Composite Flywheel Research Articles

A Proposal for Optimum Design of Composite Flywheel

A Proposal for Optimum Design of Composite Flywheel

Automobile flywheel energy storage: Practical vacuum requirements

For passenger automobiles with 1367 kg curb weight during typical driving conditions in city traffic, fuel efficiency improvements between 50 –100% (5–7 km/h) can be realized by proper utilization of a flywheel‐energy storage unit (0.2 kW h) and a heat engine. A brief introduction is given concerning the pros and cons of flywheels compared to other energy storage options. How to provide a cost effective, quality vacuum environment and system for rotating, composite flywheels is discussed. To be practical, a vacuum system for such an environment must be reliable, safe, and economical (in energy resources and dollars) to manufacture, monitor, maintain, and repair. Each embodiment of flywheel energy storage may be sufficiently unique to require a vacuum environment tailored to suit it. A general discussion of the important vacuum parameters and practical vacuum systems is followed by an example of a candidate design which includes a fiber array pump.

A probabilistic approach to fracture of composite flywheels

A probabilistic approach to fracture of composite flywheels

Quasi-Isotropic, Thick Composite Laminates Fabricated by the Matched Metal Die Compression Molding Process

One of the designs currently being explored under the DOE/LLL composite flywheel rotor development effort is the tapered thickness laminated disk “Stodola” rotor concept. The goal of this effort is to develop a prototype high-energy-density, economical composite laminate rotor for utilization in hybrid flywheel/electric/ICE vehicles and in stationary applications. In terms of energy density, the objective is to obtain 88 Wh/kg at failure with an operational range of 44–55 Wh/kg and an energy storage capacity of approximately 1 kWh. To that end, a high-strength graphite/epoxy (Celion 6000/5213) (0/±45/90) composite laminate tapered disk was fabricated and spin tested. Table 1 presents the test results. It appears from Table 1 that the governing failure criterion is the off-axis failure strength, which is typically lower than the strength along the fiber direction in most quasi-isotropic laminates. This strength anisotropy results in the under-utilization of the laminate strength and in lower energy densities. This suggests that there are two avenues open to improve the performance of laminated disk rotors: (1) increase the basic strength of the composite, and (2) reduce the strength anisotropy of the laminate.

Allowance for initial thermal stresses in investigating the energy storage capacity of wound composite flywheels

Allowance for initial thermal stresses in investigating the energy storage capacity of wound composite flywheels

Fiber glass for composite flywheels: Loud, S.N. SAMPE Journal Vol 13 No 3 (May/June 1977) pp 20–22

Fiber glass for composite flywheels: Loud, S.N. SAMPE Journal Vol 13 No 3 (May/June 1977) pp 20–22

Developing a Tapered Thickness Composite Flywheel Rotor

Fiber composite flywheels are being seriously evaluated as energy storage devices, to be used in combination with advanced batteries, for automobile power systems. The key attraction for composites in this application is their high strength-to-density ratio that yields high energy storage.

Investigation of energy storage capacity of wound composite flywheels

Investigation of energy storage capacity of wound composite flywheels

The use of composite flywheels for braking energy recovery in road transport vehicles

An investigation was carried out on the use of composite materials in the design of energy storage flywheels for vehicular applications. This report underlines the significance of a system approach in such a feasibility study. The control of the theory by practical considerations such as size, safety, material and fatigue is shown in this programme, which represented a serious attempt by a national transport organisation in the UK to invest in the future.

Optimization of composite flywheel design

Composite flywheels are effective energy storage devices. The multi-rimmed flywheel configuration is first chosen for this study because of its superior operating characteristics and versatility. Then the Kevlar-49/epoxy system is adopted as the basic composite material, which is sandwiched between thin layers of rubber. A general stress analysis procedure is developed for the multi-rimmed structure and a computer routine is established to investigate the effects of various material and geometric parameters on the internal stress levels. A maximum stress criterion is used for failure of the composite flywheel. The basic goal of optimization is to achieve a stress distribution such that each ring in the multi-ringed structure will fail at approximately the same angular speed. The parameters varied in the optimization process include the thickness, Poisson's ratio, Young's modulus and density of the inter-ring material, the density and thickness of the composite material, and the thickness of the flywheel in the axial direction. The optimization process demonstrated that this procedure can be applied in general when other failure criteria or performance characteristics (such as maximum kinetic energy, kinetic energy per weight and kinetic energy per volume) are preferred.

Transfer Matrix for Analysis of Composite Flywheels

Transfer Matrix for Analysis of Composite Flywheels