Welded Sheet Overlap Geometry for High-Temperature Stress Relief
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Solution Overview
Problem
Conventional brazed joints in gas turbine engine hot sections are costly and complex, and there is a need for lightweight joints that can withstand extreme temperatures and reduce stress concentrations.
Innovation Solution
A welded assembly with a specifically configured weld line, such as linear, arcuate, or elliptical, is used to connect hot and cold sheets, distributing stress more evenly and reducing peak stress concentrations, allowing for the use of laser welding and potentially eliminating the need for expensive brazes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional brazed joints are used to connect hot and cold sheets, then the joints can withstand extreme temperatures, but the manufacturing cost and complexity increase significantly
Solution Approach 1:
The patent extracts and eliminates the brazing process from the manufacturing sequence, replacing it with direct welding. This removes the complex multi-step brazing operation (surface preparation, brazing material application, controlled heating, and cooling) while maintaining joint integrity through properly designed weld configurations that accommodate thermal expansion and stress.
Solution Approach 2:
The patent changes the fundamental joining parameter from brazing (diffusion bonding with filler metal) to welding (direct metallurgical bonding). This parameter change simplifies the process by eliminating filler metal requirements, reducing manufacturing steps, and lowering cost while achieving equivalent or superior joint performance at high temperatures.
2Reliability
If conventional brazed joints are used to connect hot and cold sheets, then the joints can withstand extreme temperatures, but the manufacturing cost increases
Solution Approach 1:
The patent removes the expensive brazing materials (nickel or gold-nickel brazes) from the manufacturing process and replaces them with standard welding materials. This extraction of costly consumables directly reduces material costs while maintaining joint reliability through alternative welding configurations.
Solution Approach 2:
The patent employs standard, readily available welding materials instead of expensive, specialized brazing alloys. While welding materials may be consumed in the process, their lower unit cost and availability significantly reduce overall manufacturing cost compared to premium brazing materials.
3Reliability
If conventional brazed joints are used to connect hot and cold sheets, then the joints can withstand extreme temperatures, but the joint weight increases
Solution Approach 1:
The patent extracts and eliminates the additional material layers introduced by brazing (filler metal, flux, protective coatings) and replaces them with direct weld metal deposits. This reduction in material layers decreases joint weight while maintaining structural integrity through optimized weld geometry.
4Ease of manufacture
If weld lines with high stress concentrations are used, then the welding process is simple, but the peak stress increases and reliability decreases
Solution Approach 1:
The patent applies curved or arcuate weld line geometries instead of sharp linear transitions. These curved configurations distribute stress more evenly along the weld path, eliminating stress concentration points that would occur with sharp corners or abrupt direction changes, thereby improving joint reliability without significantly complicating the welding process.
Solution Approach 2:
The patent modifies the weld line geometry at critical locations to optimize stress distribution. By locally adjusting the weld path curvature and configuration at high-stress areas while maintaining simpler geometry in low-stress regions, the patent achieves improved reliability without requiring complete redesign of the entire weld configuration.
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 welded assemblies achieve reduced peak stress and more uniform stress distribution, making them more reliable and cost-effective, while allowing for the fabrication of lightweight joints suitable for high-temperature applications without the need for brazing.
Implementation Method 1
The weld is configured and adapted for reducing peak stress and smoothing the stress distribution within the weld and overlap area of the sheets
Implementation Method 2
allowing for the use of laser welding
Data Source
AI summary
A welded assembly includes a first sheet and a second sheet. The second sheet is disposed over a portion of the first sheet and defines an overlap portion between the first and second sheets. A weld fastening the second sheet to the first sheet in the overlap area connects the second sheet to the first sheet for distributing stress uniformly across a welded portion of the overlap area.