Study On Dynamic Mechanical Behavior And Initiation Characteristic Of PBX

Plastic bonded explosive(PBX) is widely used in the warhead of the weapons, missile warheads and large offensive weapon due to its high damage energ y and insensitive characteristic, easily machining into the required structure form, and relatively stable mechanical performance. Whether the PBX can initiate at the predetermined location and have internal damage before detonating will directly affect the maximum initiation energy release of the PBX and destroy enemy targets accurately. No matter in what kind of weapons, PBX charge structure is the weak link. It is easy to be influenced by outside factors, and the mechanical behavior of PBX explosive determines the safety of the charge, which will directly affect the safety and reliability of PBX explosive weapon warhead. Therefore, it is great significance to the study on mechanical response and initiating characteristics of the PBX explosive in the complex dynamic stress loading conditions. Based on the above background, combining with the experiment and simulation, the dynamic mechanical behavior and detonation characteristics of PBX explosive were studied, and the main research content in this paper is as follows:Shock compressed experiments of PBX explosive are studied based on SHPB experimental technology, combining with changing input pulse waveform by reshaper, laser transient displacement measurement system and high speed camera, and different stress-strain curves of PBX explosive under different high strain rates were obtained. Uniaxial compression constitutive relation associated with strain rate and different initial density was established according to the results of experimental analysis and the strain energy function. The results show that the constitutive relation agreed well with the experimental data. The simulated results agreed well with the experimental results, and it confirmed that the constitutive relation can well describe the dynamic mechanical response of PBX explosive.Macroscopic and mesoscopic damage of PBX explosive under Taylor impact and three axial impact loading was studied by light gas gun device. After that, combining with the SEM electron microscope, mesoscopic damage model of PBX explosive under different impact pressure were analyzed. Under the two different impact mode, the macroscopic damage degree has certain correlation with the initial density of PBX explosive. While the mesoscopic damage patterns associated with the impact loading form, which can make us understand the mesoscopic damage mechanism of PBX explosive better. And it established the base of initiation characteristic.Dynamic mechanical response of the PBX explosive in planar impact loading was studied, using "symmetric impact", combining with time difference measured by the pressure sensors and the velocity of flyer. The sound velocity and impact factor of the PBX were obtained by linear correlation fitting, which provides a relevant parameter for the shock initiation numerical simulation in below. 3D nephogram of state parameters of PBX explosive with different initial density after the shock wave front were obtained, providing an important basis for the state parameters of the relationship of PBX under larger shock wave pulse.Critical initiation energy release behavior of PBX explosive and numerical simulation of impact pressure were studied. In the energy release characteristics of experimental study, PBX explosive critical detonation velocity and the critical impact velocity with maximum reaction efficiency were obtained. In the experimental study of initiation characteristic, the critical bullet velocity of initiation of PBX explosive charge and critical initiation pressure were obtained. Above of experiments and related research work provided guidance and related parameters for numerical simulation study. The numerical simulation result was consistent with the experiment, and the numerical simulation model and its parameters can better express the dynamic mechanical response of PBX explosive at high speed impact loading.This paper provided the basis and technical guidance for the dynamic mechanical behavior of PBX explosive and the initiation characteristic research, and also provided basis for the design of national defense weapon warhead, which has a certain reference value and guiding significance.