Behavior of Cantilever Beam Under Impact by a Soft Projectile.

Abstract : In an attempt to determine the maximum deflection and the ultimate strength of a fan blade under the impact of a bird, experiments were performed on the impact of cantilever beams by soft-rubber projectiles. The observed response of the projectile and beam can be correlated with a simple analytic model - an equivalent mass-spring system which is derived from an assumed deflection mode. The initial velocity of the equivalent mass immediately after impact is computed from the momentum conservation principle and measured coefficient of restitution. This information and the dynamic characteristics of the equivalent mass-spring system are shown to be fairly sufficient to predict the behavior of the beam. The success of this model implies that the structural response of fan blades under bird impact can be made predictable.