Noise Vibration and Harshness: NVH Simulation Solutions

What is NVH?

Noise, Vibration, and Harshness (NVH) is a critical consideration in the design and manufacturing of vehicles and machinery. NVH refers to the study and management of sound (noise), mechanical oscillations (vibration), and the overall experience of these factors (harshness) by users. In industries such as automotive and electronics, managing NVH is essential not only to ensure user comfort but also to meet regulatory standards and maintain product quality.

In electric vehicles (EVs), NVH has gained even more significance. Traditional internal combustion engines (ICEs) generate a certain noise level that often masks other sounds within the vehicle. However, EVs, which are quieter due to the absence of an ICE, bring to the forefront other noise sources, such as road noise, wind noise, and sounds from electrical components. This shift has made effective NVH management a focal point in EV design and development.

Understanding NVH Simulation

NVH simulation involves using computational tools to predict and analyze the noise and vibrations that a product might generate. These simulations are crucial for identifying potential NVH issues during the design phase, enabling engineers to address them before physical prototypes are built. This proactive approach not only reduces costs but also shortens the development cycle and improves the overall quality of the final product.

Equivalent Radiated Power (ERP) in NVH Simulation

One of the key metrics used to quantify sound emissions in NVH analysis is Equivalent Radiated Power (ERP). ERP estimates how much sound energy a vibrating surface radiates into the surrounding environment due to its vibrations. It is particularly useful in identifying which components or areas of a product are the main contributors to unwanted noise and at which frequencies these emissions occur.

ERP is crucial for NVH simulation because it provides insight into vibration-induced noise, which is often a significant source of discomfort in vehicles. In automotive applications, ERP helps engineers evaluate how much sound a component, such as a car door, panel, or engine part, is radiating. By calculating ERP, engineers can better understand how different components contribute to the overall Noise, Vibration, and Harshness profile of the vehicle.

Evaluating ERP in SimScale

ERP evaluation feature in SimScale will be released soon.

SimScale enables engineers to compute and visualize ERP as part of the NVH simulation process, providing actionable insights into noise emissions across various components. There are two key methods by which ERP is evaluated:

• ERP as a Graph Over Frequency Range: In SimScale, engineers can evaluate the ERP of components over a given frequency range. This graph helps in identifying the highest noise-emitting frequencies, allowing engineers to focus on mitigating noise at those specific points. The ERP is presented in either absolute terms (Watts) or relative terms (dB) compared to a reference value, which is particularly useful when benchmarking the performance of different designs.
• ERP Density Field Visualization: SimScale also provides a 3D visualization of the ERP density field, which represents how sound emissions are distributed across the surface of a component. This 3D map enables engineers to pinpoint the areas with the highest sound emission, making it easier to optimize designs by reducing the radiated noise from specific regions. This capability is especially valuable in the early design stages, where adjustments can be made before physical prototypes are built.

The ability to simulate and visualize ERP in both graphical and spatial formats gives engineers a holistic view of how their design performs in terms of noise radiation. This not only helps in solving current NVH issues but also informs design choices that minimize noise in future iterations.

Key NVH Simulation Tools and Techniques

Several tools and techniques are commonly used in NVH simulation. These include:

1. Finite Element Analysis (FEA): FEA is a powerful technique that models the structural dynamics of a product, enabling engineers to simulate how vibrations propagate through the structure. In NVH simulation, FEA helps assess the impact of vibrations on noise emissions, particularly through the computation of ERP. SimScale’s FEA capabilities allow users to simulate the effects of design changes on both vibration behavior and resulting noise levels.
2. Multi-Body Dynamics (MBD): MBD simulations model the interactions between different components within a system. For example, in a vehicle, the suspension system, engine, and transmission are all interconnected, and their interactions can significantly impact NVH characteristics. By analyzing the impact of these interactions on NVH performance, MBD simulations can also be used to assess how changes in one part of the system affect the Equivalent Radiated Power of other components.
3. Acoustic Simulation: Acoustic simulations are directly linked to NVH analysis and ERP, as they predict how sound waves will propagate through different materials and environments. This is crucial for designing products that meet noise regulations or provide a comfortable user experience. For instance, in vehicle design, acoustic simulations can help optimize the placement of soundproofing materials to minimize cabin noise.
4. Vibration Analysis: Understanding the sources and transmission paths of vibrations is key to reducing NVH. Vibration analysis helps engineers identify problematic frequencies and amplitudes that can lead to excessive noise or component failure. SimScale’s vibration analysis tools allow engineers to study the sources and pathways of vibrations within a system. This data can be directly fed into ERP calculations to quantify the sound energy radiated by vibrating parts. SimScale supports detailed vibration analysis, including modal analysis to identify natural frequencies and harmonic response analysis to study system reactions to specific frequency excitations. Both analyses provide key inputs for ERP evaluations.
5. Thermal and Fluid-Structure Interaction (FSI): NVH issues are not always purely structural. In some cases, vibrations can be exacerbated by thermal and fluid dynamics, leading to increased noise emissions. SimScale offers multiphysics simulation capabilities, allowing engineers to model the interaction between thermal, fluid, and structural dynamics, leading to a more comprehensive understanding of NVH challenges and more accurate predictions of real-world NVH performance.

