Modelling and Simulation of Disc Brake Contact Analysis and Squeal (original) (raw)

Abstract

Predicting disc brake squeal by means of the complex eigenvalue method has been a popular approach in the brake research community owing to its advantages over the dynamic transient method. The positive real parts of the complex eigenvalue reflect the degree of instability of the brake system and are thought to indicate the likelihood of squeal occurrence. This paper studies the disc brake squeal using a detailed 3-dimensional finite element (FE) model of a real disc brake. A number of structural modifications for suppressing unstable vibration are simulated. Influence of contact pressure distribution on squeal propensity is also investigated. A plausible modification that results in reduced positive real parts of the eigenvalues is proposed.

Figures (7)

FIGURE 1 Contact Pressure Distribution: Topography on Sensitive Pressure Film (left) and Analysed Image (right) Modelling and Simulation of Disc Brake Contact Analysis and Squel The finite element model of a disc brake of floating caliper design consists of a solid disc, a caliper, a carrier bracket, a piston, two pads and two guide pins as illustrated in Fig. 2. There are about 8000 solid elements and a total of approximately 70,000 degrees of freedom (DOFs) in the model. Validation of the disc brake components is the first step towards a valid assembly model. A good correlation at the assembly level between FE prediction and experimental result is crucial to accurately predict the onset of squeal using the complex eigenvalue analysis.

FIGURE 1 Contact Pressure Distribution: Topography on Sensitive Pressure Film (left) and Analysed Image (right) Modelling and Simulation of Disc Brake Contact Analysis and Squel The finite element model of a disc brake of floating caliper design consists of a solid disc, a caliper, a carrier bracket, a piston, two pads and two guide pins as illustrated in Fig. 2. There are about 8000 solid elements and a total of approximately 70,000 degrees of freedom (DOFs) in the model. Validation of the disc brake components is the first step towards a valid assembly model. A good correlation at the assembly level between FE prediction and experimental result is crucial to accurately predict the onset of squeal using the complex eigenvalue analysis.

TABLE 1 Modal result of the solid disc at free-free condition TABLE 2 Modal result of the assembly model measured on the disc

TABLE 1 Modal result of the solid disc at free-free condition TABLE 2 Modal result of the assembly model measured on the disc

FIGURE 3 Prediction of Unstable Frequencies at Different Pressure and Disc Speeds of Baseline Model TABLE 3 Squeal Frequencies Generated in the Experiment

FIGURE 3 Prediction of Unstable Frequencies at Different Pressure and Disc Speeds of Baseline Model TABLE 3 Squeal Frequencies Generated in the Experiment

FIGURE 4 Contact Pressure Distribution at Piston Pad (left) and Finger Pad (right). Right Hand Side of the Diagram is the Leading Edge of the Pad.

FIGURE 4 Contact Pressure Distribution at Piston Pad (left) and Finger Pad (right). Right Hand Side of the Diagram is the Leading Edge of the Pad.

FIGURE 5 Unstable Frequencies of Modified Structures and Material Modelling and Simulation of Disc Brake Contact Analysis and Squel

FIGURE 5 Unstable Frequencies of Modified Structures and Material Modelling and Simulation of Disc Brake Contact Analysis and Squel

FIGURE 7 Partial Connections in the Axial Direction (the Red Dot Represents Removal of One Axial Connection) For the piston pad, M1, M4 and M5 follow exactly the trend of the baseline model whilst M3 almost produced the same magnitude of except in the middle of the pad, where the pressure fluctua presence of the slot. The rest of the modifications produced slightly differen ing edge and slightly del. results, where the contact pressure is much higher at the trai lower at the leading edge, than those of the baseline mo t ed occurred in the middle of the pad for M1+M2. For the finger MS lead to exactly the same trend of the baseline model whils slightly higher contact pressure at the trailing edge. pad, M1, M3, M4 and he baseline mode mildly due to the Fluctuation also the rest produced

FIGURE 7 Partial Connections in the Axial Direction (the Red Dot Represents Removal of One Axial Connection) For the piston pad, M1, M4 and M5 follow exactly the trend of the baseline model whilst M3 almost produced the same magnitude of except in the middle of the pad, where the pressure fluctua presence of the slot. The rest of the modifications produced slightly differen ing edge and slightly del. results, where the contact pressure is much higher at the trai lower at the leading edge, than those of the baseline mo t ed occurred in the middle of the pad for M1+M2. For the finger MS lead to exactly the same trend of the baseline model whils slightly higher contact pressure at the trailing edge. pad, M1, M3, M4 and he baseline mode mildly due to the Fluctuation also the rest produced

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