The failure behavior of syntactic foams as buoyancy materials for deepsea applications

Syntactic foams made of hollow particles embedded in a matrix material are widely used as buoyancy materials for underwater marine structures, where both low density and high mechanical properties are desired. In most engineering materials, however, the reduction in density is often accompanied with the decrease in stiffness and strength. Such a dilemma forces us to strike a balance between them for different application scenarios, which necessitates a profound understanding of the structure -property correlations in syntactic foams. In this paper, we investigated the mechanical properties of syntactic foams subjected to triaxial compressive loading. Taking particle crushing as the primary failure mode, we develop an analytical analysis on the compressive strength of syntactic foams. For syntactic foams with high strength under hydrostatic pressure, they may fail readily in the presence of deviatoric stress. In addition, we identify the critical conditions associated with other failure modes, including particle -matrix interface delamination and particle buckling. This study not only sheds light on the structure -property relationship in syntactic foams for deepsea usage, but also provides guideline for the design and optimization of syntactic foams, which would be of great value for the development of high-performance underwater structures.