Composite Flywheel Hub Radial Expansion Bonding
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Solution Overview
Problem
Conventional flywheel hubs face challenges in maintaining a bonded state with the rotor during high-speed rotation due to stress concentration and material weaknesses, leading to potential separation and damage, especially when using composite materials with high strength in the circumference direction but low strength in the radial direction.
Innovation Solution
A dome-shaped hub is formed by winding composite material in multiple layers, with a hollow main dome and sub domes that expand radially to maintain a bonded state with the rotor, featuring different winding angles and thicknesses to adjust stiffness and prevent stress concentration, allowing for high-speed rotation without separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If composite material is used for the hub to increase strength, then the hub can withstand high-speed rotation, but the hub becomes difficult to expand radially to maintain bonded state with rotor
Solution Approach 1:
The hub is divided into multiple layers with different material properties. The inner layer uses material with low radial stiffness to enable expansion, while the outer layer uses material with high radial stiffness to maintain strength, allowing the hub to both expand radially and withstand high-speed rotation
Solution Approach 2:
Different regions of the hub have different material characteristics. The inner layer is designed with specific material properties to facilitate radial expansion for maintaining bonded state, while the outer layer has enhanced strength properties to withstand centrifugal forces during high-speed rotation
2Adaptability or versatility
If hub is designed to expand easily in radial direction to connect rotor and rotational shaft, then hub can maintain bonded state during rotation, but hub strength decreases and may be damaged by stress concentration
Solution Approach 1:
The hub is segmented into multiple layers where the inner layer provides radial expansion capability for easy connection and maintenance of bonded state, while the outer layer provides the necessary strength to resist stress concentration and prevent damage during operation
Solution Approach 2:
The hub uses composite material structure with different layers having different mechanical properties. The inner layer material is selected for low radial stiffness to enable expansion, while the outer layer material is selected for high strength to prevent damage, achieving both radial adaptability and structural integrity
3Ease of manufacture
If conventional metal is used for flywheel material, then manufacturing is easy, but tensile stress is low and high-speed rotation is difficult
Solution Approach 1:
The patent uses composite materials for the flywheel rotor instead of conventional metals. The composite material structure provides high tensile strength to withstand centrifugal forces during high-speed rotation, while still maintaining manufacturability through established composite fabrication processes
4Ease of manufacture
If hub is made with uniform thickness and winding, then manufacturing is simple, but stress concentration occurs and hub may be damaged during high-speed rotation
Solution Approach 1:
The hub employs non-uniform thickness distribution and varied winding patterns in different regions. Areas subject to higher stress concentrations have enhanced material distribution and reinforcement, while other areas maintain simpler construction, achieving both manufacturing feasibility and improved reliability during high-speed operation
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 solution enables easy manufacturing, high strength, and adjustable stiffness, preventing hub damage from stress concentration and ensuring a firm bond between the hub and rotor during high-speed rotation, thereby enhancing energy storage capacity and resonance frequency.
Implementation Method 1
When the flywheel rotates, since the rotational shaft does not easily expand in a radial direction and the rotor further expands in the radial direction, the hub needs to connect them. Thus, the hub needs to easily expand when the flywheel rotates to connect the rotational shaft and the rotor
Implementation Method 2
in order to increase a resonance frequency of a rotation system, that is, the flywheel, than an operation speed, the stiffness needs to increase
Implementation Method 3
the hub needs to be deformed to transfer torque of the rotational shaft to the rotor
Data Source
AI summary
There are provided a hub for a flywheel and an energy storage flywheel. The hub for a flywheel is provided between a rotor and a rotational shaft of a flywheel to allow the rotor to have the same rotation speed as that of the rotational shaft. The hub includes a hollow main dome in which a through hole into which the rotational shaft is inserted is formed in one end and an opening is formed in the other end in a longitudinal direction of the rotational shaft, and that is formed by winding a composite material therearound; and a sub dome that is bonded to the rotor and is formed by winding the composite material around an outer surface of the main dome. Any one of the main dome and the sub dome expands in a radial direction of the rotational shaft along with the rotation of the rotational shaft and the rotor to allow the sub dome and the rotor to be maintained at a bonded state therebetween.