Designer linear viscoelastic composite materials tailored to optimize energy harvesting

Motion damping by energy harvesting through piezoelectric devices recharging batteries and having it available to do useful work rather than simply dissipating energy by heat is a preferable process. The piezo devices then potentially acquire triple functions as sensors, controllers and/or harvesters. While the piezoelectric devices may not necessarily completely damp out unstable motions, they may contain them by postponing the inevitable instabilities to occur at later times, higher velocities and/or loads, etc. (creep buckling, torsional divergence, flutter, failure conditions, etc.). The inverse calculus of variation analysis developed in [1] is applied to the current formulation in order to determine among others optimum fiber orientations, number of plies, material properties, piezo device placements, weight, cost, etc. These answers are achieved through solutions of the governing relations and optimum parameter values are obtained subject to enumerated constraints. One of the most fruitful approaches for these goals is to employ Lagrange multipliers. The analytical formulation is predicated on distinct linear viscoelastic material properties for the composite and for the piezoelectric devises. Furthermore, provisions are incorporated for the spatial distributions of such properties to be represented by distinct optimized functions thus leading to viscoelastic functionally graded composites and piezoelectric devises - both as nonhomogeneous materials.