摘要：The cause of force enhancement phenomenon when using cellular material, such as metal foam, for blast protection is discussed using both finite element method (FEM) and analytical method. Finite element (FE) models of cellular material under blast load are presented, in which the blast load is modeled by CONWEP blast function and the cellular material is modeled by the homogenized modeling method and the multiunit-cell modeling method. A one-dimensional analytical model is also presented for comparison purpose. Utilizing these models, an aluminum foam bar under blast load is simulated and the mechanism of both force attenuation and enhancement are depicted. The relationship between blast load intensity and the length of the foam bar is analyzed based on the simulation. It is found that the time of momentum transfer between the compacted foam bar and the protected structure is very short compared to the total time of the blast event, which causes force enhancement. Corresponding countermeasures are proposed based on this finding. The study will not only provide new modeling methods for the simulation of cellular material subjected to blast load but will also be beneficial to understand the mechanisms of force attenuation and enhancement, so as to seek for countermeasures.
