Properties of extruded polymers are strongly affected by molecular structure. For two different semi-crystalline polymers, low-density polyethylene (LDPE) and ultra-high molecular weight polyethylene (UHMWPE), this investigation measures the elastic modulus, plastic flow stress and strain-rate dependence of yield stress. Also, it examines the effect of molecular structure on post-necking tensile fracture. The static and dynamic material tests reveal that extruded UHMWPE has a somewhat larger yield stress and much larger strain to failure than LDPE. For both types of polyethylene, the strain at tensile failure decreases with increasing strain-rate. For strain-rates 0.001–3400 s⁻¹, the yield stress variation is accurately represented by the Cowper–Symonds equation. These results indicate that, at high strain rates, UHMWPE is more energy absorbent than LDPE as a result of its long chain molecular structure with few branches.

A hyper-viscoelastic constitutive model for polyurea by separating hyperelastic and viscoelastic behaviors has been put forward. Hyperelasticity represents the rate-independent responses at low strain rates, described by a three-parameter Mooney-Rivlin model and a third Ogden model. By fitting the quasi-static experimental data, the Ogden model is more appropriate to describe the hyperelastic behaviors for its better agreement at strain over 0.3. Meanwhile, viscoelasticity represents the rate-dependent responses at high strain rates, described by the Standard Linear Solids (SLS) model and the K-BKZ model. By fitting the experimental data of split Hopkinson pressure bar (SHPB), the SLS model is more appropriate to describe the viscoelastic behaviors at strain rates below 1600 s⁻¹, but the K-BKZ model performs better at strain rates over 2100 s⁻¹ because of the substantial increase of Young’s modulus and the state of polyurea transforming from rubbery to glassy. The K-BKZ model is chosen to describe the viscoelastic behavior, for its low Root Mean Square Error (RMSE) at strain rates below 1600 s⁻¹. From the discussion above, the hyper-viscoelastic constitutive model is chosen to be the combination of the Ogden model and the K-BKZ model.

In this paper, a novel linear shaped charge (LSC), called a bi-apex-angle linear shaped charge (BLSC), has been designed to investigate the improvement of penetration performance. Compared with a traditional single-apex-angle LSC, a BLSC, which consists of a small-apex-angle liner and a large-apex-angle liner, has been investigated by depth-of-penetration (DOP) test. The results show that the penetration depth of BLSC is 29.72% better than that of an ordinary LSC. An Eulerian method is applied to simulate the entire process of jet formation, as well as penetration on a #45 steel target. The effectiveness of the Eulerian model is demonstrated by the good agreement of the computational results with experimental observations. Furthermore, the numerical simulation is developed to investigate the influence of liner thickness, explosive type, combination of small and large apex angle, ratio of small to all apex angle liner, and standoff distance on the penetration performance of BLSCs. The suggested work and results can provide a guide and reference for the structural design of BLSC.

The penetration ability of a 5.8 mm standard projectile can be improved by inserting a ZrO₂ ceramic ball with high hardness, high temperature, and pressure resistance at its head. Thereby, a ceramic composite projectile can be formed. A depth of penetration (DOP) experiment and numerical simulation were conducted under the same condition to study the armor-piercing effectiveness of a standard projectile and ceramic composite projectile on 10 mm Rolled Homogeneous Armor (RHA) and ceramic/Kevlar composite armor, respectively. The results show that both the ceramic composite and standard projectiles penetrated the armor steel target at the same velocity (850 m/s). The perforated areas of the former (φ5 mm & φ2 mm) were 2.32 and 2.16 times larger, respectively, than those of the latter. The residual core masses of these two projectiles (φ5 mm & φ2 mm) were enhanced by 30.45% and 22.23%. Both projectiles penetrated the ceramic/Kevlar composite armor at the same velocity (750 m/s). Compared with the standard projectile, the residual core masses of the ceramic composite one (Ø5 mm & Ø2 mm) were enhanced by 12.4% and 3.6%, respectively. This paper also analyzes the penetration mechanism of the ceramic composite projectile on target plates by calculating its impact pressure. The results show that the ceramic composite projectile outperformed the standard projectile in penetration tests. The research results are instructive in promoting the application of the ZrO₂ ceramic composite in an armor-piercing projectile design.

In this study, the dynamic responses under blast loading of carbon fiber reinforced aluminum alloy laminates with different curvature radii, different numbers of layers, and different layer directions of carbon fiber under blast loading were compared numerically. The finite element models were built with ABAQUS/Explicit. To calibrate the numerical models, experiments on curved carbon fiber and curved aluminum alloy were modeled, and the numerical results showed good agreement with the experimental data. The calibrated numerical models were used to simulate the dynamic response of cylindrical panels subject to external explosion loading. The stiffness degradation coefficient was introduced to more accurately simulate the failure mode of the composite structures. The deformation and energy absorption of carbon fiber reinforced aluminum alloy laminates under different structural parameters were obtained. These simulation findings can guide the theoretical study and optimal design of carbon fiber reinforced structures subject to external blast loading.