Actran Acoustic Simulation: Solving the EV NVH…

The electric vehicle transition has exposed an acoustic truth that combustion engines conveniently masked for decades: every vibration in the vehicle structure is audible to occupants when the powertrain is silent. Road noise, wind noise, gear whine from the reduction drive, inverter switching harmonics, and structural resonances that were imperceptible in an ICE vehicle become the dominant noise sources in an EV. This shift has made acoustic simulation a first-order design discipline, not a refinement step performed late in the development cycle.

Actran, the acoustic simulation solver from the Cadence simulation portfolio, addresses this challenge with a purpose-built finite element and infinite element acoustic solver designed from the ground up for NVH, vibro-acoustics, and aero-acoustics analysis. For Indian automotive teams in Pune, Chennai, and Bengaluru developing electric two-wheelers, electric passenger vehicles, and commercial EVs, Actran provides the acoustic fidelity that general-purpose FEA solvers treat as an afterthought.

Why General FEA Falls Short for Acoustics

Most structural FEA solvers can compute acoustic response to some degree, they model the structural vibration and couple it to an acoustic fluid domain. The limitation is in the acoustic element formulations, radiation boundary treatment, and material modelling.

Actran addresses each of these with specialised technology:

Infinite elements for radiation. Sound radiating from a vibrating structure propagates to infinity. General FEA either truncates the acoustic domain with an absorbing boundary (introducing reflection errors) or uses a very large acoustic mesh (wasting computational resources). Actran’s infinite element formulation accurately models unbounded sound radiation without artificial boundaries.

Porous material modelling. Acoustic trim, the foams, felts, and multilayer treatments that line vehicle cabins, determines interior noise levels. Actran’s porous material models (based on Biot theory) capture the frequency-dependent absorption and transmission behaviour of real acoustic materials, not just idealised impedance values.

Coupled vibro-acoustics. Actran couples directly with MSC Nastran structural models, using the structural vibration as the source for acoustic analysis. The coupling is bidirectional when needed, the acoustic pressure field can influence the structural vibration (strong coupling for lightweight panels), though one-way coupling suffices for most automotive applications.

Key Application Areas

Interior Cabin NVH

The primary use case for Indian automotive teams: predicting interior noise levels at driver and passenger head positions under road, powertrain, and wind excitation. Actran computes the sound pressure level (SPL) distribution inside the cabin, accounting for structural vibration transmission through the body-in-white, acoustic leakage through seals and gaps, and the absorption characteristics of interior trim.

For EVs, the high-frequency content of inverter and motor harmonics requires acoustic meshes fine enough to resolve wavelengths at 2-5 kHz and above. Actran handles this frequency range with computational efficiency that makes parametric studies practical, evaluating different trim configurations, seal designs, and structural reinforcements against acoustic targets.

Pass-By Noise

Indian vehicles sold in Europe must comply with UN Regulation 51 pass-by noise limits. Actran models the exterior sound radiation from tyre-road interaction, powertrain noise, exhaust noise (for hybrids), and aerodynamic sources to predict pass-by noise levels at the regulatory measurement positions. Acoustic shielding, underbody panel design, and encapsulation strategies can be optimised virtually before physical testing.

Aero-Acoustics

Wind noise, generated by airflow around mirrors, A-pillars, door seals, and roof racks, becomes the dominant interior noise source at highway speeds. Actran AeroAcoustics couples with CFD solvers (including Cradle CFD from the same Cadence simulation portfolio) to model flow-induced noise sources and their transmission into the cabin. For HVAC systems, fan noise and duct acoustics are modelled with the same solver.

Aerospace Applications

Beyond automotive, Indian aerospace teams use Actran for cabin acoustic comfort analysis in aircraft and helicopter programmes, jet noise prediction, acoustic liner optimisation for engine nacelles, and community noise assessments for airport compliance. The solver handles both interior (cabin, cockpit) and exterior (pass-by, community) acoustic problems with the same element technology.

The MSC One Advantage

Actran is available through the MSC One token pool, the same token allocation that covers MSC Nastran, Adams, Marc, Simufact, and Digimat. For teams that already use Nastran for structural analysis, adding Actran for acoustic simulation does not require a separate license negotiation. Tokens flow between solvers based on project demand.

This flexibility is particularly valuable for Indian engineering services companies and multi-disciplinary R&D teams where the mix of structural, dynamic, acoustic, and manufacturing simulation varies across projects.

Why Buy from GSAS

GSAS supports Indian automotive and aerospace NVH teams with Actran licensing, workflow setup for Nastran-Actran vibro-acoustic coupling, and integration consulting for CFD-Actran aero-acoustic workflows. Our application engineers help teams establish acoustic simulation methodology, from mesh requirements through material characterisation to correlation with physical test data.

Teams in Bengaluru, Hyderabad, Chennai, Pune, Mumbai, Delhi NCR, and Visakhapatnam can contact GSAS for Actran evaluation, training, and deployment support.

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