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Composite pyramidal lattice structures with hollow trusses afford a convenient means to enable functionality by inserting elements into free volumes within or between trusses. In this study, vibration and low-velocity impact tests were carried out to investigate the dynamic behavior of hollow composite pyramidal lattice structures filled with silicone rubber. Frequencies and the corresponding damping ratios were obtained, which revealed that the damping ratios of space-filled composite pyramidal lattices increased by two times but those of hybrid composite pyramidal lattices decreased by 2% for the first three orders compared with hollow composite pyramidal lattices. Energy absorption capability for rubber-filled structures increased and the rubber filled between trusses can prevent tup penetration. Desired functional potentials can be realized for composite pyramidal lattice structures by serious selection of filling materials and the corresponding geometry. [ABSTRACT FROM PUBLISHER]

This research focuses on the dynamic response of sandwich panels with multilayered graded hourglass lattice core subjected to blast loading. A three-layer lattice core configuration is proposed to improve the absorption efficient of kinetic energy resulted from blast shock wave. The relative density of each core layer is changed with sectional dimension of core truss members to regulate the energy absorption of each core layer. Three-dimensional numerical simulation analyses of dynamic response are carried out, and the applied impulsive pressure distribution on the surface of the panels is calculated using the CONWEP code. The panels are made of stainless steel AL6XN, which is assumed to follow bilinear strain hardening and strain rate-dependence. Peak back sheet deflection and energy absorption of core layers for four types of hourglass lattice panels are comparatively analyzed and the effects of load intensity on the peak deflection are discussed. Furthermore, the near-optimal configuration under blast loadings is proposed. [ABSTRACT FROM AUTHOR]

Integrative sandwich panels with multifunction of load bearing, thermal protection, and heat insulation are manufactured through co-injection resin transfer molding process. These panels have a polymethacrylimide foam core for heat insulation and two composite layers made of carbon/epoxy for load bearing and carbon/phenolic for thermal protection. In co-injection resin transfer molding process, the epoxy resin and phenolic resin are synchronously injected and cured in order to make integrative structures and improve the properties of the interface between different layers. The influence of main factors in the process of co-injection is investigated: the vacuum assistance is indispensable to improve the efficiency of manufacture and guarantee the properties of the products, volume fraction of carbon fiber plays the main role in determining size accuracy of the product, adjusting injection pressure is a simple and efficient way to adjust the infusion time of resin, while injection temperature has smaller influence in the features of manufacture. The mechanical properties of sandwich panels manufactured through co-injection resin transfer molding process and multi-step process are tested and compared to validate the advantage of the co-injection resin transfer molding process. The test shows that the in-plane compressive strength, three-point flexural strength, and interface shear strength are all improved by the co-injection resin transfer molding process. Co-injection resin transfer molding process is proved to be a feasible and efficient way to manufacture the integrative sandwich panel with good interface features. [ABSTRACT FROM AUTHOR]