TATB is currently the safest explosive in terms of safety performance. Polymer bonded explosive (PBX) formed by pressing TATB particles has important applications in military. Under the action of stress, the evolution of TATB particle system determines the microstructure and overall quality of molding grain. The molding method of PBX is usually realized by molding technology. During the process of molding, the structural evolution and mechanical properties of TATB particle system are very complex under the action of loading, and the high discreteness, strong non-linearity and bonding characteristics are difficult to characterize.
In this study, X-μ CT tomography and synchronous in-situ force loading were used to develop a set of image processing technology for TATB particle system, which was a multi-component, irregular, multi-particle size, heterogeneous, viscoelastic special composite material. High-quality CT images of TATB particles under force loading were obtained. A three-dimensional pore network model (PNM) of TATB particle system was established by CT image processing and analysis. Based on the model, the evolution characteristics of key parameters such as contact number, contact area, contact strength and coordination number were obtained.
The results indicate the following evolutionary characteristics: at 0~5 MPa, with the process of pressing, the stress of TATB particle system increased continuously, and the number of particle contacts in the particle system decreases, with a reduction rate of53.3%; The total contact area decreased by31.5%, but the average contact area of a single particle continued to increase; The strength and weak contact of the entire particle system showed a downward trend, but the proportion of strength and weak remained almost unchanged, reflecting the stable characteristics of the TATB molding particle system in the external stable, linear, and slow loading process, and the average proportion of strong contact was 37.74%; The average increase rate of particle volume was 45.50%, and the curve of equivalent radius was very consistent with the curve of average particle volume; The average coordination number of the entire particle system increased from 7.27 to 9.44, and the highest coordination number range was 6~10. The morphological distribution showed the characteristics of approximately normal distribution, double-peak nearly normal distribution, flat-peak nearly normal distribution. At 5 MPa, some particles showed the characteristics of rotation and adaptive rearrangement, which was consistent with the quantitative analysis of the trend of particle contact number.
This study reveals the movement, deformation and fusion rules of particles in the initial stage of the forming process, achieving the three-dimensional, quantitative and In-situ analysis of the force loading process of the particle system, and has important scientific and engineering significance for the understanding of the mechanical characteristics of the explosive particle pressing process.