Abstract
The realistic prediction of material damping is crucial in the design and dynamic simulation of many components in mechanical engineering. Material damping in metals occurs mainly due to the thermoelastic effect. This paper presents a new approach for implementing thermoelastic damping into finite element simulations, which provides an alternative to computationally intensive, fully coupled thermoelastic simulations. A significantly better agreement between simulation results and experimental data was achieved, when compared with the empirical damping values found in the literature. The method is based on the calculation of the generated heat within a vibration cycle. The temperature distribution is determined by the mechanical eigenmodes and the energy converted into heat, and thus dissipated, is calculated. This algorithm leads to modal damping coefficients that can then be used in subsequent analyses of dynamically excited oscillations. The results were validated with experimental data obtained from vibration tests. In order to measure material damping only, a test setup excluding friction and environmental influences was developed. Furthermore, comparisons with fully coupled thermoelastic simulations were performed. It was clear that the new approach achieved results comparable to those of a computationally expensive, coupled simulation with regard to the loss factors and frequency response analyses.
Highlights
The simulation of dynamic processes is essential in almost every engineering discipline, including structural and mechanical engineering, aerospace engineering and micro- and nanotechnology
We present an approach that allows the calculation of thermoelastic damping to be performed based on the stress and strain distribution in the mode shapes
We here present a method to calculate modal thermoelastic damping coefficients for arbitrary components discretized with solid elements
Summary
The simulation of dynamic processes is essential in almost every engineering discipline, including structural and mechanical engineering, aerospace engineering and micro- and nanotechnology. Besides the stiffness and mass of a structure, the accurate modeling of damping behavior is highly important to predict amplitudes and frequencies correctly, to avoid resonance phenomena, etc. Several mathematical models have been established to consider energy dissipation, e.g., viscous damping or Rayleigh damping. These assumptions are sufficient in many applications, they can lead to inaccurate predictions. In practice, it is often necessary to perform experimental vibration analyses in addition to the computational development process. To avoid this effort, there is a need for precise and fast usable damping models
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