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FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
Industry Sector RTD Thematic Area Date Deliverable NrLand Transport & Aerospace Multi-Physics 13-Nov-01
Finite Element & Boundary Element Technology in Acoustics & Structural Dynamics : Current Status & Key Trends for the FutureIr. Peter SEGAERTLMS International - Leuven, Belgium
SummaryOverview of current FEM/BEM based simulation technology in Acoustics & Structural Dynamics, including obstacles to efficient use and key trends to satisfy needs of automotive & aerospace industries
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
1st FENET Workshop
Wiesbaden [Germany]13-14 November 2001
Finite Element & Boundary Element Technology in Acoustics & Structural Dynamics : Current Status & Key Trends for the Future
Ir. Peter SEGAERTProduct Support Manager - CAE VibroAcoustic Modeling Group
LMS International [Leuven, Belgium] www.lmsintl.com
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
LMS & FENETLand Transport & Aerospace Industry Sector
LMS develops, markets and supports CAE tools in the field of numerical vibro-acoustics based on FEM/BEM technology:
• Acoustics => LMS SYSNOISE• Structural Dynamics => LMS SYSNOISE & LMS GATEWAY• Durability & Fatigue => LMS FALANCS• Motion => LMS DADS• Acoustics, Durability & Motion => LMS VIRTUAL.LAB (next generation software)
Main application fields of these tools are within R&D and Engineering departments of
• Automotive industry OEMs : car, truck & bus• Automotive industry “tier 1” component suppliers• Aerospace industry : aircraft & satellite manufacturers
General perspective from the software industry on • Current practice of FEM/BEM vibro-acoustic codes in industry• Obstacles to effective use of FEM/BEM technology• Industry needs & key trends to satisfy these needs in the future
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
What is Numerical Vibro-Acoustics ?
SourceSource PropagationPropagation ReceiverReceiversound path & absorption
airbornestructure-bornemixed
vibrating bodyspeaker
microphoneear
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
Why is Vibro-Acoustic Simulation becoming more important ?
Noise reduction and sound quality have become major issues• Important contribution to perceived product quality• Delivering low-noise level products creates a competitive advantage• Government regulations constantly impose lower noise levels in the quest for a
cleaner environment
Analysis can be performed at several levels in the design cycle...• Explaining and understanding the physics behind it• Troubleshooting• Evaluate design alternatives & reduce costly physical prototyping
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
Tools for Numerical Vibro-Acoustics
(Semi-) Analytical Methods• Closed form solutions, only for simple geometries
Finite Element Method (LMS SYSNOISE/FEM)• Volume discretization of fluid region
Boundary Element Method (LMS SYSNOISE/BEM) • Discretization of bounding surface only
Statistical Energy Methods• Energy exchanges between system components• LMS SEADS
Ray Tracing Methods • Geometrical Acoustics• LMS RAYNOISE
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
Example : SYSNOISE Modular ArchitectureFEM & BEM Methods – Uncoupled & Coupled
KernelKernel
Acoustic FEM
I-FEM
DBEM
IBEM
Struct.FEM
Struct.FEM
Struct.FEM
Struct.FEMH
armonic H
arm
onic
Transient
Transient
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
Numerical Vibro-Acoustics : Current Industrial Practice of FEM/BEM-based
CodesApplied in R&D or Advanced Engineering depts :
• “up-front” troubleshooting• “what if” experiments = virtual prototyping to reduce amount
of physical prototypes• gainining insight in the “physics” beyond analytical models
In general, not applied in everyday use as “mainstream”design codes
Typically used for :• component-level analyses• not for system-level analyses• e.g. engine block radiation, oilpan radiation, exhaust
radiation, but not complete powertrain, etc…
Typically lower frequency range or low modal density ranges (from a few hundred up to 2-3 KHz)
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
Numerical Vibro-Acoustics : Current Obstacles for More Efficient Use
Large computational effort involved• large matrices, especially in BEM (dense matrices),
requiring large amounts of RAM• each analysis frequency forms an independent problem
=> analysis over a large frequency range can take several days of solving time
High-frequency limit• Maximum analysis frequency linked to mesh refinement
(λ/6 rule), leading to very large meshes for high frequencies
• Control of numerical error propagation at high frequencies
Uncertainty with respect to “impedance” properties of acoustic damping materials
• for many materials, impedance is not known as a function of frequency
Intake model Courtesy of Allied Signal
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
Numerical Vibro-Acoustics : Key Trends to satisfy Auto & Aerospace Industry Needs (1)
Reducing computational efforts through novel techniques• Acoustic Transfer Vector [ATV] concept – LMS patent• improving solver technology => importance of fundamental research at
universities + dissemination by FENET
Reducing computational efforts by exploiting networked computers as virtual parallel machines
• “frequency level” distribution for vibro-acoustic problems : multiple processors solve simultaneously for different frequencies => already implemented in LMS SYSNOISE
• introduction of “domain decomposition techniques” or “distributed domain solvers”: each processor resolves part of the solution domain, with appropriate continuity conditions at the sub-domain interfaces
• research work on improving parallel algorithms => role of fundamental research
FENET THEMATIC NETWORKCOMPETITIVE AND SUSTAINABLE GROWTH(GROWTH) PROGRAMME
Numerical Vibro-Acoustics : Key Trends to satisfy Auto & Aerospace Industry Needs (2)
FE analyst “user profile” is changing over time !• from “FE analysis specialist” to “design engineer doing analysis” => role of
academia and organizations like NAFEMS & FENET to provide continuous education & grounding in best practices
• from “central computer in batch” to “interactive UNIX workstation” to “Windows-based PC platform” user => role of industry to provide adapted software tools
• importance of proper initial training & continuous updating of knowledge cannot be overestimated => role of FENET !
Most significant technical trend in numerical vibro-acoustics is the move towards aero-acoustics :
• flow-induced noise & fluid-structure interaction• interfacing & coupling of Vibro-Acoustic simulation software with CFD software