The Dynamic Equation and Simulation of a Linkage Mechanism Fabricated from Three-Dimensional Braided Composite Materials

The work in this paper is concerned with a four-bar linkage mechanism with links fabricated from three-dimensional braided composite materials. The dynamic equation of the mechanism is established by finite element method (FEM), it includes composite materials parameters and structural parameters of the mechanism. The mass matrix of the beam element is obtained in light of the mass distribution characteristics of the composite materials. According to the 3-dimensional microstructure characters of the three-dimensional braided composite materials, the anisotropic beam element is considered to be made up of four parts, and then the stiffness matrix of the beam element is derived from the constitutive equations of each part and the relation between the strain distribution of each part and the node displacement of the beam element. Based on the damping element model and the expression of dissipation energy of the 3-dimentional braided composite materials, each modal damping value of the mechanism is calculated and the damping matrix of the mechanism is established. The dynamic responses and natural frequency of the mechanism are obtained by simulation, respectively. The work presented in the paper provides theoretical basis to a certain extent for the further research on nonlinear vibration characteristics and optimum design of this kind of mechanism.

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