It is fortunate then, that in every sector of industry, in every part of the scientific community, and
in all aspects of our daily lives, there are people who dedicate their working lives to sound and
vibration, controlling their harmful effects. Noise is a controllable pollutant that deserves the
attention of lawmakers, health and occupational specialists, and consumers. Modern research
affords us the opportunity to understand the subject better and to develop abatement
technologies.
NVH reduction seems to be the primary objective, continuing slogan and goal of any industry
today. Competition has been growing rapidly to see who can make the quietest and smoothest
running cars, vacuum cleaners, and washing machines. In crowded and mature markets, such as
domestic appliances, sound quality testing is one way to differentiate a product from that of
competitors. It also plays a vital role in the saleability of a product.
TEST EQUIPMENT:
Analyzers, shakers and controllers, accelerometers, noise dosimeters, octave band filters,
transducers for vibration and acoustics, dynamometers, sound level meters, microphones, and
analysis software.
With technology changing every day, focus is shifting more toward the development of PC based
analyzers, multichannel NVH data acquisition systems, acoustic holography devices, laser
vibrometers, and anechoic test cells.
NVH test equipment are used for various applications such as:
Engine noise vibration testing
Acoustic performance testing
Sound power testing
Pass by noise testing
Telephone testing
Environmental noise measurements and noise field mapping
Structural dynamics and vibration testing
Occupational health and safety
Advantages of NVH Test Equipment
Real-time multi-analysis is possible in one test run
Results obtained are accurate and precise
Report generation is made easy
Shorter lead times, and hence improved productivity
INTRODUCTION TO TRUE FULL NVH VEHICLE SIMULATION
1. Meshing
2. Assembly
3. Load case setup
4. Full vehicle optimization
1. MESHING:
ACOUSTIC CAVITY MESHER:
Capability to preview cavities found by auto scan
Separate hole and gap control
Generates congruent mesh with seat cavities or MPCs to couple with existing seat mesh
High quality tetra or mixed hexa/tetra mesh
Creates hole elements that can be modified to customize cavity definition
Browser can be used to select which cavities in preview should be meshed.
• Can create non-conforming hexa-tetra or all-tetra meshes.
• Can input response points from CSV file or use existing nodes (thus, maintain ID).
• Can specify minimum values for resulting hexa jacobian ratio and tet-collapse
2. ASSEMBLY:
Step 1: Start NVH
Step 2: Define Assembly Hierarchy
Step 3: Load an Assembly Definition XML file
Step 4: Save an Assembly Definition XML file
Step 5: Define Module Representations
Step 6: Import Display Representations
Step 7: Manage TagPoints
Step 8: Prepare a Module for Assembly
Step 9: Define Connections between Modules
Step 10: Define Connection Information and Properties
Step 11: Manage Analysis
3. LOAD CASE TOOLS:
The loadcase setup framework
• Process manager to gather user input and generate solver cards
• 3D display for entity selections as a part of the user input
• Optionally, loadstep browser can be used to review and customize generated solver cards
Loadcase setup process managers have been developed for
• Normal modes
• CMS SE generation
• Unit input frequency response
• Random PSD frequency response
• General frequency response
THE PROCESS MANAGER TO GENERATE A DYNAMIC STIFFNESS FRF:
Step 1: Start Process Manager
Step 2: Select Solution Type
Step 3: Select Analysis Frequencies
Step 4: Normal Mode Extraction
Step 5: Define Loads / Inputs
Step 6: input Transfer Function Requests
Step 7: Add Response Points
Step 8: Miscellaneous Options
Step 8 and 9: SPC and MPC Selection
Step 10: Parameter Selection
Step 11: Export Deck
FULL VEHICLE NVH OPTIMIZATION:
Run vehicle simulation
• Identify problem loadcase and responses
Identify key areas to optimize
• Perform diagnostic analysis
• Conduct what-if studies
• Identify key component/panel and design variables
• Keep ‘design’ area as detailed FE mesh
Reduce non-design parts of the vehicle
Reduce to CMS Super Elements
Combined Fluid-Structural SE
Acoustic Cavity is included in the SE
Export of reduced matrices
Stiffness
Mass
Structural damping and viscous damping
DMIG input and output
Optimize design variables
Size, shape, topology, topography
Mastic or Beads on panels
Weight
