The squealing of disk and drum brakes is still a major problem to design engineers. It has been observed by Fieldhouse and others that the introduction of asymmetries into the brake rotor can lead to a reduction of brake noise. However this insight has not yet solved the squeal problem. One reason for this is that it is not a priori obvious which kind of asymmetries of the rotor are preferable and which ones are not. This lack of knowledge most likely originates from the fact that most models explaining disk brake squeal rely on a symmetric rotor. In this paper, models for disk brake squeal are presented which are suitable to study asymmetric brake rotors. The excitation mechanism for squeal is explained by the formulation of a stability problem. It is shown that multiple eigenfrequencies of the rotor make it extremely sensitive to self-excited vibrations, i.e. squeal. Therefore an optimization problem is formulated, with the goal to split all eigenfrequencies in the audible range as much as possible in order to make the brake more robust against squeal. The study can be seen as a follow up of the results of the 2004 SAE paper of Fieldhouse et al., who presented experimental evidence for the usefulness of the approach.Replace this description with text.