Tailoring Concepts For Improved Structural Performance Of Rotorcraft Flexbeams

Quasi-static tension tests were performed on tapered glass/epoxy laminates with internally dropped plies. Four different internal ply drop configurations were examined which achieved the same transition in thickness. Delamination loads and corresponding bending stiffness losses were measured. Delamination onset loads varied by 384 and bending stiffness retention varied by 56% among the internal ply drop configurations. Three of the four configurations delaminated in an unstable manner, while stable delamination initiation and growth occured in one of the configurations. In general, a trade-off existed between delamination strength and retention of bending stiffness. However, the configuration which delaminated in a stable fashion had the best bending stiffness retention as well as intermediate delamination strength.