Torsional vibrations are quite often a source of issues and faults on the rotating shafts. Our rotational and torsional vibration analysis module combined with the order tracking analysis module is a perfect tool for troubleshooting shafts, crankshafts, gears in automotive, industrial or power-generation applications.
Rotational and Torsional Vibration Analysis
- EASY SENSOR SETUP: The math module supports any type of sensors. The sensors type can be totally different for both ends of the rotor. SuperCounter technology provides 10 nano seconds resolution of determining rotational angle and speed.
- ACCESS TO ALL DATA: all data, such as reference angle, individual sensor rotational angle, speeds and acceleration, torsional angle and velocity are readily available for advanced analysis
- ADVANCED MATH: different input filters and rotational DC filters are available as well as a chance to enter rotational speed ratio for gearbox analysis;
- ORDER TRACKING INTEGRATION: closely combined with order tracking, advanced data analysis is available based on same angle sensors as the source of frequency
- LIFETIME FREE SOFTWARE UPGRADES AND SUPPORT: Our data acquisition systems come bundled with award-winning Dewesoft X data acquisition software. The software package is always evolving and new features are being added. We offer lifetime FREE software upgrades and technical support to all our users.
What is Rotational and Torsional Vibration
Torsional vibrations are angular vibrations of an object, typically a shaft along its axis of rotation. They are mechanical vibrations caused by time-alternating torques which are superimposed on the otherwise steady running speed of a rotating shaft. In automotive engineering torsional vibration is primarily caused by the fluctuations in engine power output.
Torsional vibrations are evaluated as the variation of rotational speed within a rotation cycle. RPM variations are typically induced by a rough driving torque or a varying load.
Rotational vibration is simply the dynamic component of the rotational speed. If we measure the rotational speed of the shaft with high precision, we will notice that we get a high deviation of rotational speed in some regions of the run-up. This is caused by the angular vibration crossing the angular natural frequency of the shaft. It is calculated by cutting off the DC component of the rotational speed or the rotation angle
The level of torsional vibration is influenced by a number of parameters, such as material properties and operating conditions such as temperature, load, RPM, etc.
Torsional Vibration System Overview
Our data acquisition systems for collecting data for torsional vibration analysis offers very flexible channel configurations and easy connection of sensors. With advanced TEDS sensors support and integrated smart DAQ technologies, the sensor setup and channel configuration will be instant and you will be able to start measure in minutes.
The award-winning Dewesoft X data acquisition software already includes a predefined display for torsional vibration. Just run your machine and the data and results will start displaying in real-time on the screen. Visual displays are freely configurable and you can change your display at any time online or offline. Connect a simple web camera and have synchronized video of your measured machine next to your measured data.
Simple built-in reporting tools and extensive file format export functionalities will enable you to create quick PDF reports or export data to Excel, Matlab or other supported SW packages for further analysis, if needed.
Connect Any Type of Angle Sensor to DAQ
Torsional and rotational vibration can be measured with either an encoder sensor (up to 3600 pulses per revolution) or a special sensor (CA-RIE-360/720) that has a lower resolution (up to 720 pulses per revolution) but is much less sensitive to vibrations that could damage standard encoders.
Some very typical sensors are already predefined in the Dewesoft X DAQ software. However, if your type is not listed, you can define your own sensor in sensor editor. Note, that for the torsional vibration module the sensor has to be either an Encoder or a CDM type.
A variety of angular sensors is supported:
- CDM with/without zero pulses (Geartooth)
- Zebra tape sensor (tacho and auto-gap detection)
- Sensors with missing teeth (e.g. 60-2)
Dewesoft SuperCounter Technology
Dewesoft data acquisition systems utilize a patented and registered technology called SuperCounter®. SuperCounters allow for a perfect synchronized angle measurement of rotating shafts from the counter and encoder sensors and perfectly time-synchronized with the analog data.
Counter inputs can measure the RPM and angle of rotating machines. In comparison to standard counters, which only output integer numbers one sample later (e.g. 1, 1, 2, 2, 3, 4), SUPERCOUNTERs® are able to extract the accurate values like 1.37, 1.87, 2.37, etc. fully synchronized for time and amplitude. This is done by measuring the exact time of the rising edge of the signal with an additional counter. Our SUPERCOUNTERs® work on a 102.4 MHz time base, independent from the current sampling rate.
Counter inputs are fully synchronized with analog, CAN bus, and other data sources to enable easy applications like balancing, order tracking, and torsional vibrations.
For more information on our SuperCounter inputs please navigate to the Digital Counter online training course.
Torsional Calculation Output Channels
Dewesoft X torsional vibration module automatically calculates several different parameters. The calculations can be done either online in real-time or offline on the saved RAW data.
- Rotational angle: filtered angle value of vibration.
- Rotational velocity: filtered velocity vibration value.
- Torsional angle: the Dynamic torsional angle that is the angle difference from sensor 1 to sensor 2.
- Torsional velocity: difference in angular velocity from sensor 1 to sensor 2.
- X-axis reference angle: the reference angle, which is always from 0 to 360 and can be used as a reference in angle based XY diagrams.
- Frequency: in the RPM units.
Input Filter and Rotational DC Filter
The input filter is needed to prevent glitches and spikes in digital encoder pulse signal. It can be set from 100ns to 5us, the optimal setting is calculated.
The rotational DC filter needs to be set to cut the DC component of the RPMs. We need to set the filter to include all wanted frequencies, but not too low, or else we will have static DC deviations on the output signal. It can be set from 0.1 to 10 Hz. You have to ensure that your lowest RPM is not filtered out!
Reference Curve Configurations
Centered mounting is very important. Off-center mounting and unsteady pulses from the encoder can be compensated in Dewesoft X using the reference curve.
However, it is required that the load must be removed from the engine - it must be free-running. Otherwise, you would also cancel out vibrations you want to analyze. When the machine is running at idle speed with no real torsional vibration, press the “Set” button.