Process for reducing wrinkles in composite laminated structures

Abstract

A wrinkle control process for manufacturing a closed cross-sectional, composite laminate structure on a male tool cured under temperature and pressure. The process includes the step of creating a plurality of filled or unfilled depressions at strategic locations in the laminate prior to curing. The depressions are created by depression forming elements that have a predetermined size designed to create a depression in under plies, alone or combined with intensification techniques. The depressions may be left unfilled or be partially or completely filled. Depression forming elements are removed after cure or remain part of the structure. The number of elements being determined by the following equation: N=(OPL−OPC)÷(Li−Lj), where OPL is the outside perimeter of the composite structure after lay-up and prior to curing, OPC is the outside perimeter of the composite structure after lay-up and after curing, Li is the linear length of the composite segment formed by a depression forming element and Lj is the theoretical linear length of the corresponding composite segment without a depression.