A reliability accelerated screening method for missile-borne fiber-optic gyroscope combined device

Abstract

A method for accelerating the reliability screening of missile-borne fiber optic gyroscope assemblies is disclosed, relating to the field of device reliability screening technology, particularly to the field of missile-borne fiber optic gyroscope assemblies. By lowering the lower limit of the test temperature from -45℃ to -50℃ and raising the upper limit from 70℃ to 85℃, increasing the temperature change rate from 5℃ / min to 25℃ / min, and changing the vibration load from uniaxial to simultaneous triaxial six-degree-of-freedom excitation, the screening and testing time is shortened, achieving the goal of accelerating reliability screening. Furthermore, to make the testing scheme more closely resemble actual usage conditions, the sequential temperature variation test and uniaxial random vibration test scheme are modified into a comprehensive environmental test scheme that applies vibration while conducting two cycles of temperature variation tests. This approach aims to fully expose early failures of the missile-borne fiber optic gyroscope assemblies, improve their reliability, and provide a new option for accelerated reliability screening.

Description

Technical Field

[0001] This invention relates to the field of device reliability screening technology, and in particular to the field of reliability screening technology for missile-borne fiber optic gyroscope assemblies. Background Technology

[0002] In missile guidance systems, a key component is a fiber optic gyroscope assembly. This assembly provides the missile with angle and angular velocity signals in inertial space, providing a basis for missile flight control. The zero-bias and zero-drift parameters of the fiber optic gyroscope assembly are important parameters indicating the product's qualification. After the assembly is manufactured and its zero-bias and zero-drift parameters are tested to ensure they are qualified, a reliability screening test must be conducted before delivery and installation. The existing reliability screening test involves five cycles of temperature variation testing, with the temperature decreasing to room temperature in the last cycle. This is followed by a 5-minute uniaxial random vibration test at room temperature, and finally ten cycles of temperature variation testing, with the temperature decreasing to room temperature in the last cycle. Zero-bias and zero-drift parameters are tested after each temperature variation test cycle and during the vibration test. Passing all tests constitutes passing the reliability screening test. The temperature change over time during the temperature variation test cycles before and after the vibration test is as follows: holding at -45℃ for 60 minutes, then increasing to 70℃ at a rate of 5℃ / min, holding for 60 minutes, and then decreasing to -45℃ at a rate of 5℃ / min. The power spectrum of the vibration test is: a power spectral density of 0.006g at 20Hz. 2 / Hz, the power spectral density was increased from 0.01g at a rate of 3dB / OCT between 20Hz and 80Hz. 2 / Hz increased to 0.04g 2 / Hz, maintaining 0.04g between 80Hz and 350Hz. 2 The power spectral density was measured at / Hz, and the power spectral density was reduced from 0.04g at a rate of 3dB / OCT from 350Hz to 2000Hz. 2 / Hz decreased to 0.007g 2 / Hz.

[0003] This screening and assessment method suffers from a high failure rate because the narrow temperature range, short holding time at the upper and lower limits of the test temperature, and the use of single-axis random vibration, all of which fail to fully expose the early failures of the fiber optic gyroscope assembly. In addition, the low temperature change rate during screening and assessment results in a long screening and assessment time. Summary of the Invention

[0004] The purpose of this invention is to reduce the failure rate of actual testing of fiber optic gyroscope assemblies and shorten the original reliability screening time. Therefore, a method for accelerating the reliability screening of airborne fiber optic gyroscope assemblies is proposed.

[0005] The technical solution of this invention is as follows: Existing evaluation and screening methods only consider the temperature and vibration environment of missiles during normal transportation and use, but do not consider the drastic temperature changes throughout the four seasons during missile storage, or the drastic vibration changes during short-distance transportation or natural disasters, especially earthquakes; on the other hand, they do not consider the performance degradation caused by component aging after long-term storage of missiles. Therefore, the original evaluation scheme design will have a gap with actual usage conditions. To minimize this gap, while keeping the failure mode unchanged, the temperature change rate of the screening test is increased to reduce the screening test time, thereby accelerating the reliability screening process. This will fully expose the early failures of the missile-borne fiber optic gyroscope assembly and improve its reliability level. The specific accelerated screening scheme is as follows: conduct two cycles of temperature change testing and simultaneously apply a comprehensive environmental test of three-axis six-DOF non-Gaussian broadband pseudo-random vibration. Vibration is applied 3 minutes before the temperature change from low temperature to high temperature or high temperature to low temperature, held for 10 minutes, and then unloaded. After the last unloading, the temperature is raised to room temperature at a rate of 25℃ / min. The zero bias and zero drift parameters are monitored during the vibration process, the high temperature holding stage, and the final room temperature state. If any monitoring data fails to meet the requirements, the reliability test is stopped and the device is deemed to have failed the test. Only when all monitoring data meet the requirements is the reliability screening test considered passed.

