Carbon Nanotube Sheets for Uniform Composite Curing
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Solution Overview
Problem
Current methods for curing composites, such as prepregs and liquid resins, rely on externally applied elevated temperatures, leading to overheating issues due to exothermic reactions, which can damage the materials and molds, especially in thicker stacks where heat control is challenging and time-consuming.
Innovation Solution
The use of self-supporting, nonwoven carbon nanotube sheets with connector portions and coupling mechanisms to distribute heat uniformly by running an electric current through them or subjecting them to alternating electromagnetic fields, allowing for controlled curing without excessive heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If externally applied elevated temperatures are used to cure curable systems, then the curing process can be initiated, but excessive heating and overheating occur leading to damage of the curable system and molds
Solution Approach 1:
The patent replaces the conventional mechanical/thermal heating system with an electromagnetic field-based heating system. Electromagnetic fields (such as microwave or radio frequency fields) are applied to the curable system, causing molecular vibration and rotation that generates heat internally within the material. This substitution allows for more uniform and controllable heating throughout the curable system, avoiding the external heat gradient problems that cause overheating and damage.
Solution Approach 2:
The curable system heats itself through the application of electromagnetic fields. The electromagnetic energy is absorbed by the curable system and converted to thermal energy internally, allowing the material to cure from within rather than being heated from the outside. This self-heating mechanism ensures uniform temperature distribution and prevents the external surfaces from overheating while the interior remains uncured.
2Productivity
If the curable system is made thicker to reduce the number of layers, then manufacturing efficiency improves, but the propensity for overheating increases due to inability to control heat application
Solution Approach 1:
The patent replaces conventional external thermal heating with electromagnetic field heating. Electromagnetic fields can penetrate through thick curable systems and generate heat uniformly throughout the entire volume, regardless of thickness. This allows thick single-layer curable systems to be cured efficiently without the overheating problems that occur with conventional external heating methods, thereby improving manufacturing efficiency while maintaining temperature control.
Solution Approach 2:
The patent transitions from surface-based heating (conventional external heating that applies heat from the boundaries inward) to volumetric heating (electromagnetic field heating that generates heat throughout the entire volume simultaneously). This dimensional change in the heating approach allows thick curable systems to be cured uniformly without creating excessive temperature gradients between the surface and interior, enabling thicker sections to be manufactured safely and efficiently.
3Object-affected harmful factors
If the cure cycle is extended to avoid excessive heat generation, then overheating is prevented, but the process becomes time and cost intensive
Solution Approach 1:
The patent replaces slow external thermal heating with rapid electromagnetic field heating. Electromagnetic fields can be applied at high power levels that generate heat quickly and uniformly throughout the curable system, significantly reducing the curing time compared to conventional methods. The ability to control the electromagnetic field power and duration allows for rapid curing cycles that prevent overheating while completing the process much faster than traditional extended cure cycles.
Solution Approach 2:
The electromagnetic field heating provides continuous and uniform energy input throughout the curable system during the curing process. Unlike external heating that must be applied slowly to avoid surface overheating before the interior cures, electromagnetic fields deliver energy continuously and uniformly to all parts of the material simultaneously, enabling faster curing times without creating temperature gradients or excessive heat generation in any region.
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 method enables efficient and controlled curing of composites, preventing overheating and damage, while reducing energy requirements and ensuring uniformity in the curing process, even in thick stacks, by effectively managing heat distribution within the curable system.
Implementation Method 1
distribute heat uniformly by running an electric current through them
Implementation Method 2
subjecting them to alternating electromagnetic fields
Data Source
AI summary
A method of producing composites that are capable of being used in various industries, including the aerospace and automotive industries. In particular, the present disclosure relates to methods of curing one or more prepregs and/or a liquid curable composition using one or more self-supporting, nonwoven carbon nanotube sheets comprising substantially non-aligned carbon nanotubes.