Method and apparatus for fabrication of lattice composite fuselage for commercial aircraft employing steered fiber lay up

Abstract

A system for fabrication of an aerospace structure incorporates a mold having a surface and at least one unidirectional SFL head adapted to lay down a plurality of collimated tows in a predetermined laminated pattern on the mold surface to produce a fuselage skin. At least one cross plied laminate SFL head is adapted to lay down a cross plied laminate base interface on the fuselage skin to establish a lattice rib shape for each of a plurality of lattice ribs. The cross plied laminate SFL head has a band placement head steerable to avoid structural design features and to maintain spacing from adjacent steered lattice ribs. The unidirectional SFL head is further adapted to lay down a plurality of collimated tows on the base interface of each of the plurality of lattice ribs for a first plurality of unidirectional tow plies in each lattice rib. The unidirectional SFL head has a fiber placement head steerable to match the lattice rib shape to avoid structural design features and to maintain spacing from adjacent steered lattice ribs.

Description

BACKGROUND INFORMATIONField[0001]Embodiments of the disclosure relate generally to fabrication of composite structures for aircraft and more particularly to fabrication of aircraft fuselages having a modified lattice structure for carrying structural loads created with steered fiber layup using two or more heads for fiber placement with unidirectional tows and cross plied laminates providing high damage tolerance.Background[0002]Composite fuselages employed in existing commercial aircraft use composite skin supported by separately fabricated stiffening elements. Frames and stringers carry the substantial operational loads and are added to the composite skin after fabrication similar to metallic structural assembly approaches (a.k.a. “Black Aluminum” design). Skin, Frames and Stringers are typically fabricated based on different manufacturing technologies which require different manufacturing equipment, transportation of fuselage components from different production sites to the fina...

AI Technical Summary

Benefits of technology

This patent describes a method and system for making a damage-tolerant structure using a lattice rib structure with a skin made from collimated tows. The lattice ribs are shaped and positioned to displace from features in the skin. A first layer of collimated tows is placed on the base interface of each lattice rib for a single direction. A cap is then placed on top of the first layer, followed by a second layer of collimated tows for another single direction. A second cap is then placeover the second layer, creating a double-layered, damage-tolerant structure. This method and system provide a strong and durable lattice rib structure that can withstand damage.

Problems solved by technology

Furthermore, existing designs are based on the concept of orthotropic material which does not take full advantage of the available anisotropic properties of modern composite unidirectional materials.

This results in excessive weight and cost, in growth of both Non-Recurring and Recurring Expenses (NRE, RE) in the course of manufacturing of composite fuselages.

However, a uniform Lattice is less efficient in aircraft structures like fuselage sections which incorporate doors, windows, other openings and design features which disrupt the geometric lattice pattern.

WFW processes do not allow variation of the lattice geometry and rib shape in the course of the winding of the structure to incorporate doors, windows and other design-driven features.

Such an approach results in non-optimal structural efficiency, loss of potential weight savings and in increase of manufacturing cost.

Further, WFW cannot be employed for a concave manufactured surface.

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