Jiancheng Wan

Calculation Method of Stiffness Matrix in Non-linear Spline Finite Element for Suspension Cable

Abstract: Through the characteristics of cubic B spline function, the stiffness matrix expression is obtained for the non-linear spline finite element of the suspension cable, and the three calculation method is put forward such as the integral by parts method, the matrix assembly method based on spline integral and the matrix assembly method based on Gauss integral, which are applied to calculate the non-linear stiffness matrix. The integral by parts method using the Leibniz formula as foundation can calculate every item of the stiffness matrix directly, but its efficiency is low when the matrix order is high. The matrix assembly method based on spline integral fully uses the local non-zero property of the spline function, converts the calculation of high order matrix into calculation of 4 order matrix and its assembly, with high efficiency and small storage in calculation. The matrix assembly method based on Gauss integral is similar with the method based on spline integral, but its workload is larger than the method based on spline integral when the matrix order is high. These calculation methods can all be processed by parallel algorithm to improve calculation efficiency, which can provide new ideas for high efficient numerical analysis works.

Application of Piecewise Catenary Method in Length Calculation of Soft Busbar in Ultra-high Voltage Substation

Abstract: According to actual setting-up operation condition of the soft busbar in the ultra-high voltage substation, the nonlinear piecewise catenary equations are established including weight of the insulator string, elastic elongation of the busbar, weight load of the electrical fitting etc. several influence factors on basis of the elastic catenary equation. The initial value selection plan is also given out for Newton iteration method of the nonlinear equations. The method sets both the insulator string and the busbar as the catenary lines, and considers the weight of fitting of multiple split conductors in the final cable shape, which greatly improves calculation accuracy. Reliability of the method is validated through comparison between calculation result of the piecewise catenary method and actual data. The piecewise catenary calculation forwarded in this paper is simple in formation and small in calculation quantity, which is liable to realize by program. The sags corresponding to the different blanking length of the busbar are obtained according to calculation results. The method can provide the effective mean for the length calculation and engineering construction of the soft busbar in the ultra-high voltage substation.

Stress Analysis of Boom of Special Mobile Crane for Plain Region in Transmission Line

Basis of the boom force analysis of special mobile crane for plain region in transmission line, the load type of boom design is confirmed. According to the different combinations of boom sections, the composite pattern of the different boom length is obtained to suit the actual conditions of boom overlapping. The large deformation model is employed with FEM to simulate the stress distribution of boom, and the calculation results are checked. The performance curves of rated load with different arm length and different working range are obtained, which ensures the lifting capacity of special mobile crane meeting the requirement of tower erection of transmission line. The proposed FEM of boom of mobile crane would provide certain guiding and reference to the boom design.

Dynamic analysis of suspension cable based on vector form intrinsic finite element method

A vector finite element method is presented for the dynamic analysis of cable structures based on the vector form intrinsic finite element (VFIFE) and mechanical properties of suspension cable. Firstly, the suspension cable is discretized into different elements by space points, the mass and external forces of suspension cable are transformed into space points. The structural form of cable is described by the space points at different time. The equations of motion for the space points are established according to the Newtons second law. Then, the element internal forces between the space points are derived from the flexible truss structure. Finally, the motion equations of space points are solved by the central difference method with reasonable time integration step. The tangential tension of the bearing rope in a test ropeway with the moving concentrated loads is calculated and compared with the experimental data. The results show that the tangential tension of suspension cable with moving loads is consistent with the experimental data. This method has high calculated precision and meets the requirements of engineering application.