Thermo-mechanical tests on W7-X current lead flanges

•There are significant mechanical loads on the cryostat and radial flanges for W7-X current leads.•These are due to evacuation of W7-X cryostat, cool-down of cold mass, electro-magnetic forces and self weight of leads.•The actual mechanical loads were reduced to simplify the experimental set-up.•The tests were carried out on mock-up flanges test assembly at ambient temperature and at 77K.•The thermo-mechanical tests on W7-X current lead flanges validate the design and joints of these flanges to the leads. Fourteen pieces of high temperature superconducting current leads (CL) arranged in seven pairs, will be installed on the outer vessel of Wendelstein 7-X (W7-X) stellarator. In order to support the CL, it is provided with two glass fiber reinforce plastic (GFRP) flanges, namely, the lower cryostat flange (CF) remaining at room temperature and upper radial flange (RF) at about 5K. Both the flanges i.e. CF & RF experience high mechanical loads with respect to the CL, due to the evacuation of W7-X cryostat, cool-down of cold mass including the CL, electro-magnetic forces due to current & plasma operations and self weight of CL. In order to check the integrity of these flanges for such mechanical loads, thermo-mechanical tests were carried out on these flanges at room temperatures and at liquid nitrogen (LN2) temperatures. The details of test set-up, results and modeling are described in the paper.