Philosophy of stress-strain measurement for proto-type cryo-line of ITER

Large and complicated network of cryo-lines are required for the ITER cryogenic system, connecting cryo-plant, cryo-distribution system and applications. Fixed support, sliding support and vacuum barrier are the integral part of the design of the cryo-lines. These supports, apart from the purpose of supporting the dead weight of internal process pipes, take care of different forces generated due to the thrust, spring and the thermal load. Therefore, stresses are generated on them. In order to have a measurement of the stress, experiments are done with strain gages mounted on these components. For the proto-type cryo-line of ITER, stress analysis has been carried out and the contours of stress on these components are available. The measurement with strain gages will be done to validate the design as well as to get the idea of the absolute values of the stresses expected to generate. The temperature zones will be in the range of 4.5 K to 80 K. Therefore, special strain gage and its measurement have been planned for this purpose. The paper will discuss mounting process of the strain gages, the basis of deciding the location of gages, measurement procedure with error compensation and correction as well as data acquisition techniques.