Epicyclic Gearbox Input Shaft Stiffness for Load Isolation

The patent applies parameter changes by optimizing the tilt stiffness within a specific range (5×10^4 to 5×10^6 Nm/radian) rather than maximizing it. This controlled parameter adjustment ensures the shaft provides sufficient isolation from excessive loads while maintaining acceptable deflection levels that preserve load distribution uniformity across planet gears.

The patent applies local quality by differentiating the importance of stiffness properties - tilt stiffness is given higher priority (5-10 times more important than radial bending stiffness) based on its greater impact on load distribution. The shaft is designed with specific local properties (tilt stiffness in the optimized range) at critical locations to achieve the desired balance between isolation and uniformity.

The patent applies parameter changes by establishing a specific range for radial bending stiffness (6×10^5 to 3×10^7 N/m) and prioritizing tilt stiffness optimization over radial bending stiffness. This approach achieves gearbox isolation through the more critical tilt stiffness parameter, avoiding the need for complex shaft designs that would be required to achieve isolation solely through radial bending stiffness increases.

The patent applies the extraction principle by separating the two stiffness parameters (tilt stiffness and radial bending stiffness) and treating them independently with different priority levels. By extracting tilt stiffness as the primary isolation mechanism and radial bending stiffness as a secondary parameter, the design avoids the complexity that would arise from optimizing both parameters equally.