Are you concerned about accumulating damage over long periods of cyclic loading?
Fatigue testing of composite materials is becoming increasingly important as they find use in a wider range of critical structural applications with the expectation of long service life. It is now widely recognized that these materials do accumulate damage over long periods of cyclic loading, even if the failure mode and mechanisms are radically different to conventional metallic fatigue. One of the challenges, when performing fatigue tests on polymer composites, is to produce a good S-N curve in the shortest possible time without subjecting any specimens to excessive temperature generated by self-heating. Traditionally, the test frequency has to be set to a conservatively low value in order to ensure that overheating does not occur. In response to this, a new feature in WaveMatrix™ Software continuously monitors the specimen temperature and automatically adjusts the test frequency to minimise the test time and ensure that the specimen is never subject to an excessive temperature rise. Read Dr. Peter Bailey’s interview with AZOM where he discusses this exciting new development.
JEC Europe 2014
Instron recently exhibited at JEC Europe 2014, the major global composites exhibition that gathers state-of-the-art materials, equipment, and technology companies in the composites world. With a solid focus on the composites industry and global research, our international team of experts appreciated talking to the visitors that stopped by the booth for advice on what they should pay attention to, what could be the best configuration for their testing system, and also those who came to inquire about our full range of testing equipment they would need for their testing.
This year, we demonstrated the full range of testing systems required for composites applications testing. A 5980 tensile tester equipped with a compression after impact (CAI) fixture, the Advanced Video Extensometer (AVE), Bluehill® 3 Testing Software, and our brand new Digital Image Correlation (DIC) software. This software allows the technician to investigate the strain in 2 dimensions during the test or after with post treatment. The power of this system lies in the simplicity and the consistency of the configuration: no need of additional cameras and software that is known to generate trouble and data transfer issues.
Fatigue testing becomes more and more required, especially for aerospace application. At JEC, we found it important to demonstrate the all-electric range of dynamic system, equipped with Wavematrix™ Software and the SSHC (Specimen Self-Heating Control) module. Even if the capacity of ElectroPuls™ is limited to 10 kN, which could be low for composites, the system is now utilized more frequently to test smaller specimens. The powerful SSHC module was developed after feedback from our customers that their main testing challenges with composites is the temperature of the specimen that tends to climb with the frequency. Our SSHC module allows the frequency of their fatigue testing system to be controlled according to the specimen temperature, so that it won’t be heating. A good point when you don’t want your material properties to change as it is heating.
The very last equipment that was demonstrated at JEC 2014 was a CEAST 9340 drop tower, with a temperature chamber and the DAS data acquisition system. With a capacity up to 1800 J, the 9300 impact testers range allows to test composites in high energy and temperature. This very safe instrument offers a motorized crosshead positioning system and changeable tups and inserts for the user comfort and safety. Our specialist from our CEAST factory in Italy received a lot of questions on impact testing standards for all kind of applications and was happy to give tips and advice. If you visited us during JEC 2014, we thank you for your time to meet with us. It was great to speak to so many of you! We are already looking forward to meeting you at JEC 2015, Paris, March 10-12th!