Vibration testing of bolt connections 13 January 2022

TesT has launched the next generation of Junker testing machines with transverse displacement amplitude control, enabling stimulation of the conditions in the field even more realistically.

A bolted connection often bears a lot of responsibility eg. in railroad or aeronautical engineering. But what can it withstand and how long before it loosens? The Junker test has always been the preferred method to get the required answers for quality assurance. It is used in particular to measure the service life of a bolted connection under dynamic transverse load. But the established method still had its weaknesses.

Up to now, it has only been possible and standardised on a vibration test stand to adjust the transverse stroke without specimen before the test. During the test, however, the actual resulting stroke declined because the bolted connection was tightened. If the bolt then loosened during the test, the stroke continued to change. In the field it is ultimately the forced transverse stroke that leads to the loosening of bolt connections.

In order to enable a more differentiated test setup, the new TesT 208.200kN allows to control the transverse stroke in a closed loop as desired during the running test. The transverse displacement amplitude can be kept constant. Any desired ramps or other sequences can be simulated. The product innovation already anticipates the new aviation standard ISO 16130, which describes amplitude regulation during the execution of experiments as preferred.

It meets DIN 65151, DIN 25201-4, DIN 16130 and can be used to test all elements of bolt connections and locking systems. With the 208.200kN, TesT has further developed the Junker test decisively, setting new standards in the quality assurance of bolted joints.

Claire Aldridge Deputy Editor t: +44 (0) 1727 743 889

Having joined the magazine in 2012, Claire developed her knowledge of the industry through the numerous company visits, exhibitions and conferences she attended both in the UK and abroad.

Claire prides herself on keeping readers well informed and up to date with the latest industry news.