Weldable Prepreg Laminate for Strong Composite Joining
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Solution Overview
Problem
Existing fiber-reinforced composite materials using thermosetting or thermoplastic resins face challenges in joining processes, such as prolonged production times and insufficient joining strengths, especially in tensile shear, out-of-plane tension, and impact resistance, making them unsuitable for complex shapes and structural applications.
Innovation Solution
A prepreg and laminate design incorporating reinforcing fibers, an epoxy resin with an average epoxy value of 2.0 to 5.0 meq./g, and a thermoplastic resin, allowing for welding and achieving excellent tensile shear, out-of-plane tensile, and impact joining strengths through a strong interface between resin areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical joining methods using bolts, rivets, or screws are used to integrate fiber-reinforced composite materials, then the joining strength is improved, but the production process is prolonged and production cost is increased due to pre-processing steps like drilling
Solution Approach 1:
The invention changes the physical state of the thermoplastic resin from solid to molten state through heating, enabling the material to flow and fill the interface between components. This parameter change (temperature increase) transforms the joining mechanism from mechanical (bolts/rivets) to thermal-fluid (molten resin flow), eliminating the need for drilling and pre-processing while maintaining strong joining through the molten resin that penetrates and bonds the fiber-reinforced composite materials.
2Ease of manufacture
If joining methods using adhesive are used to integrate fiber-reinforced composite materials, then the production process is simplified compared to mechanical joining, but the production process is still prolonged due to bonding preparation, coating, and curing processes
Solution Approach 1:
The invention extracts and eliminates the separate adhesive material and its associated processing steps (preparation, coating, curing). Instead, the thermoplastic resin that is already present in the fiber-reinforced composite material is heated to a molten state to serve as the joining medium. This removes the need for external adhesive applications and their lengthy curing processes, significantly reducing production time while maintaining process simplicity.
Solution Approach 2:
The thermoplastic resin serves multiple functions: it acts as the matrix material within the fiber-reinforced composite, provides structural integrity to the individual components, and simultaneously serves as the joining medium when heated to molten state. This multi-functionality eliminates the need for separate adhesive materials and reduces the number of processing steps required for joining.
3Productivity
If welding method is used to join members formed from thermoplastic resin, then the joining time is shortened, but the joining strength in tensile shear, out-of-plane tension, and impact resistance cannot achieve sufficient reliability
Solution Approach 1:
The invention introduces molten thermoplastic resin as an intermediary material between the fiber-reinforced composite materials during joining. When heated, the thermoplastic resin becomes molten and flows to fill the interface between components, creating a strong bonding medium. This intermediary molten resin enables both rapid joining (like welding) and achieves high reliability in tensile shear, out-of-plane tension, and impact resistance by penetrating and bonding the fiber structures effectively.
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 prepreg and laminate enable rapid joining processes with enhanced structural integrity, reducing molding time and cost, suitable for applications like aircraft parts, windmill blades, and computer components.
Implementation Method 1
heating it to a molding temperature, which is a melting point or a softening point of the thermoplastic resin
Implementation Method 2
applying a pressing load to the fiber-reinforced composite materials while heating it
Data Source
AI summary
An object of the present invention is to provide a prepreg and a laminate for producing a laminate suitable as a structural material, which have excellent joining strength and interlaminar fractural toughness values and can be firmly integrated with another structural member by welding. The present invention provides a prepreg including the following structural components, [A] reinforcing fibers, [B] an epoxy resin, and [C] a thermoplastic resin, wherein all epoxy resins included in [B] have an average epoxy value of 2.0 meq./g or more and 5.0 meq./g or less, [C] is present in a surface of the prepreg, and the reinforcing fibers [A] are present, which are included in a resin area including [B] and a resin area including [C] across an interface between the two resin areas.