer content and burning rate of the propellant are measured to obtain the original effective stabilizer content data and the original burning rate data; Step two: Conduct an accelerated aging test at a constant temperature. Based on the type of propellant, at least four isothermal temperature points should be selected for isothermal accelerated aging tests. Step 3, scheduling the testing time points: Of the four constant temperature points, 75℃ was selected for the constant temperature accelerated test pre-test. Multiple detection time points were arranged according to the change of effective stabilizer content. At each detection time point, the effective stabilizer content and the burning rate were measured respectively. In step three, the range of the multiple detection time points is from the original effective stabilizer content to an effective stabilizer content of less than or equal to 50%. Step 4, scheduled testing time: The remaining three of the four isothermal temperature points are scheduled for testing, and the distribution interval of these scheduled testing time points is the same as the distribution interval of the multiple testing time points obtained in step three; at each testing time point, the effective stabilizer content and the burning rate are measured respectively. Step 5: Experiment and record the data: In the constant temperature accelerated aging test at each temperature point, the sampling time at each test time point was recorded, and the effective stabilizer content measurement data and burning rate measurement data were recorded. Step 6, truncate: The truncation method for the isothermal accelerated aging test process of effective stabilizer content adopts constant truncation, and the critical point of truncation is 50% effective stabilizer content. When the burning rate is below the unacceptable value, the truncation method of the isothermal accelerated aging test of the burning rate adopts constant truncation, and the critical point of truncation is the unacceptable value. When the burning rate does not reach an unacceptable value but the effective stabilizer content reaches the critical point first, the truncation method of the isothermal accelerated aging test process of the effective stabilizer content is timed truncation. Step 7, Create the feature parameter-time curve: Effective stabilizer content-time curves and burning rate-time curves were established at four constant temperature points. Step 8: Lifetime prediction using effective stabilizer content as a characteristic parameter: Based on the effective stabilizer content-time curve obtained in step seven, the safe period of the propellant at different temperatures, the safe storage life of the propellant at room temperature, and the aging decomposition temperature coefficient of the propellant are calculated. Step 9, Lifetime prediction using burning rate as a characteristic parameter: Based on the burning rate-time curve obtained in step seven, the burning rate failure period of the propellant at different temperatures, the service life of the propellant at room temperature, and the burning rate decrease temperature coefficient of the propellant are calculated, and the burning rate is noted as the characteristic parameter. In step nine, the method for calculating the burning rate failure period of the propellant at different temperatures is as follows: obtain the critical point of propellant burning rate failure, draw a line parallel to the horizontal axis on the burning rate-time curve obtained in step seven, intersect it with the burning rate-time curve at different temperatures, and calculate the time corresponding to each intersection point, which is the burning rate failure period of the propellant at different temperatures. In step nine, the calculation method for the service life of the propellant at room temperature is as follows: based on obtaining the burning rate failure period of the propellant at different temperatures, the service life of the propellant at room temperature is calculated by extrapolation according to the Bethelot equation or the Arrhenius equation, and the characteristic parameter is noted as the burning rate. In step nine, the method for calculating the propellant burning rate reduction temperature coefficient is as follows: …………………………………………Form III; In the formula: The temperature coefficient of the propellant burning rate decrease is the rate of change of burning rate for every 10°C increase or decrease in temperature. is a coefficient.
2. The propellant safe service life assessment method based on characteristic parameters as described in claim 1, characterized in that, In step two, the temperature interval between any two adjacent temperature points among the four constant temperature points is 10℃.
3. The propellant safe service life assessment method based on characteristic parameters as described in claim 1, characterized in that, In step three, the multiple detection time points refer to six to seven detection time points.
4. The propellant safe service life assessment method based on characteristic parameters as described in claim 1, characterized in that, In step eight, the calculation method for the safe period of the propellant at different temperatures is as follows: Using 50% effective stabilizer content as the critical point for propellant safe storage life failure, a line parallel to the horizontal axis is drawn through this point and intersected with the effective stabilizer degradation curve at different temperatures. The time corresponding to each intersection point is the safe period of the propellant at different temperatures. τ i .
5. The propellant safe service life assessment method based on characteristic parameters as described in claim 1, characterized in that, In step eight, the method for calculating the safe storage life of the propellant at room temperature is as follows: Equation I; In the formula: τ 30 This refers to the safe storage life of the propellant at 30°C. A and B All are coefficients.
6. The propellant safe service life assessment method based on characteristic parameters as described in claim 1, characterized in that, In step eight, the method for calculating the aging decomposition temperature coefficient of the propellant is as follows: …………………………………………Form II; In the formula: γ 10 The aging decomposition temperature coefficient of the propellant is the rate of change of the decomposition rate for every 10°C increase or decrease in temperature. B is a coefficient.