Composite Reinforcement Blocks for Gas Turbine Fillet Stress
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Solution Overview
Problem
Composite structures in gas turbine engines, particularly those with laminar cores, face premature failure due to high tensile stress and delamination issues caused by dynamic pressures and temperature variations, which limit component life and require additional reinforcement to manage stress gradients and prevent delamination.
Innovation Solution
The incorporation of reinforcement blocks near fillets formed by bends or curves in composite structures, which reduce in-plane and through-thickness tensile stresses by extending across the apex or run-out curve of bends, providing additional plies of material in high-stress areas and altering stress distributions to shift peak tensile stress to compressive stress, thereby enhancing structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If composite structures use laminar cores with bends or curves to achieve aerodynamic shapes, then the aerodynamic performance and weight reduction are improved, but high tensile stress and delamination occur at fillet areas leading to premature failure
Solution Approach 1:
The patent applies local reinforcement blocks specifically at fillet areas where high tensile stress and delamination occur, rather than uniformly reinforcing the entire structure. This localized approach addresses the specific weakness at bend/curve regions while maintaining the overall weight benefits of composite construction.
Solution Approach 2:
The patent uses reinforcing blocks made of composite material that are coupled to the laminar core. This composite reinforcement strategy allows the structure to maintain its composite nature while adding targeted strength at critical fillet locations to prevent premature failure.
2Reliability
If reinforcement blocks are added to laminar cores to reduce tensile stress, then component life and through-thickness strength are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Reinforcement blocks are strategically placed only at fillet areas where high tensile stress occurs, rather than throughout the entire laminar core. This localized reinforcement minimizes the increase in structural complexity while effectively addressing the reliability issue at critical locations.
3Strength
If reinforcement blocks are added to laminar cores to prevent delamination, then through-thickness strength is improved, but manufacturing complexity and production time increase
Solution Approach 1:
The reinforcement blocks are designed to be integrated with the laminar core during the manufacturing process, with coupling mechanisms that are prepared in advance. This preliminary preparation of coupling features allows for more efficient assembly and reduces manufacturing complexity compared to post-production reinforcement methods.
Data Source
AI summary
A composite has a laminar core assembly defining a bend, the bend having a radially inner surface defining a fillet. A reinforcement block adjacent to the radially inner surface of the bend has sufficient thickness to at least partly bury the fillet. The reinforcement block reduces the through-thickness tensile stress in the laminar core assembly and thereby reduces the risk of delamination.