How to compare Manatee e-NVH results with a third party numerical simulation software?

Introduction

Manatee e-NVH CAE collaborative platform is complementary to general purpose multiphysic software suites. Due to its specialized algorithms, Manatee is much faster for pre-processing (multiphysic simulation workflow setup), running (solving of the multiphysic numerical problem at variable operating points) and post-processing (assessment of variable speed e-NVH metrics, troubleshooting and solving of e-NVH issues).

When using FEA-based simulation models, Manatee speed-up algorithms do not degrade calculation accuracy. For other modeling assumptions (e.g. quick magnetic or NVH models), it might be interesting to compare Manatee simulation results with a reference multiphysic FEA software suite. This comparison must be carried carefully in order to compare the right things, this article gives some hints to explain differences between different simulation methodologies.

A step by step comparison of the virtual protyping toochains following the causal chain (from current / flux to sound) is highly recommended.

Electromagnetic models

Comparison between CAE software results must start with same electrical / magnetic model assumptions:
– current-driven Vs voltage driven (check current & voltage levels in both cases)
– magnetostatics FEA Vs transient FEA Vs other magnetic models (permeance / magnetomotive force, reluctance networks, subdomain, etc)
– 2D Vs 2.5D Vs 3D
– B(H) curve and extrapolation method

Magnetic force models

Comparing different numerical simulation of magnetic noise & vibrations must be made with same excitation force calculation methods:
– Maxwell Stress Tensor method (integration contour ?) Vs Virtual Work Principle
– load case applications (radial Vs circumferential forces, rotor Vs stator load cases, application of axial forces or tooth tip bending moments)
– distributed force Vs lumped force (use of RBE3, nodes of application, magnetic mesh & mechanical mesh fineness, mesh to mesh projection technique)
– unit of post processed forces (N/m^2 Vs N, force per slice or force per tooth)

Mechanical models

Manatee software includes different mechanical modelling levels suitable for early design and detailed design stages, it is therefore important to compare the mechanical model assumptions:
– Finite Element Method Vs Beam Element Method Vs Semi-analytical or analytical techniques
– boundary conditions & contact models
– material properties (winding modelling strategy, orthotropic properties of the stator stack, etc)
damping model (material Vs modal Vs Rayleigh)
– dynamic model (eigen problem solver, modal expansion with/without residual vectors)
– unit of post processed vibrations (dB Vs m/s, normalization factor of dB unit, RMS vibration velocity over a surface or over 3 directions of a single node, reference frame, vibration of an element or a node)

Acoustic models

Manatee software including different modeling levels for the acoustic radiation of the electrical machine under electromagnetic excitations. Again it is important to analyse:
– Equivalent Radiated Power (check surface of integration) Vs Finite Element Method Vs Analytical techniques
– air-borne Vs structure-borne noise
– cavity noise, fluid/structure strong interactions
– unit of post processed acoustics (dB Vs dBA, Sound Power Vs Sound Pressure, distance from the machine for sound pressure level)