Composite Box Structure with Spar Cavities for Rib Insertion
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Solution Overview
Problem
The manufacturing process of box-shaped structures for aircraft horizontal stabilizers using composite materials is complicated, especially when inserting reinforcing ribs, leading to potential errors in dimensional tolerances and increased complexity, particularly in smaller aircraft where the assembly of these structures is challenging due to the nature of composite materials and the need to remove material from existing components.
Innovation Solution
A method for manufacturing a box-shaped structure in composite material that includes the use of support tools with shape memory polymers and a unique spar design with longitudinal cavities and ribs, allowing for easier insertion of reinforcing ribs without the need for extensive modifications or probing, thereby simplifying the assembly process and reducing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcing ribs are inserted into the box-shaped structure after manufacturing, then structural rigidity is improved, but the manufacturing complexity and assembly difficulty increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-forming longitudinal cavities and ribs within the spar structure during the initial manufacturing process, before the box-shaped structure is fully assembled. This allows reinforcing ribs to be easily inserted later without requiring complex post-manufacturing operations or material removal, thus improving structural rigidity while avoiding manufacturing complexity increases
Solution Approach 2:
The patent segments the spar structure into multiple components including longitudinal cavities and ribs that can be independently formed and then assembled. This segmentation allows the reinforcing elements to be prepared separately and integrated into the box-shaped structure without requiring complex monolithic manufacturing, thereby improving rigidity while simplifying the overall manufacturing process
2Strength
If material is removed from existing components to insert reinforcing ribs, then structural reinforcement is achieved, but dimensional tolerance errors increase
Solution Approach 1:
The patent pre-forms longitudinal cavities within the spars during the initial manufacturing stage, creating dedicated receptacles for reinforcing ribs. This eliminates the need for subsequent material removal operations that would compromise dimensional tolerances, as all critical features are established in their final positions during the primary manufacturing process
Solution Approach 2:
The longitudinal cavities act as intermediary structures that facilitate the integration of reinforcing ribs without requiring direct modification of the existing spars. These pre-formed cavities serve as mediators that accommodate the reinforcing elements while maintaining the original dimensional integrity of the spar components
3Adaptability or versatility
If the center box is removed to elongate the stabilizer, then adaptability is improved, but structural stability may be compromised
Solution Approach 1:
The patent pre-forms longitudinal cavities and ribs within the spars that extend along the length of the box-shaped structure. These pre-formed structural elements provide continuous reinforcement that maintains structural stability even when the center box is removed, enabling the stabilizer to be elongated or adapted without compromising overall structural integrity
Solution Approach 2:
The patent applies local quality by concentrating reinforcing ribs and longitudinal cavities in specific critical areas of the spar structure. This localized reinforcement strategy ensures that structural stability is maintained in key regions even when portions of the structure are modified or removed for adaptability purposes
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 method enhances the structural rigidity and stability of the box-shaped structure while simplifying the manufacturing process, reducing assembly errors, and allowing for the removal of the center box without introducing structural criticalities, thus enabling easier elongation of the stabilizer and integration of control systems.
Implementation Method 1
a) providing a support tool comprising a shape memory polymer
Data Source
Figure 1
Figure 1a
Figure 2
AI summary
A method for manufacturing a box-shaped structure for aircrafts (1) is described (4), the structure (1) extending along a longitudinal direction (A) between a first longitudinal end (1a) and a second longitudinal end (1b), and comprising: a first longitudinal wall (5); a second longitudinal wall (6) facing the first wall (5) and arranged spaced from the first wall (5) by a non-zero amount; a plurality of spars (7) extending longitudinally and between said first wall (5) and second wall (6); and at least one reinforcing rib (23) arranged transversal to the spars (7) at a transversal sector (S1) interposed between the first and the second longitudinal end; each spar has a spar cavity (21) defining a lack of material extending longitudinally from an axial coordinate (X), which corresponds to the transversal sector (S1), up to the second longitudinal end, so that the reinforcing rib (23) can be easily inserted even after the integral coupling between the first wall, the second wall and the spars without compromising the structural properties of the box-shaped structure (1).