Slit Caul Plate for Composite Fiber Wrinkle Control
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Solution Overview
Problem
Fiber distortion during the fabrication of composite parts, particularly due to geometric changes, leads to uncontrolled wrinkling in cured parts, reducing strength and potentially exceeding engineering specifications, resulting in additional material costs, weight, and potential discarding of parts.
Innovation Solution
A caul plate with strategically positioned slits is applied over uncured composite material undergoing geometric changes, combined with reduced pressure vacuum bagging, to control fiber alignment and prevent wrinkling during the curing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the uncured composite part experiences geometric changes such as positioning to extend about a radius of curvature or having a ply drop, then the composite part can be formed to match the desired geometry, but the fibers become distorted from straight line alignment and bunching occurs
Solution Approach 1:
The patent applies preliminary action by positioning the caul plate with pre-defined slits over the uncured composite material before curing. The slits are strategically positioned to anticipate and accommodate the geometric changes that will occur during curing, allowing the fibers to follow the slits and maintain alignment even as the part geometry changes.
Solution Approach 2:
The caul plate acts as an intermediary between the mold and the composite material. The slits in the caul plate provide a controlled path for the fibers to follow during geometric changes, mediating the interaction between the rigid mold geometry and the flexible uncured composite material to prevent fiber distortion.
2Ease of manufacture
If fibers are positioned in compression within the uncured composite part, then the composite part can be formed, but the fibers are distorted from straight line alignment and experience bunching
Solution Approach 1:
The caul plate is segmented with multiple slits positioned at specific locations corresponding to areas where compression and fiber bunching are expected. These slits divide the continuous fiber path into segments that can independently accommodate compression without causing overall fiber distortion or bunching.
Solution Approach 2:
The patent applies local quality by positioning slits only in specific areas of the caul plate where compression and fiber bunching are anticipated to occur. Not the entire caul plate has slits, but only localized regions where the composite material experiences geometric changes or compression, allowing fiber alignment to be maintained precisely where needed.
3Strength
If additional composite material is added to reinforce wrinkled locations, then the strength of the composite part is improved, but time, labor and material cost increase
Solution Approach 1:
The patent prevents the need for subsequent reinforcement by taking preliminary action during the initial layup and curing process. The caul plate with slits is positioned before curing to control fiber alignment and prevent wrinkling from occurring in the first place, eliminating the need for time-consuming post-cure reinforcement operations.
Solution Approach 2:
The patent converts the potential harm of compression-induced fiber bunching into a benefit by using the slits to guide the fibers. Instead of trying to prevent compression entirely, the slits channel the compressed fibers along controlled paths, transforming what would be a defect into a controlled feature that maintains strength without requiring additional material or time.
4Strength
If additional composite material is added to reinforce the composite part, then the strength is improved, but weight is added to the finished composite part
Solution Approach 1:
The caul plate applies local quality by positioning slits only in specific areas where fiber distortion occurs, rather than uniformly across the entire part. This localized approach maintains fiber alignment and prevents wrinkling only where needed, avoiding the addition of unnecessary reinforcement material and weight in areas that would otherwise be fine.
5Shape
If the uncured composite material experiences geometry changes, then the desired part shape is achieved, but uncontrolled wrinkling occurs in the cured composite part
Solution Approach 1:
The caul plate with slits serves as an intermediary that mediates between the mold geometry and the composite material during shape formation. The slits provide a controlled interface that allows the composite to conform to the desired geometry while preventing uncontrolled wrinkling by guiding fiber movement along predetermined paths.
Solution Approach 2:
The patent applies parameter changes by modifying the physical structure of the caul plate to include slits of specific dimensions and positions. These parameter changes in the caul plate design allow it to accommodate geometric changes in the composite part while maintaining wrinkle control, effectively changing the caul plate's interaction characteristics with the composite material.
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 method ensures controlled wrinkling within acceptable limits, maintaining part strength and compliance with engineering specifications, reducing the need for additional reinforcement material and avoiding part discard.
Implementation Method 1
reduced pressure vacuum bagging
Data Source
AI summary
A method for positioning wrinkling of a cured composite material at a predetermined location in fabricating a composite part, which includes positioning a caul plate in contact with an uncured composite material. The uncured composite material has a geometric change in shape and the caul plate has a first slit which extends through and along the caul plate. The method further includes positioning a fiber and a resin of a portion of the uncured composite material within the first slit and curing the uncured composite material positioning a wrinkle within the first slit of the caul plate.