Investigation of the dynamic behavior of the ITER tokamak assembly using a 1/5.8-scale model

The dynamic behavior of the ITER tokamak assembly has been investigated, using a 1/5.8-scale model. In the static load test, the observed deformations and stresses were confirmed to be linearly proportional to the applied loads. In the vibration test, the first and third eigen-modes corresponded to horizontal vibration modes, with natural frequencies of about 29 and 81 Hz, respectively. The global-twisting and oval modes were found to be in the second and forth modes, with frequencies of about 60 and 86 Hz, respectively. A comparison of experimental and analytical results showed that the deflections and the induced stresses in the analysis were approximately half of those found in the experiment. Natural frequencies have also been compared. The frequency in the first mode was almost the same for both the experiment and the analysis. However, in higher vibration modes, the natural frequencies in the experiment were found to be smaller than those in the analysis. To further examine the dynamic behavior of the coil structure, a vibration test of the entire sub-scale model is planned using the vibration stage rather than the shaker.