Composite Reinforced Ring Gear Centrifugal Stress Reduction
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Solution Overview
Problem
Ring gears in high rotation applications face significant centrifugal stress leading to deformation and breakage, and increasing steel content to enhance stiffness results in increased mass, which is undesirable in aircraft applications where weight affects performance.
Innovation Solution
A composite reinforced ring gear design featuring a metal rim with a composite backing having a lower coefficient of thermal expansion, providing a mechanical interference fit that reduces centrifugal loading through compressive stress and weight reduction while maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional steel material is added to increase stiffness, then the stiffness of the ring gear is improved, but the mass increases which increases centrifugal forces
Solution Approach 1:
The patent applies composite materials by combining a metal rim with a composite backing material. The composite backing provides the necessary stiffness to resist centrifugal forces while having lower density than steel, thereby reducing the overall mass of the ring gear. This composite construction allows the gear to maintain structural integrity at high rotational speeds without the penalty of increased weight that would result from adding more steel.
2Speed
If the ring gear operates at high rotational speeds, then the power transmission capability is improved, but centrifugal stress increases causing deformation and breakage
Solution Approach 1:
The composite construction with a metal rim and composite backing provides superior resistance to centrifugal stress at high rotational speeds. The composite backing material, having lower density, reduces the overall centrifugal loading on the gear structure while maintaining the necessary stiffness to prevent tooth deformation and breakage during high-speed operation.
Solution Approach 2:
The patent changes the material parameters of the ring gear by substituting steel with a composite material that has different density and mechanical properties. This parameter change allows the gear to operate at higher rotational speeds by reducing the centrifugal stress that would otherwise cause deformation and failure of the steel gear teeth.
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 composite reinforced ring gear significantly reduces stress and deformation at the teeth roots by up to 65-75% and radial deformation by 35-45% compared to all steel ring gears, while minimizing weight and maintaining stiffness, thus enhancing performance in high rotational speeds.
Implementation Method 1
a composite backing positioned circumferentially about the rim outer circumference
Implementation Method 2
a lower coefficient of thermal expansion (CTE) of the composite backing is less than the CTE of the metal rim
Implementation Method 3
The composite reinforced ring gear significantly reduces stress and deformation at the teeth roots by up to 65-75%
Data Source
AI summary
A hybrid composite reinforced ring gear minimizing radial deformation during high RPM conditions includes a composite backing secured to a metal rim. In use, at operating temperature the composite backing contracts while the metal rim expands thus creating a compressive stress on the metal rim and significantly reduces radial deformation due to centrifugal forces as compared to an all steel ring gear.