No abstract

Two innovative re-entrant hierarchical sandwich panels constructed by substituting the cell walls of re-entrant honeycombs with isotropic regular hexagon substructure (RHH) and equilateral triangle substructure (RHT) are proposed in this paper, and their crashworthiness performance has been investigated systematically. Based on the Euler beam theory, the Young's moduli of units of re-entrant hierarchical sandwich panels are derived. A comparison between the re-entrant hierarchical sandwich panels and re-entrant sandwich panel has been conducted to study their energy absorption ability. Furthermore, the parametric analysis based on numerical analysis has been carried out to discuss the effects of the gradient, arranged orientation of hierarchical sandwich cores and the impact velocities.Results show that both the two proposed sandwich panels can greatly improve the in-plane stiffness and the energy absorption capacity, and the energy absorption mechanisms are discussed. In addition, the graded sandwich panels can effectively reduce initial peak force under quasi-static compression, and the configuration of large-medium -small (LMS) performs the best when under high impact velocity. The cross-arranged cores can significantly improve the impact resistance ability of RHT sandwich panels.This work provides a new solution for designing lightweight sandwich structures.

With the rapid development of economy and the improvement of people's living standard, the domestic waste is greatly increasing. Based on the multi-agent evolutionary game theory, an evolutionary game model among the recycling industry, urban management officer and government is established to address the environmental issues of rising municipal solid waste production and low recycling utilization rates in China. Through numerical example analysis, the relationship between relevant factors on the evolutionary stable state of the system is studied. The findings demonstrate that when the likelihood of severe oversight by the government and of significant enforcement by urban management officers grows, the recycling industry becomes more ready to select waste separation strategy. Additionally, the government is far more affected by the likelihood of significant enforcement by urban management officers than the recycling industries are. In addition, effective acceleration of waste sorting may be achieved by giving the recycling industries the proper government subsidies and increasing the recycling industries' profits from garbage sorting. Moreover, the government's increased fines for the urban management officers can significantly lower the incidence of bribery between the recycling industries and the urban management officers.