Random Mat Composite Material Fiber Orientation Control
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Solution Overview
Problem
Conventional fiber-reinforced composite materials using random mats with thermosetting resins face challenges in achieving high mechanical strength, isotropy, and efficient fiber reinforcement due to fiber orientation and entanglement issues, leading to low strength development and long shaping times.
Innovation Solution
A random mat comprising thermoplastic resin and discontinuous reinforcing fibers with specific dimensions, such as average fiber length, weight-average fiber width, and thickness, which allows for dense and uniform fiber incorporation, resulting in a fiber-reinforced composite material with improved mechanical strength and isotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the volume content ratio of reinforcing fibers is increased to improve mechanical properties, then strength is improved, but fiber entanglement and three-dimensional orientation make it difficult to heighten the volume content ratio in random mats
Solution Approach 1:
The patent segments the fiber structure by using cut fibers with specific length ranges (5-50mm) and controlling the fiber width distribution. This segmentation reduces fiber entanglement while maintaining high volume content ratio, allowing mechanical properties to be improved without excessive entanglement complexity.
Solution Approach 2:
The patent changes key parameters including fiber length (5-50mm), fiber width (0.1-2.0mm), and fiber width distribution ratio (0.5-2.0) to optimize the balance between volume content ratio and entanglement. By carefully controlling these parameters, the patent achieves high fiber content while minimizing entanglement issues.
2Strength
If continuous fibers are used to enable sufficient strength exhibition, then strength development is improved, but random mats employ discontinuous cut fibers which limit strength to 50% of theoretical value
Solution Approach 1:
The patent optimizes the fiber length parameter to 5-50mm, which is sufficiently long to develop strength while maintaining the discontinuous nature of random mats. This parameter optimization allows strength development to reach 70% or more of theoretical value, improving upon the 50% limitation of conventional cut fibers.
3Productivity
If thermosetting resin is used with conventional shaping methods, then composite material is obtained, but shaping time requires 2 hours or longer using autoclave
Solution Approach 1:
The patent replaces the conventional autoclave heating and pressing method with a cold pressing method. This substitution eliminates the need for prolonged thermal curing, reducing shaping time from 2 hours or longer to significantly shorter durations while still achieving proper composite material formation.
Solution Approach 2:
The patent changes the processing parameters by eliminating high-temperature curing and using cold pressing instead. This parameter change dramatically reduces the time required for shaping while maintaining the integrity and properties of the composite material.
4Productivity
If RTM method is used to reduce shaping time, then time is reduced, but 10 minutes or longer is still required for each component to be shaped
Solution Approach 1:
The patent replaces the RTM method's resin injection and curing process with a cold pressing method. This substitution reduces the shaping time from 10 minutes or longer to significantly shorter durations by eliminating the resin injection and thermal curing steps, achieving faster production cycles.
5Productivity
If thermoplastic stamping is used to complete molding in about 1 minute, then productivity is improved, but thin-walled products cannot be molded and fiber orientation is disordered
Solution Approach 1:
The patent optimizes fiber length to 5-50mm and fiber width to 0.1-2.0mm, with specific control over fiber width distribution ratio (0.5-2.0). These parameter changes enable better fiber orientation control during cold pressing while maintaining short molding times, overcoming the limitations of thermoplastic stamping for thin-walled products and disordered fiber orientation.
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 enables the production of composite materials with enhanced mechanical strength, isotropy, and high strength development, suitable for various applications including motor vehicle components and electrical products, while reducing shaping time.
Implementation Method 1
a random mat which includes reinforcing fibers having an average fiber length of 3-100 mm and a thermoplastic resin
Data Source
Figure 1~2
Figure 3
AI summary
Provided are a fiber-reinforced composite material shaped product which is isotropic and has excellent mechanical strength and a random mat for use as an intermediate material for the shaped composite material. The random mat includes reinforcing fibers having an average fiber length of 3 to 100 mm and a thermoplastic resin, wherein the reinforcing fibers satisfy the following i) to iii). i) The reinforcing fibers have a weight-average fiber width (Ww) which satisfies the following equation (1). 0mm<Ww<2.8mm ii) The reinforcing fibers have an average-fiber-width dispersion ratio (Ww/Wn), which is defined as a ratio of the weight-average fiber width (Ww) to a number-average fiber width (Wn), of 1.00 or more and 2.00 or less. iii) The reinforcing fibers have a weight-average fiber thickness which is smaller than the weight-average fiber width (Ww) thereof.