In this paper, the ballistic damage mechanism and residual bearing capacity of ceramic/backing plate armor were investigated. First, a series of lightweight armors were prepared, consisting of ceramic and ultra-high molecular weight polyethylene fiber-reinforced resin matrix composite (UHMWPE) plates, and were wrapped in a high-strength fabric. Then, the ceramic/UHMWPE armors were hit by one or two bullets, and finally subjected to compression testing. The results showed that the main failure mode of integral ceramic/UHMWPE armors was ceramic brittle fracture. Many zigzag patterns on the compression curve indicated that the specimens had undergone the stages of crack propagation, ceramic fragment reorganization, plastic deformation of UHMWPE backing plate, interlaminar tearing, and overall fracture. The failure of spliced ceramic/UHMWPE armors was mainly due to the dislocation between ceramic sheets; the smooth compression curves indicated that there was no recombination of ceramic fragments and obvious interlayer debonding during the compression. Under the maximum load, each ceramic/UHMWPE armor with ballistic damage did not suddenly break and fail. The structure and thickness of ceramic plates all had an impact on residual strength: under the same structure, the greater the thickness, the greater the residual strength, but the relationship between them was not linear; under the same thickness, the residual strength of the spliced ceramic/UHMWPE armor was higher. The residual strength was also related to the number of shots: after two bullets hit, its value was only one-third of that after one bullet hit.

This study investigates eutectic morphology transitions in Ni-Sn alloys using Bridgman directional solidification with a transition variable speed coupled with cellular automaton (CA) simulations. Steady-state solidification (0.1–2000 μm/s) produced only regular lamellar/rod-like eutectics, while velocity jumps triggered anomalous eutectic formation. As the drawing speed increased, the lamellar spacing decreased from ~3 μm to 0.4 μm, while the microhardness increased from ~426 HV to 500 HV. The experiments on Ni-Sn alloys revealed that anomalous eutectic morphologies form specifically at velocity transition interfaces (0.1–1000 μm/s), consistent with CA simulations showing destabilization of the lamellae, epitaxial growth of the Ni₃Sn phase, and decoupled nucleation of the α-Ni phase for the formation. The work defines a processing window for anomalous eutectic formation and provides mechanistic insights bridging undercooling and directional solidification regimes.

Some quantification methods were developed for microstructure characterization of pyrocarbon (PyC) in carbon/carbon (C/C) composites fabricated by chemical vapor infiltration. Firstly, the feature parameters were strictly defined based on 002 lattice fringe images in high-resolution transmission electron microscopy. They were illustrated with the diagram. Image analysis was adopted to measure or calculate the feature parameters of describing individual fringe or expressing the relationship between fringes. An improved comprehensive parameter, crystallinity factor, was introduced to indicate the crystallization of PyC. Then, judgment rules of microcrystal units were considered from three aspects: interlayer spacing, stacked position, and parallelism between layers. The latter two were analyzed by drawing geometrical figures. Finally, the extracted parameters were displayed in statistical histograms, and also compared with the measurements from manual observation, X-ray diffraction, and selected area electron diffraction. The results were in general agreement. The developed algorithms were performed automatically by the computer. They are especially applicable to analyze the microstructure evolution of C/C composites in graphitization process. The extracted feature parameters supply the basis for studying mechanism of graphitization and interfacial structure of PyC.

The transition from regular to anomalous eutectic structures critically impacts the mechanical properties of eutectic alloys. This study investigated the non-equilibrium solidification behavior of Ni-Sn alloys using Bridgman directional solidification coupled with Cellular Automaton (CA) simulations. Unlike deep undercooling methods, this approach can offer a solution by decoupling temperature gradient and growth velocity during the solidification process, revealing that anomalous eutectic formation occurs specifically at growth velocity transition zones, not during steady-state growth (0.1–2000 μm/s). CA simulations confirmed that velocity jumps destabilize regular lamellae, the Ni3Sn phase epitaxially grows along the substrate in a cellular manner, triggering independent α-Ni nucleation followed by Ni₃Sn encapsulation. This work identifies a distinct process window for anomalous eutectic formation and elucidates its decoupled nucleation mechanism, advancing non-equilibrium solidification theory.

A kind of C/C-SiC ceramic/metal matrix composite foam composite armor was designed to meet the lightweight requirements of protective armor. Based on numerical simulations of impact dynamics, the anti-penetration process and anti-penetration performance of the ceramic composite armor was verified through live-fire shooting. The results indicate that, through numerical simulations and live-fire shooting experiments, it has been confirmed that the designed ceramic composite armor meets the protection requirements of the MIL-A-46103E III Class 2A bulletproof standard. The results of the projectile impacts are basically consistent with the numerical simulation results, which validaties that the established anti-penetration performance model can effectively analyze and predict the anti-penetration capabilities and damage processes of the ceramic composite armor. The propagation characteristics and shear mechanisms of stress waves in the adhesive layer are revealed, and it is found that the stress wave diminishes gradually in the radial direction from the impact point, however, in the longitudinal direction, the stress wave value near the bulletproof backplate interface are greater than those near the bulletproof panel interface due to the effect of reflected compression waves, and as the thickness of the adhesive layer increases, its shear resistance progressively improves and the degree of stress wave attenuation also increases accordingly.