Composite Prepreg Forming with In-Plane Tension
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Solution Overview
Problem
Current high-performance protective materials, such as ballistic helmets, often suffer from structural imperfections like wrinkling during manufacturing, which compromises their effectiveness against high kinetic energy projectiles like rifle bullets, and there is a need for defect-free, lightweight, and comfortable protective solutions.
Innovation Solution
The use of pre-impregnated (prepreg) fiber-reinforced composite materials is employed to create ballistic helmets through a process involving shaping, cutting, and layering of prepreg plies, with in-plane tensional forces applied to prevent wrinkling and form a net-shape preform, using a die press apparatus to consolidate the material into a uniform thickness for enhanced ballistic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers of materials are stacked together and subjected to additional processing to convert into high performance protective material products, then ballistic protection capability is improved, but structural imperfections such as wrinkling occur during manufacturing
Solution Approach 1:
The patent applies preliminary action by pre-impregnating fiber layers with resin before stacking and forming. The fibers are pre-coated with a thin layer of resin that prevents wrinkling during the forming process, while the bulk of the resin is added later during consolidation. This preliminary preparation of the fiber layers eliminates structural defects before the final product formation.
Solution Approach 2:
The manufacturing process is segmented into distinct stages: (1) preparing pre-impregnated fiber layers with minimal resin, (2) stacking and forming the layers into the desired shape, (3) consolidating the formed structure with additional resin. This segmentation allows each stage to be optimized independently, preventing wrinkling during forming while ensuring proper consolidation in the final stage.
2Ease of manufacture
If traditional manufacturing methods with multiple processing steps are used, then protective material products can be made, but the process complexity and time consumption increase
Solution Approach 1:
The patent merges the forming and consolidation operations into a single continuous process. The pre-impregnated layers are formed into the desired shape, and then consolidated with additional resin in the same tooling without removing the workpiece. This combining of operations eliminates intermediate handling steps and reduces overall manufacturing time.
Solution Approach 2:
By pre-impregnating the fiber layers before forming, the patent eliminates the need for separate resin injection or coating steps after forming. The preliminary preparation of fibers with a thin resin layer ensures that the material is ready for immediate forming and subsequent consolidation, reducing the total number of processing steps.
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 produces helmets with superior ballistic performance, uniform thickness, and minimal defects, providing effective protection against high kinetic energy projectiles while maintaining a lightweight and comfortable design.
Implementation Method 1
The binder plate is independently actuated constraining the ply stack by applying in-plane tensional force through the binder plate to the plies controlling in-plane shear strain and ply stack wrinkling
Implementation Method 2
The ply stack may be preheated to a temperature of 50-500° C., more preferably 80-200° C., more preferably about 125° C., for a period of about 1 minute to 24 hours
Implementation Method 3
A punch is activated to drive at least a portion of the ply stack through the flat die plate cut out
Data Source
AI summary
A method of forming a net shape preform for a high performance ballistic helmet includes preparing one or more full prepreg plies, preparing one or more filler prepreg plies, wherein a shape and orientation of one filler prepreg ply of the one or more filler prepreg plies is different from a shape and orientation of another filler prepreg ply of the one or more filler prepreg plies, layering the one or more full prepreg plies with one or more filler prepreg plies to form a ply stack and deforming a portion of the ply stack while constraining the ply stack by applying in-plane tensional force to the ply stack to form the net-shape preform.