Dual-Source Curing for Composite Residual Stress Reduction
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Solution Overview
Problem
Curing of fiber-reinforced composite structures with complex geometries often results in residual internal stresses due to uneven thermal expansion and contraction, which existing methods fail to adequately address.
Innovation Solution
The use of two distinct heat sources, one for internal conductive heating and another for external surface heating, optionally combined with a heat sink for active cooling, to manage thermal expansion and contraction more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heating is applied exclusively from the external surface during curing, then the structure can be heated uniformly from outside, but residual internal stresses result due to thermal expansion and shrinkage of the composite binding material
Solution Approach 1:
The heating system is segmented into multiple independent heat sources positioned at different locations (e.g., top, bottom, and internal heat sources) that can be controlled separately. This allows different regions of the composite structure to be heated independently, enabling compensation for thermal expansion and contraction stresses by adjusting heating in specific zones.
Solution Approach 2:
Different regions of the composite structure receive different heating intensities or thermal treatments based on their specific geometric characteristics and stress requirements. Internal complex geometry regions may receive enhanced heating compared to external surfaces, allowing localized stress management while achieving overall curing.
2Ease of manufacture
If the structure is heated from the external surface inward, then heating can be applied simply, but the composite binding material expands and shrinks causing internal stresses
Solution Approach 1:
Heat sources are nested within the mold cavity or positioned in close proximity to internal regions of the composite structure, allowing heating from the inside out while maintaining external heating for overall temperature control. This nested arrangement enables simultaneous internal and external heating without complicating the manufacturing setup.
3Stress or pressure
If multiple heat sources are used to heat from internal and external surfaces, then residual stresses can be reduced, but the system complexity increases
Solution Approach 1:
The heating system is designed with multi-functional components that can serve multiple purposes. For example, heating elements can function both as heat sources and as temperature sensors, or mold heating zones can serve both curing and stress relief functions. This reduces the number of separate components needed while maintaining the ability to apply complex thermal profiles.
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 reduces residual internal stresses in fiber-reinforced composite structures by ensuring more uniform heating and cooling, thereby improving the curing process and reducing stress-related issues.
Implementation Method 1
A first heat source is configured to apply heat to an internal portion of a complex fiber-reinforced composite structure for conductive heating of the complex fiber-reinforced composite structure from the internal portion
Implementation Method 2
A second heat source distinct from the first heat source is configured to apply heat to an external surface of the complex fiber-reinforced composite structure for conductive heating of the complex fiber-reinforced composite structure from the external surface
Implementation Method 3
Some systems and methods optionally also utilize a heat sink to actively withdraw heat from the internal portion of the complex fiber-reinforced composite structure being cured to cool the complex fiber-reinforced composite structure from within the internal portion
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
Systems (20) and methods (102) for curing complex fiber-reinforced composite structures (14) utilize two distinct heat sources. A first heat source (22) is utilized for heating a complex fiber-reinforced composite structure (14) from within an internal portion (18) of the complex fiber-reinforced composite structure. A second heat source (24) is utilized for heating the complex fiber-reinforced composite structure (14) from an external surface (16) of the complex fiber-reinforced composite structure.