Learn the basic functionality of our NVH software product m+p Analyzer. We will start with basic vibration data display and progress to data handling, filtering, and more complex features like post-processing and advanced visualization of data. Features will be illustrated by animated graphics.
m+p Analyzer offers four different types of charts for specific data analysis needs:
- 2D Single chart
- 2D Multi-chart
- 3D Waterfall chart
- Colormap chart
In the first issue we will explain 2D chart functionalities including chart layout, online data display and basic analysis features.
Single and Multi-charts are the key tools to use when acquiring and reviewing measurement data. The single chart can display up to 256 traces in a single diagram and is continually updated during a measurement. The multi-chart tool is useful for a more structured display of data. Scaling may be applied to several charts at once and groups of traces can be displayed together in separate sub-charts. Similar to a webbrowser, all charts may be arranged freely on the working plane either side-by-side or as tabs.
Charts can be configured to show a secondary axis on the right hand side with independent scaling, which streamlines acquisition of data with different units, e.g. acceleration [g] and force [N]. Comparison of signals, such as phase difference between sine waves, can be done automatically online during the measurement.
Both the single and multi-charts are completely customizable. The size and color of titles, legends, annotations and the plot area can be tailored to the user’s preference. The grid and traces may be individually colored and styled.
The 2D chart capability is not limited to the display of time data. m+p Analyzer’s real-time FFT feature allows for online display of different metrics calculated from measurement data. This includes real-time spectra of windowed time signals, histograms, auto- and crosscorrelations, power spectral densities, auto- and crosspower spectra and frequency response functions.
The display type of the chart may be individually customized to fit the requirements of a given measurement type, e.g. a frequency response function. Common axis types such as real/imaginary, amplitude/phase, logarithmic/phase and dB (referenced)/phase plots are available with different types of scaling such as peak, peak-to-peak and rms.
m+p Analyzer offers four different types of charts for specific data analysis needs: 2D Single chart, 2D Multi-chart, 3D Waterfall chart and Colormap chart. The second article of our series „m+p Analyzer basics“ will focus on the advanced functionality of 2D charts.
The overview feature is useful when post-processing and reviewing large data sets. It allows to select a zoom region and pan this region in the overview field to get a close-up view of a subset of data.
To review the data values at specific time instances, vertical and horizontal cursors may be used. Besides the charts a display with useful metrics at the cursor location is displayed. Multiple cursors may be linked with the "band cursor" feature where slave cursors will move together with the master cursor at a given distance. Together with the "seek to peak" feature, extrema and their relative distances (in time or frequency) may be easily tracked and displayed in the chart legend.
2D charts offer specifically tailored cursors for the analysis of spectra (basically anything with a frequency axis). The harmonic cursor displays slave cursors at frequency locations of the 1st, 2nd, 3rd, ... harmonic based on the master cursor frequency. The sideband cursor displays slave cursors equally spaced to the left and right around the master cursor.
The tacho tool can be used to extract RPM values from a tacho signal or sine wave. It is a simple tool that is real-time capable in that it can be used at acquisition time. More advanced features "tacho spline fit" and "RPM extractor" are part of the m+p Analyzer "Rotate" toolbox and allow for more complex RPM extraction methods such as smoothing of the extracted RPM signal and extraction of RPM from vibration data. In the following example we will show the basic tacho tool which comes with the 2D chart. Suppose a sine sweep from 20 Hz to 100 Hz was recorded. We can now configure the tacho tool displaying the rotational speed, which - in the case of our sine sweep - yields an RPM range of 1200 to 6000 RPM. The result may either be shown as a cursor on the original data or shown as a new signal "RPM over time". In this example we use a sine sweep, yet any rectangular pulse train - which is typically measured by tachometers - is applicable.
Reference traces may be overlaid in the 2D chart to compare previously acquired results to the currently acquired data in real time. Besides showing recorded measurements as a reference, this feature is also useful to show, for example, upper and lower limits when measuring time signals such as forces. In the following example we show how to set up a previously acquired spectrum as a reference trace and perform several impulse response measurements which can then visually compared to the reference response. Tip: Reference traces may be added quickly by holding the "alt" key while dragging and dropping a measurement into the chart.
In the last issues of our series “m+p Analyzer Basics” we showed basic features of 2D charts such as formatting and positioning and more advanced features such as different types of cursors and reference traces. This issue is dedicated to data manipulation. The m+p Analyzer provides a rich set of data manipulations within packages like "modal analysis", "rotational analysis" and "acoustic analysis". Yet basic analysis features are included in the 2D charts which come with the standard licence and are available to all customers.
The 2D chart can be configured to perform basic calculations on the data it currently shows. These functions include integration and differentiation in time and frequency domain, octave spectra with A-, B-, C-weighting, orbit plots and many more. All calculations may be chained consecutively in arbitrary order and will be applied during run time. The following animation shows how acceleration data can be integrated to velocity or displacement during the time of measurement.
For an application example we will use our demonstrator for rotational analysis such as balancing and orbit analysis.
On the left journal we placed two accelerometers to measure vibrations in X- and Y-direction. Within the chart we can now integrate these accelerations twice to get the displacement and then setup an orbit plot. This will show us the movement of the journal in the X-Y-plane during the run-down of the demonstrator.
In a real world application, one is typically interested in time histories and spectra as well. In that case we would setup different charts showing the desired metrics. The following animation shows a typical setup and how to export and import such a setup for repeated use.
m+p Analyzer offers four different types of charts for specific data analysis needs, a 2D single chart, a 2D Multi-chart, a 3D Waterfall chart and a Colormap chart. In this issue we take a look at the 3D chart and its online capabilities.
The 3D chart displays a set of waveforms against a third axis such as time, frequency or RPM. Applicable waveforms include time histories, spectra, FRF, PSD and many more. Just like the 2D charts, the format and properties of the 3D chart can be easily edited and stored as a template, see also Issue 1: Basics of 2D Charts. The following animation shows different styles of the chart: Several spectra are recorded and shown in the waterfall chart during measurement. The user may easily switch between a waterfall and a colormap display by a double click on the chart. In this case we configured the waterfall chart to show a shaded surface, though several other styles are also available.
For the following example we recorded acceleration data of a rotating machine during run-up. We used m+p Analyzer (DSA-Pro license) and an m+p VibPilot acquisition front-end. In addition to the acceleration on the mount we recorded the RPM of the machine. The measurement was configured so that the 14.25 s of time data is automatically split into 57 blocks of 250 ms length. For each block a spectrum is calculated using a FFT algorithm and a Hanning window. The spectra are displayed in a colormap of frequency vs. time. As we also recorded the RPM of the machine, m+p Analyzer will automatically attribute every spectrum with the average RPM during the time of aquisition. Therefore we can easily generate a colormap of RPM vs. frequency, giving a clear indication of the machine’s rotating frequency and its harmonics (i.e. the orders). Exemplarily, a cursor is used to extract the amplitudes of the 1st order over the rotational speed.
This example shows a simple and quick way to analyze a rotating machinery in m+p Analyzer. For more advanced analysis the rotate package may be licensed, which offers advanced tacho acquisition, RPM and time based colormap generation and more sophisticated order tracking features. Contact us for more information about m+p Analyzer and its rotate capabilities.