A novel method for modeling large deformation flexible mechanism connected with mass blocks or rigid bodies

An efficient and simple method to treat mass blocks or rigid bodies connected to flexible bodies is proposed, namely the equivalent beam (EB) method, and the corresponding equivalent equations are provided based on rigid body plane motion. Through this method, the rigid body connected to the flexible body is equivalent to flexible beams with higher stiffness, and a unified Absolute Node Coordinate Formulation (ANCF), is used to establish the model of the EB. Only the node constraints of EBs and flexible bodies are considered, greatly simplifying the constraint analysis and improving modeling efficiency. Meanwhile, six constraint forms based on one-dimensional two-node beam element are summarized, and corresponding node coordinate expressions are provided. Finally, the static and dynamic analyses on three typical planar flexible mechanisms are conducted, and results are compared with those obtained by the lumped mass (LM) method and finite element analysis (FEA), verifying the superiority of the EB method.