Showing papers on "Inertia published in 1980"

Identification of Nonlinear Structural Dynamic Systems

Abstract: Two methods of system identification of n degrees-of-freedom nonlinear structural dynamic systems are studied and applied to identification of the hydrodynamic coefficient matrices associated with nonlinear drag and linear inertia forces appearing in the equations of motion of offshore structures subjected to wave forces. These two methods, being essentially the methods of state estimation, use nonlinear Kalman filtering algorithms which can be applied to parameter estimation problems by regarding each of the parameters involved in the system as an augmented state variable. One of these methods uses the extended Kalman filter while the other was the iterated linear filter-smoother. Analytical simulation studies are performed for two degrees-of-freedom structural systems on the basis of artificially generated input and output observations under the various output noise conditions. Both methods yield good estimates even under the conditions of fairly large amounts of output noise and are moderately...

A Simple Theory on the Dynamical Effects of a Stratified Fluid Core upon Nutational Motion of the Earth

Abstract: The theory of Molodensky (1961) on dynamical effects of a stratified fluid outer core upon nutations and diurnal Earth tides is reconstructed on a new and probably much simpler ground. A theory equivalent to Molodensky’s is well represented on the basis of two linear equations for angular-momentum balance of the whole Earth and the fluid outer core, which differ from the well-known equations of Poincare (1910) only in the existence of products of inertia due to deformations of the whole Earth and fluid outer core. The products of inertia are characterized by four parameters which are easily computed for every Earth model by the usual Earth tide equations. A reciprocity relation exists between two of the parameters. The Adams-Wiliamson condition is not a necessary premise of the theory. Amplitudes of nutations and tidal gravity factors are computed for three Earth models. A dissipative core-mantle coupling is introduced into the theory qualitatively. The resulting equations are expressed in the same form as those of Sasao, Okamoto and Sakai (1977). Formulae for secular changes in the Earth-Moon system due to the core-mantle friction are derived as evidences of internal consistency of the theory.

Dynamic pre-strain and inertia effects on the fracture of metals

Abstract: A combined experimental and theoretical study is described which examines the influence of strain-rate and dynamic pre-strain on the ductile fracture of thin cylinders The thin-cylinder configuration is particularly important in this case because it allows inertia terms to be directly incorporated into the theory of plastic instability A series of quasi-static and dynamic tests is conducted on three materials with differing degrees of strain-rate sensitivity and strain-hardening The experimental observation that fracture is inhibited at high strain-rates is in accord with the theory when inertia can no longer be considered insignificant It is also shown that dynamic pre-strain has little or no effect on the flow stress or the strain at fracture in materials which-are essentially strain-rate insensitive, but does reduce the fracture strain in the strain-rate sensitive materials

Control system for manipulator apparatus

Abstract: A control system is provided for a programmable manipulator having an arm movable in a plurality of axes that results in improved dynamic performance and control of a manipulator arm over a wide range of arm loads, dynamic operating parameters of the arm, and over the full range of arm operating positions. The control system for one or more of the controlled axes includes several servo control loops utilizing force or pressure feedback from the axis actuators and variable inertia scaling of selected loop command signals and loop parameters. The variable inertia scaling in accordance with the inertia of the arm provides improved dynamic performance of the manipulator arm while maintaining stable servo-loop operation over a wide range of operating parameters. In a preferred arrangement, the variable inertia scaling is accomplished by the use of a look up table with appropriate interpolation of the table entries. The look up table is stored in a digital axis processor with the appropriate variable inertia scaling factors being determined by the axis processor for use by the respective axis servo-loop. The look up table in accordance with various predetermined operating requirements of the manipulator apparatus includes data entries representing inertia scaling factors according to the mass of the arm load, the commanded velocity in a particular axis, and the operating positions of one or more of the major control axes of the arm.

Three directional vibration isolator

Abstract: A three-directional vibration isolator, connecting two bodies, which includes spring elements for coupling vibratory forces between the bodies and an inertia assembly for generating inertia forces to attenuate these vibratory forces. The assembly includes a drive member having one end coupled to one body to allow pivotal movement about a first assembly pivot point and an opposite end which extends axially through a tubular member and which is coupled to radially-extending, equiangularly-disposed, inertia arms to allow pivotal movement of the arms about respective first pivot axes orthogonal to the assembly axis. One end of the tubular member is coupled to the other body to allow pivotal movement about a second assembly pivot point and an opposite end thereof is coupled to the inertia arms to allow pivotal movement of the arms about respective second pivot axes parallel to the first pivot axes. Axially-directed vibratory forces cause vibratory movements of the inertia arms which generate inertia forces to oppose these vibratory forces. Vibratory forces acting orthogonally of the assembly axis cause vibratory movements of the entire assembly which generate inertia forces to oppose these vibratory forces. Assembly parameters are selected so that axial movement of one body relative to the other not only causes a change in the distance r' between the two assembly pivot points, but also causes a corresponding change in the distance R' between the assembly center of gravity and the adjacent assembly pivot point, so that the ratio R'/r' is essentially constant.

