| Flexible materials are widely applied in the field of bionic robots because of their remarkable features such as lightweight and large deformability.Mechanical systems based on these materials demonstrate great flexibility and efficiency of motion,but their practical application is still very limited.The geometric nonlinearity and material nonlinearity make the dynamic modeling much more difficult.Meanwhile,the large deformation during the motions heavily affect the dynamic performance and the motion accuracy of the flexible structures,which leads to an unpredictability of the trajectory.Thus the key point to study the kinematic performance of the flexible system is to develop an accurate and reliable dynamic model in consideration of material behaviors.In this paper,the geometric nonlinearity and material nonlinearity are taken into consideration and the dynamic models of the flexible plate system are developed by using the Absolute Nodal Coordinate Formulation.Various material constitutive models are then introduced to study the kinematic performance of the system.The kinematic stability of the viscoelastic plate system is studied based on a stability criterion.The main contents are listed as below:(1)Dynamic model of the flexible system based on ANCFMooney-Rivlin hyperelastic model and Neo-Hookean hyperelastic model are introduced to derive the generalized elastic force based on the nonlinear continuum mechanics approach,and the dynamic models are established by using ANCF.Their kinematic performances are investigated in numerical simulations,which reveals that the dynamic models based on these hyperelasic constitutive models are feasible.(2)Effects of various factors on kinematic performance of the hyperelastic systemThe effects of geometric and material factors on kinematic performance of the hyperelastic system are studied.The results indicate that as the dimension increases,the deformation of the structure decreases,but the influence of the external force fluctuation on the system increases;as the elastic modulus increases,both the deformation and the influence of the external force fluctuation decreases,and the responsive time in the case of hysteresis also decreases.(3)Kinematic performance and dynamic stability of the viscoelastic systemKelvin-Voigt viscoelastic model is introduced to derive the generalized viscoelastic force.A criterion of kinematic stability is developed based on the Lyapunov theory.The kinematic performance and dynamic stability of the viscoelastic system are studied in numerical simulations.The results indicate that the viscosity of the material efficiently decreases the deformation of the structures,and increases the kinematic stability of the system. |
