The following examples are from the
software simulators available in the Mobius Institute classes.
Of course not all simulators are used in all classes. But when
they are used they make the topic much easier to understand.
There is nothing like watching the instructor click a couple of
buttons to explain a concept that was difficult to understand.
You can almost hear the light come on as everyone in the class gets
the point.
It should be said that these screen
captures do not show all of the simulators. Also, for every
screen capture you see below, there are typically a number of
options and settings that are used to demonstrate a large number of
different concepts.
The bottom line is that these
simulators enable you to quickly understand difficult concepts and
procedures with a clarity that ensures that you will go on
understanding the concept long after the course ends.
New: See them in action!
If you have a good Internet
connection, click here to see
animations of some of the simulators in action. The page will
take a moment to load, but it is worth the wait.
Fundamentals
This simulator is used to demonstrate
the basics of vibration. It can actually be used in six
different modes, starting with very simple dynamic movement,
building up to an explanation of the waveform, as well as frequency,
period, amplitude and rms/peak/crest factor.
This simulator is helpful to introduce
the spectrum. As the knob is turned the waveform changes and
the peak in the spectrum moves.
This simulator is used to demonstrate
phase. It starts with very basic phase relationships, and
grows to demonstrate more complex phase relationships.
This program allows you to begin with
the basics of one signal and waveform, and slowly add two more
signals and show the spectrum to see how it changes as the signals
are changed. Then you can change the waveforms and spectrum in
3D mode - from one side of the cube you can see the waveforms, while
from the other side you can see the spectrum.
This program demonstrates what happens
when signals are added together. Phase can also be
demonstrated.
This program allows you to demonstrate
how orbits are generated from two proximity probes. In an
advanced mode you can easily simulate a number of common fault
conditions.
This simulator is primarily used to
demonstrate the relationship between displacement, velocity and
acceleration. It shows what happens as the speed is increased from
low frequency to high frequency in both the time waveform and
spectrum.
When describing the relationship between
the time waveform and the spectrum, it is helpful to demonstrate it
with sound. This program shows the spectrum, waveform, and
"spectral map" based on sounds received by the computer's
microphone.
This simulator demonstrates how rms
meters work, and what information is lost when the standard 10-1000
Hz filter is used. You can select data from different types of
machines (with different types of faults), and switch in different
filter settings. You can hear the vibration and therefore hear
the effect of the filter.
Signal Processing
This program is used to explain the
sampling process - the conversion from analog to digital.
It is also used to explain
aliasing, as you can control the sample rate and control the
frequencies in the 'analog' signal.
And it can be used to demonstrate
resolution - as the number of samples (i.e. the sample rate) is
increased, the resolution of the spectrum increases.
This program demonstrates the
relationship between resolution, the number of samples and the Fmax.
This program demonstrates aliasing.
You can generate signals below and above the Fmax setting with the
anti-alias filters turned off.
This program demonstrates averaging:
free run, linear, peak hold, and time synchronous averaging.
You can experiment with real signals, simulated signals, and signals
from coast-down tests.
This program demonstrates windowing and
leakage.
This program enables you to understand
how low-pass, band-pass, bad-stop, and high-pass filters works.
You can select different signals from real machines so that you can
see and hear the effect of the filter.
This program demonstrates the
relationship between the Fmax settings, the sample rate, resolution,
the number of averages and collection time.
You can set a running speed and a
"defect frequency", and set the Fmax and resolution. You can
see visually what information would be included in the spectrum, and
you can see how many cycles will appear in the waveform. It
also demonstrates how overlap averaging works, and the limitations.
Signals
This program demonstrates the waveform
and spectrum for a wide range of classic signal types: sine wave,
square wave, pulse train, impulse, clipped (distorted) wave,
amplitude modulation, frequency modulation, beating, and sum &
difference signals.
This
demonstration allows people to understand why the waveforms and
spectrum look the way they do.
As with most of these programs, you
can listen to the waveform at the same time.
Spectrum analysis
This program allows you to build models
of machines, compute the forcing frequencies and simulate the
vibration.
You can start with simple machines
and build up to very complex machines (gearboxes, rolls, etc.).
You can even create bearings or add bearings from a large database.