Seat back inertia latch system

Abstract: An inertia latch return linkage for a seat back inertia latch system normally biasing the inertia latch to an engagement oriented position maintained by inertia effect upon sudden vehicle deceleration, such linkage being rendered inoperative to permit gravity disengagement of the inertia latch upon initial seat back tilting in a forward direction when the vehicle is stationary.

Stability Analysis of a Constant Torque Static Slip-Power-Recovery Drive

Abstract: The stability analysis of a static slip-power-recovery drive is presented A set of nonlinear differential equation describing the dynamics of the system are developed and linearized about an operating point using perturbation technique. Using the characteristic equation obtained from the motional impedance matrix and the Routh-Hurwitz criterion instability regions have been plotted in the torque-firing angle plane. The effects of system inertia, filter parameters, and applied voltage upon the instability regions have been investigated. An experimental verification of the stability region has also been presented.

Flow between eccentric disks rotating at different speeds: Inertia effects

Abstract: The problem of flow between infinite eccentric disks rotating at different speeds is considered and a solution to the complete Navier-Stokes equations obtained. An approximate analytic solution is also presented.

Rubber/viscous torsional vibration dampers

Abstract: Tuned rubber/viscous torsional vibration damper assemblies of the kind having a supporting rotor disk mounting an inertia mass coupled to the disk by viscous damping medium and elastic tuning spring, spacing and sealing rubber rings located in rubber ring accommodating grooves. A viscous damping medium working chamber is defined within the inertia mass radially outwardly about the rings. The rubber rings are molded and vulcanized in situ in said grooves and to the rotor disk and the inertia mass. The dampers may be provided with rubber spacer and bumper fingers extending from the rubber rings into the working chamber of the damper. The rubber rings may also be keyed to the inertia mass by means of integral lugs extending into socket apertures in the inertia mass. The dampers may be coated with a rubber skin on outside areas, the skin being connected to exposed areas of the rubber rings.

Limited spring and inertia latch system

Abstract: An improved inertia latch system for a vehicle seat having a pivotally adjustable backrest and a separate more forwardly pivoted hinge member to accommodate forward tilting of the backrest for rear passenger entry and exit provides a limit for the seat angle at which release of the inertia latch can be effected in order to enhance safety, a manual override for releasing the inertia latch and a reduction in weight and cost of the inertia latch mechanism.

Vibration isolator with crank driven inertia bar

Abstract: A vibration isolator of the dynamic antiresonant type, for reducing the transmission of vibratory forces along a given line of action between two bodies having a component of vibration relative to one another along such line, includes an inertia bar driven by a crank and having its center of gravity so arranged as to allow the bar to be oriented at any angle to the line of action. This gives the isolator the capability of being designed to make it adaptable to the limitations of the space available between the vibrating bodies.

A Simple Low Deborah Number Model for Unsteady Hydrodynamic Lubrication, Including Fluid Inertia

Abstract: In unsteady hydrodynamic lubrication the film thickness varies with time, producing the squeeze film term in the Reynolds equation, where the fluid is assumed to be Newtonian and fluid inertia effects are neglected. A Deborah and Reynolds number perturbation solution correction to lubrication theory is presented which can accommodate arbitrary smooth two‐dimensional surface geometry and arbitrary time variation in film thickness. The constitutive equation used is one recently proposed by Harnoy in which a new type of material derivative is used allowing separate consideration of relaxation and normal stress effects, each governed by a separate material parameter. A low Deborah number expansion is developed to obtain a simple two‐parameter (viscosity and relaxation time) stress‐explicit relation. Corrections to the lubrication theory for inertia and viscoelastic effects in terms of Reynolds and Deborah numbers are presented. Solutions to several problems are presented: (1) parallel surfaces with constant a...

