Cai Ganwei

Dynamic analytic model of mechanism with links fabricated from symmetric laminates

A four-bar linkage mechanism with links fabricated from symmetric laminates was studied. The mass matrix of the beam element was obtained in light of the mass distribution characteristics of composite materials. The stiffness matrix of the beam element was derived from the constitutive equations of each layer and the relationship between the strain distribution and the node displacement of the beam element. The specific damping capacity of the beam element was analyzed according to the strain distribution of the beam element and the strain energy dissipation caused by vibration in each direction of each layer; and the damping coefficients were obtained according to the principle that the total energy dissipation of the beam element was equal to the work done by the equivalent damping force during a cycle of vibration, from which the damping matrix of the dynamic equations was obtained. Using the finite element method, the dynamic analytic model of the mechanism was obtained. The dynamic responses and natural frequency of the mechanism were obtained by simulation, respectively, and those of the simulation obtained by the proposed model were analyzed and compared with the results obtained by the conventional model. The work provides theoretical basis to a certain extent for the further research on nonlinear vibration characteristics and optimum design of this kind of mechanism.

A gradient-based nested Latin hypercube DOE for quadratic polynomials RSM in FEM simulation

A nested Latin hypercube DOE (Design Of Experiment) involves at least a low accuracy experiments and a high accuracy one in Finite Element Method (FEM) Simulation. How to use the information contained in the regression model of previous low accuracy experiments in the design of high accuracy one needs deeply study because such information may be ignored in evenly sampling method, leading to a imprecise regression model of high accuracy experiment. This paper employ the gradient of the regression model of low accuracy experiments as the index of the information distribution of tested object to adjust the DOE of high accuracy one. Thus more information of object can be obtained in those high accuracy experiments and a more precise quadratic polynomials RSM (Response Surface Method) model is built.