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.
A novel design of parallel piezoelectric six-degree-of-freedom accelerometer
According to the drawback of elastic style six-degree-of-freedom (6-DOF) accelerometer, a novel parallel piezoelectric six-degree-of-freedom accelerometer is proposed. First, the operating principle and structure of the accelerometer is presented, then the finite element model of accelerometer is established by ANSYS analysis tools, and getting some parameters, such as output charge sensitivity, resonance frequency etc. Finally, on the basis of analysis of simulation results, a conclusion can be given that cross-axis sensitivity is less than 1%. The resonance frequency is more than 5900Hz, the accelerometer has simple and rational structure and all parameters meet requirement.
Blades Forced Response Analysis With Friction Dampers
A multiharmonic frequency domain analysis combined with a Craig-Bampton component mode synthesis is presented to compute the dry friction damped forced response of blades. The accuracy of the analysis is established, for a cantilever beam with a dry friction damper attached, by comparison with experimental results and time domain analysis. The method has then been applied to a model fan blade damped by a blade to ground damper.