Deformation and pattern transformation of porous soft solids under biaxial loading: Experiments and simulations

In this work, we combine both experiments and numerical simulations to study the large deformation mechanics of two-dimensional patterned porous silicone rubber under biaxial loading, by focusing on the combined compressive and tensile loading. Particularly, we design a loading apparatus to impose the biaxial loading and fabricate patterned porous silicone rubbers through 3D printing. Although the pattern transformation with alternating elliptic voids has been observed under uniaxial compression before, our results show that the pattern transformation can be promoted by biaxial compression, while biaxial compression/tension can delay it. When the ratio between tension and compression is larger than a critical value, a new pattern transformation has been observed. In addition, if the imposed tension in one direction is larger than the compression in the other direction, the pattern transformation with alternating elliptic voids cannot occur. Biaxial loading provides new opportunities to fabricate the tunable devices and imprint complex patterns with soft solids.