Modeling And Simulation For Dynamics Characteristics Of Outside Lamina Emergent Torsional Compliant Joint

Compared with traditional mechanisms, compliant mechanisms has many advantages such as novel transfer and transformation in motion, force and energy of mechanism, high transmission precision and free of friction, wear and impact caused by clearance etc. Because of these advantages, widely attentions and applications has been casted on. However, an important field in the research, of compliant mechanisms is the design and analysis of compliant joints. In this paper, the slope discontinuity situation of Absolute Nodal Coordinate Formulation is applied to establish the dynamic models of two compliant joints, and a sirmulation and experiment was carried out. The main works of this paper are as follow:Based on the pseudo-rigid body model method, the 1R Pseudo-Rigid-Body Model(PRBM)of the flexible cantilever beam is established, and the torsion spring constant of the model is deduced. Based on this, the LET(Lamina Emergent Torsional) of the equivalent spring model,the expression of the equivalent spring constant and the total torque expression of the compliant hinge are obtained. According to the obtained expression, the shortcomings of PRBM method in accurately depicting the deformation of flexible hinge are analyzed.The corresponding analogous linear coil spring models of outside Lamina Emergent Torsional(LET) compliant joint and half outside LET compliant joint are introduced simply, and their equivalent spring constant are deduced using 1R P.seudo Rigid Body Model(PRBM) of flexible cantilever beam. These models which based on the thought of the equivalent substitution and static theory are use two rigid beams and torsional spring between them instead of the flexible beams of compliant joint to describe the joint of bending deformation.Aim at disadvantages of the pseudo-rigd-body model method in research and analysis of compliant joint, a three-dimensional-two-node beam element definited in Absolute Nodal Coordinate Formulation(ANCF) is introduced to calculate its shape function matrix,transtformation matrix between element coordinate system and global coordinate system, mass matrix, elastic force matrix, external force matrix and system dynamics equations. The dynamics equations of flexible pendulum and L shape flexible pendulum are established to calculate and analyze the results. It is first verify the feasibility of the method. Furthermore, The dynamics equations of half outside LET compliant joint and outside LET compliant joint under various forces are established. By numerical simulation, their motion configurations and the strain of some points of half outside LET compliant joint are obtained.At last, the experimental results of half outside LET compliant joint in same the condition with simulation verify the correctness and effectiveness of the ANCF method in dynamics modeling and simulations of compliant joints.