Thermoplastic Molded Object With Random Fiber Stacking
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Solution Overview
Problem
The production of fiber-reinforced resin molded objects using thermoplastic resin and carbon fibers faces challenges such as complex stacking processes, high production costs, anisotropy in mechanical properties, and potential cracking or delamination, which affect the strength and appearance of the final product, especially in thin or deeply uneven molded objects.
Innovation Solution
A method involving a first layer of thermoplastic resin with strip-shaped reinforcement fiber bundles aligned unidirectionally and randomly stacked, and a second layer of woven fabric reinforcement fibers, both using late-reactive thermoplastic epoxy resin, which are applied on both surfaces of the first layer, allowing for improved strength and appearance through three-dimensional random stacking and woven fabric reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon fibers are aligned unidirectionally and prepreg sheets are stacked in different fiber axial directions, then anisotropy is reduced and strength is improved, but the operation becomes complex and production cost increases
Solution Approach 1:
The patent uses woven fabric where carbon fibers are interlaced in multiple directions (typically 0度和90度), creating a homogeneous distribution of fiber orientations throughout the material. This eliminates the need for complex multi-directional stacking of prepreg sheets, as the woven structure inherently provides balanced mechanical properties in all directions while simplifying the manufacturing process to a single-layer placement operation.
Solution Approach 2:
The patent combines carbon fiber woven fabric with thermoplastic resin to create a composite material that integrates the strength benefits of aligned fibers with the ease of processing of woven structures. The thermoplastic resin matrix binds the woven fibers together, allowing the material to be handled as a single prepreg sheet rather than requiring multiple stacked layers with different orientations.
2Strength
If woven fabric is used and prepreg sheets are stacked, then mechanical strength is improved, but fabrics peel off each other or the molded object cracks when dropped or hit
Solution Approach 1:
The patent changes the material parameters by selecting thermoplastic resin with appropriate melting point and viscosity characteristics that enable effective bonding between woven fabric layers during the molding process. The resin parameters are optimized to ensure sufficient flow into the fabric weave and strong interlaminar adhesion, preventing delamination under impact while maintaining the strength benefits of the woven structure.
3Stability of the object's composition
If reinforcement fibers are stirred in thermoplastic resin, then anisotropy is reduced, but reinforcement fibers may crack and break and strength decreases
Solution Approach 1:
Instead of stirring fibers into resin (which causes mechanical damage), the patent inverts the approach by first creating woven fabric structures with pre-aligned fibers, then impregnating with resin during molding. This reverse sequence protects fiber integrity while achieving the desired isotropic properties through the woven pattern and resin distribution.
4Strength
If thermosetting prepreg sheets are used, then mechanical strength is achieved, but they cannot be remolded and require low-temperature storage and long curing time
Solution Approach 1:
The patent changes the fundamental chemical parameter of the resin system from thermosetting to thermoplastic. This enables remoldability through melting and reprocessing, eliminates the need for low-temperature storage (as thermoplastics are stable at room temperature), and dramatically reduces curing time by replacing lengthy chemical curing reactions with rapid thermal melting and solidification processes.
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 results in molded objects with enhanced strength, shock resistance, and uniform mechanical properties in all directions, reducing the likelihood of cracking and delamination, while also simplifying the production process and eliminating the need for low-temperature storage and long curing times.
Implementation Method 1
heating and applying pressure to a stack object obtained by randomly stacking a fiber-reinforced resin material including thermoplastic resin
Implementation Method 2
heating and applying pressure to a stack object obtained by randomly stacking a fiber-reinforced resin material including thermoplastic resin
Implementation Method 3
heating and applying pressure to a stack object obtained by randomly stacking a fiber-reinforced resin material including thermoplastic resin
Data Source
Figure 1A~2
Figure 3~4
Figure 5~6
AI summary
A molded object includes: a first layer (10) formed using a fiber-reinforced resin material including thermoplastic resin and strip-shaped reinforcement fiber bundles each composed of a plurality of reinforcement fibers aligned unidirectionally, the strip-shaped reinforcement fiber bundles being three-dimensionally and randomly stacked; and a second layer (20) made of a fiber-reinforced resin material including thermoplastic resin and reinforcement fibers of filaments, and formed on at least one surface of the first layer (10).