Design of arbitrary shaped pentamode acoustic cloak based on quasi-symmetric mapping gradient algorithm.

Due to solid and broadband nature, pentamode acoustic cloak is more promising for engineering applications. A simple algorithm based on an elasticity equation is proposed to obtain quasi-symmetric mapping gradient and in turn the characteristic stress for arbitrary shape cloaks. A high degree of symmetry of the obtained mapping gradient and nearly perfect cloaking effect of the designed pentamode cloaks are confirmed by numerical examples. The proposed method paves the way to design more complicated transformation devices with pentamode materials.