Advanced Characterisation of Soft Polymers under Cyclic Loading in Context of Engine Mounts

Abstract

The experimental investigation of viscoelastic behavior of cyclically loaded elastomeric components with respect to the time and the frequency domain is critical for industrial applications. Moreover, the validation of this behavior through numerical simulations as part of the concept of virtual prototypes is equally important. Experiments, combined measurements and test setups for samples as well as for rubber-metal components are presented and evaluated with regard to their industrial application. For application in electric vehicles with relevant excitation frequencies substantially higher than by conventional drive trains, high-frequency dynamic stiffness measurements are performed up to 3000 Hz on a newly developed test bench for elastomeric samples and components. The new test bench is compared with the standard dynamic measurement method for characterization of soft polymers. A significant difference between the measured dynamic stiffness values, caused by internal resonance of the bushing, is presented. This effect has a direct impact on the acoustic behavior of the vehicle and goes undetected by conventional measurement methods due to their lower frequency range. Furthermore, for application in vehicles with internal combustion engine, where the mechanical excitation amplitudes are significantly larger than by vehicles with electric engines, a new concept for the identification of viscoelastic material parameters that is suitable for the representation of large periodic deformations under consideration of energy dissipation is described. This dissipated energy causes self-heating of the polymer and leads to the precocious aging and failure of the elastomeric component. The validation of this concept is carried out thermally and mechanically on specimen and component level. Using the approaches developed in this work, the behavior of cyclically loaded elastomeric engine mounts in different applications can be simulated to reduce the time spent and save on the costs necessary for the production of prototypes.

Measurement, Modeling, and Analysis of the Dynamic Properties of Resilient Elements Used for Vibration Isolation

“…the excitation frequency generated by the powertrain of the electric vehicles can exceed 2000 Hz [29] and may be up to 3000 Hz [28]. In fact, "high frequency" is a relative concept depending on the size, stiffness and mass of the element under test.…”

“…Based on the standard indirect method, Gejguš et al [28] designed a high-frequency test bench to perform the dynamic stiffness measurements for an elastomeric component used for an electric motor over the frequency range of 50-3000 Hz. A large shaker was used and attached to a 500 kg stone table through rubber air springs.…”

“…The requirements can be very different according to the purpose of the analysis. For example, the stiffness data from rail fastening systems required for use in ground-borne noise models are different from those to be used in rolling noise studies [27]; the elastomeric mounts in electric vehicles carrying motors experience loads with small amplitudes that can be applied at high frequencies, while those in conventional vehicles with internal combustion engines are exposed to vibrations with large amplitudes in the lower frequency range [28], [29]. Moreover, normally only information in one, or at most three, translational directions can be obtained from such test systems.…”

On the injection molding of thick‐walled thermoplastic vulcanizates: linking static and dynamic mechanical properties with morphology

“…By design, anti‐vibration components are subjected to complex mechanical loads. Under those structural requirements, elastomeric materials need to exhibit tailored static and dynamic mechanical properties, together with a maximized durability or fatigue life 5–7 …”

“…Under those structural requirements, elastomeric materials need to exhibit tailored static and dynamic mechanical properties, together with a maximized durability or fatigue life. [5][6][7] Commonly elastomeric anti-vibration components are made of thermoset rubbers. However, new drivers related mainly to the requirements of the new sustainable mobility industry (new legislation, sustainability impacts and electrical mobility, among others) are pushing towards the substitution of thermoset rubbers by thermoplastic elastomers (TPEs), which are a special category of elastomeric materials that combine properties of thermoplastics and elastomers, in such components.…”