Once you have created the model you can
design band alarms and mask/envelope alarms. You can
experiment by adding signals to see how the band/envelope copes.
Fault diagnosis
This program demonstrates how bearings
generate vibration, and it demonstrates why sidebands are generated.
This program can also be used to
explain amplitude modulation.
As the inner race rotates in the
animation, you can see the vibration generated by a variety of fault
conditions.
This program demonstrates how gears mesh
together, and why you see amplitude and frequency modulation in
vibration data. It also demonstrates a variety of fault
conditions, including gear wear and the hunting tooth frequency.
By listing the prime factors and
common factors, it also demonstrates the preferred frequencies
(based on the combination of prime numbers).
You can simulate a damaged tooth to
see how other teeth can be damaged.
The gears rotate on-screen and you
can change the number of teeth dynamically.
We have a virtual test rig (fault
demonstrator) that is used to demonstrate a wide range of signal
types and fault conditions. Rather than wasting time in class
while the test rig is re-configured to demonstrate some type of
fault, the instructor is only three clicks away from demonstrating
real vibration data.
The
vibration is displayed on screen, but can also be played through
computer speakers or fed into a data collector.
Rather than just using images of spectra
from unhealthy machines, we have a database of vibration
measurements that came from machine with faults. You will see
the time waveforms and spectra from three axes, as well as a history
of data that lead up to the fault occurring.
In addition to the case histories with
historical data, we have 25 case histories that use "live data".
It is like having the machines right there in the classroom.
At each test location we have 30 seconds of vibration in three axes.
This data can be analyzed on screen, played through the computer
speakers, or fed to a data collector.
In some classes, the instructor will use
the "practical challenge" program. You will be able to test
your skills on special, interactive case studies. You go
through the process of deciding what tests are required, and you
must make the diagnosis and recommend the repair action.
This program demonstrates resonances,
and the analysis techniques used to detect and understand them.
The software models the first three
modes of a cantilevered beam, and a beam pinned at both ends.
You can change the mass, stiffness, damping, length and material of
the beam.
You can then excite the beam with
different signals and see an animation of the vibration.
The data can be viewed as a
response spectrum, Nyquist plot, Bode diagram, waterfall plot,
Campbell diagram. You can simulate run-up and coast down tests
and bump tests.
Peak-hold averaging and negative
averaging can be used for analysis purposes.
This program allows you to enter
vibration amplitude and phase readings for a motor and driven
component (e.g. pump) to visualize how the machine moves.
You can manually enter the data and
watch the machine animate (watch the motor rock back and forth, for
example), or you can select one of the demonstration settings to
understand phase relationships for common fault conditions.
This tool is used when learning
about "bubble diagrams", and when teach select fault conditions:
imbalance, misalignment, resonance, bent shaft, eccentricity, and
more.
This program demonstrates resonances in
a practical sense, and it is used to explain how Operating
Deflection Mode-Shape (ODS) analysis is performed.
You can define a structure and enter
vibration amplitude and phase readings at each of the points.
The structure then animates according to those readings.
It is very easy to visualize how
the structure is vibrating, and it demonstrates the power of ODS
analysis.
Corrective action
This simulator is used to demonstrate
vectors and the entire single-plane balancing process.
This simulator is used to demonstrate
two-plane balancing. Each step can be revealed so that the
process and calculations involved can be properly understood.
This simulator is used to demonstrate
the calculations and procedures required to split balance weights
between available blades or holes.
This simulator is used to demonstrate
the calculations and procedures required to combine existing balance
weights to determine the mass and angle of a single final weight.
This simulator allows you to add and
remove shims and tighten and loosen jacking bolts to alter the
alignment of the machine. The graphics are all in 3D.
This simulator is used in the
alignment course, and in the ISO vibration Cat II and II courses.
This simulator allows you to go through
the complete dial-indicator alignment process. Animations
demonstrate each step of the process. The dials show the
readings. The bar-sag test is simulated. The results are
shown in 3D, and the results can be shown graphically. You can
enter constraints to demonstrate bolt-bound and base-bound
situations.
This simulator is
used in the alignment course, and in the ISO vibration Cat II and II
courses.
This simulator allows you to demonstrate
the graphical method, and enables you to demonstrate how different
feet can be moved when the machine is base-bound or bolt-bound.
