3D Permeable Interlayers for Tougher Resin-Infused Composites
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Solution Overview
Problem
Conventional composite materials with fiber tows suffer from cracking and delamination under stress, particularly at high-stress concentration regions, and existing through-thickness toughening techniques either fail to enhance fracture toughness without degrading in-plane properties or introduce manufacturing defects.
Innovation Solution
A three-dimensional network of filaments and pillars is integrated into the composite material, forming a physical barrier that deflects cracks without degrading the material's integrity, using a 3D printer to deposit the pillars and filaments, which interlock with fiber tows to create a continuous, permeable veil interlayer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional through-thickness toughening techniques (z-pins, stitches) are used, then mode I fracture toughness is significantly increased, but in-plane properties (OHC strength) are degraded due to microstructural imperfections
Solution Approach 1:
The patent employs a porous foam interlayer material that allows resin penetration while providing through-thickness reinforcement. The porous structure enables the material to absorb resin during infusion, creating a void-free laminate without the microstructural imperfections caused by conventional z-pins or stitches, thus maintaining in-plane properties while improving fracture toughness
Solution Approach 2:
The invention uses a composite interlayer consisting of foam material saturated with fiber tows and resin. This composite structure combines the toughness-enhancing properties of the foam with the reinforcement benefits of fiber tows, achieving both improved mode I fracture toughness and preserved in-plane mechanical properties
2Strength
If film adhesives are used for toughening, then through-thickness toughness is improved, but resin flow path is disrupted during infusion, leading to defects such as voids, porosity and dry spots
Solution Approach 1:
The porous foam interlayer is specifically designed to be permeable to resin, allowing controlled resin flow through the interlayer during infusion. This prevents the formation of voids, porosity, and dry spots that occur with impermeable film adhesives, while still providing the through-thickness toughness enhancement
3Strength
If 3D woven/3D knitted/3D braided preforms are used, then through-thickness reinforcement is achieved, but fiber tow misalignment occurs during manufacturing, limiting application to specific geometries
Solution Approach 1:
The invention segments the reinforcement function into two separate components: the foam interlayer provides through-thickness reinforcement, while the fiber tows provide in-plane reinforcement. This segmentation allows each component to be optimized independently, with the foam material able to conform to complex geometries without the fiber misalignment issues that plague 3D woven or braided preforms
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
The solution enhances fracture toughness and maintains in-plane properties, preventing damage from through-thickness reinforcements while allowing resin infusion, thus improving the composite material's structural integrity.
Implementation Method 1
using a 3D printer to deposit the pillars and filaments
Implementation Method 2
forming a physical barrier that deflects cracks without degrading the material's integrity
Implementation Method 3
allowing resin infusion
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A three dimensional permeable thermoplastic tape useful for joining of layers of fiber tows (plies) together so as to form highly toughened resin infused structures. In one or more embodiments, the tape is manufactured using three dimensional printing and is applied between layers of fiber tows so as to tack the layers of fiber tows in place and prevent movement of the layers of fiber tows.