Two-dimensional fatigue debonding in GFRP/balsa sandwich panels

摘要: Abstract An experimental investigation of the two-dimensional (2D) debonding behavior GFRP/balsa sandwich panels with embedded circular disbonds at face sheet/core interface subjected to out-of-plane fatigue loads was conducted. The constant amplitude experiments were performed under load control and different R-ratios. Two sheet configurations investigated: a pure woven ply layup (SPA) combination continuous filament mat (CFM) plies (SPB). For latter, CFM layers (which are prone develop fiber-bridging) placed above below plies. In contrast one-dimensional (1D) beam-like fracture experiments, decreasing crack growth rates stable propagation achieved as result 2D disbonds. performance obtained R = 0.1 for SPB configuration less efficient than SPA owing fiber-bridging crushing associated high amplitudes. Under higher R-ratios, reduced amount observed, leading corresponding arrest much longer life. load-displacement hysteresis loops exhibited an increase in cyclic stiffness within each cycle throughout experiments. This stiffening mainly caused by in-plane stretching stresses that developed debonded part sheets whose magnitude evolution evaluated based on strains monitored during