Compression fatigue performance of a fire resistant syntactic foam

Compression–compression fatigue test study of a fire resistant Eco-Core was conducted at two values of stress ratios (R = 10 and 5). Tests were conducted at Smin/So values of 0.9–0.6 for R = 10 and 0.95–0.8 for R = 5. Here Smin is the maximum compression stress and So is the compression strength. The study showed that Eco-Core has well defined failure modes and associated fatigue lives. The failure modes are: damage on-set; damage progression, and final failure. The damage on-set, propagation and final failure were characterized by 2%, 5% and 7% changes in compliance. The three failure modes were found to be same for both static and fatigue loadings. The endurance limit was found to be 0.72So, 0.75So and 0.76So, respectively for three failure modes for R = 10 and 0.81So, 0.82So and 0.82So, respectively for R = 5. The fatigue life is defined by a power law equation, Smin/So = AoNα. Constants of the equation were established for all three modes of failures and the two stress ratios. Finally, fatigue life was found to be less sensitive to R ratio when expressed in terms of stress range versus number of load cycles, which is similar to that of metallic materials.