Blister-Free Composite Molding via Porous Scrim Air Evacuation
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Solution Overview
Problem
The existing methods for forming fibrous composite materials often result in blistering due to entrapped air, which can lead to weakness and catastrophic failure upon projectile impact, requiring active monitoring and control to prevent blister formation.
Innovation Solution
A dry processing technique where fibrous plies are partially coated with a discontinuous, non-liquid dispersed polymeric binder, allowing air to diffuse out during stacking and molding without forming blisters, resulting in a blister-free composite with a unitary structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fibrous plies are pressed together using conventional methods, then the plies are consolidated into a unitary structure, but air becomes entrapped causing blister formation and areas of weakness
Solution Approach 1:
The patent applies a porous or open mesh scrim material between fibrous plies during consolidation. This scrim material provides a pathway for air to escape during the pressing process, preventing air entrapment and subsequent blister formation while still allowing the plies to consolidate into a unitary structure. The scrim acts as a temporary porous framework that facilitates air evacuation without compromising the final structural integrity.
Solution Approach 2:
The scrim material serves as an intermediary element between the fibrous plies being consolidated. It mediates the consolidation process by providing a controlled pathway for air to escape while the plies are pressed together, preventing direct air entrapment between the plies. The scrim is temporarily present during processing and is subsequently removed, having fulfilled its mediating function.
2Object-affected harmful factors
If active monitoring and intermediate processing steps are used to eliminate blisters, then blister formation is controlled, but the process complexity and time increase
Solution Approach 1:
The patent employs a preliminary action by placing the porous scrim material between the plies before consolidation begins. This preliminary placement of the air escape pathway prevents blister formation from occurring in the first place, eliminating the need for subsequent monitoring and intermediate processing steps to detect and remove blisters. The prevention is built into the consolidation process itself.
Solution Approach 2:
The consolidation process becomes self-service regarding blister prevention, as the porous scrim automatically provides air escape pathways during pressing without requiring external monitoring or intervention. The system self-regulates air evacuation through the scrim material, eliminating the need for active monitoring systems or manual blister removal steps.
3Object-affected harmful factors
If degassing or vacuum molding is used to remove entrapped air, then blister formation is reduced, but additional processing time and equipment are required
Solution Approach 1:
The patent merges the air escape function with the consolidation process itself by incorporating the porous scrim material into the stacking sequence. Instead of separating air removal into a distinct degassing or vacuum step, the air escape pathways are integrated directly into the structure being consolidated. The scrim layers are positioned between plies and remain in place during consolidation, providing continuous air evacuation routes without requiring separate processing equipment or additional time.
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 efficiently prevents blister formation without active monitoring, ensuring the integrity of ballistic resistant composites and other fibrous materials by maintaining a low empty space volume within the composite, enhancing their structural reliability.
Implementation Method 1
the particulate binder is heated such that the binder at least partially melted, allowing it to at least partially flow on and between the fibers/tapes of each respective fibrous ply
Implementation Method 2
Upon the subsequent stacking and molding of a plurality of such open plies, entrapped air will diffuse through the open areas and out of the stack without forming blisters
Data Source
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Figure 3A~4B
Figure 5A~6B
AI summary
A process for forming defect-free fibrous composite materials. More particularly, a process for forming blister-free fibrous composites without having to actively monitor or control blister formation during molding of a stack of plies, and to blister-free composite materials fabricated therefrom. Fibrous plies are coated with a dry, particulate binder without impregnating the plies with the binder. Gaps between fibers/tapes allow air to diffuse out of the stack without affecting the binder coating, thereby avoiding blister formation.