In this paper. the model reference adaptive control (MRAC) of a flexible st
ructure is investigated. Any mechanically flexible structure is inherently
distributed parameter in nature, so that its dynamics are described by a pa
rtial, rather than ordinary, differential equation. The MRAC problem is for
mulated as an initial value problem of coupled partial and ordinary differe
ntial equations in weak form. The well-posedness of the initial value probl
em is proved. The control law is derived by using the Lyapunov redesign met
hod on an infinite dimensional Hilbert space. Uniform asymptotic stability
of the closed loop system is established, and asymptotic tracking, i. e., c
onvergence of the state-error to zero, is obtained. With an additional pers
istence of excitation condition for the reference model, parameter-error co
nvergence to zero is also shown. Numerical simulations are provided.