Composite Laminate Reinforcement Using Heated Clips
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Solution Overview
Problem
Conventional bonding methods for composite laminate structures are inadequate, failing to provide significant reinforcement and are cumbersome, especially when dealing with pre-impregnated laminates, as they often lead to micro-cracking and negligible reinforcement, and cannot be used on pre-impregnated materials due to resin clogging issues.
Innovation Solution
A composite laminate reinforcing system using clips with tapered posts that are heated to increase pliability, allowing them to pierce through laminate elements and deflect inwardly, forming a reinforced joint, which can be used with both pre-impregnated and dry fabric laminates, and includes a tool for efficient installation and curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Z-pinning is used to fasten laminates, then the laminates are joined together, but the pins are weakened due to micro-cracking when protruding ends are removed
Solution Approach 1:
The invention extracts the problematic protruding ends of the pins by using a trim piece that covers and conceals them. The pins are inserted through the laminate with ends protruding from both sides, and the trim piece is applied over one side to cover the protruding ends, effectively removing them from the system without compromising the pin structure.
Solution Approach 2:
The solution segments the pin structure by having pins extend through the laminate and be covered by a separate trim piece. This segmentation allows the pin to maintain its structural integrity while the trim piece handles the function of covering the ends, preventing micro-cracking issues.
2Strength
If stitching is used to bond laminates, then reinforcement is provided, but pre-impregnated laminates cannot be stitched because resin clogs the sewing mechanism
Solution Approach 1:
The invention replaces the mechanical stitching system with a thermal bonding system. Instead of using a sewing mechanism that physically pierces and stitches the laminate (which gets clogged by resin), the invention uses heat and pressure applied through a trim piece to bond the laminate edges, which is compatible with pre-impregnated materials.
Solution Approach 2:
The solution changes the bonding parameters from mechanical (stitching) to thermal (heat and pressure). By applying heat through the trim piece during compression molding, the resin is activated to bond the laminate edges without requiring physical penetration through the material, thus avoiding resin clogging issues.
3Strength
If conventional bonding methods are used, then laminates are joined, but significant reinforcement is not achieved and the process is overly burdensome
Solution Approach 1:
The trim piece serves multiple functions simultaneously: it covers the protruding pin ends, provides compression during bonding, applies heat through thermal conduction, and acts as a bonding surface. This multi-functionality consolidates what would otherwise be separate complex processes into a single integrated operation.
Solution Approach 2:
The invention merges the trimming, bonding, and reinforcement functions into a single integrated process. The trim piece is applied during the compression molding process itself, combining what would traditionally be separate operations (mechanical trimming and adhesive bonding) into one simultaneous operation that achieves both edge sealing and structural reinforcement.
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
The system provides effective out-of-plane reinforcement by forming mechanical locks along bond lines, enhancing the structural integrity of composite laminate structures while being compatible with various laminate types, reducing the risk of micro-cracking and resin-related issues.
Implementation Method 1
a heating element thermally coupled to the plunger head and configured to heat the first joint section sufficiently above an ambient temperature to increase a pliability of the first joint section
Data Source
AI summary
A composite laminate reinforcing tool may be used to form a reinforced joint at a bond line of a composite laminate structure. The tool may hold one or more clips having posts, and the tool may be positioned along the bond line between at least two composite laminate elements. Joint sections of the clip may be heated to increase a pliability of the joint section, and the tool may be actuated to drive the post through the at least two composite laminate elements. The posts may be deflected toward a base of the clip, thereby to seat the clip. The reinforced composite laminate structure may then be cured.