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The effect of impact pressure on energy release behavior of high-energy insensitive particle reinforced composites is investigated. The results show that as the impact pressure reaches 5.39 GPa, the high-energy insensitive particulate reinforced composites initiation occurs for the first time. With the increase of the impact pressure, the gas pressure inside the high-pressure explosion chamber increases gradually until the impact pressure increases to 11.95 GPa. The quantitative relationship between impact pressure and energy release behavior is established.

In order to correctly understand the mechanical behavior, damage mode and damage mechanism of AlSi10Mg optimized structure under compressive load, a series of experimental and simulation studies were carried out. The stress-strain response, bearing capacity, energy absorption characteristics, damage mode and mechanism of the structure are analyzed and discussed. The results show that AlSi10Mg porous structure has obvious strain hardening effect, but no obvious strain rate effect. The volume fraction of AlSi10Mg porous structure increased from 9.43% to 22.15%, and its bearing strength increased from 22.34 MPa to 50.98 MPa. The optimized design structure is complex in this paper, which eliminates undesirable failure modes, and the benefit of high specific energy absorption is retained. The experimental and simulation results show that shear failure is the main cause of structural damage, and the normal of the failure section and the load action direction are roughly inclined at an angle of 45° ∼ 55°. The research results can provide an important reference for the optimal design of porous metal structure.

Influence of adhesive layer, used to bond ceramic tiles and back plate, on high velocity impact performance of the ceramic/metal composite armor was studied by experimental and numerical investigations. Two types of targets, monolithic ceramic structures and laminated ceramic structures backed by aluminum alloy, with different thicknesses of adhesive layer (0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm) were considered. Results indicated that the size of fractured ceramic was decreased with the increase of adhesive thicknesses. And the size of fragments in the laminated ceramic/aluminum structures with adhesives was smaller than that of in the monolithic ceramic/aluminum structures. A change in crack trajectory were observed at the ceramic/adhesive layer interface of the laminated ceramic composites armor. It showed that the capacity of energy absorption would be improved at the lateral direction, and the failure of the second ceramic plate would be delayed by the change. The penetration depth of the monolithic ceramic/aluminum structures bonded by epoxy resin was found to be greater than that of the armor without adhesive. But the addition of adhesive layer improved the impact performance for the laminated ceramic/aluminum structures. In addition, the depth of penetration was decreased with the increase of adhesive thicknesses for both forms of composite armor. Then simulation results showed that adhesive thickness has little effect on stress wave propagation of inner adhesive layer. Due to the difference of elastic impedance among target plates, the pressure amplitude in different plates was decreased by addition of the adhesive layers, especially for the laminated ceramic/aluminum structures. Lastly, the shear strain and shear strain rate of adhesive layer was decreased with the increase of adhesive thicknesses, which improved the impact performance of laminated composites armor.

Rate-dependent mechanical response of fly ash cenospheres polyurethane syntactic foams (CPSFs) with hierarchical cell structure was examined through dynamic compression tests. Quasi-static compression strength and specific energy absorption varied in the range of 9.5–29.5 MPa and 4.8–13.0 MJ/m3 within the density of 0.5–0.7 g/cm3. The thermal conductivity coefficient of CPSFs increased from 0.08 W/m/K to 0.13 W/m/K with density, while the specific heat capacity varied in a narrow range of 0.9–1.07 J/g/K. At high strain rates the strength and plateau stress of CPSFs with density of 0.6 g/cm3 increased 25%–39% and 13%–43%. The proposed foam is comparative potential in civil engineering according to its thermal insulation performance and excellent shock dissipation properties. Due to complicated microstructure, CPSFs exhibited different strain rate sensitive behaviors in the initial collapse stage and the stable collapse stage. A constitutive relation was developed to describe dynamic stress-strain response which includes the elastic stage, the initial collapse stage characterized by nonlinear stress increasing and decreasing process, the platform stage and the densification stage. The predictions shown good accordance with the experimental results in wide strain rate range.

