Computer simulation of circular plastic compression of a lightning protection cable with an optical module

Abstract

In the work, using computer simulation, the geometric parameters of the elements of a lightning protection cable (strands of the LK-О type) with an optical module at circular plastic compression are determined. A delay in the formation of side contacts (arch effect) between the wires of the outer layer of the strand of 1 + 9 + 9 structure with a dense lay of elements is established, which creates conditions for transferring pressure to the inner layers and causes a significant (up to 20 %) deformation of the optical module surface at a degree of compression of ql = 5.5 %. In this case, the filling level of inner layer gaps reaches a critical one, which contributes to the transition to the elongation deformation (drawing) of the wires and to a decrease in the longitudinal stiffness of the strand. Violation of the condition of tight laying of the strand elements by choosing the geometric dimensions of the wires during modeling, which ensure the presence of initial gaps between the layers, reduces the deformation on the surface of the optical module to ql = 7–8 % at a degree of compression ql = 6 %, which is explained by more intensive formation of lateral contacts between wires of the outer layer, reducing the radial component of the pressure transmitted inside the strand. It is shown that its reduction can also be achieved by increasing the number of wires in the layers. For a strand of 1 + 10 + 10 construction, in the presence of a gap between the inner layer and optical module, the deformation on the core surface is 3–4 % at a compression ratio of ql = 6.3 %, which ensures the operability of the optical module (core) after circular plastic compression and integrity of optical fibers.