A consecutive series of tests was performed using mock-ups equipped with modified components. Each test sequence included activities at ambient temperature (assembly, bolt preload, and check of the measurement system) and load tests in liquid nitrogen. To simulate the expected lifetime of W7-X, several thousand load cycles were executed. Additionally, high load tests were performed to investigate the limits of the connection.
It was shown that the connection could take the nominal loads with a safety margin of about 1.2. Above this the bolts starts to deform plastically. A MoS2 lubricant layer introduced between the relevant sliding surfaces of the bolted connection significantly reduced stick-slip which was detected during previous test campaigns.
This paper gives an overview on the functionality test and main conclusions of the experimental test campaign.