材料期刊网

针对密度处于0.08~0.5 g·cm-3区间的聚氨酯高聚物，在扫描电镜下观察材料微观形貌特征，记录单轴受压下材料的应力应变曲线，通过提取扫描电镜图中微泡孔的尺寸，基于几何参数拟合材料抗压强度。试验结果表明：随密度增大，材料的泡孔由接近多边形转变为圆球形，平均孔径与泡孔间接触面积均减小，高密度试件的泡孔分布特征遵循能量最小原理，以保证体系稳定。材料的受压响应有三阶段特征：弹性阶段(应变小于5%)高密度试件应变发展较快：屈服平台阶段(应变5%~50%)的应力可以作为抗压强度的表征，致密阶段(应变大于50%)高密度试件发生脆性破坏。基于泡孔几何参数的 Gibson-Ashby 模型可以较好地拟合材料强度，该强度受密度影响显著，不同密度的材料可以灵活应用于多种工程场合。

This study conducted comprehensive experimental and modeling investigations on compressive properties of polyurethane grout materials with the density of 0.08 0.5 g·cm-3 .SEM and uniaxial compression tests were applied to specimens with varied density.Parameters obtained from SEM images were employed to predict compres-sive strength.It is found that foams in higher density specimens are spheres owning less contact area,which ensures the system stability based on the minimum energy principle.While majority foams in lower density specimen are polyhedrons and their contact area is larger.The uniaxial compression can be divided into elastic (strain less than 5%),yield (strain from 5% to 50%)and densification (strain higher than 50%)stages.In elastic stage,strain of higher density specimen develops faster with normalized stress,while the corresponding stress at yield stage can be viewed as compressive strength and develops with density,and in densification stage higher density specimens are characterized with brittle failure.Gibson-Ashby model based on geometric parameters of foams obtained from SEM image can be used to predict the compressive strength,and materials with varied density characterized with different strength can be applied in infrastructure maintenance.