Jun-ichi Igarashi

Bio: Jun-ichi Igarashi is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Flywheel. The author has an hindex of 1, co-authored 1 publications receiving 8 citations.

Deformation and life analysis of composite flywheel disk systems

Abstract: In this study an attempt is made to put into perspective the problem of a rotating disk, be it a single disk or a number of concentric disks forming a unit. An analytical model capable of performing an elastic stress analysis for single/multiple, annular/solid, anisotropic/isotropic disk systems, subjected to pressure surface tractions, body forces (in the form of temperature-changes and rotation fields) and interfacial misfits is summarized. Results of an extensive parametric study are presented to clearly define the key design variables and their associated influence. In general the important parameters were identified as misfit, mean radius, thickness, material property and/or load gradation, and speed; all of which must be simultaneously optimized to achieve the ‘best’ and most reliable design. Also, the important issue of defining proper performance/merit indices (based on the specific stored energy), in the presence of multiaxiality and material anisotropy is addressed. These merit indices are then utilized to discuss the difference between flywheels made from PMC and TMC materials with either an annular or solid geometry. Finally two major aspects of failure analysis, that is the static and cyclic limit (burst) speeds are addressed. In the case of static limit loads, a lower (first fracture) bound for disks with constant thickness is presented. The results (interaction diagrams) are displayed graphically in designer friendly format. For the case of fatigue, a representative fatigue/life master curve is illustrated in which the normalized limit speed versus number of applied cycles is given for a cladded TMC disk application.

Optimum design of variable composite flywheel

Abstract: A composite flywheel is designed using a composite of low density and high strength for the center portion, with constant stress as the design criteria and a constant thickness outer portion using a high density composite attached at the boundary of the constant stress disk. This combination produces the maximum energy density for a flywheel energy storage system. 6 references.

Conceptual design of a liquid-based variable inertia flywheel for microgrid applications

Abstract: For a rural microgrid requiring simplicity and robustness, a flywheel-generator combination directly coupled to the grid offers both energy storage and inherent stability. The tradeoff of using a directly-coupled flywheel with a constant moment of inertia is that the amount of energy extractable from within the narrow band of synchronous speeds is limited. Furthermore, a large amount of unusable energy remains within the flywheel below the grid's minimum frequency. By using a flywheel with a variable moment of inertia, although the nett energy may be less, the extractability can be increased by straightforward design. This paper presents the concept of a liquid-based flywheel where the moment of inertia is engineered to be a function of speed by appropriately sizing and shaping the liquid's spinning container.