Thick Composite Laminate Bonding via Stepped Polymerization
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Solution Overview
Problem
The existing methods for creating thick composite structures are time-consuming and labor-intensive, often resulting in residual stress and high thermal loads due to the use of adhesives and multi-stage curing processes, which can damage the laminate and introduce inconsistencies.
Innovation Solution
A method involving the use of prepreg structures that undergo controlled stepped polymerization, where the resin advances in molecular weight and viscosity is monitored in real-time to form a chemical bond between layers without an identifiable interface, allowing for the creation of thick laminate structures without adhesives and reducing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adhesive bonding and multi-stage curing processes are used to create thick laminate structures, then the structures can be formed with controlled thickness, but the process becomes time-consuming and labor-intensive with surface preparation required between each laminate
Solution Approach 1:
The curing process is segmented into multiple stages with progressively increasing temperatures. The process begins at a first temperature to advance the resin partially, then continues at a second higher temperature to complete curing. This segmented approach eliminates the need for adhesive bonding between laminates while maintaining thickness control, significantly reducing process time and eliminating surface preparation steps between layers.
Solution Approach 2:
The curing process utilizes parameter changes by varying temperature through different stages. The first temperature stage advances the resin to a partially cured state with controlled viscosity, enabling proper flow and consolidation. The second higher temperature stage completes the curing process. This parameter change strategy allows thick laminate structures to be formed without adhesives while maintaining manufacturing precision.
2Ease of manufacture
If one-step curing is performed for total thickness, then the process is simplified, but residual stress and high temperatures result in excessive thermal load
Solution Approach 1:
The curing process is divided into temperature stages rather than performed in one step. The first temperature stage advances the resin partially with lower thermal load, and the second stage completes curing at higher temperature. This segmentation reduces excessive thermal load and residual stress while maintaining process simplicity through automated temperature control.
Solution Approach 2:
The curing process employs periodic action through staged temperature application. Rather than continuous high-temperature curing, the process uses periodic temperature increases with the first temperature stage followed by the second temperature stage. This periodic approach reduces thermal shock and excessive thermal load while completing the curing process effectively.
3Ease of manufacture
If adhesives are used to bond laminate structures, then the structures can be assembled in layers, but surface preparation becomes labor and time intensive
Solution Approach 1:
The invention extracts and eliminates the adhesive component from the laminate assembly process. By using resin that flows and consolidates during controlled temperature curing, the need for separate adhesives and surface preparation steps is completely removed. The resin itself provides the bonding function, simplifying both manufacturing and operation.
Solution Approach 2:
The resin performs the bonding function itself without requiring external adhesives. The resin flows during the first temperature stage to consolidate layers and creates chemical bonds between laminates during curing. This self-service approach eliminates surface preparation requirements while maintaining assembly capability, as the resin automatically bonds layers together during the curing process.
4Manufacturing precision
If traditional layup process with adhesives is used, then laminate structures can be formed, but inconsistencies and residual stress are introduced
Solution Approach 1:
The invention achieves homogeneity by using a continuous resin system that flows and consolidates uniformly throughout the laminate structure during controlled temperature curing. The resin advances consistently from the first temperature stage through the second stage, creating uniform chemical bonds between all layers without the inconsistencies introduced by adhesive interfaces. This homogeneous curing process eliminates residual stress and improves structure consistency.
Solution Approach 2:
The curing process maintains continuity of useful action through staged temperature application. The resin continues to flow and consolidate continuously from the first temperature stage into the second temperature stage without interruption or adhesive interfaces. This continuous resin advancement and curing process eliminates discontinuities and residual stress, improving manufacturing precision and structural integrity.
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 enables the efficient fabrication of thick laminate structures with improved mechanical properties and reduced residual stresses, eliminating the need for surface preparation and adhesives, and allowing for the creation of large composite components like watercraft and aircraft parts without the limitations of traditional autoclave curing.
Implementation Method 1
the first prepreg structure comprises a resin that begins to flow and advances slightly in cure in response to the heating to the first temperature
Implementation Method 2
heating a first prepreg structure to a first temperature, wherein the first prepreg structure comprises a resin that begins to flow and advances slightly in cure in response to the heating to the first temperature
Implementation Method 3
heating the first prepreg structure and the second prepreg structure together to form a chemical bond between the first prepreg structure and the second prepreg structure
Data Source
AI summary
Methods of creating thick composite structures are provided. The methods may be applied to two or more prepreg structures of composite materials to form laminate structures that are thicker than approximately five (5) inches without excessive exothermic events resulting in inconsistent cure and high residual stresses. The method may include heating a first sheet to achieve a specified increase in resin viscosity. In response to achieving the specified resin viscosity, a second portion of composite material may be applied to the first portion. The assembly may be heated to create a laminate structure which is chemically bonded with no interface.