Strain rate dependent compressive mechanical properties and dynamic failure of pre strained epoxy syntactic foam

Syntactic foam is increasingly used in engineering applications. This paper studies the dynamic mechanical properties and failure of syntactic foam, with emphasis on the influence of pre-strain and the embedded collapsed microballons. The epoxy syntactic foam (ESF) with different levels of pre-strain is successfully produced using a confinement sleeve technique. The initial and pre-strained ESF are tested and compared from quasi-static to high strain rates about 1000 /s. The dynamic deformation processes of the initial and pre-strained ESF are monitored using high speed photograph techniques. The stress–strain relationships of the initial and pre-strained ESF show different strain rate dependence. The pre-strained ESF presents good deformability. The dynamic failure of the ESF results from shear strain localization, regardless of the pre-strain. The initial ESF shows macro elastic brittle behaviour, and the fracture surface consists of partially deformed and localized regions. The produced ESF with pre-strain, however, presents the collapsed microballons surrounded by the flow like behaviour of the severely deformed matrix, which would be associated with the thermomechanical coupling process. This study indicates the ESF with embedded collapsed microballons shows deformability and high energy absorption capacity