**7. Conclusions**

In this paper, a finite element, fully three-dimensional solid modeling method was used to study the mechanical response of a steel-cored aluminum strand (ACSR) with a mid-phase jumper under a wind load. The whole model (simplifying an ACSR into a solid cylinder) and a local model (modeling according to the actual structure of an ACSR) of the mid-phase jumper were established. First, the movement of the mid-phase jumper of the tension tower under a wind load was studied based on a whole finite element model, and the equivalent Young's modulus of the whole model was adjusted based on the local model. The results of the whole model were then imported into the local model, and the stress distribution of each strand of the ACSR was analyzed in detail to provide guidance for the treatment measures. Therefore, the whole model and the local model complemented each other, which could reduce the number of model operations and ensure the accuracy of the results. Although this method was applied to the stress and deformation analysis of a mid-phase jumper in this paper, it can be used to study the bending deformation of rope structures with a complex geometry and a main bending deformation.

The analysis showed that the swing of the mid-phase jumper in the east–west direction caused a greater bending moment at the lower area of the mid-phase jumper, which led to the stress concentration appearing near the outlet of the tension clamp. This explained why the actual mid-phase jumper breakage occurred at the outlet of the tension clamp. The maximum stresses of the outermost and third layers were higher than the yield strength under a level-6 wind. The difference in σa between the outermost and third layers increased gradually when the wind load increased, and the difference was approximately 10 MPa under a level-6 wind load.

Interestingly, σa of the third layer of the conductor (79.7 MPa) was greater than σa of the outermost conductor (71.4 MPa), which was verified by the results of the fatigue tests. Based on the analysis of the surface wear of the third layer of the conductor, the reason for the fracture of the third layer of conductor was explained. The feasibility of the element modeling method was verified through a comparison with the results of a subsequent series of experiments.

In addition, the effects of the friction coefficient on the bending of a mid-phase jumper were studied. It was found that the friction coefficient influenced the bending of the mid-phase jumper, but the effect was not great.

**Author Contributions:** Methodology, W.X., P.M., and C.H.; validation, P.M. and W.X.; investigation, C.H.; data curation, P.M.; writing—original draft preparation, P.M.; writing—review and editing, W.X.; project administration, Y.L.; funding acquisition, J.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the State Grid of China Science and Technology Project, under the gran<sup>t</sup> no. 52130417002U.

**Conflicts of Interest:** The authors declare no conflict of interest.
