Co-cured Hat Stringer Pulloff Load Transfer
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Solution Overview
Problem
Conventional composite wing stringers lack sufficient load-carrying capability to connect ribs to the cap efficiently, leading to the use of additional shear ties that increase weight, complexity, and cost, particularly for pulloff loads.
Innovation Solution
A hat stringer structure co-bonded or co-cured with the skin member, featuring a base portion and webs with equal quantities of wrap and cover laminates, and noodles, allowing direct attachment of ribs to the cap or webs through brackets and fasteners, enhancing load transfer capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional composite hat stringers are used to connect ribs to the cap, then the structure is simple and lightweight, but the load-carrying capability for pulloff loads is insufficient
Solution Approach 1:
The patent applies composite materials by integrating the hat stringer with the skin through co-curing or co-bonding processes. The hat stringer comprises composite materials such as carbon fiber reinforced polymers, which provide high strength-to-weight ratio. The composite construction allows the stringer to sustain pulloff loads effectively while maintaining structural simplicity and lightweight characteristics, eliminating the need for additional shear ties.
2Strength
If shear ties are added at each rib-stringer intersection to sustain pulloff loads, then the load-carrying capability is improved, but the weight increases significantly
Solution Approach 1:
The patent merges the hat stringer with the skin into a single integrated structural component through co-curing or co-bonding. This integration allows the hat stringer itself to sustain pulloff loads without requiring separate shear ties at each rib-stringer intersection. The merging of functions eliminates redundant components and significantly reduces the overall weight of the aircraft structure.
3Reliability
If shear ties are installed at each rib-stringer intersection, then the reliability for sustaining pulloff loads is improved, but the manufacturing complexity and production time increase
Solution Approach 1:
The patent employs preliminary action by co-curing or co-bonding the hat stringer with the skin during the initial manufacturing process. This integrated construction approach ensures that the hat stringer is pre-configured to sustain pulloff loads without requiring subsequent installation of shear ties. The preliminary integration simplifies manufacturing operations, reduces production time, and eliminates complex assembly steps while maintaining high reliability for load sustainability.
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
A structure may comprise a skin member (12) and a hat stringer (26). The hat stringer (26) may include a base portion (28) and first and second webs (30,32) extending outwardly from the base portion. Each one of the first and second webs (30,32) may be comprised of a wrap laminate (58) having wrap plies and a cover laminate (50) having cover plies. The first and second webs (30,32) may be interconnected by a cap. The hat stringer (26) and skin member (12) may be co-cured.