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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, combine...
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... cogging torque occurs in every permanent magnet machine and is defined as the torque ripple, which is caused by the uneven attraction of the magnets on the rotor to the teeth and slots on the stator. In the position where the pole aligns with the teeth, the highest attraction or the maximum of magnetic flux density occurs-shown schematically in Figure 5. Neapolitan and Nam [7] state that the cogging torque depends on the rotational frequency, on the number of poles and slots and on the load of the motor. ...
Context 2
... cogging torque occurs in every permanent magnet machine and is defined as the torque ripple, which is caused by the uneven attraction of the magnets on the rotor to the teeth and slots on the stator. In the position where the pole aligns with the teeth, the highest attraction or the maximum of magnetic flux density occurs-shown schematically in Figure 5. Neapolitan and Nam [7] state that the cogging torque depends on the rotational frequency, on the number of poles and slots and on the load of the motor. ...
Citations
... 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. ...
... The frequency range of interest may extend to much higher frequencies in many applications related to vibration isolation or acoustic comfort. In certain applications, for example, rail fasteners [75] and rubber engine mounts [81] may be required to operate at frequencies as high as 5 kHz; the excitation frequency generated by the powertrain of the electric vehicles can exceed 2 kHz [29] and may be up to 3 kHz [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. ...
Resilient elements are widely applied for vibration and noise control in many areas of engineering. Their complex dynamic stiffness gives fundamental information to describe their dynamic performance and is required for predicting structure-borne sound and vibration using dynamic modelling. Many laboratory measurement methods have been developed to determine the dynamic properties of resilient elements. This paper presents a review of recent developments of the measurement methods from the perspective of force-displacement relations of the resilient element assembly rather than of their material properties. To provide context, the review begins with an introduction to modelling methods for resilient elements, especially for rubber and rubber-like isolators, and three standardized measurement methods are introduced. Recent developments are then discussed including methods to extend the frequency range, which are mainly developments of the indirect method. Mobility methods, modal-based methods, recent active frequency-based substructuring (FBS) and inverse substructuring (IS) methods to study the dynamic properties of resilient elements are also described. Laboratory test rigs and the corresponding identification methods are outlined. Methods to evaluate nonlinear dynamic properties of resilient elements by laboratory measurements are also discussed. Finally, the review is concluded by discussing advantages and limitations of the existing methods and giving suggestions for future research.
... Internal combustion engine vehicles generate vibration and noise in a frequency range of up to 200 Hz [12]. In electric cars, this upper limit grows up to 2-3 kHz [13]. ...
... Thus, representing the rational function of Γ's contained in the summation of Equation (7) (see equation (11)) for different values of and , ( , ) function tends to 'NaN' result (Not a Number) after the critical value = 171, because Γ(172) = ∞ for float64 variables. In many coding languages, the use of the function ( ) = ln (Γ( )) increases this capability to very high values, changing the equation that represents ( , ) to the one included in Equation (12). Fig. 7 represents a sensitivity analysis of | * | and for a conventional Zener model with coefficients 0 = 1000 N/mm, 1 = 1000 N/mm, and 1 = 1000 N.s/mm. ...
Estimation of the viscoelastic properties of rubber bushings at very high frequencies (up to 2 kHz) is a challenge for many damping component manufacturers in the design stage of a quality monitoring procedure. This investigation is focused on the capability of lower strain rate testing procedures, such as relaxation tests, to estimate and extrapolate the dynamic behavior of rubber bushings from low to moderate frequencies. Fractional Zener models are employed to approach bushing behavior in experimental relaxation tests, thus leading to a linear viscoelastic model which is employed to estimate the dynamic behaviour of rubber bushing under harmonics loads up to 150 Hz. The validation of this extrapolation procedure is performed by comparing these analytical results with experimental dynamic harmonic tests applied to the same rubber bushings. The deviation between both curves demonstrates that it is difficult to compare the behavior from very small deformation rates (relaxation tests) to higher deformation rates (harmonic dynamic tests) due to the nonlinear behaviour of the rubber and its amplitude dependence. However, this investigation demonstrates that the relaxation tests contain enough data to define the frequency behavior of linear viscoelastic materials up to moderate frequencies.
