Undulating Balance Bracket for Diffuser Case Thermal Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engines face challenges in stress relief for diffuser cases due to thermal and mechanical stresses, leading to cyclic fatigue and potential failure of mounting brackets under repeated expansion and contraction.
Innovation Solution
A balance bracket with undulating portions is designed for mounting to bosses on the diffuser case, allowing for radial expansion and providing localized support to mitigate stress concentrations, featuring reduced thickness and width sections that enable expansion without hindering the diffuser case's thermal growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid balance bracket is used to provide strong mounting support, then structural strength is improved, but thermal stress concentration increases causing cyclic fatigue and potential failure
Solution Approach 1:
The balance bracket transitions from a rigid structure to a dynamic one by incorporating undulating portions that can flex and deform elastically. These undulating portions allow the bracket to dynamically adapt to thermal expansion and contraction forces, distributing stresses throughout the structure rather than concentrating them at fixed mounting points, thereby preventing cyclic fatigue while maintaining support strength.
Solution Approach 2:
The bracket's geometry is modified by changing the thickness parameter in specific regions to create undulating portions. These regions have reduced thickness compared to the nominal bracket thickness, creating areas of controlled flexibility. This parameter change allows the bracket to maintain overall structural integrity while providing localized compliance to accommodate thermal growth of the diffuser case.
2Adaptability or versatility
If the balance bracket thickness is reduced to allow thermal expansion, then adaptability to thermal growth is improved, but structural strength decreases
Solution Approach 1:
The balance bracket employs local quality by creating undulating portions with reduced thickness only in specific regions where thermal expansion accommodation is needed. The majority of the bracket maintains its nominal thickness to preserve overall structural strength. This localized modification allows the bracket to be both strong and adaptable, providing compliance only where required while maintaining rigidity in support-critical areas.
3Strength
If a rigid mounting structure is used to maintain structural integrity, then strength is improved, but stress concentration during thermal cycles increases leading to fatigue
Solution Approach 1:
The undulating portions transform the rigid mounting structure into a dynamic system that can absorb and distribute thermal stresses. During thermal cycles, these portions flex to accommodate expansion and contraction, converting concentrated static stresses into distributed dynamic stresses that are less likely to cause fatigue failure.
Solution Approach 2:
The undulating portions introduce curved geometries into the bracket structure. These curved regions naturally distribute stress more evenly compared to sharp corners or flat rigid connections, reducing stress concentration factors during thermal cycling while maintaining overall structural integrity.
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 balance bracket effectively relieves stress and supports the diffuser case during thermal expansion, preventing fatigue and failure by allowing for circumferential expansion while maintaining structural integrity.
Implementation Method 1
allowing for radial expansion and providing localized support to mitigate stress concentrations, featuring reduced thickness and width sections that enable expansion without hindering the diffuser case's thermal growth
Implementation Method 2
The first undulating portion defines a first thickness in a thickness cross section and the first thickness is less than or equal in value to a nominal thickness of the first bracket portion of the balance bracket
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A balance bracket (450; 550a; 550b; 550c; 550d; 550e) for a diffuser case (228; 230; 330; 430) of gas turbine engine (20) is disclosed. In various embodiments, the balance bracket (450; 550a; 550b; 550c; 550d; 550e) includes a first portion (452) configured for mounting to a first boss (340; 440) on the diffuser case (228; 230; 330; 430), a second portion (454) configured for mounting to a second boss (342; 442) on the diffuser case (228; 230; 330; 430), the second portion (454) spaced a distance from the first portion (452), and a first undulating portion (462) positioned intermediate the first portion (452) and the second portion (454).