TheQ-factor of flexure membranes

We report on the intrinsic or material quality factor (Q-factor) of a number of different materials, possible suited for the construction of low loss flexures. Clamped foil flexure membranes made from titanium, a glassy alloy, Cusil and Havar (high strength non-magnetic alloy), as well as monolithic flexure membranes made from titanium, niobium and Marval 18 (maraging) steel, have been tested. The results show that the highest intrinsic Q-factor occurs for monolithic flexure membranes constructed from niobium, with maraging steel also yielding a high intrinsic Q-factor. Other materials tested were shown to be significantly inferior. For a pendulum of mass 10 kg, with a stress safety factor of δ = 0.3, we predict a maximum Q-factor of 3.1×107 for a niobium flexure, and 2.9×106 for a maraging steel flexure.