Effect of the cenospheres size and internally lateral constraints on dynamic compressive behavior of fly ash cenospheres polyurethane syntactic foams

Abstract

In this paper, novel syntactic foams (CPSFs) composed of the rigid polyurethane foam (PUR) and the fly ash cenospheres were prepared through the pressure infiltration approach. The aluminum honeycombs were proposed to improve the mechanical response of CPSFs by internally restricting the lateral deformation. The influences of the cenospheres size and the reinforcement on the dynamic behavior of the CPSFs were specified. The dynamic compression tests were carried out for the plain and Al honeycomb reinforced CPSFs with the strain rate ranging from 0.001/s to 2000/s. The results shown that the dynamic strength of the CPSFs containing large cenospheres was 35%–77% higher than that under quasi-static compression. But, the plateau stress was insensitive to the strain rate because the main failure mechanism of the CPSFs at different stages was dominated by different material compositions. The dynamic compressive strength and plateau stress of the plain CPSFs containing small cenospheres shown obvious strain rate sensitivity. The failure mechanism of the two plain CPSFs both transformed from shear failure into longitudinal cracking with the loading condition changed from the quasi-static to high-velocity impact. For the reinforced CPSFs, the dynamic mechanical properties including the strength and the plateau stress were sensitive to the strain rate. The failure mode of the reinforced CPSFs was dominated by the gradual compressive deformation. It was suggested that the Al honeycombs can not only enhance the mechanical properties, but also improve the dynamic response of the CPSFs. As a consequence, the dynamic energy absorption of the CPSFs varied in the range of 7–14 MJ/m3, and was about 23%–32% higher than that under static compression. This study expects to provide a potential approach in disposing the industrial waste and an innovation to adopt the internal constraints to improve mechanical behaviors of syntactic foams.