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Full Vehicle NVH
Access the Assemble, Analyze, NVH Tools, NVH Post, and Physics AI ribbons.
Post-processing and Diagnostics
Define radiation conditions and create emissivity models.
Model Correlation
The Model Correlation utility determines the degree of similarity or correlation between two sets of results.
Frequency Response Assurance Criterion (FRAC)
Frequency Response Assurance Criterion (FRAC) is a measure of the correlation between two frequency response functions (FRFs) representing the same input-output relationship.

Welcome
What's New
View new features for HyperMesh NVH 2025.1.
Get Started
Learn the basics and discover the workspace.
Tutorials
Discover NVH functionality with interactive tutorials.
Full Vehicle NVH
Access the Assemble, Analyze, NVH Tools, NVH Post, and Physics AI ribbons.
- Assembly
  Learn how to create, open, import and save models.
- Analysis
  Set up the simulation model, materials, domains and boundaries.
- NVH Tools
- Prepare Module
  Create, organize and manage the CAE parts.
- Post-processing and Diagnostics
  Define radiation conditions and create emissivity models.
  - Load an NVH Utility
  - Integrated Diagnostics
    Calculate a response, perform contribution analysis, plot results, and perform diagnostic studies and study response changes.
  - Modal Participation
    Plot modal/panel participation curves from an OptiStruct .h3d file or an MSC Nastran .f06/.pch file.
  - Grid Participation
    The Grid Participation utility allows you to plot panel grid participation results and then use advanced scaling contour capabilities to isolate key contributing areas.
  - Energy Distribution
    Visualize the distribution of energy within a full vehicle NVH model, as a way to understand what components are dominating the vehicle response.
  - Transfer Path Analysis
    Identifies the complex contribution of the excited structure through attachment points to a response in the responding structure.
  - Design Sensitivity Analysis
    Design sensitivity represents a change in response with respect to a change in a design variable, which is typically used for optimization.
  - Order Analysis
    Generates and post-processes engine order related data from an OptiStruct or Nastran frequency response analysis that contains either RPM-based loading subcases or order-based loading subcases.
  - Modal FRF
    Calculate a frequency response based on modal results.
  - Model Correlation
    The Model Correlation utility determines the degree of similarity or correlation between two sets of results.
    - Modal Assurance Criterion (MAC)
      Modal Assurance Criterion (MAC) is a measure of the correlation between two vibration shapes.
    - PreTest
      PreTest allows prediction and optimization of the sensor locations (accelerometers) for measurements and directions along with test excitation point location, a very important step in the experimental modal analysis process directly affecting the accuracy of test results. Driving point residue (DPR) calculation gives information on optimum point for excitation location.
    - Frequency Response Assurance Criterion (FRAC)
      Frequency Response Assurance Criterion (FRAC) is a measure of the correlation between two frequency response functions (FRFs) representing the same input-output relationship.
      - FRAC - Load Tab
        The FRAC utility's Load tab allows you to select and load the reference and correlation files to prepare them for a FRAC analysis.
      - FRAC - Display Tab
        The FRAC utility’s Display tab allows you to filter FRAC results and select various plotting options using the FRAC sub-tab.
  - Radiated Sound
    The Equivalent Radiated Sound utility post-processes the results of exterior structure-borne radiated sound.
  - Global Modes
    Identifies global modes from an OptiStruct or Nastran modal analysis.
  - Flow Induced Noise/General Signal Processing
    The General Signal Processing utility processes the time domain pressure results from CFD simulations and visualizes the results in both the time and frequency domain.
  - Green House Noise
    Post-process the pressure result of a vehicle panel obtained from ultraFluidX.
  - Mount Optimization
    Predicts powertrain rigid body mode frequencies and kinetic energy distribution, which play a critical role in optimizing the mount stiffness and layout configuration, by decoupling powertrain rigid body modes and reducing vibration transmission.
  - Optimization, RBDO
    Optimizes sensitive parameters for multiple sample analysis results using the RBDO or Deterministic approach.
  - Multiple Sample Analysis
    Post-process results from a Multiple Sample Analysis, including plotting a spread of responses (+/-95% and mean).
  - Deterministic Optimization
    Reads results from an OptiStruct optimization run and processes the results to review the overlay of the NVH responses, baseline versus optimized. Compare changes in the design variable values, baseline versus optimized.
  - Display Options
    Customize plots using the following options
  - Filter Contributors
    Filters contributors to a smaller set of data.
High Frequency NVH
High frequency NVH is an implementation of Statistical Energy Analysis (SEA), and is used to predict and analyze the vibration and acoustic response of complex dynamic systems.
Squeak and Rattle
Create and evaluate evaluation lines and optimize interfaces to eliminate squeak and rattle issues.

Frequency Response Assurance Criterion (FRAC)

Frequency Response Assurance Criterion (FRAC) is a measure of the correlation between two frequency response functions (FRFs) representing the same input-output relationship.

Supported vibration shapes include:

The frequency response results are assumed to come in one of the following result files:

H3D – binary result file typically generated using OptiStruct.
OP2 – binary result file typically generated using OptiStruct or Nastran.
PCH - ASCII result file typically generated using OptiStruct or Nastran.
UNV – ASCII result file typically exported from testing software.