Free vibration of coupled disk-hat structures

The free vibration of disk-hat structures, such as automotive brake rotors, is investigated analytically and through laboratory experimentation. Of pa rticular interest are the role played by the hat element's depth in influen cing the three-dimensional vibration of the disk, and the manner in which t he bending and in-plane modes of the disk alone evolve as a hat of increasi ng depth is incorporated in the model. The lower: vibration modes of disk-h at structures are shown to be characterized by the numbers of nodal circles NC and diameters ND present on the disk, as well as the phase relationship between the disk's transverse and radial displacements due to coupling wit h the hat element. Such modes map continuously back to the pure bending and in-plane modes of the disk alone, appear in ordered pairs, and can exist a t close frequencies. Those characteristics are explored particularly with r espect to sensitivities in the disk's thickness and the hat's depth with a view towards shifting particular natural frequencies, or minimizing transve rse disk motion in certain vibration modes. Results obtained through analys is and measurement of a prototypical disk-hat structure are applied ill a c ase study with a ventilated automotive brake rotor. (C) 2000 Academic Press .