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All methods for Experimental Modal Analysis in ARTeMIS Modal are born multiple input multiple output polyreference methods. This means that the techniques are capable of estimating closely space modes and even repeated modes with a high degree of accuracy. Below there is an example of a perfectly symmetric structure where the polyreference methods have been applied on a setup with two reference accelerometers and a rowing impact hammer.
Operating Deflection Shapes analysis is very beneficial in combination with Operational Modal Analysis as it determines and visualizes the combination of the actual forcing functions acting on the structure and the dynamic behavior of the structure. Results can be shown as displacement, velocity or acceleration in SI, Imperial or user-defined units. Decimation and various filters (low-pass, band-pass, band-stop and high-pass) can be applied to frequency limit the analysis.
You might wonder what Operational Modal Analysis, OMA, is and how it differs from the traditional Experimental Modal Analysis (EMA) that has been around for the past few decades. Operational Modal Analysis is also called output-only modal analysis, ambient response analysis, ambient modal analysis, in-operation modal analysis, and natural input modal analysis.
ARTeMIS Modal Pro has a series of plugin modules designed for Structural Health Monitoring purposes. All modules are designed to analyse and present the health of a monitored structure in various manners, and they all rely on the same common data manager base module. This module administrates the recorded measurement files as well as the results obtained during a periodic monitoring.
ARTeMIS Modal is produced in three versions and the key features are listed below. All versions have estimators for Operational Modal Analysis (OMA) and Operating Deflection Shapes (ODS). As optional features for all versions are the Data Acquisition plugin, allowing direct control of selected data acquisition hardware, and the Experimental Modal Analysis plugin, allowing classical input/output modal analysis. If both the data acquisition plugin and the experimental modal analysis plugin are available, then it is possible to run the Impace Testing module.
This is the basic version having a frequency domain method for Operational Modal Analysis, and optionally direct data acquisition support and two frequency domain methods for Experimental Modal Analysis. Specifically it contains the following tasks and features:
This is the mid-size version that, besides all the tasks and features of the Basic version above, also has the following additional tasks and features:
With our flexible upgrade policy you can get started in an affordable way, and then upgrade whenever needed.
1: Requires the National Instruments data acquisition plugin. Please ask if your hardware is supported.
2: Requires the SINUS Messtechnik data acquisition plugin. Please ask if your hardware is supported.
3: Requires the Experimental Modal Analysis plugin as well as one of the above data acquisition plugins.
4: Requires the Experimental Modal Analysis plugin.
ARTeMIS Modal includes up to three frequency domain modal analysis techniques derived from the patented Frequency Domain Decomposition technology utilizing the singular value decomposition of the estimated spectral densities of the measured response. The techniques available are:
All three techniques are based on peak-picking in the frequency domain using either automatic picking or manual picking using the mouse. Once picked, the mode shapes are ready for immediate animation. The techniques are all specially designed to account for the presence of deterministic signals (harmonics) in case of rotating structural parts or other sinusoidal excitation.
Read more about Frequency Domain Decomposition
ARTeMIS Modal Pro includes up to five time domain modal analysis techniques. They are all of the data driven Stochastic Subspace Identification (SSI) type and all implementing the powerful Crystal Clear SSI feature. This feature result in extremely clear stabilization diagrams with un-seen accuracy of the physical parameters and nearly no noise modes. The techniques available are:
These techniques estimate the modal parameters directly from the raw measured time series. The SSI techniques incorporate effective ways of dealing with noise. As a result, the modal parameter estimations are the most accurate commercially available today. The SSI techniques can work with closely space and repeated modes with light or heavy damping. Since they are working in time domain there are no leakage bias or lack of frequency resolution, see below. As a result, the modal parameter estimates are asymptotically unbiased. Further, as the SSI techniques are low model order estimators, the statistical errors of the modal parameter estimates are extremely small.
Read more about Stochastic Subspace Identification
ARTeMIS Modal includes time as well as frequency domain Operating Deflection Shapes (ODS). These features allow you to study the overall vibration pattern either over a time segment or at a specific frequency.
ODS analysis is very beneficial in combination with Operational Modal Analysis as it determines and visualizes the combination of the actual forcing functions acting on the structure and the dynamic behavior of the structure. Results can be shown as displacement, velocity or acceleration in SI, Imperial or user-defined units. Decimation and various filters (low-pass, band-pass, band-stop and high-pass) can be applied to frequency limit the analysis.
Both time and frequency domain ODS are available in all versions of ARTeMIS Modal.
ARTeMIS Modal includes an Experimental Modal Analysis plugin1 that opens for frequency domain estimation of modal parameters from Frequency Response Functions (FRF’s).
FRF’s can be uploaded using Universal File Format (UFF/UNV), or be internal estimated by uploading input and output time domain measurements in the Manage Measurement Task, or by using the Impact Testing Module2.
Two polyreference methods are available:
In ARTeMIS Modal estimated modes can be validated by comparing modal results from the different estimation techniques used for the same project. Results of different projects can also be compared, allowing an older analysis of a structure to be compared with a new analysis. External results may also be imported using Universal File Format, allowing e.g. numerical modes of a Finite Element model to be compared with experimentally obtained modes.
Features