Study On Compression Performance Of PBX In Wide Temperature Domain By Image Method

Polymer Bonded Explosives(PBX)is a kind of particle highly filled materials.PBX has good mechanical properties and safety,so it is widely used in weapons.PBX will experience external load and the environment temperature changes during its use,so the study of the mechanical properties of PBX in wide temperature range is of vital significance.This paper study the compressive mechanical properties of two kinds of PBX at different temperatures mainly using digital image correlation method.The properties include the stress-strain curve,constitutive model,the change of Poisson's ratio;and the failure mode of PBX are also researched by scanning electron microscopy and image analysis.The properties of PBX materials are affected by the type of explosive crystal and binder.In this paper,the mechanical properties of two kinds of materials,PBX-03 and PBX-14,are studied at different temperatures.The range of experimental temperature is from-40? to 200?,which are divided into three groups,110-200?,50-170? and-40--10?.The real-time strain field of the sample surface is obtained by the method of three-dimensional digital image correlation,and the corresponding stress is obtained by the material testing machine and the synchronous controller.The small sample was used in the high temperature experiment and the standard sample was used in the low temperature experiment.The ultimate strength and strain of two kinds of PBX under high temperature decrease quickly with temperature rise,but PBX-03 shows abnormal phenomenon,the mechanical properties in 155-170? are almost identical,and the mechanical properties in 185-200? are improved significantly with the rise of temperature.The explosive crystal of PBX-03 is HMX,which can maintain constant mechanical properties during the ??? crystal transformation happened in 154 ?.However,the ??? crystal transformation of HMX happened in 167-183? can increase the mechanical properties significantly with temperature rise.Under low temperature,the mechanical properties of the two kinds of PBX are affected by the temperature not so much as high temperature,and the elastic modulus and strength limit increased slightly with the decrease of temperature.The Poisson's ratio of the two PBX increases with the increase of temperature,and the change is more obvious at high temperature.The plate-like structure of two PBX can be seen from the SEM photos.The photos also show crystal edge aging and binder softening drawing at high temperature,and debonding at low temperature.It is inferred that debonding is the main reason for the compressive failure.The results show that the stress-strain relationship of the two kinds of PBX can be obtained by using Gauss's function,and the physical meaning can be approximated by the probability density function of the debonding of the explosive crystal and the binder.The correlation between the stress-strain curves of Johnson-Cook model and its improved model is poor.In addition,this paper analyzes a set of CT images in situ detection of PBX compression process by MATLAB image method.In this paper,several filtering methods and threshold segmentation methods are analyzed,and then to study the distribution of cracks in the compressed PBX samples.In summary,this paper mainly studies the mechanical properties of two kinds of PBX under different temperature,failure form and internal crack distribution through the method of digital image correlation,scanning electron microscopy and CT.This paper also found that the influence of HMX phase transition on the mechanical properties of PBX-03 under high temperature.It is helpful to study the effect of temperature and stress on the properties of PBX material,which has important reference value for studying the use conditions of PBX.