... The output performance (V out ≈ 240 V) of the Mica-PVS TENG remained highly stable and uniform throughout the operation (Fig. 13a(i) & a(ii)). The long durability of the Mica-PVS TENG lies in the combination of hard and soft tribo-layer materials, which tend to exhibit highly stable mechanical response under continuous cyclic loading [86,87] (the PVS is highly soft and compliant with Young's modulus of 3.4 ± 0.2 MPa; whereas, the mica is much stiffer and harder with Young's modulus of 5.4 GPa [53]). ...
Triboelectric nanogenerators (TENGs) are energy harvesters generating electricity via the triboelectric effect and electrostatic induction. However, the influence of interface mechanics on TENG performance requires attention. Here, we study the effect of random multiscale surface roughness on TENG performance using a novel in-situ optical technique to directly visualise the contact interface. To achieve this, a new type of TENG is developed based on transparent mica in contact with polyvinyl siloxane (PVS). A wide range of surface roughness instances were created on the PVS surface (Sq from 1.5 to 82.5 µm) by replicating 3D-printed masters developed from numerically generated rough surfaces. TENG output was found to be highly sensitive to surface roughness over a wide range of forces and frequencies. The dependence of real contact area on roughness was identified as the underlying cause. In this work, electrical output (and contact area) decreased significantly with increasing roughness. The highest output (smoothest PVS surface) gave open circuit voltage 222.8 V, short-circuit current density 53 mA/m² and peak-power density 4256 mW/m²: a competitive output given the rapid and simple fabrication, low cost and long durability demonstrated. The new Mica-PVS TENG, the direct technique for TENG interface visualisation and the insights on the role of topography and contact area will be invaluable for future TENG design.
It is no secret that elastomers are involved across a wide range of industrial applications. These are exposed to various environmental influences, which ultimately have a significant impact on the service lifespan of the elastomer. If the elastomer is used as a decoupling element within a mechanical system, it is exposed to complex static with superimposed dynamic loads, frequently at elevated temperatures. To design a component that can withstand such loads while keeping the product development costs as low as possible, a numerical simulation can be of a great help—the design can be varied quite easily and the simulation results can determine the critical areas within the component geometry with sufficient accuracy. These areas play an essential role if the service lifespan of the component is of interest. The determination of the lifespan becomes even more complicated when the dependence of the mechanical stresses on temperature and the fact that the component can heat up due to a partial dissipation of the mechanical energy are taken into account. These considerations raise a series of problems that severely complicate the development of such a product. This study presents the approaches to experimentally determine the material properties which are used within a thermodynamically-consistent numerical model.
In order to design and produce a component that can reliably withstand varying dynamic loading, an extensive characterization of the component material must be performed across a wide range of frequencies. This study uses dynamic mechanical thermal analysis (DMTA) to determine the viscoelastic behavior of a blend of natural and butadiene rubber, a dummy material used to showcase the capabilities of a newly developed time-temperature superposition procedure. This procedure is embedded in a user-friendly graphical user interface (GUI), which allows for quick postprocessing of the measurement results with very little effort. The workflow and the possibilities of this postprocessing interface will be explained from the point of importing the raw measurement data up to the export of the master curve, its further use in calibration of the suitable material model or a definition of the material properties directly for a finite element software.
Elastomers are widely used in the automotive industry in anti‐vibration components. Commonly, elastomeric anti‐vibration components are made of thermoset rubbers. However, new drivers related to the requirements of the new sustainable mobility industry are pushing towards the substitution of thermoset rubbers by thermoplastic elastomers. Among thermoplastic elastomers, thermoplastic vulcanizates (TPVs) represent an interesting material choice for anti‐vibration products due to their light weight, recyclability, ease of processing by means of injection molding and design flexibility. In this work, the correlation between static and dynamic mechanical properties and the morphology of injection molded thick‐walled TPVs is investigated. Interestingly, when comparing TPVs of different hardnesses, the softest TPV demonstrated an improvement in elastic ability to recover of up to 50% in transverse to flow direction as well as a highly anisotropic viscoelastic behavior. These phenomena are interpreted in terms of the orientation of ethylene‐propylene‐diene particles together with polypropylene crystals and chain alignment observed in microstructural characterization tests. This study opens new opportunities to develop TPV‐based anti‐vibration components with superior elasticity and customizable static and dynamic mechanical properties by considering the anisotropic character of soft TPV materials in product design and development strategies. © 2022 Society of Industrial Chemistry.
