Research on Dynamic Cumulative Damage Effect of Metal Rubber and Stress Wave Propagation Characteristics of Layered Composite Structure

The development of protective materials and structures is of great significance for improving the impact resistance, penetration resistance and spalling resistance of military equipment. At present, the layered composite structure has been widely used due to its good protective performance. In this paper, a special elastic porous material-metal rubber (MR) with excellent cushioning and damping properties was used to prepare high-performance layered composite structures. To begin with, the dynamic mechanical response and the dynamic cumulative damage effect of MR were studied through Split-Hopkinson Pressure Bar (SHPB) tests. Then, the failure form and stress wave propagation characteristics of the layered composite structures were investigated through SHPB tests and finite element method. The results show that repeated impacts can enhance the compactness of MR, thereby increasing the ultimate bearing capacity and energy absorption capacity, which is beneficial for MR to resist repeated impacts. The MR in composite structures can reduce ceramic damage, attenuate stress wave and smooth stress distribution. The titanium alloy on the back of the ceramic will aggravate the damage of the ceramic, and ultra-high molecular weight polyethylene on the back of the ceramic provides cushioning for the ceramic. Therefore, the impact resistance of the composite structure can be improved by adding MR and the reasonable arrangement of materials, and the SiC/UHMWPE/MR/TC4 composite structure has relatively reasonable stress distribution and better protection performance.

Selection and Optimization of a K0.5Na0.5NbO3-Based Material for Environmentally-Friendly Magnetoelectric Composites

Li- and Ta-modified K 0.5 Na 0.5 NbO 3 compounds are among the most promising lead-free ferroelectrics for high-sensitivity piezoelectric ceramic materials, and are potentially capable of replacing Pb(Zr,Ti)O 3 . They are also being investigated as piezoelectric components in environmentally friendly magnetoelectric composites. However, most suitable modifications for this application have not been identified. We report here a simulation study of how the magnetoelectric voltage responses of layered composite structures based on Li x (K 0.5 Na 0.5 ) 1 − x Nb 1 − y Ta y O 3 varies with the chemical composition of the piezoelectric. Instead of relying on material coefficients from the literature, which would have required using different sources, an ad hoc set of materials was prepared. This demanded tailoring preparation by conventional means to obtain dense ceramics while controlling alkali volatilization, perovskite phase and microstructure, as well as characterizing their dielectric, elastic and electromechanical properties. This provided the set of relevant material coefficients as a function of composition, which was used to obtain the magnetoelectric responses of model layered structures including a reference magnetostrictive spinel oxide by simulation. The piezoelectric material leading to the highest magnetoelectric coefficient was identified, and shown to be different to that showing the highest piezoelectric coefficient. This reflects the dependence of the magnetoelectric response on all material coefficients, along with the complex interplay between composition, processing and properties in K 0.5 Na 0.5 NbO 3 -based ceramics.