Comparison of moisture aging effect on flexural and buckling behavior of two types of balsa core sandwich structures

Despite the unique superior properties of balsa such as reasonable price and excellent mechanical properties, the hydrophilicity and high sensitivity of this material to moisture absorption have posed a serious challenge to its increasing use in the construction of advanced marine structures. If moisture can penetrate into the composite skins, the balsa core sandwich structures will absorb a lot of water and compromise its structural integrity. In this study, to improve the mechanical properties and the environmental resistance of sandwich structures with balsa core against the moist environmental conditions, the idea of using fiber metal laminates instead of polymer composite skins has been proposed. For this purpose, sandwich structures with balsa core and two types of composite skins made of glass fiber/epoxy and fiber metal laminate were subjected to environmental and mechanical tests. The most important results obtained from the 100-day aging test in water show that the maximum water absorption in sandwich specimens with glass fiber/epoxy composite and fiber metal laminate skins having sealed edges and artificial damage is 106.71% and 83.32%, respectively. In addition, by evaluating the flexural and buckling behavior of two types of sandwich structures, before and after the moisture aging process, it was found that the reduction of flexural load, flexural stiffness and maximum buckling load due to moisture aging in sandwich specimens with glass fiber/epoxy composite skin with sealed edges were 23.43%, 23.15% and 36.14%, respectively, and for specimens with fiber metal laminate skin were much less, and 13.57%, 11.06% and 16.14%, respectively.