目的 不同密度的硬质聚氨酯泡沫(RPUF)适用于不同的工程应用，通过对不同密度RPUF力学性能开展研究，并对现有的本构模型加以修正，得到材料真实的本构关系。方法 通过开展不同密度RPUF材料的准静态压缩实验(0.001 s⁻¹)及不同加载速率(100~1 000 s⁻¹)下的动态压缩力学性能实验，得到材料的应力-应变曲线，在此基础上分析RPUF材料的密度效应及应变率敏感性，得到其真实本构关系。结果 RPUF材料力学性能受到密度和应变率的耦合影响，随着密度以及应变率的增大，RPUF材料的屈服应力呈指数函数形式增大;给出了RPUF材料屈服应力与应变率及密度之间的函数关系式。结论 得到了基于实验数据以及横向惯性效应修正后的Sherwood-Frost模型(M-S-F模型)，研究结果可为RPUF材料在抗冲击方面的工程应用提供指导。

Rigid polyurethane foam (RPUF) with different densities is suitable for different engineering applications. The work aims to study the mechanical properties of RPUF with different densities and modify the existing constitutive model to obtain the real constitutive relation of the material. The stress-strain curves of RPUF materials with different densities were obtained by conducting quasi-static compression tests (0.001 s−1) and dynamic compression mechanical properties tests at different loading rates (100-1 000 s−1). On this basis, the density effect and strain rate sensitivity of RPUF materials were analyzed to obtain the real constitutive relation. The mechanical properties of RPUF materials affected by the coupling effect of strain rate effect and density effect, and with the increasing density and strain rate, the yield stress of RPUF materials increased exponentially, giving the functional relation between yield stress, strain rate and density of RPUF materials. A modified Sherwood-Frost model (M-S-F model) based on experimental data and lateral inertia effect is obtained. The research results can provide guidance for the engineering application of RPUF materials in impact resistance.