Design optimization of integral stiffeners for 3D woven composite preforms

Abstract

Although 3D orthogonal textile woven composite panels demonstrate good impact damage resistance, they often have relatively low bending stiffness. Typically, stiffeners are added to improve the bending resistance through fabrication processes such as sewing and panel/flange joining through matrix adhesion. These secondary processes can be undesirable, adding expense and potential weak points to the structure. Inspired by bio-structures such as peanut shells with surface ridges and graded through-thickness densities, we seek to develop embedded stiffeners for 3D orthogonal textile woven composite panels at sub-component scale to enhance the bending stiffness. Such stiffened textile architecture can be integrally fabricated in an orthogonal loom using standard weaving methods and provides a balance between improving structural bending stiffness and the manufacturing cost and maintaining good impact damage resistance. Utilizing a manufacturing-based parameterization method, a low-fidelity evaluation tool based on the iso-strain method is developed and a straightforward design methodology is proposed to implement these novel composite structures. Numerical design optimization examples are demonstrated.