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 review of friction damping modeling and testing
This survey provides an insight into the modeling and testing of uniaxial friction dampers. The focus is on attenuating the linear relative movement along planar surfaces for frequencies between 10 Hz and 1 kHz. An overview of the different approaches seen in the literature concerning friction damping is provided. Examples and evaluation of such dampers excited over a wide range of frequencies are presented. The information required to develop models of friction dampers is covered. To that end, different modeling approaches are presented for dry friction. Dynamic friction models with an internal state are covered, and their advantages are described. Other modeling approaches are reported for complete systems with friction dampers. Both numerical and analytical models are covered. Experimental configurations from a selection of authors are also included. Finally, a series of suggestions for the numerical modeling and experimental testing of a friction damper are given.
First Along the River: A Brief History of the U.S. Environmental Movement
Chapter 1: Philosophical Foundations Chapter 2: The 1400s through the 1700s: Inhabiting a New Land Chapter 3: The Early 1800s: Destroying the Frontier Chapter 4: The Late 1880s: Building an Industrial Nation Chapter 5: The 1900s through the 1930s: Beginnings of the Conservation Movement Chapter 6: The 1940s through the 1960s: Prelude to the Green Decade Chapter 7: The 1970s: The Conservation Movement Matures Chapter 8: The 1980s: A Conservative Backlash Chapter 9: The Early 1990s: Government Retrenchment and Public Apathy Chapter 10: The Environmental Movement in the Post-9/11 World Conclusion