A Combined Approximation Method with Application to Non-Linear Numerical Creep Groan Analysis: DE (Berichte des Instituts für Mechanik) - Tapa blanda

Sinopsis

In the automotive industry, the suppression of unwanted noise, such as brake noise, plays an important role within the manufacturing process of vehicles. These noises decrease the perceived quality and should therefore be detected and eliminated early on in the development process. In addition to measurements on real assemblies, simulation-based prediction of brake noise is also used. In industrial applications, the (linear) Complex Eigenvalue Analysis (CEA) of the mathematical brake models is commonly used as simulation-based detection. The CEA detects e.g. creep groan vibrations at an unstable rest position. However, there are operation points where creep groan occurs but the rest position remains stable and the linear evaluation failed. The aim of this work is therefore to implement a suitable non-linear approximation method for the prediction of creep groan vibrations. Two points are crucial here: first, the approximation method must be suitable for both creep groan and the respective mathematical models. Secondly, in order to prove the latter, a representative mathematical model of application-orientated FEM models is also required. Within this work, the creep groan phenomenon and macroscopic friction models are first discussed. The findings are condensed into an experimentally validated mathematical model with three degrees of freedom that shows low- and high-frequency creep groan vibrations. By adding two FE-discretised strain rods, mathematical properties of application-oriented mathematical models are replicated. Then, nonlinear approximation methods and the Predictor-Corrector continuation framework are discussed. Core element is the motivation and derivation of the combined Finite Difference/Harmonic Balance method (FD/HBM). This method is suitable for approximating periodic oscillations with equations of motion that exhibit strong non-linearities in only a few degrees of freedom. In the last part, the proposed FD/HBM is used to approximate creep groan vibrations in the strain rod-expanded mathematical model. For systems with many (linear) degrees of freedom, the FD/HBM requires less computing time than established approximation methods while maintaining the same accuracy. Furthermore, a creep groan stability map is systematically derived using linear (CEA) and nonlinear (FD/HBM) analysis.

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