Learn about SEAM for Noise and Vibration

In 2019, Altair acquired Cambridge Collaboratives SEAM (Statistical Energy Analysis for Mechanical) software after years of it being included in the Altair Partner Alliance. Now included in the NVH Director in Altair HyperMesh platform, SEAM is an advanced tool using the SEA (Statistical Energy Analysis) method and is used primarily for analyzing high-frequency noise and vibration within complex systems. In this post, we will look at the SEAM functionality in the Altair portfolio, its applications, and its integration with other tools in the ecosystem.

How is SEAM different?

In a system undergoing vibration, energy is distributed among different components or subsystems. Rather than focusing on the detailed results between each component, SEAM takes a higher-level approach, focusing on the overall energy distribution between these subsystems. SEAM is particularly effective when analyzing complex systems where sound or vibration energy spreads through these subsystem components in multiple paths.

SEAM doesn’t provide detailed local results but instead applies estimates of the average energy in different parts of a system. This makes it faster and more efficient for large, complex systems at high frequencies. For results, SEAM provides average energy levels and power flow between subsystems, useful for understanding general noise and vibration, which is different than general results like stress and displacement seen in typical FEA simulations.

Fig 1: Energy distribution result using SEAM

Core Features of SEAM

Fast Solution Times

High-frequency noise and vibration problems often involve large models with many components and complex interactions. To run vibration analysis on these models would require robust computing resources and time to run. SEAM’s underlying statistical methodology enables it to deliver fast, accurate results, which can significantly reduce the design cycle. This makes it an ideal choice for iterative design processes where multiple scenarios must be evaluated in a short amount of time.

Advanced SEA Modeling

As mentioned before, SEAM applies energy estimates for interactions between components, rather than the detailed results from other methods. This makes SEAM very effective for high-frequency or large/complex scenarios. It also goes beyond traditional SEA by integrating hybrid methods that allow for the combination of SEA with finite element models for mid-frequency problems.

It also provides libraries for standard SEA components and subsystems (beams, plates, shells, etc.) as well as advanced materials such as composites. This overall flexibility to apply SEA or hybrid methods enables engineers to model a wide range of applications.

Fig 2: SEA Toolbar in Altair HyperMesh

Noise Transmission Path Analysis

SEAM allows for detailed transmission path analysis, enabling engineers to understand how noise propagates through a system. Essentially, it tracks how sound energy moves through different parts of a structure, like from a car’s engine to the passenger cabin or through an airplane’s fuselage.

SEAM breaks down these complex pathways into easy-to-analyze subsystems, showing how noise travels and where it can be reduced. By modeling the entire transmission path, from the noise source to the receiver, SEAM gives you a clear picture of where sound energy is leaking or amplifying. This helps engineers pinpoint problem areas early and optimize materials or designs to keep noise under control, making for a quieter, more comfortable final product.

Integration with Multi-Disciplinary Tools

SEAM is not a stand-alone tool. One of its strengths is its ability to integrate with other tools within the Altair HyperMesh portfolio. For example, if you're designing an aircraft, you can use Altair HyperMesh to create a detailed structural model, then run a finite element analysis (FEA) in Altair OptiStruct to get insights into how the structure behaves under load.

Once you have that data, SEAM can take those results and perform a vibro-acoustic analysis to understand how vibrations will propagate through the structure and affect noise levels in the cabin.

Fig 3: Workflow between Altair OptiStruct and Altair SEAM

Material Damping and Energy Dissipation

In a basic explanation, SEAM helps users figure out how much energy is absorbed and lost as vibrations pass through different materials, like metals, plastics, or composites.

For example, in automotive design, if you're working on reducing noise inside a car's cabin, SEAM can help model how different damping materials, like acoustic foams or viscoelastic layers, reduce vibrations from the engine or road noise. It helps you see how much energy each material absorbs and where you can minimize vibrations effectively, keeping the interior quiet without adding too much weight. This functionality is critical in the design of structures and products where specific damping properties are required to control vibrations effectively.

Vibro-Acoustic Coupling

SEAM excels in the analysis of vibro-acoustic coupling, which is critical in environments where both structural vibrations and airborne noise must be addressed.

Let’s use a commercial high-end speaker as an example. When designing a speaker, the goal is to ensure that the sound is clear, precise, and free of distortion. SEAM can simulate how the speaker's casing, internal components, and even the materials used in the diaphragm or enclosure will affect the transmission of sound waves and vibrations.

SEAM can help you understand how the vibrations from the speaker driver interact with the enclosure. If these vibrations aren’t properly controlled, they can cause rattling or distortion, which impacts the clarity of the audio. SEAM allows you to model different materials and design changes, such as adding damping layers inside the enclosure or changing the stiffness of the casing, to reduce these unwanted vibrations.

Fig 4: Above – Speaker Mode Shapes under load. Below - Example with sound pressure in a room.

To summarize what we’ve covered in this post:

• SEAM’s ability to handle high-frequency vibration and noise analysis for large, complex systems makes it stand out from traditional simulation methodology.
• The energy flow-based approach means faster, more efficient simulations, saving users a lot of time, which is typically one of the biggest obstacles in running complex vibration simulations.
• Because of its integration into Altair HyperMesh, specifically the NVH Director Module, users can run multi-discipline and vibro-acoustic simulations all within the same interface.

To learn more about Altair SEAM, Altair HyperMesh, NVH Director or anything else discussed in this post, contact us here.