NVH Simulation in SimScale

SimScale enables NVH simulation and helps enhance NVH performance thanks to its cloud-native simulation infrastructure. This helps improve attribute balancing, predict and remove undesired noise, and avoid costly late design changes.

SimScale’s advantages for NVH simulators are plenty, among which are:

• Accessibility and Collaboration: Unlike traditional on-premise simulation tools, SimScale is accessible from any device with an internet connection. This makes it easier for teams to collaborate in real time, regardless of their geographical location. Engineers can share simulation results, discuss potential solutions, and iterate on designs more efficiently, leading to faster decision-making and reduced development times.
• Scalability: SimScale’s cloud-based platform can scale to handle simulations of varying complexity. Whether you are running a simple vibration analysis or a full-system NVH simulation involving thousands of components, SimScale provides the computational power needed without requiring expensive hardware investments.
• Integration with CAD Tools: SimScale integrates seamlessly with various CAD tools, allowing engineers to import their designs directly into the platform for simulation. This integration streamlines the workflow and reduces the chances of errors that can occur when transferring data between different software environments.
• Cost-Effectiveness: By eliminating the need for on-premise hardware and offering flexible pricing models, SimScale makes advanced simulation more accessible to companies of all sizes. This democratization of simulation technology allows even smaller firms to compete on a level playing field with larger organizations.
• Expert Customer Support: SimScale provides real-time support from a dedicated team of simulation experts, ensuring that engineers can address NVH challenges as they arise. Whether troubleshooting technical issues, optimizing simulation workflows, or receiving guidance on best practices, SimScale’s team is available to assist in real time. This hands-on, immediate support helps users achieve faster problem resolution, leading to more accurate and efficient simulation results.

Minimizing NVH with SimScale

Effective NVH management requires a holistic approach that considers the entire system rather than just individual components. SimScale’s comprehensive suite of simulation tools enables engineers to address NVH issues at every stage of the design process.

• Early Detection of NVH Issues: By simulating NVH and evaluating ERP during the early stages of design, engineers can identify potential issues before they become costly problems. For example, a vibration analysis might reveal that a particular component resonates at a frequency that could cause noise in the cabin. By addressing this issue early, engineers can modify the design to avoid the problem altogether.
• Optimizing Component Design: Engineers can use ERP results to modify materials, geometries, and mounting configurations of components to reduce noise emissions. For example, SimScale’s FEA simulations can assess how changes to a car door’s structure impact its radiated power, leading to quieter designs.
• System-Level NVH Optimization: SimScale’s platform supports the simulation of complex systems, allowing engineers to optimize the entire system for NVH performance. This is particularly important in automotive applications, where the interactions between various subsystems can have a significant impact on overall NVH levels. ERP plays a critical role in these analyses, as engineers can assess how different parts of the system contribute to overall sound emissions and adjust designs accordingly.
• Iterative Design Process: The cloud-based nature of SimScale enables rapid iteration, allowing engineers to test multiple design alternatives and compare multiple design alternatives for ERP and overall NVH performance quickly. This iterative process is crucial for finding the optimal design that meets all NVH requirements without compromising on other performance criteria.

Challenges and Future Trends in NVH Simulation

Despite the advances in NVH simulation, several challenges remain. The increasing complexity of EV powertrains presents new NVH challenges that require more sophisticated simulation models. For instance, the high-frequency noise generated by electric motors and inverters is more difficult to predict and control compared to the lower-frequency noise of internal combustion engines.

Furthermore, as products become more complex and integrated, the need for simulations that can model multiple physical phenomena simultaneously (e.g., thermal, fluid, and structural interactions) is growing. SimScale is addressing these challenges by continually updating its platform with new features and capabilities that enhance its multiphysics simulation capabilities.

Looking ahead, the integration of artificial intelligence (AI) and machine learning (ML) into NVH simulation holds great promise. These technologies could enable predictive simulations that automatically adjust design parameters to minimize NVH. Additionally, AI and ML could help engineers explore a wider range of design alternatives in less time, leading to more innovative solutions.

Conclusion

Noise, Vibration, and Harshness are critical factors that affect the quality, safety, and user experience of products, particularly in the automotive and aerospace industries. Effective NVH management is essential for meeting regulatory standards, reducing warranty costs, and ensuring customer satisfaction.

SimScale provides a powerful, accessible platform for NVH simulation, offering a range of tools that enable engineers to predict, analyze, and mitigate NVH issues throughout the design process. By leveraging SimScale’s cloud-based capabilities, engineering teams can achieve better NVH performance, reduce development costs, and deliver higher-quality products.

As NVH challenges continue to evolve, particularly with the rise of EVs and more complex systems, SimScale’s ongoing development and integration of advanced technologies will ensure that engineers have the tools they need to stay ahead of the curve.

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