基于Sherwood–Frost模型构建聚乙烯泡沫拉伸本构

目的 研究聚乙烯泡沫的拉伸力学性能，并构建聚乙烯泡沫的拉伸本构模型。方法 利用万能材料试验机对不同密度的聚乙烯泡沫进行不同拉伸速率的单轴拉伸实验，得到聚乙烯泡沫的拉伸应力–应变曲线；在Sherwood–Frost唯象本构模型框架的基础上，构建将密度和应变耦合的密度项，以及将应变率、应变和密度耦合的应变率项的拉伸本构模型。结果 聚乙烯泡沫在断裂前的拉伸力学特性为非线性弹性，表现出明显的应变率强化效应，现有的密度项和应变率项与实验数据的拟合精度较低，最大平均误差分别可达11.76%、7.90%。新构建的密度项和应变率项与实验数据拟合精度较好，最大平均误差分别为1.17%、1.92%。结论 新构建的拉伸本构模型能够更精确地描述聚乙烯泡沫单轴拉伸的应力应变关系，为聚乙烯泡沫的综合力学性能的进一步研究提供参考。

Construction of Constitutive of Polyethylene Foam Under Tensile Based on Sherwood-Frost Model

The project aims to study the tensile mechanical properties of polyethylene foam and construct its constitutive model under tensile. The universal material testing machine is used to perform uniaxial tensile tests on polyethylene foams of different densities at different tensile rates, and the tensile stress-strain curves of the polyethylene foams are obtained; Based on the Sherwood-Frost phenomenological constitutive model frame, a tensile constitutive model of the density term coupling density and strain and the strain rate term coupling strain rate, strain and density are constructed. The tensile properties of polyethylene foam before fracture are nonlinear elasticity, showing obvious strain rate correlation. The existing density term and strain rate term have low fitting accuracy with experimental data, and the maximum average error can reach 11.76% and 7.90% respectively. The newly constructed density term and strain rate term have better fitting accuracy with the experimental data, and the maximum average error is 1.17% and 1.92% respectively. The constructed tensile constitutive model can more accurately describe the stress-strain relationship of polyethylene foam under uniaxially tensile, and provide a reference for further research on the mechanical properties of polyethylene foam.