Experimental Study On Fatigue Of Upper Cell Bellows In Fusion Device

The International Thermonuclear Fusion Experimental Reactor(ITER)is a plan to produce large-scale nuclear fusion superconducting Tokamak experiment device。The bellows as connected channels between the vacuum vessel and cryostat,cryostat and external buildings,absorb the relative displacement between vacuum vessel and cryostat,cryostat and external building,maintain devices under various conditions of stable operation,performance is very important.According to the requirements of the project,ITER device needs to design the bellows of all Windows according to EJMA standards.Then,three-dimensional model of bellows is established through CATIA three-dimensional modeling software,and imported into ANSYS Workbench to carry out finite element analysis of strength,plastic failure and fatigue life under various working conditions.Finally,the prototype is processed according to various working conditions for experimental verification.After the analysis and experimental results meet the requirements of the actual working conditions,mass production begins.In this paper,the upper cell bellows is taken as the research object,and the fatigue analysis of the bellows under various working conditions is carried out and verified through experiments to meet the contract requirements.In the finite element analysis of plastic failure,the maximum linearized principal stress of the corrugated joint is obtained.The membrane stress under NO condition is5 MPa,and the membrane stress + bending stress is 20 MPa.The membranestress under NO + Cr ICE II condition is 5MPa,and the membrane stress + bending stress is20 MPa.The membrane stress under BK + SL-1 condition is 46 MPa,and the membrane stress + bending stress is 99 MPa.In the finite element analysis of fatigue life,the stress under NO condition is 102 MPa,and the number of cycles can be calculated to be 1e6 times.The stress under NO + Cr ICE II condition is 428 MPa,and the number of cycles is 40965.The stress in BK + SL-1 condition is 436 MPa,and the number of cycles is 38,170.The finite element analysis results of plastic failure and fatigue life show that the allowance is large and meets the design requirements.During the experimental test,the displacement load is-12 mm ～ +19mm,and the fatigue test cycle is 300 times.The average experimental stiffness K of the upper cell bellows is 361.79N/mm,and the upper cell bellows pass the test smoothly.The above research provides theoretical basis and technical guarantee for the engineering design and manufacturing of ITER device Upper Cell Bellows,provides technical reference for other window bellows and provides reference for the design and research of such large rectangular bellows in the future.