Inertia

About: Inertia is a research topic. Over the lifetime, 12006 publications have been published within this topic receiving 164291 citations.

Dynamometer for simulating the inertial and road load forces encountered by motor vehicles

Abstract: A dynamometer for simulating the inertia and road load forces for motor vehicles is described. The dynamometer includes a moveable frame on which is mounted one or more rolls for engaging the driven wheel or wheels of the test vehicle, a power supplying and/or absorbing unit such as an electric motor and one or more mechanical flywheels. The moveable frame is pivotally mounted about the axis of rotation of the rolls. A force transducer is disposed between a point on the moveable frame spaced from the roll axis and a stationary surface for measuring a force which includes as components thereof the roll/wheel interface force and a force associated with the roll, motor and flywheel parasitic losses. A velocity transducer measures the roll speed. A controller responsive to signals from the force and velocity transducers and to the selected simulated inertia and road load controls the motor to supply power to or absorb power from the rolls so that the force applied to or received from the vehicle wheels is identical to the forces associated with the selected simulated inertia and road load.

Measurement-Based Estimation of Inertia in AC Microgrids

Abstract: This paper presents an improved method to estimate the available inertia in an islanded AC microgrid. Inertia estimation is carried out based on measured frequency response for any arbitrary disturbance that occurs in the system. Modifications are made to the conventional swing equation-based curve-fitting method to obtain an accurate estimate for a system with high penetration of renewable generations. A polynomial curve fit over the total power generation is introduced to estimate the size of the disturbance accurately. Additionally, a variable order polynomial fit is carried out over the measured frequency, which not only improves the estimate of inertia but also helps to refrain the influence of network topology and size/location of the disturbance. The test microgrid system considered is a modified Standard IEEE distribution network, which consists of radial feeders and distributed generations. Firstly, the proposed method is tested on a system with only synchronous generations to assess the accuracy of the estimate. This is followed by the integration of Type 3 and Type 4 wind turbines, and a PV array within the microgrid system. Virtual inertia control is then implemented in the wind turbines to obtain inertial support. Estimation study of the microgrid system with virtual inertia is then carried out. The developed estimation method can accurately estimate the inertia provided by the synchronous sources within the generation mix. Finally, from all the results and observations, the inertia estimation process in a microgrid system is segregated into synchronous and nonsynchronous inertia estimation.

Dynamic stability of axially accelerating Timoshenko beam: Averaging method

Abstract: This study investigates dynamic stability in transverse parametric vibrations of an axially accelerating tensioned beam of Timoshenko model on simple supports. The axial speed is assumed as a harmonic fluctuation about the constant mean speed. The Galerkin method is applied to discretize the governing equation into a finite set of ordinary differential equations. The method of averaging is applied to analyze the instability phenomena caused by subharmonic and combination resonance. Numerical examples demonstrate the effects of the mean axial speed, bending stiffness, rotary inertia and shear modulus on the instability boundaries.

The design of a vehicle inertia measurement facility

Abstract: This paper describes the design of a vehicle inertia measurement facility (VIMF) used to measure: (1) vehicle center of gravity position; (2) vehicle roll, pitch, and yaw mass moments of inertia; and (3) vehicle roll/yaw mass product of inertia. The rationale for general design decisions and the methods used to arrive at the decisions are discussed. The design is inspired by the desire to have minimal measurement error and short test time. The design was guided by analytical error analyses of the contributions of individual system errors to the overall measurement error. A National Highway Traffic Safety Administration (NHTSA) database of center of gravity position and mass moment of inertia data for over 300 vehicles was used. This database was used in conjunction with the error analyses to design various VIMF components such as the roll and yaw spring sizes. This provides for a design that yields good experimental repeatability for the full range of lightvehicles that can be tested on the VIMF. The paper also discusses aspects of the VIMF software, for example: (a) the analytical curve fitting; and (b) the error checking of results. Results from the VIMF for two calibration fixtures are presented and compared to the computed center of gravity position and inertia values. For the covering abstract of the conference see IRRD 875861.

Contribution to Inertial Mass by Reaction of the Vacuum to Accelerated Motion

Abstract: We present an approach to understanding the origin of inertia involving the electromagnetic component of the quantum vacuum and propose this as a step toward an alternative to Mach's principle. Preliminary analysis of the momentum flux of the classical electromagnetic zero-point radiation impinging on accelerated objects as viewed by an inertial observer suggests that the resistance to acceleration attributed to inertia may be at least in part a force of opposition originating in the vacuum. This analysis avoids the ad hoc modeling of particle-field interaction dynamics used previously by Haisch, Rueda, and Puthoff (Phys. Rev. A 49, 678, (1994)) to derive a similar result. This present approach is not dependent upon what happens at the particle point, but on how an external observer assesses the kinematical characteristics of the zero-point radiation impinging on the accelerated object. A relativistic form of the equation of motion results from the present analysis. Its manifestly covariant form yields a simple result that may be interpreted as a contribution to inertial mass. We note that our approach is related by the principle of equivalence to Sakharov's conjecture (Sov. Phys. Dokl. 12, 1040, (1968)) of a connection between Einstein action and the vacuum. The argument presented may thus be construed as a descendant of Sakharov's conjecture by which we attempt to attribute a mass-giving property to the electromagnetic component—and possibly other components—of the vacuum. In this view the physical momentum of an object is related to the radiative momentum flux of the vacuum instantaneously contained in the characteristic proper volume of the object. The interaction process between the accelerated object and the vacuum (akin to absorption or scattering of electromagnetic radiation) appears to generate a physical resistance (reaction force) to acceleration suggestive of what has been historically known as inertia.