Characteristics Of Magneto-rheological Damper With Squeeze Mode And Its Effect On Helicopter "Ground Resounance" Dynamic Stability

Stability of the coupled rotor-body system has long been one of basic topics of helicopter dynamics. To improve the stability, one common method is to install dampers at the roots of blades. However, commonly used dampers can hardly meet different demands when helicopter working in different conditions. Therefore, in this thesis, the magneto-rheological damper (MRFD) was studied which is of simple structure, high reliability and self adaption.First, some main structural parameters of the MRFD as well as the rheological quality of the magneto-rheological fluid were analyzed; some common experiment methods were introduced. Second, taking the characteristics of the MRFD and its matching with blades into consideration, the squeeze mode MRFD was designed. After that, the mechanical characteristics of the squeeze mode MRFD was tested to tell us that, compared with those MRFD work in other modes, the squeeze mode is advantageous for its compact structure, less displacement and higher strength. Third, with the test data, we get the force model which use imitatation.Later on, the non-linear dynamic model of the coupled rotor-body system with the MRFD was constructed and A test-bed which is fit for this model was designed. At last, the dynamic stability test for the system was implemented. The result of which says that the MRFD can improve the dynamic stability of the system markedly.