Gerald Pinter, Florian Arbeiter, Johannes Wiener, Andreas Frank, Otmar Kolednik
Papers # 2018 Las-Vegas
In order to further increase the fracture toughness of pipes, biomimetic layer design of the pipe wall can be used. Therein, soft polymer interlayers can act as crack-arresters in a matrix of stiffer and inherently more brittle polymers. The effectiveness of the crack arresting role of soft interlayers in a multi-layer system was investigated by applying elastic plastic fracture mechanics. Bending tests using the J-integral as toughness parameter were performed. Preliminary results confirmed that fracture toughness in the vicinity of the soft layers could indeed be increased to multiples of the matrix values.
This work aims to offer some insight into the advantages of biomimetic multi-layered materials, the mechanisms behind their unique properties and the applicability of bio-inspired structures for engineering applications. The layered structure of the deep-sea sponge serves as an idea giver for future multi-layered pipewall design. After millions of years of evolution this marine animal has developed a skeleton that combines high stiffness with high fracture toughness by using soft protein layers inside a brittle bio-glass matrix . However, the question remains, whether these principles can be adapted for engineering materials.
An unreinforced polymer and a mineral reinforced polymer were used to mimic the deep-sea sponge’s structure in an effort to achieve advantageous material properties. Due to non-linear behavior of both materials, it is necessary to apply elastic plastic fracture mechanics. J-integral was used to accurately describe the material’s fracture toughness. Single edge notch bending (SENB) tests were performed to measure the effect of a single soft interlayer on the crack resistance. The comparison between a bio-inspired multi-layer structure and a homogeneous material revealed a significant increase in fracture toughness due to the biomimetic design.