Development of a Computationally Efficient Fabric Model for Optimization of Gripper Trajectories in Automated Composite Draping

Abstract

An automated prepreg fabric draping system is being developed which consists of an array of actuated grippers. It has the ability to pick up a fabric ply and place it onto a double-curved mold surface. A previous research effort based on a nonlinear Finite Element model showed that the movements of the grippers should be chosen carefully to avoid misplacement and induce of wrinkles in the draped configuration. Thus, the present study seeks to develop a computationally efficient model of the mechanical behavior of a fabric based on 2D catenaries which can be used for optimization of the gripper trajectories. The model includes bending stiffness, large deflections, large ply shear and a simple contact formulation. The model is found to be quick to evaluate and gives very reasonable predictions of the displacement field.

Generation of feasible gripper trajectories in automated composite draping by means of optimization

“…The material properties are chosen to be linear elastic for computational efficiency. The following gives an overview of the model and details can be found in Krogh et al [17].…”

“…This determination is achieved by a minimization scheme, where the arc lengths of the cables are constrained to their prescribed lengths and the sum of squares of the reaction forces are minimized. Details can be found in Krogh et al [17].…”