Strain Measurement


MAN B&W uses the TEAC data recorder RX-816 to determine the operational reliability.
With a market share of nearly 50 percent each second horse power of ocean liners world wide comes from MAN B&W in Augsburg, Germany. The product line ranges from four stroke diesel engines with 610 HP up to 31,825 HP, two stroke engines, four stroke natural gas operated diesel engines, power generators and exhaust turbo chargers. Because engines in ships and power plants have to be extremely reliable and have to run around the clock in the Augsburg factory several departments have to approve the quality of the engine components. Measured are mechanical oscillations, distances, velocities and accelerations, and fatigue of stiff and elastic components. For measurements of regular and cyclic events normally a PC will do the job. Some times the storage capacity of a computer is not sufficient. The disadvantage of PC based recording is that the ability of recording unpredictable events can be relatively difficult.


The Data Rekorder RX-816


Diplom Ingenieur Mr. Albert Zeitlmeir (34) decided to use the TEAC data recorder RX-816  for strain measurement at exhaust valves because it offers 16 channels and a Hi8 8mm video tape with 7.7 GB data capacity. The test engineers used strain gages to measure the tensions at the highly strained valve shafts. This configuration allows measuring even smallest mechanical forces. They were converted into electrical signals, amplified and fed analogous into the RX-816. Each of the strain gages is connected to one of the 16 channels of the RX-816.


Measurement at High Frequency


Because the signal produced by the exhaust valves is relatively high in frequency and it undergoes heavy changes the measurement is achieved with high frequency over longer periods of time. The MAN B&W staff benefit of the high sample rates of the TEAC RX-816. This recorder offers a signal bandwidth from DC to 20 kHz. Its sample rate is 48 kHz per channel resulting in a total sample rate of 768 kHz over all channels. Triggers are set when measuring the tensions of the valve shafts. Signals of interest are filtered (like the acceleration while the valve is operated) and processed further. The transfer of data to the PC is achieved with the TEAC software tool Quik VU. The recorder can be controlled with the PC and several automation functions (triggers) can be set. In contrast to other sometimes much more expensive programs Quik VU do not need lots of memory and it can be installed without problems.