Damped vibrations of inhomogeneous composite box rods

Studies have been carried out on damped oscillations of non-uniform shell thicknesses composite box rods. The shell of the box rod is formed outer strength layer made of unidirectional carbon fiber and inner vibration-absorbing layer of stiff elastic material. Two structures for reinforcing the load-bearing layer of a box-shaped shell are considered rod: symmetrical and asymmetrical. The influence of orientation was noted reinforcement of the load-bearing layer of the shell for the occurrence of various types coherence of vibrations of inhomogeneous composite box rods. It has been established that if the differential equations of natural vibrations contain odd derivatives of eigenfunctions with respect to spatial variable (symmetrical rod, bending-bending interaction asymmetrical rod), then the change in reinforcement orientation is accompanied mutual transformation of the eigenmodes of interacting vibration modes. If the equations contain only even derivatives (longitudinaltorsional interaction of an asymmetric rod), then mutual transformation of the eigenmodes of the interacting vibration modes does not occur. The possibility of a significant increase in the dissipative characteristics of composite box-shaped rods by including a vibrationabsorbing layer of a stiff elastic material in their shells is shown. Estimates are given of the influence of the relative thickness of the vibration-absorbing layer of the shell and the ambient temperature on the values of natural frequencies and loss factors of coupled vibrations of inhomogeneous composite box-shaped rods.