Lagzdiņš Aivars, Zilaucs Alberts, Beverte Ilze, Andersons Jānis
Institute for Mechanics of Materials, University of Latvia, 3 Jelgavas St., LV-1004 Riga, Latvia.
Materials (Basel). 2022 Jan 28;15(3):1033. doi: 10.3390/ma15031033.
Rigid low-density plastic foams subjected to mechanical loads typically exhibit a nonlinear deformation stage preceding failure. At moderate strains, when the geometrical nonlinearity is negligible, such foam response is predominantly caused by the nonlinearity of deformation of their principal structural elements-foam struts. Orientational averaging of stresses in foam struts enables estimation of the stresses taken up by foams at a given applied strain. Based on a structural model of highly porous anisotropic cellular plastics filled with clay nanoplatelets and the orientational averaging, a method for calculating their nonlinear deformation is derived in terms of structural parameters of the porous material, the mechanical properties of the monolithic polymer, and filler particles and their spatial orientation. The method is applied to predicting the tensile stress-strain diagrams of organoclay-filled low-density rigid polyurethane foams, and reasonable agreement with experimental data is demonstrated.
承受机械载荷的硬质低密度塑料泡沫在失效前通常会经历一个非线性变形阶段。在中等应变下，当几何非线性可忽略不计时，这种泡沫的响应主要由其主要结构元件——泡沫支柱的变形非线性引起。对泡沫支柱中的应力进行取向平均，可以估算出在给定施加应变下泡沫所承受的应力。基于填充有粘土纳米片的高孔隙率各向异性多孔塑料的结构模型以及取向平均，根据多孔材料的结构参数、整体聚合物的力学性能、填料颗粒及其空间取向，推导了一种计算其非线性变形的方法。该方法用于预测有机粘土填充的低密度硬质聚氨酯泡沫的拉伸应力-应变曲线，并与实验数据取得了合理的一致性。
