Browse Topic: Vibration
Electric vehicles (EVs) are particularly susceptible to high-frequency noise, with rubber eigenmodes significantly influencing these noise characteristics. Unlike internal combustion engine (ICE) vehicles, EVs experience pronounced variations in dynamic preload during torque rise, which are substantially higher. This dynamic preload variation can markedly impact the high-frequency behaviour of preloaded rubber bushings in their installed state. This study investigates the effects of preload and amplitude on the high-frequency dynamic performance of rubber bushings specifically designed for EV applications. These bushings are crucial for vibration isolation and noise reduction, with their role in noise, vibration, and harshness (NVH) management being more critical in EVs due to the absence of traditional engine noise. The experimental investigation examines how preload and excitation amplitude variations influence the dynamic stiffness, damping properties, and overall performance of
Automotive audio components must meet high quality expectations with ever-decreasing development costs. Predictive methods for the performance of sound systems in view of the optimal locations of loudspeakers in a car can help to overcome this challenge. Use of simulation methods would enable this process to be brought up front and get integrated in the vehicle design process. The main objective of this work is to develop a virtual auralization model of a vehicle interior with audio system. The application of inverse numerical acoustics [INA] to source detection in a speaker is discussed. The method is based on truncated singular value decomposition and acoustic transfer vectors The arrays of transfer functions between the acoustic pressure and surface normal velocity at response sites are known as acoustic transfer vectors. In addition to traditional nearfield pressure measurements, the approach can also include velocity data on the boundary surface to improve the confidence of the
The electric motor is a significant source of noise in electric vehicles (EVs). Traditional hardware-based NVH optimization techniques can prove insufficient, often resulting in trade-offs between motor torque or efficiency performance. The implementation of motor control-based torque ripple cancellation (TRC) technology provides an effective and flexible solution to reduce the targeted orders. This paper presents an explanation of the mathematical theory underlying the TRC method, with a particular focus on the various current injection methods, including those that allow up to 4DOFs (degrees-of-freedom). In the case study, the injection of controlled fifth or seventh order current harmonics into a three-phase AC motor is shown to be an effective method for cancelling the most dominant sixth order torque ripple. A dedicated feedforward harmonic current generation module is developed the allows the application of harmonic current commands to a motor control system with adjustable
Due to the vibration of the vehicle, the performance of the vehicle carbon canisters will be changed, which will affect its control effect on the fuel evaporation emission. In this study, a vibration test platform capable of simulating vehicle vibration characteristics was used to simulate the possible vibration effects of the vehicle carbon canisters, and to analyze the absorption and desorption performance of the carbon canisters before and after long-term operation and its influence on vehicle evaporation emissions. The results show that the carbon canisters will precipitate the carbon powder after the continuous action of the forward and backward vibration of the vehicle. As a result, the ultimate adsorption and desorption amount of fuel vapor decreased, and the adsorption amount decreased more obviously. In the 48-hour Diurnal Breathing Loss (DBL) test, fuel vapor diffusion is more difficult due to the increased flow resistance of the carbon canisters after vibration, and fuel
The stiffness and positioning of engine mounts are crucial in determining the powertrain rigid body modes and kinetic energy distribution. Therefore, optimizing these mounts is essential in the automotive industry to separate the torque roll axis (TRA) and minimize vibration. This study aims to enhance mount locations by isolating the engine rigid body modes and predicting the inter-component force (ICF) and transfer function of the vehicle. The individual ICFs for engine mountings are calculated by applying a unit force at the bearing location. Critical frequencies are identified where the amplification exceeds the unit force at the mounting interface between the engine and the frame. The transfer function approach is utilized to assess the vibration at the handlebar. Both ICF and transfer functions analyze the source and path characteristics linked to critical response frequencies. This understanding aids in enhancing mounting positions to minimize vibration levels, thereby enhancing
Researchers have been testing ways to continuously and more comfortably detect these tiny fluctuations in pressure. A prototype smart contact lens measures eye pressure accurately, regardless of temperature. The contact lens wirelessly transmits real-time signals about eye pressure across a wide range of temperatures.
The Korea Research Institute of Standards and Science (KRISS) has developed a metamaterial that traps and amplifies micro-vibrations in small areas. This innovation is expected to increase the power output of energy harvesting, which converts wasted vibration energy into electricity, and accelerate its commercialization.