[0006] The temperature changes over time during the temperature variation test cycle are as follows: after holding at -50℃ for 92 min, the temperature is increased to 85℃ at a rate of 25℃ / min, and after holding at -50℃ for 92 min, the temperature is decreased to -50℃ at a rate of 25℃ / min. The vibration test parameters are: a three-axis, six-degree-of-freedom non-Gaussian broadband pseudo-random vibration with a vibration frequency range from 5Hz to 10KHz, a vibration stress starting from 0Grms and increasing to 25Grms at a rate of 20Grms / min, held for 10 min, and then decreasing to 0Grms at a rate of 20Grms / min.

[0007] The present invention has the following advantages: the comprehensive environmental assessment of applying vibration load simultaneously during temperature variation cycles is closer to the actual use environment of fiber optic gyroscope assemblies; increasing the temperature change rate from 5℃ / min to 25℃ / min and changing the application of vibration load from uniaxial to triaxial six-degree-of-freedom excitation both raise the requirements for the reliability screening method of airborne fiber optic gyroscope assemblies, and correspondingly shorten the reliability screening time from 30 hours to 3 hours and 40 minutes, providing a new option for accelerated reliability testing methods. Detailed Implementation

[0008] The present invention will be described in detail below with reference to embodiments:

[0009] The following reliability screening accelerated test was carried out on a certain type of missile-borne fiber optic gyroscope assembly: First, the missile-borne fiber optic gyroscope assembly was placed at -50℃ for 92 min, then heated to 85℃ at a rate of 25℃ / min, held for 92 min, then cooled to -50℃ at a rate of 25℃ / min, held for 92 min, then heated to 85℃ at a rate of 25℃ / min, held for 92 min, then cooled to -50℃ at a rate of 25℃ / min, held for 5 min, and then heated to room temperature at a rate of 25℃ / min. Three minutes before the above temperature change from low temperature to high temperature or from high temperature to low temperature, a three-axis six-degree-of-freedom non-Gaussian broadband pseudo-random vibration with a vibration frequency width from 5Hz to 10KHz, a vibration stress starting from 0Grms and increasing to 20Grms / min at a rate of 20Grms / min, held for 10 min, and then decreasing to 0Grms at a rate of 20Grms / min was applied. Its zero bias and zero drift parameters were monitored during the vibration process, the high temperature holding stage, and the final room temperature state. By increasing the screening stress, the reliability screening time was shortened from 30 hours to 3 hours and 40 minutes. When the airborne fiber optic gyroscope assemblies whose zero bias and zero drift parameters meet the requirements until the final room temperature monitoring are put into actual testing, the failure rate of the fiber optic gyroscope assemblies is reduced compared with the existing reliability screening methods.

Claims

1. A method for accelerating reliability screening of missile-borne fiber optic gyroscope combination devices, characterized in that: Two cycles of temperature variation testing, along with a comprehensive environmental test involving triaxial, six-DOF non-Gaussian broadband pseudo-random vibration, were conducted simultaneously. Vibration was applied 3 minutes before the temperature change from low to high or high to low, held for 10 minutes, and then unloaded. After the final unloading, the temperature was increased to room temperature at a rate of 25°C / min. Zero bias and zero drift parameters were monitored during each vibration cycle, the high-temperature holding phase, and at the final room temperature. The reliability test was stopped and deemed a failure if any monitoring data failed to meet the requirements; only when all monitoring data met the requirements was the test considered successful. To pass the reliability screening test, the temperature changes over time during the temperature variation test period were as follows: after holding at -50℃ for 92 min, the temperature was increased to 85℃ at a rate of 25℃ / min, and after holding at -50℃ for 92 min, the temperature was decreased to -50℃ at a rate of 25℃ / min. The vibration test parameters were: a three-axis, six-degree-of-freedom non-Gaussian broadband pseudo-random vibration with a vibration frequency range from 5Hz to 10KHz, a vibration stress starting from 0Grms and increasing to 20Grms / min at a rate of 20Grms / min, held for 10 min, and then decreasing to 0Grms at a rate of 20Grms / min.