Design of Vehicle-body for Best NVH refinements

A: Vehicle body shape and aerodynamics significantly influence wind noise and vibration induced by airflow. Streamlined shapes tend to reduce turbulent airflow, thereby lowering wind noise inside the cabin. However, certain aerodynamic features like side mirrors, roof rails, and antennae can cause vortex shedding, leading to aerodynamic noise. Computational Fluid Dynamics (CFD) is often used to analyze and optimize aerodynamic NVH. For more detailed understanding, NASA’s aerodynamic noise research documents can be helpful.

A: Material selection is crucial because different materials have varying densities, stiffness, and damping properties that affect noise and vibration transmission. For example, composites and polymers often provide better vibration damping than traditional steel. Using layered materials or sandwich structures can improve sound absorption. High-strength steels allow thinner panels that reduce weight but may require additional damping treatments to maintain NVH performance. Technical papers on material NVH performance, such as those from JEC Composites, may offer more insights.

A: NVH stands for Noise, Vibration, and Harshness. It is a critical aspect in vehicle design because it directly affects the comfort, safety, and perceived quality of a vehicle. Effective NVH control can lead to quieter cabins, reduced vibrations, and smoother rides, enhancing the overall customer experience. For more detailed technical insights, you can refer to SAE International's technical papers on NVH: https://www.sae.org/publications/technical-papers/

A: The design of a vehicle body influences NVH through its structural stiffness, material selection, and geometry. A stiffer body structure can reduce vibrations and noise transmission. Materials with better damping properties can absorb and dissipate vibrational energy. Additionally, design features such as strategically placed reinforcements, isolation mounts, and acoustic barriers help in controlling NVH. For an in-depth study, the book 'Noise and Vibration Control for Engineers' by Leo L. Beranek is a valuable resource.

A: Common methods to measure NVH include the use of accelerometers, microphones, and modal analysis tools. Testing can involve stationary engine runs, drive-by noise measurements, and interior sound pressure level assessments. Advanced methods include using finite element analysis (FEA) and computational fluid dynamics (CFD) for simulation to predict noise and vibration behavior before physical prototyping. Standards like ISO 5128 help define procedures for vehicle interior noise measurement.

A: Mounting systems such as engine mounts, suspension mounts, and body mounts serve to isolate vibrations and reduce their transmission to the cabin. Properly designed mounts use materials and geometries that absorb vibrational energy, minimizing harshness and noise. For example, rubber or hydraulic mounts provide damping characteristics tailored to specific frequencies. The SAE International handbook on vehicle dynamics and mounts provides comprehensive design guidelines.