Kinetostatics of Deployable Concrete Formworks

Abstract

To reform the traditional concrete formwork, an overconstrained deployable frame is designed. It is composed of closed-loop deployable units formed by scissor-form elements and orthogonal telescoping rods. Using the reciprocal screw theory, the mobility of the deployable frame is studied, and it has one degree of freedom (DoF). To analyze the kinematic performance of the frame in the deployment and folding processes and the static characteristics under external loads at different deployed states, a general approach to analyzing the kinematics and statics by modeling in screw form is proposed. The velocities of joints could be solved in screw coordinates, the position and acceleration of joints could be obtained via a first-order numerical integration and a first-order numerical differential interpolation, respectively. Then, the position information for each joint can be forwarded onto the static equilibrium equations. Through the static analysis at each deployed state, the inner forces in each rod and the active control forces are derived. Kinematics and statics are associated by using velocities as the global variable, which allows a unified analysis of mechanisms. This method is computationally highly efficient and also fits for kinematic and static analysis of different kinds of multi-rigid-body mechanisms.