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NVH — Noise | Vibration | Harshness 

The right solution for every task ...

... with an easy-to-use graphical user interface, which is based on common standards. However, it can also be individually designed by the user.

  • Analyze and evaluate sound and vibrations via various, individually determinable reference variables.
  • Automation of commands for analysis and documentation processes
  • Support of ASAM ODS NVH. ODS (Open Data Service) is an international standard of the Association for Standardization of Automation and Measuring Systems (ASAM) and is widely used, especially in the automotive industry.

TAILOR-MADE SOLUTIONS

Basic analyses: Acquisition of raw time data, spectral analyses, overall level analysis, third octave analysis, octave analyses, online filtering.

Rotating systems analyses: Order analysis, torsional vibration analysis, crank angle analysis, combustion analysis, dynamic balancing.

Structural analyses: Shaker excitation, impulse hammer excitation, airborne excitation.

Technical accoustics: Sound power, sound intensity, sound source localization.

Sound quality: Psychoacoustic analyses, operational transfer path analyses, sensitivity analyses.

Control and monitoring: For measuring systems used in the test bench; e.g. limit values for levels and frequencies can be specified.

Interactive visualization/presentation: Using interactive graphic functionalities of PAK in Microsoft® Office.

Basic analyses

An excellent measurement and analysis system for acoustic and vibration validation should meet the following criteria:

    • All common measurement quantities and methods are available in parallel – for efficient, bundled acquisition and evaluation of all relevant parameters.
    • The measurement result is reproducible at any time – for reliable, sustainable and verifiable measurement results.
    • The measurements can be effectively evaluated and documented – for a stringent, time-saving workflow.
    • The system can grow with the requirements – for a secure return on investment and more flexibility in use.

    Best suited for test bench and troubleshooting

    No matter what your measuring task is: The basis of all evaluations are the precise time signals, which are recorded with different sampling rates depending on the task. Spectral analyses by transformation from time to frequency domain, total level observations or third-octave analyses allow detailed, further evaluations.

    PAK-Systems perform these tasks perfectly. The user decides whether he only records raw time data that are later analyzed or whether the analysis data is also stored (online analysis). Measurement results can be displayed directly in a prepared graphic and thus comply directly with company or customer standards. PAK systems are equally suited for test bench operation, mobile measurement and quality assurance as well as for troubleshooting.

    • Signature (FFT-Analyzer)
    • Detector
    • Digital Order Tracking
    • FIR Filter
    • Polynomial Calibration
    • Nth Octaves
    • and more

    AnalysIS ON rotATING Systems

    Rotating machines can cause unwanted noises and vibrations. Examples include combustion engines and electric motors, but also turbines and other aggregates such as turbochargers.

    The overall sound of a rotating machine comprises the acoustic contributions of various individual components such as drive shafts, gearboxes, bearings, belt and chain drives. To assign disturbing noises and vibrations to individual components, the user can resort to various rotation analyzes in the PAK-Software.

    The basic prerequisite for a meaningful analysis of rotating systems is precise speed measurement with high-resolution tachometer inputs.

    • Order analyses
    • Torsional vibration analysis
    • Angle-related analyses
    • Crank Angle analysis
    • Combustion analysis
    • Dynamic Balancing
    • and more

    Downloads for rotational analyses

    Structural analyses

    Structural analyses are a suitable instrument for the exact determination of individual vibroacoustic properties. To determine parameters such as absorption, reflection or transmittance, analysis objects are artificially excited.

    The transfer functions result from the ratios of response signal to excitation signal. Typical excitation types are:

    • Shaker excitation
    • Impulse hammer excitation
    • Airborne sound excitation

    Animation of Vibration Modes

    An important tool is the representation or animation of vibration modes, which can be done from raw time data or frequency selective. Operational Deflection Shape analysis (ODS) is the animation of directly measured signals. However, transfer functions (normalized accelerations) or modally disassembled vibration modes can also be animated.

    Transfer Path Analysis

    Response signals are comprised of typically components from different sources or paths. To investigate this composition, methods of transfer path analysis (TPA) methods are used. Since the concrete tasks or questions can be very different, different TPA methods have been established.

