Solving Automotive Noise and Vibration Challenges with Simulation

The Challenges of Noise and Vibration in Automotive Design

In the competitive automotive market, manufacturers are already pushing performance, price and efficiency to their limits. In such a tight market, the ride experience can be the decisive factor that leads the customer to choose one model over another. Some drivers expect a quiet, smooth and comfortable ride, while others prefer a more sporty feeling. Optimizing noise, vibration and harshness (NVH) to the desires of the target customer helps a product model stand out.

The transition to electric vehicles (EVs) is introducing new challenges for controlling noise and vibration characteristics. EV batteries are very heavy, which requires weight-saving elsewhere in the vehicle. This can lead to thinner, less stiff body structures and reduced scope for insulation. Structural vibration in the battery pack can also lead to NVH problems throughout the entire vehicle.

Traditionally, NVH is studied in test driving once prototypes have been constructed. However, if problems are discovered late in development, resolving them can be expensive and risk delays to the entire project. Often, late-stage fixes are limited to expensive countermeasures, which in turn increase the weight of the vehicle.

Tackling Noise and Vibration Problems Sooner with Simulation

In order to identify NVH problems earlier in development, automotive manufacturers use simulation. With a virtual twin of the car, engineers can analyze NVH without needing a prototype. A simulation provides quick feedback about the performance of the design at any stage of development. NVH can be optimized and trade-off studies with other design KPIs such as weight and fuel efficiency.

Modal analysis visualizes the sources of NVH and helps engineers to find the optimal mitigation method. For example, battery pack vibrational modes can lead to unpleasant seat shaking. By identifying the vibrational modes of the battery, engineers can find the best places to add additional bolts. A quick optimization minimizes the number of bolts needed while meeting all vibrational requirements.

Using simulation accelerates development and cuts costs by reducing the number of expensive prototypes required. Risk is decreased as NVH performance can be tested before committing to a design. Optimization provides a competitive advantage and allows design teams to work towards the best trade-offs to meet all design requirements.

Avoiding the Development Pains by Unifying Modeling and Simulation (MODSIM)

Simulation is a powerful tool for any engineering team, but organizational problems sometimes prevent it from meeting its full potential. Often, teams are siloed and there is little contact between groups working on each individual subsystem. However, NVH problems often emerge from the interaction of many different components at the system level. Simulation is often only performed by specialist analysts with no connection to the designs, and departments working in digital silos causes data management delays. Collaboration and data exchange can be made much more efficient with unified modeling and simulation (MODSIM).

In a development cycle using MODSIM, the computer-aided design (CAD) and computer-aided engineering (CAE) are integrated together into a seamless workflow: the geometry produced by designers can be used directly in the simulation. This reduces the time and work needed to create simulation-ready models, and allows designs to be analyzed at any time – even at the concept stage.

In traditional design development cycle, the CAE analysis loop can take weeks – by which point the design itself may have already changed. Under MODSIM, the CAE loop happens in the same unified environment as the CAD, and design iterations take days instead of weeks. All information, including requirements, geometry and simulation results, are stored in a cloud-based data model that offers a single source of truth and complete collaboration between the entire team.

Example of a MODSIM Workflow for NVH Analysis, from Subsystem to Full System Level

The image above shows some of the analyses that need to be considered during the NVH development of a full vehicle. Each subsystem is evaluated at its own level, but the full system assembly is also taken into account.

Using MODSIM on the Dassault Systèmes 3DEXPERIENCE platform, engineers have a one-step solution for analysis. Individual load cases can apply to sub-assemblies anywhere in the part tree – one for trimmed body modes, one for body-in-white modes – but when it comes time to launch the solver jobs, they can all be run simultaneously in a single step. The simulation uses the industry-standard structural simulation tool Abaqus in the Cloud, and the 3DEXPERIENCE platform is fully flexible in how analyses are grouped.

MODSIM also enables design improvement studies. Analyzing design variations helps engineers make quick improvements by varying a given set of parameters.  This is a very simple, easy to use and powerful tool that runs right alongside standard analysis. The example below shows structural battery pack modes. These are key to avoiding shake issues on road.  Perimeter bolt pattern optimization can help meet targets while minimizing installation costs.

To explore the product with larger more sophisticated design variations, engineers can use the advanced 3DEXPERIENCE app Concept Structures Engineering. This can be used to build parameterized CAD models with integrated mesh generation.  By adjusting input parameters, users can build and analyze a variety of architecture concepts in a short amount of time.

Conclusion

Simulation helps automotive engineers to investigate noise and vibration at any stage of vehicle development, from the initial concept onwards. NVH issues can be identified before committing to a design or building a prototype, reducing the risk of issues emerging later. Simulation also reveals the root causes of NVH issues, allowing targeted interventions to mitigate noise rather than add expensive countermeasures that increase vehicle weight. MODSIM integrates simulation into the modeling process, allowing designers to harness the power of simulation to analyze and improve their designs, and to use parametric design improvement to automatically optimize NVH and find the best trade-offs between multiple factors.

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Keep reading:

• Maximizing Product Development Efficiency with MODSIM
• Faster Model Build for Accelerated Automotive Innovation
• Lighter, Quieter, More Comfortable Vehicles

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