Rotary vibration absorbing device for vehicle internal combustion engine

Abstract: PURPOSE:To obtain a maximum vibration absorbing effect by equalizing the inertia moment of the whole drive side including the engine and the first flywheel to the inertia moment of the whole driven side including the axle system and the second flywheel. CONSTITUTION:A vibration damping element 13 having a flexibility coefficient number K and a damping coefficient number c is arranged between the drive side flywheel 15 directly connected with an engine and the driven side flywheel 17 directly connected with the axle system. The inertia moment of the first rotary inertia body including said engine (crankshaft 1, piston 3) as well as the drive side flywheel 15 and the inertia moment of the second rotary inertia body including the axle system (clutch 5, transmission 7, propeller shaft 9, differential mechanism 11) are both equalized, whereby minimizing the tortional compliance and gaining maximum vibration absorbing effect.

Free-piston stirling engine inertial cancellation system

Abstract: A free piston Stirling engine inertial cancellation system includes a displacer reciprocating in a hermetic vessel enclosing a working space to circulate working gas through a heater, regenerator, and cooler to create a pressure wave in the working space. A power piston, mechanically unconnected to the displacer, is reciprocally driven by the pressure wave to produce a power output stroke in one direction and a working gas compression stroke in the other direction. The displacer and the power piston form substantially a first mass in the working space. A second mass, outside the working space and preferably including an alternator plunger, is mounted in the vessel and is coupled to the first mass momentum exchange relationship. Spring means and tuning means cause the second mass to reciprocate out-of-phase with the displacer and the power piston so that the phase of the moving masses produces inertia phasors which substantially cancel and so that little or no inertia of the reciprocating masses is transmitted through the vessel to the mounting structure of the engine.

Influence of the Gas-film Inertia Forces on the Dynamic Characteristics of Externally Pressurized, Gas Lubricated Journal Bearings : Part l, Proposal of Governing Equations

Abstract: The conventional analyses based on the classical Reynolds equation are incomplete to get five predictions of the dynamic characteristics of externally pressurized gas bearings. This seems to be attributed to the fact that the Reynolds equation ignores entirely the inertia forces of the gas-film. This paper process modified Reynolds equations, which are derived by averaging out the inertia forces in Navier-Stokes equations across the film thickness, and their adequate boundary conditions, in order to determine the influence of the inertia forces on the dynamic characteristics such as the whirl instability and the squeeze damping.

The role of inertia in the fracture of rock

Abstract: A theory for the accumulation of damage in one dimension in fast deformation of a brittle material is developed. The theory is consistent with thermodynamics and takes crack inertia into account. The problem of damage accumulation due to a step pulse in strain is solved, and shows good agreement with experimental results.

Inertia and recovery: an approach to stream classification and stress evaluation'

Abstract: The concepts of inertia and elasticity were applied to existing fish data from Conowingo Creek. It was determined that these two concepts could form the foundation for a stream classification sys- tem based on the structure and function of fish communities. Inertia appears to be more useful for predicting the effects of potential stress than elasticity (a stress must first occur before elasticity can be fully evaluated). The relationship between structural and functional redun- dancy and their influences on the inertia index is discussed. (KEY TERMS: recovery; inertia; elasticity; stress evaluation; structural and functional redundancy.)

Apparatus for effecting compensation of free moments resulting from inertia forces in an internal combustion engine.

Abstract: of EP0010973Apparatus for compensating moments created by inertia forces in an internal combustion engine (2) used for a ship's propulsion comprises a balancer (8) spaced in the fore-and-aft direction from the engine and including one or more rotary unbalanced masses (9). Each unbalanced mass is driven by a positive displacement hydraulic motor (12) connected through feed and return conduits (14, 15) with a positive displacement hydraulic pump (13) driven by the engine (2) in such a way that the rpm of the mass is equal to or twice the rpm of the engine crankshaft (3) and that a desired phase relationship between the rotation of the mass and the movements of the oscillating masses of the engine is maintained. The hydraulic drive provides a simpler and cheaper apparatus as compared to known electrically driven balancers.

The inertial mass and anomalous internal angular momentum of a phase-locked cavity

Abstract: It has been shown that phase-locked cavities have a quantised transfer function (Jennison 1979) and that they account for the property of inertia (Jennison and Drinkwater 1977). The analysis shows that only half of the rest energy of a phase-locked cavity contributes actively to the inertial force. The moment of inertia of such a system about its own axis is only half that of a classical rigid body of the same total rest mass distributed in the same region of space. If a phase-locked cavity is used as a model of a fundamental particle then it is concluded that the particle is a fermion with a rest mass corresponding to its total rest energy.