Effects of Statistics of Cell’s Size and Shape Irregularity on Mechanical Properties of 2D and 3D Voronoi Foams
Liqun Tang (South China Univ. of Tech.), Xuepeng Shi (), Lue Zhang (), Zejia Liu (), Zhenyu Jiang (), Yiping Liu ()
Prager Medal Symposium in honor of George Weng: Micromechanics, Composites and Multifunctional Materials
Tue 2:40 - 4:00
MacMillan 117
In the study of the mechanical properties of metal foam, the initial density (or porosity) and the mean radius of cells are two key parameters of the meso-geometry, but it is also well known experimentally that mechanical properties of metal foams are different even the metal foams have the same two parameters, which means that it is not enough to depict mechanical properties with the two parameters only. Many researchers have learned that the irregularity of cell may affect the mechanical properties of metal foams, in which the irregularity mainly relates the non-uniform size of cells. In this paper, we classified the irregularity of cells into two types which are called size irregularity and shape irregularity respectively. Two indicators of irregularity are recommended to describe polygonal or polyhedral cells in 2D or 3D metal foams. The size irregularity reflects the deviation of the size of a cell from the average cell size in the foam; the shape irregularity reflects the deviation of the shape of a cell from a circle with same area (2D) or a globe with same volume (3D). With the two kinds of definitions, effects of the irregularity of cells in aluminum foam on mechanical properties were analyzed by 2D and 3D Voronoi models, in which initial density and average radius are same, and statistic distributions of size and shape irregularity of cells in models were well designed. The simulations of compression of Voronoi-based models show that the yield stress of metal foam is seldom affected by the size irregularity, but significantly affected by the shape regularity. The results indicate that the statistics of shape irregularity would be a key issue of metal foams in addition to the two parameters-- initial density and average radius. Key words: size irregularity; shape irregularity; Voronoi foam; mechanical properties Acknowledgements: The authors are grateful for the financial support from the NSFC (Grant No. 90916026, 61070092).