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Damping device exhibiting no hysteresis effect and capable of preload is used in place of a preload spring in an aneroid bellows to provide viscous damping. It operates about the action of a pressure sensing outer bellows attached to an active header above and a static header below.
Damping device limits spring surging in delicate instrumentation subjected to shock loading to tolerable limits. The device consists of a spiral formed plastic member interleaved between the spring coils in the same helix configuration.
Oscillation damping of tall structures by hanging chains
Suspension and energy dissipation couplings in satellity gravity gradient stabilization system
Shock and vibration damping device using temperature sensitive solid amorphous polymers
Dynamic precession damping of spin-stabilized vehicles by using rate gyroscope and angular accelerometer
Blade vibration damping pins for turbomachinery
A dual-spin spacecraft is a spin-stabilized spacecraft consisting of two major structures. Momentum is stored in the spinning wheel, while the sail, or platform, can be despun at various rates about the spacecraft axis. Factors that affect the design of nutation-control systems for single- and dual-spin spacecraft are discussed. The nutation-control system of the Orbiting Solar Observatory spacecraft is described.
An experimental program is described which verifies the theoretical model that acoustic damping devices undergoing high intensity oscillations dissipate energy via jet kinetic losses. Pressure measurements within the damping devices and flow duct together with detailed surveys of the jet velocities provide the experimental confirmation. The theory accounts for duct flow effects, both steady and unsteady, as well as the jet dissipation. Discrepancies between theory and experiment can be traced to neglect of higher order terms or ignoring the difficult wall friction term in the case of the quarter-wave tube.
A method which uses a mathematical accelerometer is proposed for determining the 3rd derivative of the displacement in shock absorbers.
Device for rotating machinery has noncircular support that allows changes in dynamic properties. Device can be controlled for either manually or automatically altering its stiffness and damping properties without interruption of operation.
Parameters controlled in design determine the stability of hydraulic pressure regulators in service. The non-linear sensing line restrictor can provide stability, but degrades the transient response. Linear damping is not always physically realizable and is sensitive to clearance and viscosity. Design relationships are analytically derived through which regulators can be made to be stable without the use of either of these damping means. The analytical distinctions between the parameters derived and those in prior literature are discussed. An analytically derived circuit component that stabilizes an otherwise unstable regulator and its experimental verification is described.
A lumped parameter model is developed to determine the stiffness and damping characteristics of inherently compensated gas film bearings. The model relies on the average static pressure over a one dimensional strip bearing. Results of the model are compared with known computer solutions for the distributed strip and a two dimensional square bearing. The results for the stiffness agree well with the computer solutions although the model proved to be inadequate for predicting the film damping.
A direct-acting hydraulic pressure regulator design which incorporates stability margin, response and droop margin is developed. The pressure regulator system does not involve a nonlinear sensing line restrictor (which may degrade transient response) or linear damping (which is sensitive to clearance and viscosity). The direct-acting hydraulic pressure regulator makes use of the technique of lead network stabilization (i.e., the tuned stabilizer concept). An analytically derived circuit pressure regulator is tested to study the stability limit under a parallel capacitive plus resistive load and the stabilizing effect of the tuned stabilizer.
This paper describes the methods used to design elastomerically damped supports for high-speed, flexible rotor-bearing systems. The procedure consists of using a damped natural frequency analysis to identify stiffness and damping requirements for the supports over the speed range. Optimum values for these coefficients are found and unbalance response analysis is used to calculate expected rotor behavior. Equations for calculating the shear and compressive stiffness and damping of button-type elastomer mounts are given, as is a procedure for their application to the design of the elastomeric mounts. These techniques were successfully applied to the design of damped elastomeric supports for a high-speed rotor, which traverses two bending critical speeds. Results of the testing showed that the rotor was well behaved and showed linear response to unbalance. Measured modal damping exceeded expectations and tests were conducted with both high- and low-loss elastomers, enabling the exploration of the practical range of elastomer damping capability.
Method of installing support tubes allows retrofitting of vibrationreducing elements. Tubes deform elastically as inserted and expand partially as gap becomes wider. Force-fit tubes eliminate fatigue problem.
Cryogenic turbomachinery used to pump high pressure fuel (liquid H2) and oxidizer (liquid O2) to the main engines of the Space Shuttle have experienced rotor instabilities. Subsynchronous whirl, an extremely destructive instability, has caused bearing failures and severe rubs in the seals. These failures have resulted in premature engine shutdowns or, in many instances, have limited the power level to which the turbopumps could be operated. The feasibility of using an eddy current type of damping mechanism for the Space Shuttle Main Engine is outlined.
A solution is presented for the equations of motion for the damped linear oscillator, Mx(double dot) + Cx(dot) + Kx = 0. The algorithm solves a transformed set of equations in terms of the modal variables of the undamped system and, at the same time, solves the adjoint equation of the transformed problem. The adjoint solution is normalized to give the inverse of the solution matrix of the transformed problem. The normalized inverse is useful in design for direct computation of sensitivity derivatives of damping ratios with respect to damping rates. The algorithm is programmed to reduce storage requirements by a factor of three-fourths compared to standard complex eigenvalue subroutines. A numerical example is included.