Composite Preform Forming with Grip Strip and Beads
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Solution Overview
Problem
Current methods for forming shaped composite bodies, such as those used in aerospace applications, face issues with wrinkling and kinking of fibers during the shaping process, particularly when dealing with complex geometries and curvatures, which affect the mechanical properties and reproducibility of the final product.
Innovation Solution
The use of a male inner mold line tool with tensioning/forming beads and a grip strip mechanism, combined with vacuum-bagging or positive pressure mechanisms, to apply controlled tension and pressure, ensuring excess material is drawn into forming beads, thereby minimizing wrinkling and kinking while conforming the preform to complex shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional forming methods are used to shape composite bodies, then the shaping process can be completed, but wrinkling and kinking of fibers occur during the process
Solution Approach 1:
The patent applies preliminary action by using a preform with pre-curved fibers that are designed to match the target geometry before forming. This pre-curved preform is then formed over a male inner mold line tool, allowing the fibers to be positioned correctly in advance to prevent wrinkling and kinking during the forming process.
Solution Approach 2:
The patent employs parameter changes by modifying the curvature radius of the preform to be smaller than the curvature radius of the male inner mold line tool. This parameter difference creates the necessary tension to draw excess material into forming beads, preventing fiber wrinkling and kinking while maintaining fiber integrity.
2Shape
If pressure is applied to force excess material into forming beads, then the preform conforms to complex shapes, but uneven pressure distribution causes deformation
Solution Approach 1:
The patent applies local quality by positioning forming beads at specific locations along the male inner mold line tool where excess material needs to be accommodated. The forming beads are strategically placed to handle local geometric complexities while the grip strip mechanism applies localized tension to draw material into these beads, ensuring uniform pressure distribution and preventing deformation.
Solution Approach 2:
The patent uses an intermediary mechanism - the grip strip with clamps - to mediate between the pressure application and the preform. This intermediary distributes the forming pressure evenly across the preform surface, allowing the material to be drawn into forming beads uniformly without causing localized deformation or compromising dimensional accuracy.
3Shape
If tension is applied to stretch the preform over the mold line, then the preform conforms to complex geometries, but fiber kinking occurs
Solution Approach 1:
The patent applies preliminary action by pre-curing the preform to establish a stable fiber architecture before the forming process. This pre-cured state provides structural integrity that prevents fiber kinking during tension application, while still allowing the preform to be stretched over the male inner mold line tool to achieve complex geometries.
Solution Approach 2:
The patent employs parameter changes by controlling the tension magnitude and distribution during forming. The grip strip mechanism applies controlled tension that is sufficient to stretch the preform over complex geometries but remains below the threshold that would cause fiber kinking, thereby preserving mechanical properties while achieving the desired shape.
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
This approach effectively reduces wrinkling and kinking, ensuring the preform is stretched evenly over corners and radii, resulting in improved mechanical properties and reproducibility of the shaped body by applying uniform pressure and compaction.
Implementation Method 1
the pressure is a negative pressure applied via a vacuum-bagging mechanism
Implementation Method 2
the pressure is a positive pressure applied via at least one of an autoclave mechanism, a flexible caul plates and pressurized bladders mechanism, or an actuated platen press mechanism
Data Source
AI summary
A manufacturing method is disclosed herein. The method includes arranging a preform over a surface of an inner mold line; folding the preform over sides of the inner mold line; pressing an end of the preform into a grip strip coupled to a side of the inner mold line; and applying pressure to the preform to force excess material of the preform into a forming bead of the inner mold line.