Conceptual design of composite wing box structures for a medium-range passenger airplane

Аuthors

Soloshenko V. N.^*, Popov Y. I.^**

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: vladimir.soloshenko@gmail.com
**e-mail: design101@mai.ru

Abstract

Purpose

To give a review of the main requirements, which should be taken into the account during the design of a composite wing of a trunk-route airplane. To analyze the main concepts and structural layouts of composite wing box structures and wing root joints (wing box splice joints) of the new passenger airplanes. To determine the particular features of the allowable stress selection for the design of composite airframe structure of a trunk-route airplane. The object of research is a wing of a passenger aircraft with take-off weight m₀= 65000 kg and the following geometry parameters: aspect ratio λ = 11,5, 1/4 chord sweep angle Χ =25° and wingspan of 35 m.

Design/methodology/approach

Several basic design concepts and structural layouts of composite wing box and wing root splice joints of the new passenger trunk-route airplanes are shown and analyzed in the paper: multi-rib structure with stringer stiffened skin panels, multi-spar structure with flat skin panels without stringers, honeycomb sandwich panel structure. Advantages and disadvantages of each design and structural layout are emphasized and analyzed. The paper also shows several variants of wing box root splice joints for different composite wing designs and discusses the problems associated with each splice design.

Findings

It is shown that the majority of airframe manufactures use traditional structural layouts for composite wings that were used for metal wing design for many decades. Such decision is based on a rational desire to reduce the technical risk and widen the field of application of the well-known procedures of wing certification onto the cases when the wing is made of composite materials. As shown in the paper the allowable stress for wing design depends on a multitude of factors besides the composite materials characteristics, among those are: mechanical and thermal loading, design of irregular structure zones, certification requirements and damage scenarios during manufacturing and operation.
All of these factors must be taken into account at all design stages. Also all of these factors significantly decrease the advantage of utilization of composite materials over metal down to the level when it becomes rather small. The following can be proposed to increase the potential weight reduction effect: to increase the impact resistance of composite structures by using matrix systems with higher interlaminar fracture toughness; to introduce the fiberglass crack stoppers into the wing design.

Research limitations/implications

The present study provides a review of the existing designs, identifies the potential problems of their application to the research case and offers several solutions to these problems, which require further elaboration.

Originality/value

The design of composite structures for trunk-route passenger airplanes is a highly important and popular topic of today. However, the available information is still somewhat limited due to the small number of actual projects that would fully utilize the appropriate technology. This paper tries to generalize and extend the available knowledge based both on the available data about actually implemented projects as well as the theoretical systematic approach to extending this data and applying it to a given case.

Keywords:

design, wing box, composite materials, wing root joints, weight, stress

References

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