Design and test of a friction damper to reduce engine vibrations on a space launcher
Space launchers are submitted to complex vibration environments and this can impact the payload it is carrying. Ensuring the protection of the payload therefore requires the addition of a secondary system. In this paper, a rapid design method for the dimensioning of a friction damper is developed, based on the equivalent energy dissipation with that of a viscous damper. A friction damper is designed and a prototype is built. The friction damper is first characterised alone and it is then mounted inside a scale model of a launcher last stage. The friction damper is adequately modelled by a spring in series with a friction element. The damper prototype proves to efficiently damp the rocket engine vibrations, and the design method used for dimensioning the friction damper gives a good approximation for the optimal sliding force of the damper.
Passive Damping Devices For Aerospace Structures
Abstract Aerospace structures are subjected to a variety of large dynamic excitations especially during launch and ascent into orbit, leading to high dynamic responses. In order to attenuate the dynamic responses it is possible to manipulate the mass matrix or the stiffness matrix or to introduce damping. This paper deals with passive damping devices which can be incorporated in the spacecraft structure in order to introduce significant damping. Four different damping principles will be discussed. These principles are based on the following physical effects: • Shearing a viscous fluid in a small gap (hydrodynamic concept). • Throttling (hydraulic concept). • Coulomb friction. • Energy dissipation by relaxation and recovery of elastomers (viscoelastic bushings). For these damping principles formulas and material data are presented in order to pre-design corresponding damper devices. For each damping device a design proposal will be given. In order to investigate the influence of elasticities within the damper on the damper performance, simulations with simplified mathematical models of the damping devices have been performed.
Characterization and modeling of the static and dynamic friction in a damper
Abstract This paper presents a new test and analysis method for the characterization of the static and dynamic friction in a damper. In addition, a new friction model that refers to the experimental results is presented and compared with the Coulomb, Spring–Damper, and Bouc–Wen models. The proposed model accurately represents the experimental results as well as responds to the changes on the behavior due to frequency variations.