Experimental Research On Tension And Compression Characteristics And Damage Evolution Features Of Azide Polyether Propellant

The solid rocket engine is mainly under tension or compression during the whole life cycle.The traditional structural integrity analysis did not consider the influence of the propellant tension and compression.Azide polyether propellant represents the development direction of high-energy solid propellants.The study of its tensile and compressive behavior characteristics was not thorough enough,and it has become the main factor restricting the analysis of the fine structure integrity of high-energy solid motors.This paper took the azide polyether propellant as the research object,and conducted a systematic study on the tension and compression characteristics and damage evolution characteristics of the propellant.The main research work is as follows:The compression stress relaxation test of the propellant was designed and implemented,the main curve of compression relaxation of the azide propellant was obtained,and the asymmetric properties of tension and compression relaxation of the propellant were discovered and quantitatively analyzed.Based on the principle of the propellant tensile stress relaxation test,a compressive stress relaxation test was designed,the main curve of its compression relaxation modulus was obtained,and the tension-compression relaxation asymmetric characteristics of the azide polyether propellant were found.A modulus tension-compression asymmetry factor was introduced,and its relaxation tension-compression asymmetry was quantitatively analyzed.By defining the temperature sensitivity coefficient of the modulus,the influence of temperature on the tensile-compression modulus of the propellant was obtained.On this basis,a mesoscopic model of the propellant was established by molecular dynamics,and the mechanism of the tension-compression relaxation asymmetry of the propellant was analyzed through simulation.Through the constant-speed tensile test,the inherent relationship between the strain energy density and the damage evolution of the azide propellant at different stages was revealed.The constant strain cyclic loading test method of the propellant was proposed,and the evolution characteristics of tensile damage of the propellant during cyclic loading were obtained.Based on the tensile test of the azide polyether propellant at normal temperature and various strain rates,the brittle failure form of the propellant’s tensile process was found,and the effect of strain rate on the tensile properties and damage evolution characteristics of the propellant was studied.The lower tensile rate,the more serious the damage evolution of the propellant.Through the design of constant strain cyclic loading test,it was found that in the stress strengthening section,the increase of cyclic strain increased the internal damage of the propellant.The study designed and implemented a constant-speed compression test of the propellant,obtained the initial modulus and maximum strength master curve of the azide propellant,revealed the compression failure characteristics of the azide propellant at different temperatures and strain rates,and quantitatively studied the tension and compression asymmetry characteristics of the propellant mechanics.Based on the compression test of the azide polyether propellant at different temperatures and loading rates,it was found that the compression failure of the propellant was still characterized by brittle materials.The effects of strain rate and temperature on the compressive mechanical properties and damage evolution features of the propellant were studied.The main curves of the initial compressive modulus and maximum strength of the propellant was drawn by using the rate-temperature equivalent characteristics of the propellant.Through the comparative study of tension-compression test,it was found that the tension and compression asymmetry characteristics of the strength of the propellant was higher than the tension and compression asymmetry characteristics of its stiffness.In summary,this article has studied the tension and compression asymmetry characteristics and damage evolution characteristics of azide polyether propellant through the test system.The research methods and results can support the establishment of the tension and compression constitutive model and failure criterion of the azide propellant.It is a technical support for detailed structural integrity analysis of the azide engine.