Z-Direction Fiber Insertion for Composite Laminates
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Solution Overview
Problem
Current methods for Z-direction reinforcement of fiber composite laminates, such as Z-pinning, stitching, 3-dimensional weaving, and needling, disrupt the laminate structure, are labor-intensive, costly, and often weaken the material, while also failing to effectively join multiple laminates with Z-direction bondline reinforcement.
Innovation Solution
The method involves using barbed needles to pull discrete fibers through a fiber composite preform in the Z-direction, creating Z-direction loops that protrude outward, allowing for minimal disruption and improved joining of laminates, with the process being applicable to both prepreg and dry composite preforms, and enabling the use of resin transfer molding for bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Z-pinning is used to provide Z-direction reinforcement, then reinforcement strength is improved, but fiber disruption and laminate integrity are worsened
Solution Approach 1:
Instead of forcing rigid pins through the laminate (which breaks fibers), the invention uses flexible wires that are formed into loops and then pulled through the laminate. This inverted approach—using flexibility rather than rigidity, and formation before insertion rather than direct insertion—allows the wire to conform to fiber paths and be pulled through without breaking the composite fibers, thus maintaining laminate integrity while achieving Z-direction reinforcement
2Strength
If prepreg material is used for Z-pinning, then reinforcement is achieved, but storage and handling complexity increase
Solution Approach 1:
The invention extracts the resin impregnation step from the reinforcement process by using dry fiber preforms instead of prepreg material. The wires are inserted into the dry preform before resin infusion, eliminating the need for specialized prepreg storage and handling while achieving the same reinforcement effect through the subsequent resin impregnation process
3Strength
If stitching is used to mechanically sew layers together, then Z-direction reinforcement is provided, but machine complexity and operation difficulty increase
Solution Approach 1:
The invention extracts the complex stitching mechanism by replacing it with a simple wire insertion and pulling process. Instead of using needles, threads, and complex sewing machines to mechanically sew layers, the method uses loops that are pulled through the laminate with simple mechanical force, dramatically simplifying the equipment and operation while achieving comparable or superior reinforcement
Solution Approach 2:
The wire loops used in the invention are simple, inexpensive components that can be easily replaced or reconfigured. Unlike complex stitching systems that require precise needle positioning, thread tensioning, and complex machine components, the wire loop method uses simple disposable-like elements that can be quickly inserted and pulled through, reducing both equipment complexity and operational difficulty
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 enhances Z-direction reinforcement with reduced force and fiber disruption, improves the strength and ballistic response of bonded joints, simplifies the joining of multiple preforms, and reduces costs by eliminating the need for specialized fasteners and handling of prepreg materials.
Implementation Method 1
barbed needles to pull discrete fibers through a fiber composite preform in the Z-direction
Data Source
AI summary
A method and apparatus for Z-direction reinforcement of composite laminates is disclosed. Discrete fibers (25) are pulled through a fiber composite preform (11) in the Z-direction by needles (27) having bars (29) thereon to insert the Z-direction reinforcement (31) into the composite preform (11) from a discrete fiber mat (23) having discrete fibers (25) therein.