An Analysis Of Irreversible Deformation Mechanism Of TATB-based PBX Under Thermal Cycling Load

Polymer Bonded Explosive(PBX)is a heterogeneous material compressed by granular explosive(such as TATB),polymer binder,plasticizer,and inactivator Quality materials,because of the high energy density,good machining performance,low sensitivity,and good safety performance,it is widely used in military and engineering fields.In actual use,due to changes in day and night and seasons,PBX materials will be subjected to a series of thermal cycling loads,resulting in irreversible deformation.Researches at home and abroad conducted relevant research on the irreversible deformation of PBX materials,and found that after cyclic temperature loading,the structure of PBX explosives always showed deformation in macroscopic,and volume fraction increase of pore in mesoscopic.Macro-deformation causes a gap between the PBX and the casing,which is easy to friction and collision with the casing.Changes in the meso-structure will also affect the ignition performance and detonation performance of the PBX.These phenomena will affect the actual use of PBX explosives.However,although many researchers at home and abroad have conducted relevant research on the irreversible deformation of PBX materials,and have accumulated a certain theoretical basis,due to the complex microstructure of PBX explosives,diverse technological processes,and harsh service environment,the understanding of the irreversible deformation mechanism of PBX explosives under thermal cycling load is still weak,and it does not associate meso damage with macro deformation.So,it is very important to study the irreversible deformation of PBX explosives under thermal cycling load,which helps to deeply understand the irreversible deformation mechanism of explosives and lay a theoretical foundation for the subsequent research of explosives,which has certain scientific significance and engineering value.This paper takes PBX9502 as the research object,concentrate on the phenomenon of irreversible deformation and volume growth when it is subjected to cyclic heat load,and studies the cause and mechanism of this phenomenon from a meso point of view.For this problem,mainly using numerical simulation methods.At first,carry out anisotropic thermodynamic mesoscopic modeling according to the microstructure characteristics of the PBX material,Using the Monte Carlo stochastic method and Voronoi polygons,an anisotropic meso model of the PBX material was established.In this model,the volume ratio of explosive particles can reach 90%or more.Secondly,the extended finite element(XFEM)was used to simulate the debonding of the interface and the fracture of the binder in the PBX95022,obtain the damage form and stress state of at different temperatures.Finally,combining the changes in the meso-structure with the macro volume growth,plot the relationship between the residual strain and the number of loadings,and explore the factors that affect the irreversible deformation in the PBXThe main conclusions are:1)During cyclic temperature loading,the debonding of the interface and the cracking of the binder due to stress concentration are important sources of irreversible volume growth in the PBX.2)PBX is more prone to interface debonding and tensile fracture in the process of cooling.3)The plasticity of the binder is also one of the sources of irreversible volume growth of the PBX,and has a certain impact on the periodic trend of strain.