Flexural creep behavior and life prediction of GFRP-balsa sandwich beams

In this paper, the flexural creep behavior of composite sandwich beams with glass fiber- reinforced polymer (GFRP)face sheets and a balsa wood core was investigated. First, static three-point bending tests for the beams were conducted, and an average ultimate bearing capacity of 6.08 kN was obtained. Then, ten bending creep test devices were designed and manufactured based on the principle of leverage. Creep experiments were carried out for a period of 3000 h at four different load levels corresponding to 20%, 40%, 60% and 80% of the ultimate bearing capacity. The results show that the creep behavior exhibits linear viscoelastic properties when the load level is less than 40%, while creep failure occurs in all specimens at load levels of 60% and 80%. Specimens subjected to the 60% load level exhibit two failure modes, i.e., core shear failure and overall bending failure, while specimens subjected to the 80% load level exhibit only bending failure. Furthermore, the experimental creep curves at the 20% and 40% load levels are successfully fitted by the Bailey-Norton and Findley models, and a life prediction method is proposed to predict the creep life of the beams at any load level.