Over the past twenty years, the automotive sector has increasingly prioritized lightweight and eco-friendly products. Specifically, in the realm of tyres, achieving reduced weight and lower rolling resistance is crucial for improving fuel efficiency. However, these goals introduce significant challenges in managing Noise, Vibration, and Harshness (NVH), particularly regarding mid-frequency noise inside the vehicle. This study focuses on analyzing the interior noise of a passenger car within the 250 to 500 Hz frequency range. It examines how tyre tread stiffness and carcass stiffness affect this noise through structural borne noise test on a rough road drum and modal analysis, employing both experimental and computational approaches. Findings reveal that mid-frequency interior noise is significantly affected by factors such as the tension in the cap ply, the stiffness of the belt, and the properties of the tyre sidewall.
Bemis Manufacturing and BASF collaborated to develop a lighter-weight and lower-cost hydraulic tank for compact excavators that was recognized with a lightweighting award traditionally reserved for automotive innovations. Receiving an honorable mention in the Enabling Technology category of this year's Altair Enlighten Awards, the development team leveraged a combination of injection molding and vibration welding techniques to lower costs by approximately 20% and reduce mass by about 5% compared to the traditional roto-molding process. The solution also is more eco-efficient, delivering both environmental savings (reductions in lifecycle CO2 emissions) and reducing lifecycle costs.
Researchers have developed SPINDLE, a pioneering robotic rehabilitation system. Combining virtual reality (VR) with customized resistance training, SPINDLE offers personalized therapy to enhance strength and dexterity for activities of daily living (ADLs). Its adaptability and potential for home use represent a major advancement in tremor rehabilitation, with broader healthcare implications.
During design development phases, automotive components undergo a strict validation process aiming to demonstrate requested levels of performance and durability. In some cases, specific developments encounter a major blocking point : decoupling systems responsible for optimal acoustic comfort performances. On the one hand, damping rubbers need to be soft to comply with noise, vibration & harshness criteria. However, softness would provoke such high amplitudes during vibration endurance tests that components would suffer from failures. On the other hand, stiffer rubbers, designed for durability purposes, would fail to meet noise compliance. The rubber design development goes through a double-faced dilemma : design with acceptable trade-off between NVH and durability, and efficient ways to develop compliant designs. This paper illustrates two case studies where different methodologies are applied to validate decoupling systems from both acoustic and reliability perspectives. The goal was
From a Noise Vibration Harshness (NVH) perspective, electric vehicles represent a great opportunity since the noise of the combustion engine, dominant in many driving conditions, is no longer present. On the other hand, drivers accustomed to driving cars with a strong personality (for example typically sporty ones) may perceive "silence" as a lack of character. Our internal study, conducted with a jury of people, has in fact already shown that for half of customers silence should characterize (Battery Electric Vehicle - BEV) vehicle; but, at the same time, the other half of the jury expects feedback from the vehicle while driving. The silence inside the passenger compartment, from an NVH point of view, can therefore be compared to a blank sheet of paper, on which, if desired, sounds designed to satisfy the driving pleasure expected by the customer can be introduced. Starting from this scenario, the paper describes: the approach adopted to define how many and what are the levers to
Design verification and quality control of automotive components require the analysis of the source location of ultra-short sound events, for instance the engaging event of an electromechanical clutch or the clicking noise of the aluminium frame of a passenger car seat under vibration. State-of-the-art acoustic cameras allow for a frame rate of about 100 acoustic images per second. Considering that most of the sound events introduced above can be far less than 10ms, an acoustic image generated at this rate resembles an hard-to-interpret overlay of multiple sources on the structure under test along with reflections from the surrounding test environment. This contribution introduces a novel method for visualizing impulse-like sound emissions from automotive components at 10x the frame rate of traditional acoustic cameras. A time resolution of less than 1ms eventually allows for the true localization of the initial and subsequent sound events as well as a clear separation of direct from
This research aims to develop an inverse controller to track target vibration signals for the application to car subsystem evaluations. In recent times, perceptive assessments of car vibration have been technically significant, particularly parts interacting with passengers in the car such as steering wheels and seats. Conventional vibration test methods make it hard to track the target vibration signals in an accurate manner without compensating for the influence of the transfer function. Hence, this paper researched the vibration tracking system based on inverse system identification and digital signal processing technologies. Specifically, the controller employed a semi-active algorithm referring to both the offline modeling of the inverse system and the adaptive control. The semi-active controller could reconstruct the target vibration signal in a more efficient and safer way. The proposed methodology was first confirmed through computation simulations using Simulink. The
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