Composite Splice Joint Bonding Without Autoclave
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Solution Overview
Problem
The challenge lies in joining long composite structural members without the need for metal splice members and autoclave curing, as commercial autoclaves are often insufficient for large parts like wing stringers and spars, and existing methods are inefficient for forming composite splice joints.
Innovation Solution
A method and apparatus that utilize a composite splice member with a V-shaped cross section, bonded using localized heat and pressure applied by a press or inflatable pressure bladder, allowing for the formation of complex geometries like C, Z, J, T, and hat shapes without the need for fasteners or autoclave curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal splice members with fasteners are used to join composite sections, then the structural members can be assembled, but the assembly process becomes complex and requires additional fastening operations
Solution Approach 1:
The invention uses composite splice members made of the same composite material as the sections being joined, creating a homogeneous joint structure. This eliminates the need for metal splice members and fasteners, simplifying the assembly process while maintaining structural integrity through material compatibility and integrated bonding.
Solution Approach 2:
The invention extracts and removes the metal fastener system from the composite joint design. By eliminating metal splice members and fasteners entirely, the design achieves a fastenerless composite-to-composite bonded joint, reducing assembly complexity and avoiding galvanic corrosion issues between dissimilar materials.
2Strength
If composite splice members are used to join long composite sections, then the structural integrity is maintained, but commercial autoclaves cannot accommodate the length of relatively long parts
Solution Approach 1:
The invention segments the curing process by using multiple smaller, portable heating and pressure applying devices along the length of the splice joint rather than requiring one large autoclave chamber. This allows curing of long composite sections in sections or simultaneously at multiple locations, making the process compatible with commercial autoclave size limitations.
Solution Approach 2:
The invention transitions from three-dimensional autoclave chamber space constraints to a linear, distributed heating and pressure application system. By using multiple portable devices that can be positioned along the length of the splice joint, the curing capability extends beyond the physical dimensions of any single autoclave chamber.
3Ease of manufacture
If localized heat and pressure are applied to bond composite splice members, then the bonding process can be performed outside autoclaves, but additional heating and pressure application equipment is required
Solution Approach 1:
The composite splice member design incorporates features that facilitate self-bonding through the application of heat and pressure. The uncured composite material is positioned to automatically bond with the cured sections when heated and pressurized, eliminating the need for complex external bonding equipment and simplifying the overall system.
Solution Approach 2:
The invention utilizes changes in the physical parameters of the composite material during curing. By heating the uncured composite splice member to its curing temperature and applying pressure, the material transitions from a soft, moldable state to a cured, structural state, achieving bonding without requiring complex equipment beyond basic heating and pressure application.
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
Enables the efficient bonding of elongate composite sections into continuous structural members like spars, frames, and stringers with complex geometries, eliminating the requirement for metal splice plates and autoclave curing, thus enhancing assembly efficiency and reducing material costs.
Implementation Method 1
a heating element contained in said supporting member for heating the plastic to a molten state at said area
Implementation Method 2
a pressurizing assembly
Data Source
Figure 1
Figure 2~6
Figure 7~12
AI summary
A composite structural member includes first and second composite sections (104a,104b) spliced together by an overlapping composite splice member (112).