Integrated design of a lightweight metastructure for broadband vibration isolation

•Comparing with the existing ‘combined’ QZS designs with parallel arrangement of both negative- and positive-stiffness elements, a ‘monolithic’ beam-like QZS design was proposed with balanced ultra-low stiffness and nonlinear behaviors, which has the obvious benefits in terms of lightweightness and integration.•The 1–3D configurations of the metastructure with different combinations of the QZS unit cells in series or/and in parallel were investigated, which provides the design guidelines for the 3D metastructure with customizable level of load-carrying capacity and deformation space.•The developed optimization design method was a powerful tool to achieve targeted QZS feature with complex geometry of the flexural beam microstructure, and it was successfully utilized to quantitatively control the metastructure's load-carrying capacity and vibration isolation ability.•A practical engineering application was presented with the metastructure's vibration isolation performance being successfully demonstrated on a real spacecraft's control moment gyros (CMG) (up to 90% reduction in 100–600 Hz frequency range with only a 4.5% gain in mass).