Squeal analysis of thin-walled lattice brake disc structure

Abstract

This paper presents a dynamic stability study of a novel brake disc design consisting of periodic lattice truss substructures. An integrated approach of theoretical modeling, experimental modal analysis, and finite elements methods is employed in this investigation to understand the squeal characteristics. The brake system is analytically modeled by a rotating annular disc subjected to in-plane frictional loads. Natural frequencies and forced response of the brake disc are obtained and validated by finite elements results. Experimental modal analysis of the lattice brake rotor/pad system with free-free boundary conditions is performed to obtain the modal properties of the brake rotor as inputs to the finite elements model. The FEA also includes models for the heat convection during braking and the non-linear contact forces between the rotor and the pads obtained from simulations of the SAE J2521 drag braking noise test matrix. The likelihood of squeal noise occurrence or squeal propensity for both the lattice and conventional vanned type brake discs are examined. The propensity is quantified by the standard deviation of the statistical occurrence of brake instability. It is shown that the lattice brake disc design has a lower propensity in the low frequency range of about 4 to 8kHz.