Front page news

KTH has a magazine called KTH&Co. In this magazine you can read about new research and interesting reportage, which show the community benefit of the research performed at our university.  In the latest issue, we had the privilege to be on the front page. 🙂

KTH&Co nr 3 2014

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Starting up the rig after failure

A few weeks ago the testing in our corrosion-fatigue rig did not go well. The machine somehow went into position control instead of load control, which resulted in the stroke moving upwards. This put a lot of load on the test specimen and the chamber, which then both broke.  We had to repair the induction coil. Luckliy, only a small hole was formed so Teknoheat repaired it very fast using silver solder. New ceramic plates for the chamber was also manufactured. This time I have prepared an extra set in case a chamber breakage happens again. Before starting my experiment there were two important things I had to do.

1. Alignment: Looking at the test specimen we can clearly see the high force it has been exposed to. This means that the alignment of the machine might have been affected. It is therefore very important to check this before we start our expriments again. We perform the alignment by mounting a test specimen containing 8 strain gauges in the grips and then change the alingment by tighten or loosen different positions of the alignment cell. The resulting strain in the test specimen is monitored and we are satisfied when we have an aligmment resulting in zero strain of the test specimen. After calibration we reached alignment class 10. It is not perfect but it is okay. This class means that we have below 1% deviation in strain. The last time we did the alignment we got class 5, which means below 0.5% deviation.

2. Adjustment of the induction coil: To make sure we have an homogeneous temperature on the test specimen, I attached thermo couples on different positions and modified the distance between the coil wires until I reached a temperature gradient of +/- 5 to 10 degrees over the gauge length.

Alignment
Alignment of the machine after severe damage of a test specimen.
reparation coil
The induction coil was repaired with silver solder. Thereafter the wires of the coil were adjusted to generate an uniform temperature on the test specimen.

Zwick/Roell TestXpo day 2

We spent the second day at the testXpo looking at the fatigue testing machines. Vibrophore is a group of machines suitable for high-cycle fatigue testing. Some of them were extreme, like the one on the first photo below – a 1000kN machine. The second one we looked at, 50kN, is maybe more suitable for us. What is nice with these machines is that they are equipped with a high frequency pulsator with electromagnetic drive. So no hydraulic pump and high-pressure oil hoses.

We also had time to stroll around and watch other kinds of test rigs and to enjoy a nice lunch typical German style.

Zwick expo 1MN
Fatigue-testing machine Vibrophore 1000 (1000kN)
Zwick expo 50kN
Vibrophore (50kN)
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Listening to a welcome speech before lunch.

Zwick/Roell TestXpo day 1

We were invited to the Zwick/Roell TestXpo (23rd International Forum for Materials Testing) in Ulm to give a lecture about our lab. I talked about the design of our corrosion-fatigue test rig and shared some problems we had while building it. It was very nice to see the large interest in our rig.

Around 800 people working with mechanical testing visited the expo during the 2 days we were there. The Zwick Roell group opened up their company and let us look at all their products. We were able to test their machines and discuss with both salesmen and technicians. We got to learn more about our laser extensometer, which was very valuable!

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Presentation of our corrosion-fatigue test rig
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From the left: me (Madeleine Ekström), Walter Ganzenmüller (Zwick Roell) , Stefan Andréasson (Zwick Roell Sweden) and Aleksander Koprivc (Zwick Roell)
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Phillip Winkelmayer explains some features of laser- and video extensometers.

 

Networking in Lausanne

Yesterday we took part in The Innovative Smart Materials Networking Conference (ISMC) in Lausanne. It is an one-day conference organized by the Swiss-Swedish Innovation Initiative (SWII). The aim is to promote Swiss-Swedish innovation cooperation and create a larger number of Swiss-Swedish R&D projects.

Presentations by participants were followed by speed dating between companies, academia and fundino agencies. A successful day, with a few new project-proposal ideas, was finished by a very pleasant networking mingle at Le Baron Tavernier.

You can find more info at www.swii.org

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