Composite Surface Finish via Rubber-Modified Resin
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Solution Overview
Problem
Composite materials used in aerospace and automotive industries face challenges in maintaining an extremely flat surface finish due to fiber 'print-through' caused by thermal and chemical shrinkage, which reappears after hygroscopic and thermal aging, making it difficult to produce aesthetically pleasing parts that withstand environmental conditions.
Innovation Solution
Incorporating rubber particles into the matrix resin combined with a relatively flat fabric pattern and a surface finish film, applied in amounts between 100 and 800 gsm, to create a durable and extremely flat surface finish that remains flat even after extended aging periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a surface finish film is applied to eliminate fiber print-through, then the surface flatness is improved initially, but the print-through reappears after hygroscopic and thermal aging
Solution Approach 1:
The patent changes the chemical composition parameters of the matrix resin by incorporating specific rubber particles (1-20 parts by weight per 100 parts of thermosetting resin). This modification alters the resin's shrinkage characteristics and flexibility, enabling the surface finish to maintain flatness through aging cycles without print-through reappearance.
Solution Approach 2:
The patent creates a composite matrix resin system by combining thermosetting resin with rubber particles. This composite material exhibits both the structural properties needed for composite fabrication and the flexibility required to prevent print-through during thermal and hygroscopic aging, resolving the contradiction between initial surface quality and long-term durability.
2Manufacturing precision
If the thickness of the surface finish film is increased to reduce print-through, then the initial surface flatness is improved, but the overall weight of the structure increases
Solution Approach 1:
Instead of increasing film thickness, the patent changes the functional properties of the matrix resin by adding rubber particles. This allows achieving the same print-through prevention effect with a thinner surface finish film, thereby maintaining structural weight efficiency while improving surface flatness.
3Manufacturing precision
If unidirectional fibers or thin flat fabrics are used to reduce print-through, then the surface flatness is improved, but a certain degree of print-through still occurs
Solution Approach 1:
The rubber particles act as an intermediary element within the matrix resin system. They provide flexibility and shrinkage compensation that mediates between the fiber structure and the surface finish film, enabling complete elimination of print-through through aging that cannot be achieved by fabric selection alone.
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 composite materials achieve an average waviness of less than 40 BYK Gardner wavescan units, maintaining flatness both initially and after 30 and 90 days of hydro-thermal aging, ensuring long-lasting, aesthetically pleasing surfaces suitable for automotive and aerospace applications.
Implementation Method 1
The thermal shrinkage is due to the coefficient of thermal expansion (CTE) of the resin matrix being much higher than the CTE of the carbon fibers
Implementation Method 2
The chemical shrinkage is a result of the volume loss which occurs when the monomers in the resin react during curing to form the crosslinked polymer matrix
Implementation Method 3
the print-through typically re-appears fairly soon upon hygroscopic and/or thermal aging
Data Source
AI summary
The surface finish of composite materials is improved by reducing the amount of "print-through" that occurs as the surface ages. A resin matrix, which is modified with rubber particles, is used in combination with a surface finish film to provide extremely flat and durable surface finishes.