Detection And Analysis Of Three-dimensional Internal Stress And Grain Strain Of Aerospace Solid Engine Propellant

During the long-term storage or long-distance transportation of the aerospace solid engine,due to the complex environmental load,its internal propellant and grains will undergo unpredictable changes.In extreme cases,the propellant debonding or the grain fracture may occur There is a risk of ignition failure.It is of great scientific significance to study the health monitoring system of aerospace solid engine to monitor or evaluate its internal propellant state and life.At present,the health monitoring methods of aerospace solid engines mainly evaluate and predict the health status and life expectancy of solid engines through theoretical calculations or simulation methods.However,due to the complexity of the propellant composition and the environmental load,it is difficult to accurately simulate the internal stress changes.The results of this theoretical calculation or simulation method lack reliability.Therefore,research on the evaluation and prediction of the health status and life expectancy of aerospace solid engines based on a new type of sensor-based health monitoring system is a key issue to be solved urgently in this field.In response to this problem,this paper proposes a health monitoring system based on the three-dimensional stress and grain strain of the solid engine propellant based on the immersion three-dimensional force sensor and the flexible large strain sensor.The health monitoring system realizes the real-time monitoring of the three-dimensional stress inside the propellant by embedding multiple immersion three-dimensional force sensors inside the propellant of the aerospace solid engine,and at the same time realizes the strain of the propellant by pasting multiple flexible large strain sensors inside the propellant Real-time monitoring.By analyzing the measured data of the three-dimensional stress and propellant strain of the propellant,real-time monitoring of the health of the solid engine under typical transportation and storage conditions can be achieved.The research content of this paper mainly includes:research on the principle and structure of the aerospace solid engine propellant immersion three-dimensional stress sensor and the aerospace solid engine propellant grain flexible large strain sensor;subsequently,based on the aerospace solid engine three-dimensional stress and the grain strain Measurement requirements,combined with the size requirements of this project,selected and prepared the sensor’s intermediate layer and substrate materials and sensitive materials,and finally prepared the sensor principle prototype.Next,the environmental shielding method of the three-dimensional stress sensor of the aerospace solid engine propellant immersion type and the flexible electrode material of the aerospace solid engine propellant grain flexible large strain sensor were studied.Subsequently,an experimental measurement platform was designed,and two sensor performance tests were conducted through the experiment;finally,the two sensors were placed in a solid engine,and a simulation experiment of a typical transportation environment and a typical storage environment was designed.The measurement sensor was obtained in the experiment Real data.The research results show that the aerospace solid engine propellant immersion three-dimensional stress sensor designed in this paper has a tiny size of 6mm*6mm*12mm,and can detect the positive pressure in the range of 0-354 KPa and the shear force and positive pressure in the range of 0-177 KPa.The repeatability error is 14.9%.The sensitivity is 4.9 × 10^-5pF/KPa,and the repeatability error of shear force is 11.78%.The sensitivity is 3.67 × 10^-5pF/KPa.The aerospace solid engine propellant grain flexible large strain sensor is designed with a small size of 10mm*8mm*1mm,which can measure the strain from 0 to 20%,the linearity is 3.79%,and the hysteresis error is 4.15%.In the simulation experiment,it is possible to accurately measure the change of the three-dimensional stress of the internal propellant and the strain of the pellet when the external load of the solid engine changes.The change in capacitance value of positive pressure and shear force of aerospace solid engine propellant immersed three-dimensional stress sensor is positively and linearly related to the external pressure.The change in resistance value of a flexible large strain sensor of aerospace solid engine propellant grain is positively related to the sensor strain Linear correlation.The aerospace solid engine propellant immersion three-dimensional stress sensor designed in this paper and the aerospace solid engine propellant grain flexible large strain sensor meet the measurement requirements of the aerospace solid engine in the measurement range and size,and can also be fed back in real time in the simulation experiment.The response of the three-dimensional stress and propellant strain of the solid propellant when the external load changes.Therefore,these two sensors can realize the health monitoring of aerospace solid engines.The research results in this paper can improve the reliability of solid engine health monitoring,which is of great significance to solid engine health monitoring.It can not only reduce the probability of launch failure,but also save a lot of money.It can also provide data support for future new solid engine production.The overall development of the country in terms of solid motors has improved comprehensive benefits.