Stitched Fiber-Reinforced Substrate Microcrack Suppression
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Solution Overview
Problem
The formation of microcracks at the interface between stitching yarn and matrix resin in fiber-reinforced composite materials, which reduces the mechanical properties of the composite material, is not adequately suppressed by existing techniques.
Innovation Solution
Using stitching yarns with a high in-plane shear strength transition rate, a specific linear expansion coefficient, and a polar group, which are integrated into unidirectionally drawn and aligned reinforcement fiber sheets to form a stitched fiber-reinforced substrate material, thereby reducing interfacial delamination and microcrack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stitching yarn is used to integrate reinforcement fiber sheets, then the mechanical properties are improved by preventing fiber crimp, but microcracks are generated at the interface between stitching yarn and matrix resin
Solution Approach 1:
The patent changes the physical and chemical parameters of the stitching yarn by specifying a linear expansion coefficient of -50 to -150×10^-6/℃ and incorporating polar groups into the yarn structure. These parameter changes enable the stitching yarn to match the thermal expansion characteristics of carbon fiber reinforcement sheets and improve interfacial adhesion with the matrix resin, thereby suppressing microcrack formation while maintaining mechanical strength
Solution Approach 2:
The patent creates a composite structure by combining stitching yarn with specific physical properties (linear expansion coefficient and polar groups) with the reinforcement fiber sheets and matrix resin. This composite approach ensures compatibility between the stitching yarn and both the reinforcement fibers and matrix resin, preventing microcrack generation at interfaces while preserving the strength benefits of stitching
2Stability of the object's composition
If conventional stitching yarn is used, then fiber sheets are integrated effectively, but thermal expansion differences cause interfacial delamination and microcracks
Solution Approach 1:
The patent modifies the thermal expansion parameter of the stitching yarn by selecting materials with a linear expansion coefficient of -50 to -150×10^-6/℃, which matches the thermal characteristics of carbon fiber reinforcement sheets. This parameter change prevents thermal stress-induced delamination at the interface while maintaining effective integration of the fiber sheets
Solution Approach 2:
The stitching yarn acts as an intermediary element between the reinforcement fiber sheets and the matrix resin. By endowing this intermediary with specific properties (polar groups and matched thermal expansion coefficient), the patent ensures compatible thermal and chemical interactions with both adjacent materials, preventing interfacial delamination while maintaining integration stability
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 approach significantly suppresses microcrack formation, maintaining high mechanical properties of the fiber-reinforced composite material by enhancing interfacial adhesiveness and reducing thermal expansion differences between the stitching yarn and matrix resin.
Implementation Method 1
the stitching yarn exhibits a linear expansion coefficient in the fiber axial direction of -1×10 -6[0013] By reducing thermal expansion differences between the stitching yarn and matrix resin, the patent suppresses microcrack formation and enhances interfacial adhesiveness
Implementation Method 2
the stitching yarn exhibits a content of polar groups... enhancing interfacial adhesiveness between the stitching yarn and matrix resin
Data Source
AI summary
An object of the present invention is to provide a stitched fiber-reinforced substrate material capable of suppressing the formation of microcracks in a fiber reinforced composite material. The stitched fiber-reinforced substrate material of the present invention is a stitched fiber-reinforced substrate material formed by stitching reinforcement fiber sheets made of reinforcement fibers using stitching yarns that exhibit an in-plane shear strength transition rate of 5% or more. The stitching yarn is preferably adhered by an organic compound having a polar group.