Energy Decay and Control for Elastic and Viscoelastic Distributed Parameter Systems
Final technical rept. 15 Nov 1990-14 Apr 1994
VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG
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Research is reported on the dynamic behavior of viscoelastic structures, with emphasis on the interaction between passive damping and active feedback control mechanisms. A main focus is the approximation of optimal compensators for simple mechanical systems involving viscoelastic elements by realizable compensators. In the frequency domain, this corresponds to the mathematical problem of approximating a transcendental function by a rational one, under suitable stability constraints and performance criteria. The work involves the analytic study of partial product approximations to transfer functions for rods and beams, as well as a mainly numerical study concerned with replacing the complex modulus for the viscoelastic material by a rational function that reflects the most significant properties of the material. A second focus of the research is a new formula that makes clear the relation between initial data and the smoothness and decay rates of solutions of the equations for a viscoelastic system with stabilizing boundary feedback.