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. In 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, a set of image processing technologies is developed for the TATB particle system by using X-μCT tomography and synchronous in-situ force loading. The TATB particles are a special composite material with multile components, irregularities, multiple particle sizes, heterogeneity, and viscoelasticity. High-quality CT images of TATB particles under force loading are obtained. A three-dimensional pore network model (PNM) of the TATB particle system is 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 are obtained.

The results indicate the evolutionary characteristics below. At 0–5 MPa, with the press proceeding, the stress of TATB particle system increases continuously, and the number of particle contacts in the particle system decreases, with a reduction rate of 53.3%. The total contact area decreases by 31.5%, but the average contact area of a single particle continues to increase; The strong contact and weak contact of the entire particle system show a decreasing trend, but the ratio of strong contact to weak contact remains almost unchanged, reflecting the stability characteristics of the TATB molding particle system in the external stable, linear, and slow loading process, and the average proportion of strong contact is 37.74%. The average increase rate of particle volume is 45.50%, and the curve of equivalent radius is very consistent with the curve of average particle volume. The average coordination number of the entire particle system increases from 7.27 to 9.44, and the highest coordination number is in a range of 6–10. The morphological distribution shows the characteristics of approximately normal distribution, double-peak nearly normal distribution, and flat-peak nearly normal distribution. At 5 MPa, some particles show the characteristics of rotation and adaptive rearrangement, which are 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. These results are of important scientific and engineering significance for understanding the mechanical characteristics of the explosive particle pressing process.