Idealised Impact Behaviour of a Delaminated Beam Under Periodic Forcing

This paper is concerned with developing a mathematical model for the vibration of a partially delaminated cantilever and with examining the predicted response of the model to an external periodic forcing. When the cantilever is undergoing a forced vibration due to some external source, the delaminated flap will undergo an induced motion in which it moves freely until it comes into contact with the main beam. A discontinuity will arise in the velocity of the flap when it impacts the main beam and this is given in terms of the impact velocity and the effective coefficient of restitution e. Numerical results are obtained for a range of values of e and of the frequency of the forcing term. The resulting motion may be periodic, chattering or chaotic according to the values of these parameters. Experimental results are presented which show examples of periodic impact motion and of chattering behaviour.