多孔材料代表单元的性质

THE PROPERTIES OF REPRESENTATIVE UNITS OF POROUS MATERIALS

为了弄清多孔材料代表单元的基本性质,对泡沫镍的力学性能进行了实验研究和计算机模拟,两者结果的变化趋势吻合较好。在此基础上,用离散的弹性梁构成代表单元,结合连续介质力学的方法,建立了多孔材料的理想力学模型,导出了其宏观本构关系,讨论了其代表单元各向异性性质和材料常数之间的关系。结果表明由代表单元周期性排列构成的多孔材料,在宏观上呈各向异性,只有当代表单元无序地随机排列时,多孔材料才在宏观上出现统计各向同性。同时指出了一些文献中存在的错误。

To clarify the essential properties of a representative unit of cellular materials, an experimental study and computer simulations on the mechanical properties of nickel foam were performed, and the results agreed well. Considering a discrete elastic beam as representative unit and combining continuous medium mechanics theory an ideal mechanical model for porous materials was established and its macroscopic constitutive relation was given. The relation between the anisotropy nature of representative unit and material constants was discussed. The results showed that the porous material consisting of periodically arrayed units exhibited macroscopic anisotropy. Only when the units were arrayed randomly without order, the porous material exhibited statistical macroscopic isotropy. At the same time, errors in the literature were pointed out.