硬质聚氨酯泡沫力学特性的静水压力加载实验方法研究

A study of Experimental Method for Mechanical Properties of Rigid Polyurethane Foam under Hydrostatic Compressive Loading

泡沫材料在多轴载荷下的力学性能是工程中非常关心的问题。利用土壤的三轴压缩试验装置,通过试验方法的改进,提出了一种体应变测定和修正的方法,对硬质聚氨酯泡沫材料的静水压力特性进行了研究,得到了一些有价值的数据和结论。研究表明:在准静态静水压加载条件下,该材料的应力-应变曲线明显地分为弹性段、塑性段和压实段,且屈服强度比单向压缩时略大、压实应变略小。最后通过不同高度的试样对比试验,对聚氨酯泡沫材料的不均匀变形和弯曲的原因进行了分析和比较,指出了试验时应该注意的问题。

Mechanical behavior of foam under multi-axial loads has attracted much attention in engineering practice.A new experimental method for volumetric strain measurement of polyurethane（PU） foam materials was put forward by utilizing soil tri-axial compressive device.Mechanical properties of a kind of closed-cell rigid PU foam under hydrostatic loading were investigated,and some useful parameters were obtained.Results show that the shape of hydrostatic pressure versus nominal volumetric strain curve of the PU foam is an initial elastic regime followed by a long plastic plateau region and then a rapid increase with the foam densifying.And the foam under hydrostatic compression has a slightly greater plateau stress and a smaller densification strain than that under uniaxial compression.At last,some reasons resulting in the PU foam nonuniform deformation and bending of foam sample were analyzed through contrastive tests for two types of PU foam samples with different heights,which influence the experimental results greatly.