Fraunhofer IPM has partnered with Fraunhofer IWM to develop a new strain measurement system that combines the advantages of optical and mechanical measuring procedures and dramatically accelerates materials testing. This makes the new system a multifaceted tool for quickly performing material tests. The measurement system will be presented at the 8th International Conference on Low Cycle Fatigue LCF8 in Dresden from June 27–29, 2017.
Innovative materials are improving the function of components, machines and systems, and expanding their areas of application. This is particularly evident in relatively new industries such as lightweight construction. However, components based on new materials must also be reassessed in order to ensure the strength and safety of the final product.
To evaluate the mechanical properties and service life, investigators turn to methods such as fatigue tests under cyclic loading. But this measurement takes time, with the test typically lasting anywhere from several hours to several days. Now scientists at Fraunhofer IPM and Fraunhofer IWM have succeeded in reducing test times for non-contact, strain-controlled fatigue tests by a factor of ten.
No contact or markings needed
Optical strain measurements are always contactless and thus do not slip. The measurements not only determine the average strain between two points, they also allow for imaging analysis, thereby enabling, for example, the cause of material failure to be analyzed after the fact. While these advantages also apply to the standard optical systems available today, such systems have thus far come with a significant disadvantage – their slow measuring speed.
Previously, contact extensometers were needed in order to achieve short measuring times in fatigue tests. However, the necessary contact pressure distorts the results with respect to plastic deformation – especially in lightweight construction materials or at high temperatures. Now advanced image processing technologies are making it possible to combine the advantages of contact and optical extensometers for the very first time.
Thanks to fast, high-resolution cameras that reliably record microstructures, even on polished samples, complicated sample preparation with markers is a thing of the past. At the same time, measurement accuracy is improving, as all of the characteristics of the microstructure are analyzed to measure displacement.
Real-time evaluation at 1000 Hz
While state-of-the-art cameras can record the microstructure of a workpiece surface more than 1000 times per second, conventional processors can only evaluate approximately 200 computationally intensive image correlations per second. Only by parallelizing image evaluation on graphics cards is it possible to measure strain at over 1000 Hz – without the slippage limitations of contact extensometers. The measurement accuracy of the new Fraunhofer strain measurement system meets the requirements of the 0.5 class in accordance with DIN ISO 9513. The size of the field of view can be adjusted to suit the test procedure, thereby allowing the real-time evaluation of strain-controlled tests in the micro and macro range.
Holger Kock, Frauhofer IPM Kommunikation | Fraunhofer-Gesellschaft
Stable magnetic bit of three atoms
21.09.2017 | Sonderforschungsbereich 668
Drones can almost see in the dark
20.09.2017 | Universität Zürich
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy