This paper proposes a modified tangential contact stiffness model considering friction’s effect, which is the first key step to establish the dynamic model of the fixture-workpiece system, and this is the foundation of vibration suppression for the manufacturing process of aerospace blades. According to Love’s elastic deformation, the model’s derivation process starts with the potential function in each coordinate axis’s direction respectively. The generalized Hertz contact theory is employed to calculate the contact forces in this model. The symmetrical characteristic of the contact area has simplified the derivation process to obtain the eventual tangential contact stiffness model. A validation experiment focusing on a tangential stiffness measuring is achieved by putting two spherical objects in contact together to get the tangential contact stiffness. Based on the data collected in this experiment, a comparison with a most similar existed model is carried out, and the result shows that the relative error of this modified model are all less than 10%, while the original model’s (the most similar model) relative error exceeding 50% captures more than 3/4 of the 30 data sets randomly selected in each experiment group, and that means the modification of this paper brings great improvement to the contact stiffness model.

Aiming at the problem that the existing mechanism model cannot accurately predict the shear properties of MREs, in this research, a physical microscopic constitutive model of isotropic MREs based on ECC lattice structure was constructed to accurately reflect the shear properties of isotropic MREs under quasi-static and dynamic shear modes and different magnetic fields. In order to reduce the error of the potential energy model in the modeling process, the accuracy of the MRE total potential energy theoretical model based on the ECC lattice structure was improved by transforming γ=θ to γ=tanθ under finite strain, and the maximum improvement rate of the model accuracy was 6 %. Then, in order to construct a microstructure-based dynamic model, based on the exact solvable model of the topological regular network constructed by the Rouse chain, the Langevin equation was constructed based on the ECC lattice. The relationship between relaxation time, eigenvalue and magnetic flux density were revealed, and then the updated shear modulus was solved. Then, the modulus values of the prepared isotropic MREs samples at different frequencies and different magnetic flux densities were compared with the theoretical model values, and the model failure phenomenon in which the theoretical results are inconsistent with the experimental results under dynamic high magnetic field was modified by the method of piecewise function and optimization parameters. The final results show that the correlation coefficient R2 between the experimental results and the theoretical results can reach to 99 %.

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Thin-walled workpieces are widely used in the aerospace field, and milling is the main processing method of such components. However, thin-walled workpieces are prone to vibrate during milling because of their weak stiffness, and the vibrations significantly affect the processing quality. Therefore, it is important to develop a novel milling vibration suppression method for thin-walled parts. The present work focused on the milling vibration control of a thin-walled workpiece using a semi-active magnetorheological (MR) damper. The forward dynamic model and inverse control model of the MR damper were first established, and its actuating position on the workpiece was then determined by modal analysis. The dynamic model of the MR damper at this position was built based on the proposed dynamic parameter acquisition method and used in the following semi-active control algorithm design. The effectiveness of this algorithm was verified by MATLAB/Simulink simulations. Finally, six groups of milling experiments were carried out using the non-damper, the rigid rod, the damper applied with 1-, 2-, and 3-A currents, and the semi-active control damper to validate the practical effect of the proposed algorithm. It was found that the designed semi-active control MR damper outperformed the constant-current control dampers or the rigid rod. In comparison to the non-damper experiment, the root mean square (RMS) values of milling forces in x- and y-directions decreased by 45.12% and 48.58%, respectively, and surface roughness decreased by 40.22%.