Composite Splice Fairing Bond Fixture With Local Heat and Pressure
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Solution Overview
Problem
Rotary-wing aircraft rotor blades face challenges in bonding and reinforcing the splice joints due to high stresses and strains from aerodynamic forces, particularly at the leading edge, where delamination can occur, requiring effective methods to apply consistent heat and pressure for strong lamination and structural reinforcement.
Innovation Solution
A bond fixture with a frame, bladder assemblies for pressure application, and a caul assembly with a heater blanket to provide localized and uniform heat and pressure to the rotor blade, ensuring strong bonding of the sheath splice fairing to the rotor blade, using straps and a trailing edge guard for secure mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If large curing ovens are used to apply heat and pressure for bonding, then bonding quality is improved, but device complexity and space requirements increase
Solution Approach 1:
The bonding system is segmented into portable, modular components including a frame assembly with bladder assemblies, a separate heater blanket, and a caul assembly. This segmentation allows the functions of large curing ovens to be distributed across smaller, manageable units that can be applied directly to the splice fairing without requiring a large enclosed oven structure.
Solution Approach 2:
The heater blanket acts as an intermediary thermal transfer medium between the power source and the splice fairing. It distributes heat uniformly across the bonding surface while the bladder assemblies provide intermediate pressure application. This intermediary approach enables precise local control of heat and pressure without requiring a large curing oven environment.
2Strength
If consistent heat and pressure are applied to ensure strong lamination, then bonding strength is improved, but process complexity increases
Solution Approach 1:
The frame assembly combines multiple functions into a single integrated structure: it provides the mechanical framework, mounts the bladder assemblies for pressure application, and supports the heater blanket for thermal processing. The caul assembly further merges clamping and heating functions. This merging reduces process complexity by consolidating multiple bonding control functions into unified assemblies rather than requiring separate complex systems for each function.
Solution Approach 2:
The bladder assemblies are configured to automatically distribute pressure uniformly across the splice fairing surface when activated. The heater blanket self-regulates heat distribution across its surface area. These self-service characteristics reduce the need for complex external control systems while maintaining consistent bonding conditions.
3Productivity
If localized heat and pressure are applied, then bonding efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The system applies heat and pressure locally at the splice fairing location rather than requiring a large curing oven environment. The heater blanket provides localized thermal treatment precisely where needed, and the bladder assemblies concentrate pressure application at the bonding interface. This local quality approach improves bonding efficiency while the uniform distribution characteristics of these components maintain manufacturing precision.
Solution Approach 2:
The system enables independent control of thermal and pressure parameters through separate subsystems (heater blanket and bladder assemblies). This allows optimization of heat and pressure parameters independently to achieve uniform distribution across the bonding surface. The frame assembly geometry and component configuration are designed to naturally distribute parameters uniformly, reducing precision requirements while maintaining bonding efficiency.
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 bond fixture enables robust bonding of the sheath splice fairing to the rotor blade, enhancing structural integrity and reducing the need for large curing ovens, allowing for efficient bonding in a fixed location with consistent heat and pressure application.
Implementation Method 1
A caul assembly is positionable about the component and receivable within the chamber. The caul assembly heats a localized portion of the component.
Implementation Method 2
At least one bladder assembly is mounted to the frame and extends into the chamber to apply a pressure to an adjacent surface of the component.
Data Source
AI summary
A bond fixture includes a frame that defines a chamber for receiving a component. At least one bladder assembly is mounted to the frame and extends into the chamber to apply a pressure to an adjacent surface of the component. A caul assembly is positionable about the component and receivable within the chamber. The caul assembly heats a localized portion of the component.