Modal analyses of an S-cam drum brake assembly, using finite element analysis, are presented. A jiiction interface contact pressuredependent model for the coupling between the lined brake shoe assembly and the brake drum is described. Using this model, natural modes and f i e uencies are predicted which compare well with measured data for the brake assembly. A parametric study of brake design and peJormance variables is presented which predicts the noise propensity of the brake design based on the binaryjutter model. Good agreement with measured brake noise and trends, experience and other published work on S-cam brake noise is shown.

No abstract

The effects of wall vibration on the development of Tolimien-Schlichting (T-S) waves in a transitional flat-plate boundary layer are considered. Theoretically, the dynamic interaction between T-S waves and velocity perturbations induced by the vibrating wall is demonstrated through the kinetic energy balance of velocity perturbations. For a compliant wail, the response of T-S waves to velocity perturbations induced by the vibrating wall has been studied for various phase angles between the T-S wave veiocity and the wall velocity, and for various amplitudes of the wail vibration. Experimentally, T-S waves are induced by a vibrating wire located in the upstream portion of the wail. The downstream portion Is vibrated at the same frequency as that of the wire and the phase between the two oscillations can be varied. Depending on the phase angle, the T-S waves may be either amplified or attenuated, even if the wavelengths do not coincide. Notation c = w / a = c, + ici c, = phase veiocity ci = amplification coefficient H = shape parameter of boundary layer = 6,/6, p = instantaneous pressure 0 = time mean vressure q = kinetic energy of velocity perturbations = U12 4-&I2 I Rea, = Reynolds number = U,6,/v t = time U, v = instantaneous velocity components 0, F = time mean velocities U', U' = perturbations velocities U, = velocity outside of boundary layer xi,xj = space coordinates P:=cuZ+icuRe(l-c) 6 = boundary layer thickness 6 1 = displacement thickness = momentum thickness 4, a, w = amplitude, wave number and frequency of stream function perturbation Y = kinematic viscosity p = density $ = stream function C = perturbation velocity rotational = &//ay -&'/ax