Composite T-profile Junction Delamination Prevention
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Solution Overview
Problem
Composite materials used in aircraft structures face delamination issues at T-profile junctions due to out-of-plane stresses, leading to structural failures, as they lack sufficient strength in all directions and cannot effectively handle pulling loads, necessitating the use of metallic supports or excessive additional composite material which is ineffective.
Innovation Solution
A T-profile junction design featuring a T-profile with angled flanges, fillets, and a base plate, where tension bars with biasing means are used to counteract out-of-plane forces by transferring counterforces from fasteners to the flanges and base plate, preventing delamination by stiffening the T-section and applying forces to the main delamination area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used in T-profile junctions, then weight is reduced compared to metallic parts, but delamination occurs due to out-of-plane stresses
Solution Approach 1:
The T-profile junction is divided into separate components: a base plate, a T-profile with web and flanges, and tension bars. This segmentation allows each component to be optimized for its specific function while working together to resolve the delamination problem through distributed stress management
Solution Approach 2:
Tension bars are introduced as a new dimensional element that spans across the T-profile junction, providing out-of-plane support. This adds a third dimension of structural reinforcement that counteracts the out-of-plane stresses causing delamination without adding excessive weight
2Reliability
If extra composite material is added to strengthen T-profile junctions, then delamination resistance improves, but the amount of material required becomes excessive and ineffective
Solution Approach 1:
The solution uses a hybrid approach combining composite materials (T-profile and base plate) with metallic tension bars. This composite structure leverages the weight advantage of composites while using metal tension bars to provide the specific out-of-plane strength needed to prevent delamination
Solution Approach 2:
Instead of uniformly adding composite material throughout the structure, the invention applies reinforcement locally at critical stress points using tension bars positioned to counteract out-of-plane forces. This localized reinforcement is more efficient than adding excessive composite material throughout
3Reliability
If metallic supports are used to prevent delamination, then delamination resistance improves, but weight increases
Solution Approach 1:
Metallic tension bars are used only at critical locations where out-of-plane stresses cause delamination, rather than replacing the entire composite structure with metal. This localized metallic reinforcement provides necessary strength while minimizing weight increase
Solution Approach 2:
The invention creates a hybrid composite structure combining lightweight composite T-profiles and base plates with strategic metallic tension bars. This composite approach maintains the weight advantage of composites while using metal only where structurally necessary to prevent delamination
4Reliability
If design geometry is altered to avoid out-of-plane stresses, then delamination is prevented, but functional requirements of the structure are compromised
Solution Approach 1:
Tension bars are pre-installed to counteract out-of-plane forces before they cause delamination. This preliminary anti-action allows the structure to maintain its original functional geometry while being pre-equipped to resist the stresses that would otherwise compromise it
Data Source
AI summary
A T-profile junction of composite materials with a T-profile (1) and a base plate (2). The T-profile (1) comprises a web (3) and at least two flanges (4-7). The flanges (4-7) are angled with respect to the web (3). A fillet (11, 12) is provided between the web (3) and each of the flanges (4-7). At least one tension bar (16, 32, 40, 50, 65) is releasably mounted to the base plate (2). The web (3) is provided with at least one passage (23, 24, 33, 34). Said at least one tension bar (16, 32, 40, 50, 65) reaches through the at least one passage (23, 24, 33, 34). The at least one tension bar (16, 32, 40, 50, 65) is biased against the base plate (2) and the respective flanges (5, 6) of said T-Profile (1).