Bladed Rotor Repair Using Indentation for Uniform Weld Strain
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Solution Overview
Problem
The repair of integrally bladed rotors in gas turbine engines is challenging due to limitations in achieving uniform plastic strain throughout weld nuggets and heat affected zones, leading to reduced fatigue strength and grain growth issues, with existing methods failing to optimize indenter shapes and surface profiles for effective repair.
Innovation Solution
The development of optimized indenter tools and weld nugget surface profiles using multi-level optimization programs and finite element solvers to achieve uniform plastic strain levels comparable to the parent-metal, minimizing tool force and distortion, and simplifying the indenter shape for efficient repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding is used to repair integrally bladed rotors, then metal can be replaced and structural integrity restored, but the weld nugget has different metallurgical properties than parent-metal resulting in reduced fatigue strength
Solution Approach 1:
The patent applies plastic deformation through indenters to change the physical state of the weld nugget, transforming its microstructure from a coarse welded state to a refined state with improved mechanical properties. This parameter change in the material structure addresses the fatigue strength deficiency without requiring metallurgical reprocessing.
Solution Approach 2:
The patent performs plastic deformation and surface profiling as preliminary actions before final machining or service use. By pre-treating the weld nugget to achieve uniform plastic strain and desired surface profile, the method prepares the repaired area to withstand fatigue loads before the component enters service.
2Manufacturing precision
If traditional indenting tools are used, then plastic strain can be applied to the weld nugget, but non-uniform strain distribution and excessive tool force are required
Solution Approach 1:
The patent designs indenters with specific geometric profiles (spherical, conical, or flat) that concentrate deformation in targeted regions of the weld nugget. This local quality approach ensures uniform plastic strain distribution throughout the weld volume while minimizing the total force required, as each indenter geometry is optimized for its specific application location and deformation requirement.
3Ease of operation
If weld nugget surface profile is not optimized, then repair can be completed, but non-uniform plastic strain and increased distortion occur
Solution Approach 1:
The patent establishes the desired weld nugget surface profile as a preliminary condition before applying plastic deformation. By pre-defining the target surface geometry, the subsequent indenter application can be optimized to achieve both the profile and uniform plastic strain simultaneously, reducing distortion and improving repair efficiency.
Solution Approach 2:
The patent employs a systematic approach where the indenter geometry and application parameters are selected based on the desired surface profile outcome. This feedback mechanism ensures that the plastic deformation process produces both the correct surface geometry and uniform internal strain distribution, minimizing distortion.
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 method ensures metallurgical soundness of repaired components by achieving uniform plastic strain and recrystallized grain structures, enhancing fatigue strength and allowing for successful return to service of gas turbine engine blades.
Implementation Method 1
a weld nugget joins a parent-metal portion with a new-metal portion
Implementation Method 2
achieve uniform plastic strain levels comparable to the parent-metal
Implementation Method 3
application of force by optimized indenters to provide plastic strain
Implementation Method 4
after heat treatment, a recrystallized grain structure in the weld nugget and in the heat affected zone
Implementation Method 5
a recrystallized grain structure in the weld nugget and in the heat affected zone, comparable to the grain structure in the parent material
Data Source
AI summary
Repaired rotors are provided. The rotors are repaired by using an indenter apparatus for plastically straining original portions of the rotor and adjacent repair welds. The weld nugget, adjacent heat affected zones, and the adjacent parent-metal portions or new metal portions, are indented at a weld nugget and heat affected zone, to produce threshold levels of uniform plastic strain which meet or exceed plastic strain levels that provide, when the weld nugget and heat affected zone is heat treated, a recrystallized grain structure metallurgically comparable to the grain structure of the original parent-metal of the rotor. Repaired integrally bladed rotors for gas turbine engines, such as aircraft engines, are provided. Blades for gas turbine engines, including integrally bladed rotors, may be advantageously provided, having been manufactured or repaired as described.