Wehner, Jan-Hendrik ; Jekel, Dominic ; Sampaio, Rubens ; Hagedorn, Peter (2017)
Damping Optimization in Simplified and Realistic Disc Brakes.
Book
Abstract
In mechanical systems, self-excited vibrations are a frequent and unwanted occurrence. An example of this phenomenon is the squealing of automotive disc brakes, which is due to flutter-type instabilities originating from friction forces in the contact zone between the brake pads and the rotating brake disc. In the linearized equations of motion, these friction forces lead to a skew-symmetric part in the matrix of coordinate proportional forces. The stability behavior of such systems mainly depends on the structure of the damping matrix, respectively the interaction between the damping and the remaining matrices.
This work deals with techniques to optimize the linear stability behavior of simplified and realistic disc brake models with respect to preferably beneficial properties of the damping matrix in order to reduce the propensity of squeal noise. To gain insight into the fundamental physical behavior of damping, a minimal model with two degrees of freedom is studied. In realistic brake systems, however, time-variant matrices are present in the equations of motion due to holes or asymmetric cooling channels. Using the minimal model, the stability behavior of both time-invariant and time-variant systems is discussed.
Furthermore, finite element models with several thousand or even hundred thousand degrees of freedom are studied using common modal reduction techniques. Based on the results of optimization, the disc is identified as the dominant component to stabilize the system. In nearly all components, the optima are the points of maximum damping. However, it becomes apparent that there are values smaller than the optimum, above which adding damping stops being worthwhile. Even components where reducing damping has a stabilizing effect may be found. Consequently, it is not always purposeful to add damping. In some cases, it must be reduced to optimize the stability behavior which may be counterintuitive from an engineer's perspective.
| Item Type: | Book |
|---|---|
| Erschienen: | 2017 |
| Creators: | Wehner, Jan-Hendrik ; Jekel, Dominic ; Sampaio, Rubens ; Hagedorn, Peter |
| Type of entry: | Bibliographie |
| Title: | Damping Optimization in Simplified and Realistic Disc Brakes |
| Language: | English |
| Date: | 2017 |
| Place of Publication: | Cham |
| Publisher: | Springer |
| Series: | SpringerBriefs in Applied Sciences and Technology |
| URL / URN: | http://www.springer.com/de/book/9783319627120 |
| Abstract: | In mechanical systems, self-excited vibrations are a frequent and unwanted occurrence. An example of this phenomenon is the squealing of automotive disc brakes, which is due to flutter-type instabilities originating from friction forces in the contact zone between the brake pads and the rotating brake disc. In the linearized equations of motion, these friction forces lead to a skew-symmetric part in the matrix of coordinate proportional forces. The stability behavior of such systems mainly depends on the structure of the damping matrix, respectively the interaction between the damping and the remaining matrices. This work deals with techniques to optimize the linear stability behavior of simplified and realistic disc brake models with respect to preferably beneficial properties of the damping matrix in order to reduce the propensity of squeal noise. To gain insight into the fundamental physical behavior of damping, a minimal model with two degrees of freedom is studied. In realistic brake systems, however, time-variant matrices are present in the equations of motion due to holes or asymmetric cooling channels. Using the minimal model, the stability behavior of both time-invariant and time-variant systems is discussed. Furthermore, finite element models with several thousand or even hundred thousand degrees of freedom are studied using common modal reduction techniques. Based on the results of optimization, the disc is identified as the dominant component to stabilize the system. In nearly all components, the optima are the points of maximum damping. However, it becomes apparent that there are values smaller than the optimum, above which adding damping stops being worthwhile. Even components where reducing damping has a stabilizing effect may be found. Consequently, it is not always purposeful to add damping. In some cases, it must be reduced to optimize the stability behavior which may be counterintuitive from an engineer's perspective. |
| Uncontrolled Keywords: | self-excited vibrations, brake squeal, damping, stability |
| Divisions: | 16 Department of Mechanical Engineering > Dynamics and Vibrations Exzellenzinitiative > Graduate Schools > Graduate School of Computational Engineering (CE) Exzellenzinitiative > Graduate Schools 16 Department of Mechanical Engineering Exzellenzinitiative |
| Date Deposited: | 01 Aug 2017 05:35 |
| Last Modified: | 01 Aug 2017 05:35 |
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