Dynamic Analysis and FEM Modeling of Tensegrity Chain

In the thesis, we analyze a particular periodic structural system consisting of two different tensegrity structures and two different masses (diatomic structure) that act as oscillators (or resonators); a meta-structure called "tensegrity chain" was created, which is capable of inhibiting the transmission of waves in the range of 1 Hz to 10 Hz.

The thesis focuses on the numerical FEM modeling of a tensegrity frame-chain system, using the RFEM 5 program with the RF‑DYNAM Pro add-on module by Dlubal Software.

In particular, a real-world application example is analyzed where the chain is designed to inhibit signal transmission in appropriate frequency bands, specifically for the range between 1 Hz and 10 Hz, in order to seismically isolate an external object. The created structure can be defined as a unidirectional seismic isolator, where the internal complex of elements oscillates while the external one is isolated.

The proposed application involves the utilization of cables connected to a beam in order to support the weight of the internal and external masses and allow for longitudinal movement of the masses. Furthermore, one end of the chain is rigidly connected to the ground, while the other end is kept free by a pillar resting on cylindrical steel rollers that allow it to slide horizontally: Specifically, the components of the tensegrity chain are a resonant mass of 64 kg and a host mass of 1.01 kg; the stiffness of the two tensegrity prisms called "slender prism and squat prism" is 𝑘ℎ = 3,388.13 N/m (sum of two slender prisms) and 𝑘𝑟 = 1,942.64 N/m, respectively.

This structure demonstrates the efficiency of a unidirectional seismic isolator in signal transmission as an example of a real application.