The syntactic foam, a porous solid consisting of randomly distributed microballons in the polymeric matrix, is increasingly being conceived for aero engine applications to enhance overall structural reliability under impact loading. Systematic compressive tests without and with lateral confinement are carried out to investigate the deformation and failure of an epoxy syntactic foam (ESF) from quasi-static to high strain rates of about 1000/s at room temperature and elevated temperatures up to 150 °C. Likewise, the ESF with different levels of pre-strain is produced, to examine the influence of pre-strain and the embedded collapsed microballons on the subsequent dynamic flow and failure properties. The deformation process, complemented by the Digital Image Correlation technique, is monitored to reveal the dynamic strain localization of the ESF.
The stress–strain relationships of the initial ESF show significant strain rate (and temperature) dependence. The initial ESF shows macro elastic-brittle behaviour at high strain rate, and the fracture surface consists of partially deformed and localized regions. With the introduction of lateral confinement, the initial ESF presents elastic–plastic characteristics. This elastic-brittle behavior can be suppressed by lateral confinement and by elevated temperatures above 100 °C. Considering the pre-strain effect, the pre-strained ESF presents good deformability. The produced ESF with pre-strain shows the collapsed microballons surrounded by the flow like behaviour of the severely deformed matrix, which would be associated with the thermomechanical coupling process. This indicates the ESF with embedded collapsed microballons still owns deformability and good energy absorption capacity.
This work provides a better understanding of the final crushability of ESF for practical engineering applications, with considerations of the pressure effect, temperature effect, and the embedded collapsed microballons.