The Al2O3/SiC composite has an improved mechanical property compared with alumina matrix, and it can be used in the lightweight armour system. In this study, the dynamic tensile and compressive strength, strain rate sensitivity, fracture mechanism and fragments scale of the composite were carried out by experimental and theoretical analysis. Results showed that the dynamic strength of the Al2O3/SiC composite was sensitive to the strain rate, and it was controlled by its microstructure. The microfracture mechanism of the composite varied with the locations and stress states of specimen, which consisted of second phase particles effects, the intergranular and transcrystalline fracture mode, fractured core area, grain-boundary crack, grain distortion and splitting, cleavage fracture zones, slip bands et al. In the dynamic compression experiments, the statistic analysis results of recycled fragments were more agreed with the prediction of the modified DID model.

Low-velocity impact responses of typical hollow brittle particles (HBPs) were tested with a strain-limited loading technique to investigate the particle breakage characteristics at both macro and particle levels. The quasi-static compressions were also conducted for comparison. Effects of strain rate and particle size distribution on the stress-strain response, particle breakage and macro deformation behaviors were discussed. Results show that the strength, plateau stress and energy dissipation of hollow brittle particles all exhibited significant strain rate sensitivity. The particle size gradations after single-impact compression were obtained through the laser diffraction technique. Quantitative analysis on the fragmentations and the Hardin relative breakage shown that the dynamic breakage ratio and the breakage extent of the hollow particles at the same strain were larger than that under quasi-static compressions. Moreover, it was found that the Hardin relative breakage generated by specific energy dissipation decreased with the strain rate. The reduction of fracture energy dissipation efficiency and the rate-dependent breakage response of particle breakage are the intrinsic reasons for bulk-scale strain rate effects of HBPs. Finally, the macro deformation behaviors of hollow brittle particles were analyzed through digital image correlation (DIC) technique. It was observed that there exists a competition mechanism between the boundary effect and the inertial effect in dominating the compression patterns. The deformation mechanism was sensitive to the loading velocity.

In this paper, a test projectile with a recessed hole and an initially sealed vented test chamber were designed to investigate the impact initiation and energy release characteristics of the polymer bonded explosive (PBX) materials. Through a thin aluminum cover plate, the test projectile filled with PBX materials was launched into an infinitely rigid impact anvil on the interior. As the initiation takes place on the interior, great amounts of thermo-chemical energy gases were vented through a hole formed by the penetration process. The maximum pressure inside the chamber was used to evaluate the initiation characteristic of PBX materials. The experimental results suggest that the impact pressure has a significant effect on the initiation characteristic and reaction efficiency. It reveals the critical impact-initiated pressure and critical impact pressure of the maximum reaction efficiency. Combining with the theoretical analysis, a relationship between the maximum pressure and the energy deposited into gas inside the chamber is explored to analyze the energy release behavior.

In this paper, an initially sealed vented test chamber and a test projectile with polymer bonded explosive materials were designed to complete the experiments. As the initiation takes place on the interior, great amounts of thermo-chemical energy gases were vented through a hole formed by the penetration process. The gas pressure inside the chamber was used to evaluate the energy release behavior of polymer bonded explosive materials. The experimental results reveal that the impact velocity is significant to the energy release behavior, and in some extent the gas pressure improves with the velocity of the projectile. And the critical initiation velocity and the velocity as the polymer bonded explosive materials reached the maximum reactive efficiency were obtained.

Multi-scale high energy insensitive particle reinforced composites (MSHEIPRC) are the most important part of the anti-missile sandwich wall structure. Its dynamic mechanical behavior and damage mode will directly affect the success of anti-missile capability. In this paper, based on a modified Split Hopkinson Pressure Bar (SHPB) experimental technique and the design of triaxial impact loading test device, combining with theoretical study and meso analysis, the dynamic mechanical response under high strain rates and damage characteristics of MSHEIPRC under high overload were carried out. The results show that the dynamic stress-strain curves of MSHEIPRC are highly non-linear and have obvious strain rate effect and density effect. Compared with the experimental results, the modified constitutive model can accurately describe its dynamic mechanical behavior at high strain rates. Based on the energy model and related parameters, the bond strength between the surface of crystal particles and the binder is calculated to be about 0.6 MPa. Therefore, the shear debonding damage mode between the surface of crystal particles and the binder is first found at the stage of small impact loading. The critical fracture strength of cracks with different sizes is calculated by Griffith method. With the increase of impact loading pressure, the fracture phenomenon gradually appeared on the surface of crystal particles, which was basically consistent with the theory model. Continuing to increase the impact loading pressure, sufficient shock wave energy forces crystal particles to produce transgranular fracture, which leads to crystal particles breaking.