In the hot-pressing process of TATB-based polymer-bonded explosive (PBX), the viscoelastic creep occurring during the dwell stage plays a key role in determining the final density and mechanical properties of the product. To elucidate this creep mechanism at the mesoscale, this study combines the Burgers viscoelastic model with the discrete element method (DEM) to establish a meso-mechanical PBX model that incorporates realistic crystal morphologies, crystal deformability, high filler content, and non-uniform binder coating. The results show that the probability density distributions of both normal and tangential contact forces gradually evolve into a sharp peak in the weak-force region, with tangential forces exhibiting a higher proportion of weak forces than normal forces. The rise in the proportion of weak force chains reflects a more homogeneous mesoscopic stress network. Furthermore, the proportion of tensile force chains generally increases with dwell time; however, it remains consistently lower in the binder phase than in the crystal phase. Meanwhile, the explosive crystals undergo a minor rotation (up to 7.24°), progressively aligning closer to their preferred orientation (i.e., within the 20°–40° range). In addition, the average vertical displacement of both crystals and binder is approximately 20 times greater than the horizontal displacement, while the binder shows significantly larger horizontal displacement than the crystals. Finally, the internal porosity shows an oscillatory decline during creep, with a rapid initial reduction followed by stabilization at a low level. Along the loading direction, a distinct spatial gradient in porosity reduction is observed, with the most noticeable decrease occurring near the loading platen. • A novel DEM-Burgers model reveals creep-induced homogenization of the mesoscopic force network in PBX. • Viscoelastic binder relaxation and load transfer to crystals are dynamically quantified via tensile force chains. • Sustained creep enables preferential crystal reorientation (up to 7.24°), enhancing microstructural order. • Porosity reduction shows oscillatory decay with a distinct spatial gradient, dictated by binder flow anisotropy.
Yang et al. (Sun,) studied this question.