A Drum Brake Squeal Analysis in the Time Domain

Brake squeal has been a chronic customer complaint, often appearing high on the list of items that reduce customers' satisfaction with their vehicles. Brake squeal can emanate from either a drum brake or a disc brake even though the geometry of the two systems is significantly different. A drum brake generates friction within a cylindrical drum interacting with two semi-circular linings. A disc brake consists of a flat disc and two flat pads. The observed squeal behavior in a vehicle differs somewhat between drum and disc brakes. A drum brake may have a loud noise coming from three or more squeal frequencies, whereas a disc brake typically has one or two major squeal frequencies making up the noise. A good understanding of the operational deflection shapes of the brake components during noise events will definitely aid in design to reduce squeal occurrences and improve product quality. In this paper, a drum brake in a commercial van was used to develop a numerical model to predict potential squeal frequencies and related operational deflection shapes using the time domain solver LSDYNA. The model includes drum, leading and trailing linings and actuation pressure. The engineering mechanical parameters considered cover geometric nonlinear behavior, orthotropic material properties and frictional contact boundary conditions. The simulated squeal results were compared with a dynamometer brake noise test and showed good correlation for some squeal frequencies. The operational deflection shapes showed in-plane effects generated from nonlinear behavior in the drum rim ring belt area. Some potential squeal modes exhibited a harmonic phenomenon in the simulation which will also be discussed.