Topology optimization of pretensioned reflector antennas with unified cable-bar model

Abstract From innovative high-rise buildings through spacecraft, applications of prestressed cables are not uncommon. But the use of prestressed cables in ground-based reflector antennas is very rare. In this paper, prestressed cables were introduced to the ground-based antennas to achieve the lightweight design requirements. To determine the layout of the prestressed cables, a gradient-based topology optimization model was established. In this optimization model, the continuously varying 'lack of fit' is used to replace the discrete element type variables as the design variables, and smooth sigmoid functions are introduced to unify the discrete allowable stress of cable and bar elements. Eventually, the discrete topological variable optimization problem is transformed into a continuous one. Besides, to avoid the occurrence of grey elements in the optimized results, a parameter control strategy for the sigmoid functions is carried out during the optimization procedure. As an example, the optimizations of an 8 m truss antenna and an 8 m cable-truss antenna are implemented, and the discussions of the results are given.