Metal-FRP Composite Interlayer for Bake-Induced Deformation Control
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Solution Overview
Problem
Existing metal-fiber reinforced resin material composites used in automobile manufacturing face issues with deformation and thermal stress due to differences in linear expansion coefficients between metal and carbon fiber-reinforced plastic (CFRP) layers, especially during the coating and baking process.
Innovation Solution
A metal-fiber reinforced resin material composite with a laminated structure of three or more layers, including a metal layer, a fiber-reinforced resin material layer, and a resin layer located between the metal and fiber-reinforced resin material layers. The resin layer is made of a room temperature curing adhesive or a predetermined resin and this adhesive, with an elastic modulus between 0.1 MPa and 1000 MPa, and a thickness within a specific range relative to the metal layer, to minimize thermal stress and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal layer and CFRP layer are bonded with an adhesive and subjected to a baking process, then the adhesive is cured and bonding is achieved, but thermal stress occurs due to linear expansion coefficient difference causing deformation
Solution Approach 1:
A resin layer is introduced as an intermediary between the metal layer and CFRP layer. This resin layer has a linear expansion coefficient that falls between those of the metal and CFRP, allowing it to act as a buffer that absorbs and distributes thermal stress during the baking process, thereby preventing deformation while maintaining bonding strength
Solution Approach 2:
The invention creates a multi-layer composite structure consisting of metal layer, resin layer, and CFRP layer. Each layer is selected with specific material properties (particularly linear expansion coefficients) to work together as a composite system that mitigates thermal stress through the coordinated expansion and contraction of different materials
2Stress or pressure
If a thermoplastic elastomer layer is used as an intermediation layer to adjust thermal stress, then thermal stress difference is reduced, but the elastomer leaks out under harsh environment at 180°C for 20 minutes
Solution Approach 1:
The invention changes the key parameter of the intermediary material from a thermoplastic elastomer to a resin with specific thermal and mechanical properties. The resin is selected to have a glass transition temperature and melting point higher than the baking process temperature (180°C), ensuring it maintains its structural integrity and does not leak out during the harsh baking environment while still providing thermal stress adjustment
3Stress or pressure
If the resin layer thickness is increased to improve thermal stress adjustment, then thermal stress difference is better absorbed, but adhesive strength at interface may be compromised
Solution Approach 1:
The invention optimizes the thickness parameter of the resin layer to a specific range (0.01 mm to 0.5 mm). This parameter optimization balances two competing requirements: the resin layer must be thick enough to effectively absorb and distribute thermal stress, but thin enough to maintain sufficient adhesive strength at the metal-resin and resin-CFRP interfaces. The specific thickness range achieves the optimal compromise between these two functions
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 proposed composite maintains a good appearance and prevents deformation even after the coating and baking process, effectively addressing the thermal stress issues between metal and CFRP layers.
Implementation Method 1
an elastic modulus E of the resin layer is more than 0.1 MPa and 1000 MPa or less
Implementation Method 2
heating in the baking process causes volume changes with different linear expansion coefficients between the metal material and CFRP
Implementation Method 3
the resin layer is a layer constituted by a room temperature curing adhesive
Data Source
AI summary
To provide a metal-fiber reinforced resin material (FRP) composite having a good appearance even when used as an automobile outer panel and not deformed even after a coating and baking process. The metal-FRP composite of the invention has a laminated structure of three or more layers, having at least a metal layer, a fiber-reinforced resin material layer holding a reinforced fiber material in a layer constituted by a matrix resin, and a resin layer located between the metal layer and the fiber-reinforced resin material layer. The resin layer is a layer constituted by a room temperature curing adhesive or by a predetermined resin and the room temperature curing adhesive. An elastic modulus E of the resin layer is more than 0.1 MPa and 1000 MPa or less, and a thickness of the resin layer is 0.005 times or more and less than 7.500 times a thickness of the metal layer.