Hollow Fan Blade Cover Welding for Lower Joint Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for constructing hollow fan blades in gas turbine engines face challenges in achieving optimal weld strength and stress distribution, leading to potential structural weaknesses and reduced durability.
Innovation Solution
The solution involves creating a recessed region in the airfoil body with a rib pattern that divides it into pockets, and a cover skin is welded along these ribs, with a specific weld width to rib width ratio, ensuring a strong and durable attachment while minimizing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover is welded to an airfoil body to construct hollow fan blades, then the structural integrity and durability are improved, but stress concentrations may occur at the weld joints leading to potential structural weaknesses
Solution Approach 1:
The patent applies local quality by creating a recessed region in the airfoil body where the cover attaches, and by designing ribs with specific geometries (including rounded corners and varying thicknesses) at the weld locations. This local modification of the structure distributes stress more evenly across the weld joints rather than having uniform stress distribution, thereby reducing stress concentrations while maintaining strong attachment between the cover and airfoil body.
Solution Approach 2:
The recessed region is pre-formed in the airfoil body before the cover is attached. This preliminary action creates a prepared geometry that facilitates stress distribution and reduces concentration at the weld joints. The recessed region acts as a stress-relieving feature that is already in place before the welding process, preventing structural weaknesses from developing at the attachment points.
2Strength
If ribs are added to the airfoil body to support the cover, then the load distribution is improved, but the device complexity increases
Solution Approach 1:
The airfoil body is segmented into distinct regions by incorporating ribs that divide the structure into manageable sections. These ribs create separate attachment zones for the cover, allowing loads to be distributed across multiple discrete locations rather than concentrated in one area. The segmentation approach maintains relative simplicity by using standardized rib geometries that can be efficiently manufactured and assembled.
3Strength
If the weld width to rib width ratio is increased to improve attachment strength, then the joint strength is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a particular parameter range for the weld width to rib width ratio (between 3:1 and 4:1) to optimize both attachment strength and manufacturability. This parameter change establishes a design guideline that ensures sufficient weld joint strength while maintaining reasonable manufacturing precision requirements. By setting the ratio within this specific range, the design balances the competing demands of strong attachment and feasible manufacturing control.
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 approach enhances the structural integrity and durability of the fan blades by distributing loads effectively and reducing stress concentrations, thereby improving the overall performance and lifespan of the gas turbine engine components.
Implementation Method 1
At least one cover skin is welded to the airfoil body along the at least one rib to enclose the recessed region
Data Source
AI summary
An airfoil for a gas turbine engine according to an example of the present disclosure includes, among other things, an airfoil body defining a recessed region and including at least one rib dimensioned to loop about a respective pocket within a perimeter of the recessed region. At least one cover skin is welded to the airfoil body along the at least one rib to enclose the recessed region. The at least one cover skin is welded to the at least one rib along a respective weld path. The weld path defines a weld width, the at least one rib defines a rib width, and a ratio of the weld width to the rib width is equal to or greater than 3:1 for each position along the weld path. A method of forming a gas turbine engine component is also disclosed.