3D-printed bio-inspired mechanically interlocked viscoelastic dampers for energy dissipation

Viscoelastic materials are used extensively in energy dissipation applications to mitigate large lateral displacements and attenuate vibrations. One way of exploiting the capabilities of viscoelastic materials is using shear-damping mechanisms such as seismic damping devices. This study utilizes the freedom of design offered by additive manufacturing to produce 3D- printed thermoplastic parts that act as the viscoelastic layer in an energy damping device. A mechanically interlocked damping device with a bio-inspired jigsaw-like interlocking mechanism was designed and manufactured. The damping device is composed of a hard and soft phase. The hard phase is made of steel, while the soft phase is 3D-printed thermoplastic polyurethane (TPU). The mechanically interlocked damper was cyclically tested under different amplitudes and frequencies. TPU was mechanically characterized using uniaxial cyclic tension tests under different rates and different printing processing parameters. Stress relaxation tests were also conducted to obtain the viscoelastic behavior of the TPU material. Material characterization of TPU was used to develop a finite element (FE) model that is used to simulate the mechanically interlocked damper. The FE model was validated with the experimental observations and was then used to examine the significance of damper geometry on the efficiency of energy dissipation.