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This paper presents an optimized design of a magneto-rheological damper with finite element analysis. The MR damper is a new type one compared with the traditional type, which is called the parallel disks valve mode. The effects of magnetic field formation mechanism and MR effect formation mechanism on the MR parallel disks valve performance are investigated. Analytical results of the optimized design of the MR damper with different structural parameters and different materials indicated that the simulation values by the finite element method are very close to the measured values and also verifies the reliability of the simulation.

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Modal identification performs one of the most important roles in structural dynamics analysis and structural health monitoring, especially when the input excitations are not measurable. Most of the traditional blind source separation approaches can only handle determined or overdetermined blind modal identification, where the number of observed sensors is equal to or greater than the number of active modes. When the number of observed sensors is less than the number of active modes, new methods to perform underdetermined blind modal identification should be considered. To tackle this issue, a novel operational modal identification method based on an enhanced sparse component analysis with optimized clustering is proposed. Firstly, a robust K-means clustering with differential evolution algorithm is put forward to estimate the mode shape matrix utilizing the sparse property of observed mixtures. Secondly, the modal responses are recovered by the least squares method from the incomplete knowledge of the mode shape matrix and the system outputs. Subsequently, the modal responses are transformed into a time domain through time-frequency transformation, where the modal parameters are extracted. Finally, numerical simulation and experimental verification demonstrate that in both the determined and underdetermined case, the proposed method can perform accurate and robust parameter identification of structural systems.

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