Composite Layup Tension Members for Wrinkle-Free Drape Forming
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Solution Overview
Problem
Wrinkles formed during drape forming of composite parts due to imbalances in heat and vacuum forces lead to scrapped parts or reduced load-carrying capacity, necessitating additional plies that increase weight and cost.
Innovation Solution
Interleaving tension members into the composite layup to redirect forming forces, applying tension forces to counteract compressive forces and prevent wrinkle formation, using a drape forming diaphragm to constrain the tension members and redirect forces during the drape forming process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drape forming is used to form composite parts, then manufacturing efficiency is improved, but wrinkles form in the composite part causing reduced load-carrying capacity
Solution Approach 1:
Tension members are introduced as intermediary elements between the plies to prevent relative movement and wrinkle formation. These tension members act as mediators that transmit tensile forces through the laminate structure, counteracting compressive forces that cause wrinkling during drape forming.
Solution Approach 2:
The patent changes the force state parameter from purely compressive to a combination of tensile and compressive forces. By applying tension members, the stress state in the composite part is modified to include tensile components that prevent ply compression and wrinkle formation, while still allowing the part to be formed efficiently.
2Strength
If additional plies are added to compensate for wrinkles, then load-carrying capacity is restored, but weight of the composite part increases
Solution Approach 1:
Tension members are applied preliminarily during the drape forming process to prevent wrinkle formation before it occurs. By counteracting compressive forces in advance through tensile forces from the tension members, the laminate structure maintains its integrity without requiring additional plies to compensate for wrinkles.
3Manufacturing precision
If caul plates are used to support composite parts during curing, then wrinkles are reduced, but device complexity increases
Solution Approach 1:
The patent extracts the wrinkle prevention function from external support devices like caul plates and integrates it directly into the laminate structure through tension members. This eliminates the need for separate caul plate components and simplifies the overall device while maintaining wrinkle reduction capability.
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
Reduces or eliminates wrinkles, minimizing the need for additional plies, saving weight and cost by reducing rework and scrap, and enabling more complex geometries.
Implementation Method 1
applying compressive loading to the tension members with a drape forming diaphragm so that the tension members generate tension forces in the composite layup by pulling on the composite layup to counteract wrinkle forming compressive forces generated in the composite layup during drape forming
Implementation Method 2
an imbalance of heat and vacuum during drape forming, such as hot drape forming, where the imbalance of heat and vacuum may cause local forces
Data Source
Figure 1A
Figure 1B~1C
Figure 1D
AI summary
A method for drape forming a laminated composite charge comprises: interleaving tension members into a composite layup of the laminated composite charge, where the tension members are interleaved into the composite layup at one or more locations along a length of the laminated composite charge so that a free end of each of the tension members extends from the composite layup; and applying compressive loading to the tension members with a drape forming diaphragm so that the tension members generate tension forces in the composite layup by pulling on the composite layup to counteract wrinkle forming compressive forces generated in the composite layup during drape forming of the laminated composite charge.