Alf Søe-Knudsen

Theoretical and experimental analysis of the stop-band behavior of elastic springs with periodically discontinuous of curvature.

The advanced design of springs with tailored transmission characteristics is proposed. The existence of frequency stop-bands in the transmission characteristics is theoretically predicted and experimentally validated. The underlying mechanism of generating stop-band behavior is the periodic discontinuity of the curvature. The theoretical analysis is performed in the framework of the Floquet theory for an infinitely long spring. Experimental results are obtained for the springs consisting of a small number of repeated periodicity cells.

On advantages of derivation of exact dynamical stiffness matrices from boundary integral equations

Dynamical stiffness matrices are broadly used for solving problems in wave propagation in elastic structures. For elastic waveguides that support both propagating and evanescent waves, the standard use of transfer matrices to obtain their dynamical stiffness matrix may cause problems in computations. In this letter to the editor, an advanced way to derive dynamical stiffness matrices is proposed and exemplified in the classical Bernoulli-Euler beam theory.