    Operational Transfer Path Analysis (OTPA)

    On the structural dynamics side, the OTPA with the PAK software provides insight into the paths by which sound and vibrations within a structure to the receiver in the operational state. In this way, it becomes clear which design measures are expected to lead to the greatest improvement in sound and vibration behavior.

    Sensitivity Analysis

    The sensitivity analysis in the PAK software shows immediately which changes in the transmission paths can achieve the desired vibroacoustic behavior.

     

     

    • Operational Deflection Shape Analysis
    • Impact measurement
    • Shaker measurement
    • MIMO & SIMO
    • Mount Stiffness method
    • Matrix Inversion
    • TPA & Operational TPA (OTPA)
    • Transfer Path Synthesis (TPS)
    • Sensitivity / Contribution Analysis
    • Principle Component Analysis (PCA)
    • Principle Component Contribution Analysis (PCCA)
    • Dynamic Substructuring

    Downloads for structural analyses

    Road induced interior noise

    Paper, presented by Guillaume Demaziere (Michelin) and Laurent Capron (MBBM-VAS) at Automotive NVH Comfort Le Mans 2018, France

    Download (pdf, 1 MB)
    TPA - Transfer Path Analysis
    Download (pdf, 3 MB)
    PAK tools for structural dynamics
    Download (pdf, 3 MB)

    TECHNICAL ACOUSTICS

    Technical acoustics and vibration engineering deals with the physical generation of sound and vibrations and their propagation in air and solid media. With the help of our PAK software, all sound-specific characteristics can be precisely recorded, clearly displayed and evaluated according to your compliance with the standards.

    Sound power

    An important parameter for the source strength of a sound generator is the sound power. The PAK software supports the user in determining the sound power in accordance with DIN EN ISO 3740 ff. in low-reflection rooms or half-rooms (envelope surface method), in accordance with DIN EN ISO 3744 and under DIN EN ISO 3745. It is also possible to determine the sound power in a reverberation room of known reverberation time or to determine it from a comparison with a reference sound source of known sound power (comparison method). For example, the following analyses are available: sound power level, sound pressure level curve, vibration level curve, third-octave band spectra, FFT time-frequency analyses.

     

     

    Sound intensity

    If no special measuring room is available, the sound power can also be determined by measuring the sound intensity. The PAK software supports the use of different probes (pressure/pressure and pressure/velocity) and continuously checks all important sound field indicators. In addition, the radiation behavior of the test object is graphically visualized (sound field mapping).

    Sound source localization

    An imaging method is the sound source localization through a microphone array. The sound-radiating surface of the test object is "scanned" (beamforming) and the measured values ​​are color-coded via a live video image. The PAK software thus enables the graphic representation of time-varying sound emissions.

    Downloads for technical accoustics

    Vibroacoustic measurements on wind turbines
    Download (pdf, 2 MB)

    Sound Quality

    Today, just like the vibration behavior of structures, sound is no longer a random product feature, but a brand-specific success factor. Sound can be specifically designed during product development.

    The PAK software provides the development engineer with all the tools to construct an unmistakable sound design efficiently and purposefully: During the sound design process, several target sounds of the later product can be designed with freely definable filters and evaluated by test persons in listening comparisons.

    Psychoacoustic Analyses

    The reliability of the findings. The supported, associated parameters are among others

    • Loudness
    • Sharpness
    • Roughness
    • Fluctuation strength
    • Tonality
    • Articulation Index
    • Prominent Ratio and Tone-to-Noise Ratio
    • Engine roughness
    • Sound Design
    • Online filtering
    • Psychoacoustics
    • Hearing Comparison
    • Jury Validation
    •  Engine Roughness

    Downloads for sound quality

    Current status and future development of ANC systems
    Download (pdf, 527 KB)

    CONTROL AND MONITORING

    Measuring systems used in the test bench environment must be robust and efficient both during data acquisition and during online evaluation. In addition, they should offer a wide range of options for communication with other test bed control systems.

    The PAK software for data acquisition can be optimized for the test bench driver so it only passes on the relevant information for the test process.

     

    Grid control measurement

    For special applications of grid measurement, the PAK software can also provide the control specifications for performing the measurement. The combination of digital bus inputs (FlexRay™, EtherCAT®, CAN, CAN FD) with analog input channels results in a maximum of flexibility in the control of a system.

    Downloads for control and monitoring