Abstract
This paper investigates a novel design approach for a vibration isolator for use in space structures. The approach used can particularly be applicable for aerospace structures that support high precision instrumentation such as satellite payloads. The isolator is a space-frame structure that is folded in on itself to act as a mechanical filter over a defined frequency range. The absence of viscoelastic elements in such a mounting makes the design suitable for use in a vacuum and in high temperature or harsh environments with no risk of drift in alignment of the structure. The design uses a genetic algorithm based geometric optimisation routine to maximise passive vibration isolation, and this is hybridised with a geometric feasibility search. To complement the passive isolation system, an active system is incorporated in the design to add damping. Experimental work to validate the feasibility of the approach is also presented, with the active/passive structure achieving transmissibility of about 19dB over a range of 1–250Hz. It is shown here that the use of these novel anti-vibration mountings has no or little consequent weight and cost penalties whilst maintaining their effectiveness with the vibration levels. The approach should pave the way for the design of anti-vibration mountings that can be used between most pieces of equipment and their supporting structure.
Highlights
For space launch vehicles, it is essential to isolate the vibration of aerospace structures to prevent damage to the payload
Following on from this work, the present study investigates the use of a folded space-frame structure as an antivibration mounting
A Darwinian–Lamarkian hybrid approach [13] was taken to ‘repair’ infeasible geometries when discovered throughout the routine using a gradient-based sequential quadratic programming (SQP) search of an algorithmically differentiated implementation of the feasibility metric Eq (6) [14]
Summary
It is essential to isolate the vibration of aerospace structures to prevent damage to the payload. The structure was optimised based on energy flow analysis models and relied on the wavelengths of the vibrations of interest being of a similar order to the changes introduced into the geometry of the structure during optimisation [8] Because of this limitation, an active control system was used to control the lower frequency vibration. The computational design of a passive structure [9] is combined with co-located ‘sky-hook’ damping [10] into a compact vibration isolation mount with improved ease of assembly [11]. The design is tested dynamically to demonstrate the significant attenuation afforded by the combined passive and active elements This novel concept may represent a new type of lightweight and cost effective anti-vibration mounting designs.
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