A typical speaker modeling and car audio integration project is comprised of one or more of the following practices:
Speaker modeling
In the first stage, an accurate and detailed 3D speaker vibro-acoustic model is needed (finite element method/boundary element method) that can be built based on supplier data.
To increase accuracy the latter can also be refined using speaker membrane displacement measurements. This model, which is comprised of testing and simulation, can be used to predict speaker performance and directivity, including (when needed) the effect of the vehicle (door, dashboard, etc.). It enables you to evaluate the overall car interior audio performance.
Speaker integration
In the second stage, the integration of the speaker in the car panels is consid-ered. To this end, the flexible boundary conditions of the panels are studied, particularly at low frequency. Addition-ally, their excitation and sound radiation levels, as well as those of other components are examined, taking into account coupling between the internal cavities and the main vehicle cavity.
Rattle noise
To predict and eliminate rattle noise and vibration issues, experts investigate the vibro-acoustic door response under structural and/or acoustic excitation, implementing a dedicated rattle indica-tor. The input for the rattle indicator is based on a comparison of estimated gaps with respect to vibration levels, taking into account the uncertainty inherent in these parameters.
Car audio performance analysis Car audio performance is assessed over a full audio frequency range using a combination of finite element (FE) simulation models for low frequencies, and ray tracing for mid to high frequen-cies. Overall evaluation takes place on the basis of a simulation of several quantities, such as sound pressure level (SPL), transfer functions, ray path, binaural impulse response and sound replay, which require an accurate model. LMS Engineering can provide technology transfer or improve the customer process by working on these areas.
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© 2016 Siemens Product Lifecycle Management Software Inc. Siemens and the Siemens logo are registered trademarks of Siemens AG. LMS, LMS Imagine.Lab, LMS Imagine.Lab Amesim, LMS Virtual.Lab, LMS Samtech, LMS Samtech Caesam, LMS Samtech Samcef, LMS Test.Lab, LMS Soundbrush, LMS Smart, and LMS SCADAS are trademarks or registered trademarks of LMS International NV or any of its affiliates. All other logos, trademarks, registered trademarks or service marks belong to their respective holders.
50751-A10 8/16 A Speaker vibro-acoustic model.
Solutions for body
Summary
LMS™ Engineering services has used experience acquired by consistently applying source-transfer-receiver-based solutions to build up a vast knowledge of how to deal with road noise. This technology relies on the LMS transfer path analysis (TPA) methodology.
Road noise is a major contributor to overall interior noise levels, especially at extra-urban or motorway vehicle speeds. For hybrid or electric vehicles, this is further highlighted by lower powertrain masking noise levels.
Structure-borne and airborne road noise originates from the contact between the tire and road surface. It is propa-gated throughout the vehicle via the chassis and body to the passenger.
TPA plays a crucial role in the full vehi-cle noise, vibration and harshness (NVH) optimization process by enabling you to identify the contributions of the individual component source and the body or chassis sensitivity to the total interior noise level. By using test and/or computer-aided engineering (CAE) analysis to identify the dominant path or component and verify modifications, LMS Engineering can help lower road noise levels in the passenger
compartment.
Comprehensive assessment
The engineering approach starts with a vehicle assessment to identify peak frequencies and a coherence analysis of both body and chassis components.
This separates the airborne and struc-ture-borne contributions, as well as front and rear axle and suspension contributions.
LMS Engineering services identify the root causes and verify chassis and body modifications to increase passenger comfort
Benefits
• Reduce and balance road noise in passenger compartment
• Find effective solutions that do not compromise handling performance or add considerable weight or cost
• Gain insights into vehicle road noise behavior via the source-transfer-receiver methodology
• Allow separation of airborne and structure-borne contributions as well as detailed front and rear axle/
suspension contributions
• Map improvement potential by verify-ing modifications
Road noise
troubleshooting
Identifying peak frequencies.
Solutions for body
A comprehensive diagnosis is obtained by carrying out detailed operational measurements and measuring frequency response functions (FRFs).
These measurements are combined in LMS Test.Lab™ software to carry out an operational deflection shape (ODS) and transfer path analysis. The highly expe-rienced LMS Engineering specialists use the results of these analyses to diag-nose the root cause of excessive road noise.
Transfer path analysis
LMS Engineering experts have devel-oped technology innovations that dras-tically speed up TPA processes. The results equal or exceed the accuracy level of classical TPA methods, while providing engineering insight early in the development process. The clear graphical displays facilitate the under-standing of path contribution. You can interactively modify loads and/or trans-fer paths and visually assess modifica-tions in real time, comparing multiple scenarios.
Operating deflection shape
Operating deflection shape analysis is a method used for investigating the forced response of a machine or struc-ture resulting from the operation of the machine in which the force input is unknown. By using animation capabil-ity, the structural response can be visu-alized, helping to identify the root cause of noise and vibration in a vehicle.
Road noise troubleshooting
© 2016 Siemens Product Lifecycle Management Software Inc. Siemens and the Siemens logo are registered trademarks of Siemens AG. LMS, LMS Imagine.Lab, LMS Imagine.Lab Amesim, LMS Virtual.Lab, LMS Samtech, LMS Samtech Caesam, LMS Samtech Samcef, LMS Test.Lab, LMS Soundbrush, LMS Smart, and LMS SCADAS are trademarks or registered trademarks of Siemens Industry Software NV or any of its affiliates. All other trademarks, registered trademarks or service marks belong to their respective holders.
43897-A10 8/16 P Analyzing improvement potential
Once the root causes are identified, LMS Engineering experts work to verify the improvement potential. Various options are examined by means of modification prediction using the TPA model, and are validated by carrying out prototype vehicle modifications.
Siemens PLM Software www.siemens.com/plm Americas +1 314 264 8499 Europe +44 (0) 1276 413200 Asia-Pacific +852 2230 3308
Operational deflection shape.
Load and path contribution plot.
Solutions for body
Summary
LMS™ Engineering services apply a unique modeling method using SimcenterTM solutions to predict the degradation of composite structures. By combining parameters based on coupon testing with damage and durability simulation, original equipment manu-facturers (OEMs) can design both lighter and stronger structures in reduced time and at reduced cost.
Reducing mass is an important strategy to improve the fuel economy of a vehi-cle. OEMs are able to further push the limits by using composites as they are exceptionally light and have the poten-tial to increase a structure’s durability.
Composites are subject to specific degradation modes, which progres-sively reduce the structural stiffness.
However, significant weight reduction can be obtained when fully exploiting these characteristics. In order to benefit from this potential, a large amount of testing is required throughout develop-ment. Reliable and accurate prediction methods can be used to reduce testing and design an optimal solution.
LMS engineers have developed a model-ing method that enables customers to predict how composite materials will behave under complex loading scenar-ios. This method uses material parameters for which an identification procedure has been established. Using these predictive models, testing is kept to a minimum, reducing cost and the use of resources throughout the devel-opment process.
Evaluation of dynamic behavior and torsional rigidity. Image courtesy PSA
Benefits
• Use maximum potential of composite materials to reduce vehicle mass
• Reduce the need for physical testing on car prototypes by using predictive simulations
• Identify parameters accurately with minimal material testing
• Build predictive models in a virtual environment dedicated to both