The Study On Stress And Stiffness Of Conductors Under Tensile Load

The stress distribution and the tensile stiffness of conductors under tensile loading reflect the mechanical properties of conductors.In this paper,taking fixed end of LGJ-300/25 Aluminum Conductor Steel Reinforced(ACSR)as an example,the theoretical calculation method,finite element simulation method and experimental method are used to study the stress and stiffness of conductors under tension load.The force balance equation of the strand is established in the theoretical calculation,and the load and stress distribution as well as the theoretical value of tensile stiffness of conductors under tensile loading are obtained.Furthermore,the influence of temperature on the conductor material is considered,and the influence of temperature on the stress,strain and load of conductors is obtained.Using the helix symmetric characteristics of ACSR during the finite element simulation,a single-stranded model was established,according to the displacements of the corresponding nodes in the model,the constraint equations between node groups are established,and the boundary conditions and loads are applied according to the constraint equation,thereby reducing the computational scale of the model and saving calculation time.Finally,according to the measuring principle of tensile stiffness of ACSR,the tensile test apparatus is designed,the test method of the tensile stiffness is given,the tensile test of the wire is completed,the process of the test is described in detail,and the load-strain curve of the conductors is obtained.The results show that:(1)The contact zone of the center line and the layer with six strands is line contact,the area of the zone is larger than others,extrusion stress in the line contact zone is minimum,and extrusion stress of other contact zone decreases gradually from the inside to the outside.The load and stress of the strands on the cross section of the conductors are reduced from the inside to the outside.With the increase of the temperature of the conductors,the load of aluminum strands is relatively reduced,and the load and stress of the innermost aluminum strand are reduced to zero at first.(2)At the beginning of the tensile load,the tensile stiffness of the wire cross section is slightly increased.As the load increases,the plastic deformation of the aluminum wire occurs,and the tensile stiffness of the wire cross section begins to decrease drastically.