Browse Topic: Noise
The operator station or “cab” in off Highway equipment plays a critical role to provide a comfortable workspace for the operator. The cab interfaces with several elements of the off-highway equipment which can create gaps and openings. These openings have the potential for acoustic energy leakage, ultimately increasing sound within the cab. During machine operation, noise generated around the cab conducts inside through these leakages resulting in increased sound levels. Acoustic leakages are among the key noise transfer paths responsible for noise inside the cab. Therefore, before considering noise control treatments it is best to first identify and minimize any leakages from joints, corners, and pass-throughs to achieve the required cab noise reduction. In this effort the sound intensity technique is used to detect the acoustic leakages in cab. The commercial test system is used for measuring the sound intensity field over objects. For the cab, an acoustic source is used inside the
Noise generated by a vehicle’s HVAC (Heating, Ventilation, and Air Conditioning) system can significantly affect passenger comfort and the overall driving experience. One of the main causes of this noise is resonance, which happens when the operating speed of rotating parts, such as fans or compressors, matches the natural frequency of the ducts or housing. This leads to unwanted noise inside the cabin. A Campbell diagram provides a systematic approach to identifying and analyzing resonance issues. By plotting natural frequencies of system components against their operating speeds, Test engineers can determine the specific points where resonance occurs. Once these points are known, design changes can be made to avoid them—for example, adjusting the blower speed, modifying duct stiffness, or adding damping materials such as foam. In our study, resonance was observed in the HVAC duct at a specific blower speed on the Campbell diagram. To address this, we opted to optimize the duct design
To address the growing concern of increasing noise levels in urban areas, modern automotive vehicles need improved engineering solutions. The need for automotive vehicles to have a low acoustic signature is further emphasized by local regulatory requirements, such as the EU's regulation 540/2014, which sets sound level limits for commercial vehicles at 82 dB(A). Moreover, external noise can propagate inside the cabin, reducing the overall comfort of the driver, which can have adverse impact on the driving behavior, making it imperative to mitigate the high noise levels. This study explores the phenomenon of change in acoustic behavior of external tonal noise with minor geometrical changes to the A-pillar turning vane (APTV), identified as the source for the tonal noise generation. An incompressible transient approach with one way coupled Acoustics Wave solver was evaluated, for both the baseline and variant geometries. Comparison of CFD results between baseline and variant showed
An important characteristic of battery electric vehicles (BEVs) is their noise signature. Besides tire and wind noise, noise from auxiliaries as pumps, the electric drive unit (EDU) is one of the major contributors. The dynamic and acoustic behavior of EDUs can be significantly affected by production tolerances. The effects that lead to these scatter bands must be understood to be able to control them better and thus guarantee a consistently high quality of the products and a silent and pleasant drive. The paper discusses a simulation driven approach to investigate production tolerances and their effect on the NVH behavior of the EDU, using high precision transient multi-body dynamic analysis. This approach considers the main effects, influences, and the interaction from elastic structures of electric motor and transmission with accurate gear contact models in a fully coupled way. It serves as virtual end of line test, applicable in all steps of a new EDU development, by increasing
This paper presents a comprehensive methodology for replicating and quantifying the clicking-noise phenomenon occurring between Generation 3-wheel hub bearings and Constant Velocity Joints (CVJ), particularly in electric vehicles (EVs) where quiet operation makes this noise more noticeable. The study focuses on characterizing the system through contact pressure and distribution measurements, alternating torque tests, and advanced NVH (Noise, Vibration, and Harshness) data processing. The methodology includes detailed descriptions of the physical phenomena, driving conditions generating the noise, and the specific test setup used to simulate real-world conditions. The NVH analysis make use of high-pass filtering techniques to isolate clicking-noise events from background noise, ensuring accurate identification and quantification. Candidate solutions are assessed based on their ability to mitigate clicking noise through the utilization of inherent system components. The results
A research team led by scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) has developed a new fabrication technique that could improve noise robustness in superconducting qubits, a key technology for enabling large-scale quantum computers.
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