[en] Highlights: • Accelerated electrochemical corrosion results in severer plastic deformation with finer grains. • Lower applied potential can increase protein adsorption on sample surfaces. • The tribo-film decreases the shear stresses and relief subsurface deformation. • Tribocorrosion induced passive film can suppress the annihilation of stacking faults. - Abstract: The subsurface microstructures of metallic implants play a key role in bio-tribocorrosion. Due to wear or change of local environment, the implant surface can have inhomogeneous electrochemical corrosion properties. In this work, the effect of electrochemical corrosion conditions on the subsurface microstructure evolution of CoCrMo alloys for artificial joints was investigated. Transmission electron microscope (TEM) was employed to observe the subsurface microstructures of worn areas at different applied potentials in a simulated physiological solution. The results showed that applied potentials could affect the severity of the subsurface deformation not only by changing the surface passivation but also affecting the adsorption of protein on the alloy surface.

[en] The W7-X plasma vessel (PV) is part of the cryostat wall and forms a vacuum and thermal barrier between the hot vessel interior and the superconducting coils. The vessel is thermally loaded from the inside and is actively cooled by numerous cooling water pipes in order to control its temperature. However, due to the complex geometry and large number of different types of ports, the cooling pipes are distributed irregularly with varying distances in between them. So the temperature distribution of the PV becomes quite inhomogeneous even with homogeneous load density, and impermissible temperature hot spots >130 °C may arise. Particularly for the upcoming long pulse operation phase 2 (OP2), it is necessary to know the locally allowed thermal loads on the PV. Therefore, temperature distribution maps for different heat loads from 1 kW/m² to 12 kW/m² were calculated in order to determine the corresponding hot spots. The available CAD geometry was not convenient for this extensive and complex analysis; therefore, a simplified shell-beam model was employed to get an approximate temperature distribution, and a correction formula was derived to calculate more accurate values at the positions of interest. In some areas with large distances between cooling pipes, additional copper stripes are welded onto the PV to improve the heat transfer. For these regions local models were built to calculate the temperature distributions, and, in the course of this analysis, to judge the effect of the copper stripes. The calculation results indicate positions to be additionally protected and will be used to determine safe operation limits.

[en] The structural design of the vacuum barrier was introduced, and then a 3D finite element model is established by using ANSYS for the purpose of coupled thermal-mechanical analysis. The temperature distribution and thermal stress in normal and fault condition is obtained from the calculation. The calculation results can verify the reasonability of the structural design of vacuum barrier and lay the foundation for the further optimization. (authors)

[en] Highlights: • We model the reasonable finite element model for feeder thermal shield. • We analyze the temperature distribution and pressure drop of the thermal shield. • Different materials for the thermal shield were analyzed. • Thermal stress analysis was performed and analysis result be applied to the detailed design. -- Abstract: The thermal shield for ITER magnet feeder plays the role of preventing thermal radiation from the warm components to the cool superconductor and supercritical helium system. Heat loads were calculated for thermal analysis, then finite element model was established by ANSYS code. Thermal analysis was performed in order to check the temperature distribution and pressure drop of the thermal shield under normal operation state. Different materials (steel or aluminum) for the thermal shield were also checked. Thermal stress analysis was performed based on the results of thermal analyses. Compared analysis results with design criteria, it is demonstrated that the results of the simulation are within allowable design requirements and the design scheme can be applied to the detailed design

[en] A new modified homotopy perturbation method is presented for strongly non-linear oscillation by coupling the homotopy perturbation method and the modified Lindstedt-Poincaré method. The advantage of this method is that it does not need a small parameter in the physical system as in He's homotopy perturbation method, and the accuracy is greatly improved. Some examples are tested, and the obtained results show that the current method is very effective and convenient for solving strongly nonlinear oscillators. (authors)

[en] Due to the position of ITER ELM coils assembly and its working condition, these coils are subjected to large electromagnetic force and thermal expansion caused by the nuclear heat and ohmic heat. The stress analysis and optimization work within six different design schemes of ELM Coils (ELMC) support are carried out by finite element software ANSYS. The analysis results proof that when the support has the V character configuration alignment of its transversal elliptical through-holes on both ends of top and bottom, the maximum Tresca stress is at the lowest value. The final outcome brings about meaningful reference for ELMC support design. (authors)

[en] The structure of the straps on new type of ICRH antenna for EAST tokamak was introduced. Based on the calculation of the condition in which straps would work, the work temperature distribution of the straps could be obtained. Using this result, the straps resistance to thermal load and its influent on the strap structure under the operation condition are simulated. It is demonstrated that the radiation surface temperature and overall structure strength of the straps under the real thermal load (0.2 MW) satisfy the design requirements. (authors)

[en] The structure of ITER TF superconducting busbar was introduced. The electromagnetic and mechanical analysis of busbar under operating conditions was performed by means of finite element method, and then the stress and deformation of busbar was checked. The analysis results proved that the structural of busbar and its supports was reliable and safe. (authors)

[en] The ITER toroidal field (TF) in-cryostat feeder system (ICF) locates in the main cryostat of the Tokamak.It consists of 18 segments, which form a ring by connectors and hang on the corresponding TF coil terminal area. During cooling down the components in the cryostat,the shrinkage of ICF is not synchronous with the TF coil. In this case, relative displacement occurs on the circumferential end surfaces of the neighbor segments, so that the function of displacement compensation is required on the connector. Researching on cooling process of the ITER TF ICF system, finite element method (FEM) was applied on the numerical simulation of the steady-state and transient temperature field in the ICF. The heat load and temperature distributions in ICF were worked out; furthermore, the temperature-time curve and deformation-time curve were also presented. The results show that active cooling is not required on ICF, the heat load and thermal stress is very weak. Meanwhile, the results will provide primary parameters for the design of connector with compensation function. (authors)

[en] Based on the energy principle, by means of the unit force method and the Castigliano theorem, the moment and stress distribution along the S-bend under the given displacement deformation are calculated analytically. According to the calculation, the moment and the stress along the S-bend arise mainly due to the thermal contract, but the gravity effect is non negligible. The maximum stress along the S-bend will increase by over 10% after the gravity effect is taken into account. Based on the premise that the height of S-bend is limited, it is found that the smaller the radius of the circles, the smaller the maximum stress along the S-bend, so we can choose the appropriate radius according to the required stress strength and the processing technology during the detailed design. Results shows that the analytical method proposed here is effective and useful for the structure optimization of the practical engineering design. (authors)