Welded Wing Spar Joints Eliminate Rivet Stress Risks

Solution Overview

Problem

The existing methods for connecting wing spars to wing covers in airplane construction, such as riveted or threaded joints, result in high production costs, weight disadvantages, and limited durability, with cracks often growing perpendicularly to the spar direction, making internal inspections necessary for damage detection and leading to reduced design load transmission.

Innovation Solution

A welding process is used to connect the wing spar to the wing covers, allowing for the integration of the spar chords into the wing covers and enabling the use of different aluminum alloys for optimal strength and durability, with processes like friction stir welding or laser beam welding facilitating the connection of dissimilar alloys.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If riveted or threaded joints are used to connect wing spar to wing covers, then structural connection is achieved, but production costs increase and weight increases

Engineering Contradiction:

Improvestructural connectionVSAvoidproduction cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical connection systems (rivets, threaded joints) with a welding process that creates a metallurgical bond between the wing spar and wing covers. This substitution eliminates the need for separate fastening components and reduces assembly steps, thereby lowering production costs while maintaining structural integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The welding process merges the wing spar and wing covers into a single integrated structure, eliminating the need for separate connection components. This combining of parts reduces the total number of components, simplifies manufacturing, and reduces weight compared to using discrete rivets or threaded fasteners.

Inventive Principle:

Principle #5Merging (Combining)

2Strength

If riveted or threaded joints are used to connect wing spar to wing covers, then structural connection is achieved, but weight increases

Engineering Contradiction:

Improvestructural connectionVSAvoidwing assembly weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent replaces mechanical connection systems (rivets, threaded joints) with a welding process that creates a metallurgical bond between the wing spar and wing covers. This substitution eliminates the need for separate fastening components and reduces assembly steps, thereby lowering production costs while maintaining structural integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The welding process merges the wing spar and wing covers into a single integrated structure, eliminating the need for separate connection components. This combining of parts reduces the total number of components, simplifies manufacturing, and reduces weight compared to using discrete rivets or threaded fasteners.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If riveted or threaded joints are used to connect wing spar to wing covers, then structural connection is achieved, but durability decreases due to crack initiation

Engineering Contradiction:

Improvestructural connectionVSAvoiddurability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent replaces mechanical connection systems (rivets, threaded joints) with a welding process that creates a metallurgical bond between the wing spar and wing covers. This substitution eliminates the need for separate fastening components and reduces assembly steps, thereby lowering production costs while maintaining structural integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent addresses the harmful effect of stress concentration at rivet holes by using welding to create a continuous, hole-free joint. The welding process allows for controlled heat treatment and material flow that eliminates stress concentration points, thereby converting the potential harm of mechanical fastening weaknesses into a benefit through superior joint integrity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Reliability

If internal inspections are performed to detect cracks in spar chords, then damage detection is achieved, but production costs increase

Engineering Contradiction:

Improvedamage detectionVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent addresses the harmful effect of stress concentration at rivet holes by using welding to create a continuous, hole-free joint. The welding process allows for controlled heat treatment and material flow that eliminates stress concentration points, thereby converting the potential harm of mechanical fastening weaknesses into a benefit through superior joint integrity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces production costs and weight, enhances durability by eliminating critical rivet joints, allows for external visual damage detection, and increases admissible design stresses, resulting in a more efficient and cost-effective manufacturing method with improved mechanical stability.

Implementation Method 1

A first end portion of the wing spar is welded to the lower wing cover and/or a second end portion of the wing spar is welded to the upper wing cover

Methodology Applied

Scientific EffectWelding: Welding

Implementation Method 2

processes like friction stir welding or laser beam welding facilitating the connection of dissimilar alloys

Methodology Applied

Scientific EffectFriction stir welding: Friction Welding

Implementation Method 3

processes like friction stir welding or laser beam welding facilitating the connection of dissimilar alloys

Methodology Applied

Scientific EffectLaser beam welding: Laser Beam Welding

Data Source

PatentUS7641147B2Airplane wing, method for manufacturing an airplane wing and use of a welding process for welding a wing spar

Publication Date: 2010.01.05 AIRBUS OPERATIONS GMBH

AI summary

An airplane wing has a lower wing cover, an upper wing cover and a wing spar. A first end portion of the wing spar is welded to the lower wing cover and/or a second end portion of the wing spar is welded to the upper wing cover.