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Siemens opts for optical strain measurement by ZwickRoell

Siemens’ customers in the power generation sector have access to a complete spectrum of products, services and solutions for power generation and distribution. Key products in this area include steam turbines and steam-powered generators, together with gas turbines. The high operating temperatures and pressures involved place special demands on materials testing, for which Siemens relies on high-temperature testing solutions by ZwickRoell.

At Siemens’ laboratory for destructive materials testing in Mülheim, Germany, contact-type extensometers had previously been used in investigations to obtain materials data for brazed joints. This involved subjecting joints with a brazing gap less than 1mm to high-temperature fatigue tests (above 850°C) . As the measuring range of the contact-type extensometer was 10mm and the brazing-gap less than 1mm, it was mainly the behavior of the base material that was being tested. To obtain detailed information on the behavior of the joint, strain was required to be recorded locally in the region of the brazing-gap using an optical strain-measurement system to provide an indication of the ratio of local strain to overall strain. This allows better characterization of the actual bond interface of the brazed joint.

Messphysik - a member of the ZwickRoell Group - offered the ideal solution in the form of videoXtens HT, specially developed for high-temperature strain-measurement and well able to cope with the particular demands of the tests involved. videoXtens is the only measuring system able to satisfy the requirement for high-resolution optical measurement of local strains at temperatures >750°C . Other decisive factors are ease of implementation using the existing test arrangement and the user-friendly software design.

From a measurement technology point of view videoXtens HT represents a real asset for Siemens, enabling local strains in the joint to be determined which could not even be recorded before.