Vertical Laminate Noodle for Composite Stringer Pull-Off Strength
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Solution Overview
Problem
Current aircraft stringer designs using composite materials face challenges in achieving desired weight and performance characteristics, often resulting in increased complexity and manufacturing costs, with noodles not matching the rest of the stringer's characteristics, leading to reduced performance in withstanding forces that pull the stringer away from attached structures.
Innovation Solution
A structural system comprising a composite elongate member with a channel and composite structures oriented perpendicular to the surface, which are placed in the channel to increase the stringer's capacity to withstand forces that pull it away from the structure, using a filler structure with layers configured to match the composite elongate member's characteristics, enhancing attachment and load transfer capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional stringers are used to achieve desired pull-off capacity, then the structural strength is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the material parameters of the stringer by incorporating a filler structure with different elastic modulus characteristics. The filler structure has a first elastic modulus in a first range and a second elastic modulus in a second range, allowing the stringer to achieve enhanced pull-off capacity through material property modification rather than adding more stringers.
Solution Approach 2:
The patent uses composite material construction by combining the base stringer material with a filler structure made of different composite materials. This creates a heterogeneous composite structure where the filler structure provides enhanced mechanical properties, specifically improved pull-off capacity, while maintaining the overall stringer architecture.
2Weight of moving object
If the stringer weight is reduced, then the payload capacity and fuel efficiency are improved, but the pull-off capacity may be insufficient
Solution Approach 1:
The patent applies local quality enhancement by placing the filler structure at specific locations within the stringer where additional strength is needed. The filler structure is positioned to provide localized reinforcement for pull-off resistance, allowing the rest of the stringer to maintain lower weight while achieving the required overall strength.
Solution Approach 2:
The patent modifies the elastic modulus parameters of the stringer through the filler structure. The first elastic modulus (E1) is in a first range and the second elastic modulus (E2) is in a second range, where E2/E1 is between 0.5 and 2.0. This parameter optimization allows weight reduction while maintaining adequate pull-off capacity.
3Reliability
If the filler structure elastic modulus ratio (E2/E1) is kept between 0.5 and 2.0, then the structural performance is optimized, but the manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges for the elastic moduli to achieve optimal performance. By specifying that E1 is in a first range, E2 is in a second range, and their ratio E2/E1 is between 0.5 and 2.0, the patent creates a robust design window that accommodates normal manufacturing variations while ensuring reliable structural performance.
Data Source
AI summary
An apparatus comprises a composite elongate member, a channel, and a number of composite structures. The composite elongate member has a side configured for attachment to a surface of a structure. The channel is on the side and extends along a length of the composite elongate member. The number of composite structures is configured for placement in the channel and configured to attach a portion of the side of the composite elongate member to the structure. The number of composite structures has layers oriented substantially perpendicular to the surface of the structure. The number of composite structures is configured to increase a capacity of the composite elongate member to withstand forces that pull the composite elongate member away from the structure.