Composite Stringer Base Flange Load Transmission
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Solution Overview
Problem
Conventional composite stringer assemblies face limitations in load-bearing and load-transmission performance due to discontinuities in radius filler regions, leading to potential cracking and delamination, which affects their durability and efficiency in transmitting in-plane shear and axial compression loads.
Innovation Solution
Incorporating a base flange with a continuous structural connection between the skin flanges and webs, formed from multiple plies of composite material, to reinforce the stringer assembly and enhance load transmission capabilities, thereby addressing the limitations of conventional designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional composite stringer assemblies are used without a base flange, then the structure is simpler and easier to manufacture, but the load-bearing and load-transmission performance is reduced due to discontinuities in radius filler regions
Solution Approach 1:
The base flange merges the skin flanges and webs into a continuous structural connection, eliminating discontinuities in the radius filler regions. This integration creates a unified load-path that simultaneously improves load-bearing capacity and prevents cracking/delamination issues present in conventional segmented designs.
Solution Approach 2:
The base flange is constructed from multiple plies of composite material (CFRP) with optimized fiber orientations. This composite construction provides enhanced strength and stiffness while maintaining the lightweight characteristics necessary for aerospace applications, directly addressing the load-bearing performance deficiency.
2Reliability
If conventional composite stringer assemblies are used without a base flange, then the manufacturing process is simpler, but delamination and cracking occur in radius filler regions reducing durability
Solution Approach 1:
The base flange establishes continuous structural connectivity between skin flanges and webs, eliminating the discontinuous radius filler regions that are prone to cracking and delamination. This continuous load-path ensures reliable stress distribution and prevents the initiation of damage under cyclic loading conditions.
Solution Approach 2:
While the base flange creates continuity, it is itself constructed from multiple plies of composite material that can be manufactured and assembled separately before final integration. This segmented manufacturing approach reduces complexity by allowing modular fabrication while achieving continuous structural performance in the final assembly.
3Force
If a base flange with continuous structural connection is added, then load transmission capability is enhanced, but the device complexity increases
Solution Approach 1:
The base flange serves multiple functions simultaneously: it provides structural continuity for load transmission, reinforces the connection between skin flanges and webs, prevents delamination, and maintains aerodynamic fairness. This multi-functionality justifies the added structural complexity by delivering comprehensive performance improvements.
Solution Approach 2:
The base flange extends the structural connection in the through-thickness dimension, creating a three-dimensional load-path that complements the in-plane load transmission. This dimensional addition provides out-of-plane stiffness and reinforces the joint region without interfering with the primary in-plane load-carrying capacity.
Data Source
AI summary
In an example, a composite stringer is described. The composite stringer includes a composite stringer and a base flange. The composite stringer includes a top flange, a first skin flange and a second skin flange configured to be coupled to a support structure, a first web extending between the first skin flange and a first side of the top flange, and a second web extending between the second skin flange and a second side of the top flange. The support structure includes at least one of a skin of a vehicle or a base charge. The base flange includes a bottom surface extending between the first skin flange and the second skin flange. The bottom surface of the base flange is configured to be coupled to the support structure. The base flange also includes a top surface extending between the first web and the second web.