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A Modeling Framework to Develop Materials with Improved Noise and Vibration Performance for Electric Vehicles
Get PDFThe automotive and aerospace industries increasingly use lightweight materials to improve performance while reducing fuel consumption. Lightweight materials are frequently used in electric vehicles (EVs). However, using these materials can increase airborne and structure-borne noise. Furthermore, EV noise occurs at high frequencies, and conventional materials have small damping. Thus, there is an increasing need for procedures that help design new materials and coatings to reduce the transferred and radiated noise at desired frequencies. This study pioneered new techniques for microstructure modeling of coated and uncoated materials with improved noise, vibration, and harshness (NVH) performance. This work uses the microstructure of materials to study their vibration-damping capacity. Images from an environmental scanning electron microscope (ESEM) show the microstructure of a sample polymer and its coating. Tensile tests and experimental modal analysis were used to obtain the material properties of the polymer for microstructure modeling. The current work investigates how different microstructure parameters, such as fiberglass volume fraction and orientation, can change the vibration performance of materials. The damping ratio in the study was found to be affected by changes in both the direction and volume ratio of fiberglass. Furthermore, the effects of the coating are investigated in this work. Through modal analysis, it was observed that increasing the thickness of aluminum and aluminum bronze coatings caused a rightward shift in resonance frequency. Coatings with a thickness of 2 mm were found to perform better than those with lower thicknesses. Furthermore, the aluminum coating resulted in a greater shift in frequency than the aluminum bronze coating. Additionally, the coating with a higher damping ratio (i.e., aluminum bronze) significantly reduced the amplitude of surface velocity due to excitation, particularly at higher frequencies. This study provides engineers with an understanding of the effects of layer coating on the NVH performance of components and a modeling approach that can be used to design vehicles with enhanced noise and vibration performance
Mechanical characterization of human skin—A non-invasive digital twin approach using vibration-response integrated with numerical methods
No full textThis paper proposes an innovative approach to identify elastic material properties and mass density of soft tissues based on interpreting their mechanical vibration response, externally excited by a mechanical indenter or acoustic waves. A vibration test is performed on soft sheets to measure their response to a continuous range of excitation frequencies. The frequency responses are collected with a pair of high-speed cameras in conjunction with 3-D digital image correlation (DIC). Two cases are considered, including suspended/fully-free rectangular neoprene sheets as artificial tissue cutout samples and continuous layered human skin vibrations. An efficient theoretical model is developed to analytically simulate the free vibrations of the neoprene artificial sheet samples as well as the continuous layered human skins. The high accuracy and validity of the presented analytical simulations are demonstrated through comparison with the DIC measurements and the conducted frequency tests, as well as a number of finite element (FE) modeling. The developed analytical approach is implemented into a numerical algorithm to perform an inverse calculation of the soft sheets\u27 elastic properties using the imported experimental vibration results and the predicted system\u27s mass via the system equivalent reduction/expansion process (SEREP) method. It is shown that the proposed frequency-dependent inverse approach is capable of rapidly predicting the material properties of the tested samples with high accuracy
Vibration quality and ride comfort investigation with transient excitation in a ground vehicle simulator environment
No full textGround vehicle ride comfort is closely associated with vibration quality as perceived by the human occupants of a vehicle. While outstanding vibration quality is a desirable outcome of the vehicle design process, it is challenging to relate customer perceptions of vibration quality to customer-facing vehicle responses measured inside of a vehicle. Previous work with steady-state vibration has shown that human perception of vibration can be compared to how humans perceive sound, where both the amplitude and frequency of the excitation will alter its perception. Thus, a simple measurement of vibration level is insufficient to predict comfort. In this work, an analysis of human perception of transient vibration is undertaken using a ground vehicle simulator. Physical measurements from inside four different production vehicles are presented including accelerometer, microphone, and action camera recordings. The test event performed is travel over a cleat, with varying vehicle speeds and tire inflation pressures. The physical measurements are used as inputs to the simulator. A comparison is made between the perceived vibration quality of the vehicles as reported by an expert human jury and the physically measured vehicle responses. A ranking of 36 cleat test events for vibratory harshness from best to worst is presented
A Special Issue: Electric Machinery and Transformers
Get PDFAs the demand for electrical energy increases worldwide, engineers and scientists have been investigating new electrical systems and materials to meet this demand economically, having large-scale planning and employing environmentally friendly energy production and energy-efficient systems for consumption to minimize adverse environmental effects. New applications such as renewable energy production, e-mobility, and aerospace technology can be considered within the scope of this perspective. Thus, it is a necessity to establish new paradigms in the design, construction, and selection of new materials and drive systems for electric machines and transformers, where such stringent requirements, as high power density, low weight, compact size, and low cost, should be complied with. Therefore, the objective of this Special Issue is to facilitate a platform for disseminating new findings on any aspect of electric machines and transformers with certain topics of interest, including new materials used in electric machines and transformers, investigations of the performance of electric machines and transformers at dynamic state as well as at steady state, and acoustic analyses of electric machines as well as transformers due to vibrations. In this Special Issue, 11 articles address these subjects of interest
