Composite Material Structure for Thermal Expansion Mismatch
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Solution Overview
Problem
The difference in thermal expansion coefficients between light metals and carbon fiber-reinforced plastics (CFRP) poses challenges in bonding and molding, requiring special adhesives and complicating the process due to differing elongation deformations caused by heat.
Innovation Solution
A composite material structure is developed with a metal member having a larger thermal expansion coefficient in one direction and a fiber-reinforced resin member with more fibers oriented in that direction, bonded using an adhesive with thin walled portions and gaps to absorb thermal expansion differences, allowing for reduced warping and easier molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If light metal and CFRP are bonded together, then the composite structure can efficiently absorb input load, but the difference in thermal expansion coefficients causes difficult molding and requires special adhesives
Solution Approach 1:
The invention introduces gaps that segment the adhesive layer into multiple regions separated by voids. These gaps divide the continuous adhesive path into discrete segments, allowing differential thermal expansion between metal and CFRP without generating excessive stress, thereby enabling standard adhesives to be used and simplifying the manufacturing process
Solution Approach 2:
The invention creates non-uniform adhesive distribution by introducing gaps at specific locations where thermal expansion stress concentrates. This local modification of adhesive continuity allows the structure to accommodate thermal differential while maintaining bonding strength in critical areas, resolving the contradiction between bonding effectiveness and manufacturing ease
2Strength
If a continuous adhesive layer is used to bond metal and CFRP, then bonding strength is maximized, but thermal expansion differences cause warping and molding difficulties
Solution Approach 1:
By segmenting the adhesive layer through strategically placed gaps, the invention maintains sufficient bonding strength while preventing warping. The gaps break the continuous adhesive path into manageable segments that can accommodate thermal expansion differences without causing cumulative stress that leads to warping
Solution Approach 2:
The gaps act as intermediary spaces that mediate the thermal expansion conflict between metal and CFRP. These voids provide compression relief zones that absorb dimensional changes during curing and thermal cycles, preventing the warping that would occur with a completely continuous adhesive layer
3Reliability
If special adhesives are used to accommodate thermal expansion differences, then bonding reliability is improved, but device complexity and cost increase
Solution Approach 1:
The invention converts the harmful effect of thermal expansion differences into a beneficial feature by intentionally introducing gaps. These gaps, which might seem to reduce bonding area, actually provide compression relief that prevents adhesive failure under thermal stress, allowing standard adhesives to perform reliably without requiring specialized high-cost materials
Solution Approach 2:
The invention changes the physical parameter of adhesive continuity by introducing gaps, thereby altering the stress distribution pattern. This parameter change allows conventional adhesives to accommodate thermal expansion differences through mechanical compliance rather than requiring special chemical properties, reducing both complexity and cost
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 configuration reduces the impact of thermal expansion coefficient differences, eliminates the need for special adhesives, and simplifies the molding process by using the adhesive as a buffer layer and anchor, enhancing bonding strength and preventing resin flow during molding.
Implementation Method 1
the thermal expansion coefficients of the light metal and the CFRP are different, a special adhesive is necessary in order to absorb the difference in the amount of elongation deformation due to heat
Implementation Method 2
it is possible to reduce the effect of the difference in thermal expansion coefficients between metal and fiber-reinforced resin by preferentially orienting the fibers of the fiber-reinforced resin along a direction in which the thermal expansion coefficient of the metal member is small
Implementation Method 3
the metal member is formed such that the thermal expansion coefficient in a first direction along a main surface is larger than the thermal expansion coefficient in a second direction along the main surface that is orthogonal to the first direction
Data Source
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AI summary
A composite material structure 1 is provided with: a metal member 2 planarly formed such that a thermal expansion coefficient in a first direction along a main surface is larger than a thermal expansion coefficient in a second direction, which is along the main surface, and is orthogonal to the first direction; and a resin member 4, formed of a fiber-reinforced resin, bonded to the main surface of the metal member 2, and formed such that a fiber 41 quantity in the second direction is larger than a fiber 42 quantity in the first direction.