Algorithm for computing the mechanical impedances of reinforcing ribs of various shapes

The problem is considered of finding the mechanical impedances of reinforcing ribs of various shapes. The rib is modeled by a narrow plate. The thickness of the rib (the thickness of the plate from which the rib is made) is thus considered small as compared with the height of the rib (the width of the plate). The height of the rib $h$ is assumed small as compared with the lengths of waves propagating in the material of the plate. One of the edges of the rib is assumed to be free of stresses. The matrix giving the relation between the stresses and the velocities of displacements on the second (loaded) edge is called the impedance matrix. An algorithm is proposed for computing the coefficients of the expansion of the impedance matrix in a Taylor series in powers of $h$. The method is illustrated by the computation of the mechanical impedances of rectilinear and annular reinforcing ribs.