Additive Projections for Composite-Metal Joint Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for joining composite and metallic components, such as fasteners and adhesive bonds, face limitations including de-lamination, low bearing and inter-laminar shear strength, and weakness in pull-through and peel directions, particularly in aerospace applications, where they are prone to significant axial loads and weight penalties.
Innovation Solution
An additive fabrication technique is used to grow an array of projections on the bond region of components in series of layers, allowing for optimized shape and high aspect ratio protrusions, reducing surface damage and enabling complex shapes, which can be made from different materials and used to improve joint strength and resistance to axial loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fasteners are used to join composite and metallic components, then joining is achieved, but de-lamination around fastener holes occurs and bearing strength is low
Solution Approach 1:
Instead of using fasteners to mechanically join components, the invention inverts the approach by using adhesive bonding with optimized surface features. The surface features are created through additive manufacturing to provide mechanical interlocking while avoiding the de-lamination issues associated with fastener holes. This fundamental reversal of the joining mechanism eliminates the harmful de-lamination effect while maintaining joint strength.
Solution Approach 2:
The invention employs a composite joining system that combines adhesive materials with structurally optimized surface features. The surface features are designed with specific geometries that optimize the interaction between the adhesive and the substrate, creating a hybrid joining mechanism that leverages both chemical bonding and mechanical interlocking to achieve high joint strength without de-lamination.
2Strength
If adhesive bonds are used to join metallic components to composite laminates, then joining is achieved, but performance in peel and tension is poor
Solution Approach 1:
The invention applies curved and rounded surface features rather than flat or sharp geometries. The curved surfaces of the additive-manufactured features optimize stress distribution under peel and tension loads, preventing stress concentration at sharp edges. This curvature optimization allows the adhesive bond to effectively transfer loads in peel and tension directions, significantly improving performance in these critical loading modes.
Solution Approach 2:
The invention transitions from two-dimensional flat bonding surfaces to three-dimensional surface features with optimized geometries. By adding vertical dimension and complex spatial configurations to the bonding interface, the joint gains enhanced mechanical interlocking and stress distribution capabilities, dramatically improving resistance to peel and tension forces that flat bonds cannot withstand.
3Area of stationary object
If power-beam is used to create protruding features, then bond surface area is increased, but surface damage occurs and crack initiators are generated
Solution Approach 1:
The invention performs the surface feature creation as a preliminary step through additive manufacturing before bonding. This preliminary action creates the desired surface geometry without the harmful effects of subsequent material displacement. By pre-forming the features with controlled, layer-by-layer deposition, the process avoids generating crack initiators and surface damage that would occur with post-manufacturing modifications like power-beam processing.
Solution Approach 2:
The invention replaces the mechanical/material-displacement-based power-beam process with an additive manufacturing process that builds material layer by layer. This substitution eliminates the harmful mechanical action of displacing and flicking surface material, thereby avoiding surface damage and crack initiation while still achieving increased bond surface area through controlled feature growth.
4Strength
If reinforcement around fastener holes is added, then bearing strength is improved, but weight increases significantly
Solution Approach 1:
The invention inverts the reinforcement approach by eliminating fastener holes entirely and using adhesive bonding with surface features. This fundamental reversal removes the need for heavy reinforcement around holes, as the adhesive bond distributes loads across the entire bonding surface rather than concentrating them at discrete fastener locations. The result is significant weight reduction while maintaining or improving bearing strength.
Solution Approach 2:
The invention segments the bonding interface into multiple optimized surface features rather than using a single large reinforced area. This segmentation allows load distribution across many small, strategically placed features, achieving high bearing strength with minimal material. The segmented approach is more weight-efficient than large continuous reinforcement zones required by conventional fastener-based designs.
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 enhances the strength and durability of joints by minimizing material wastage, allowing for complex shapes and high aspect ratio projections, reducing the risk of de-lamination, and improving resistance to axial loads, tension, and peel, while maintaining a lightweight structure suitable for aerospace applications.
Implementation Method 1
An additive fabrication technique is used to grow an array of projections on the bond region of components in series of layers, allowing for optimized shape and high aspect ratio protrusions
Data Source
AI summary
A joint including: a first component and a second component; the first component includes a bond region and an array of projections extending from the bond region, wherein the projections are embedded in the second component.