Carbon Fiber Bundle Strength Development Rate Optimization
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Solution Overview
Problem
Carbon fibers used in composite materials for aircraft and aerospace applications do not exhibit satisfactory strength development rates when integrated with matrix resins, despite improvements in mechanical properties, due to inconsistencies in physical properties between design expectations and actual measurements.
Innovation Solution
A carbon fiber with specific properties, including a filament diameter of 4.5 to 10 μm, strand tensile strength of 4,700 MPa or more, and X-ray crystallite size of 18 to 22 Å, which satisfies the formulae Lc/d ≤ 3 and TS × d × Lc > 6.0 × 10^5, is developed, along with a method involving acrylonitrile precursor fiber bundles and controlled carbonization treatments to enhance tensile strength and modulus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon fiber mechanical properties are improved through conventional methods, then strand tensile strength increases, but strength development rate in composite materials remains insufficient
Solution Approach 1:
The invention changes the fundamental parameters of carbon fiber structure by controlling the ratio of X-ray crystallite size to filament diameter (Lc/d ≤ 3) and the product of strand tensile strength, filament diameter, and crystallite size (TS×d×Lc > 6.0×10^5). This structural parameter optimization enables both high strand tensile strength and excellent strength development rate in composite materials, resolving the contradiction between individual fiber strength and composite material performance.
2Strength
If carbon fiber crystallite size is increased to improve strength, then mechanical properties improve, but the ratio of crystallite size to filament diameter becomes excessive
Solution Approach 1:
The invention optimizes the crystallite size to filament diameter ratio (Lc/d) to be 3 or less while maintaining high strand tensile strength. This precise control of structural parameters ensures that the carbon fiber achieves excellent mechanical properties without excessive crystallite growth, enabling both high strength and good processability in composite material applications.
3Ease of manufacture
If conventional carbon fiber production methods are used, then production cost is controlled, but physical properties do not meet design expectations
Solution Approach 1:
The invention establishes specific parameter ranges for carbon fiber production: Lc/d ≤ 3 and TS×d×Lc > 6.0×10^5. These parameter specifications provide clear manufacturing targets that enable consistent production of carbon fiber meeting design requirements, bridging the gap between conventional manufacturing capabilities and advanced performance requirements.
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 carbon fiber achieves excellent strength development rates and mechanical properties in composite materials, leading to improved performance and reliability in aerospace applications.
Implementation Method 1
a method involving acrylonitrile precursor fiber bundles and controlled carbonization treatments to enhance tensile strength and modulus
Implementation Method 2
Lc is an X-ray crystallite size (Å)
Data Source
AI summary
An object of the present invention is to provide a carbon fiber which exhibits excellent strength development rate when used in a composite material. The present invention that solves the problems is a carbon fiber which simultaneously satisfies the following formulae (1) and (2):Lc/d≤3 (1)TS×d×Lc>6.0×105 (2)wherein:Lc is an X-ray crystallite size (Å),d is a filament diameter (μm), andTS is a strand tensile strength (MPa).