Momentum sensor - Electrostatic ballistic pendulum laboratory calibration unit Final report
Electrostatic ballistic pendulum momentum transducer for measuring particle impact
Jasmine, F. E.↗
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Spherical pendulum and motion in a dipole field.
Bound motion for particle in point electric dipole field, noting features of motion common to spherical pendulum motion
Fox, K.↗
Experimental determination of apparent mass and moment of inertia of a large disk suspended as a pendulum at different air densities
Experimental determination of apparent mass and moment of inertia of large disk suspended as pendulum at different air densities
Dunning, R. S.↗
Flight prototype electrostatic ballastic pendulum Final report
Flight prototype electrostatic ballistic pendulum momentum transducer
Powell, J. G.↗
Viscous pendulum damper Patent
Mercury filled pendulum damper for controlling bending vibration induced by wind effects
Reed, W. H., III↗
Advances in instrumentation and technique of torsional pendulum and torsional braid analyses
Instrumentation and techniques of torsional pendulum and braid analyses, studying trace moisture and cure cycle effects on thermomechanical spectra of polymeric materials
Gillham, J. K.↗
Torsion pendulum measurements on viscoelastic materials during vacuum exposure
A torsional pendulum apparatus designed for testing in situ in vacuum, the dynamic mechanical properties of materials is described. The application of this apparatus to an experimental program to measure the effects of vacuum on the mechanical properties of two ablator materials (a foamed material and a filled elastomer) and a solid rocket propellant (a filled elastomer) is presented. Results from the program are discussed as to the effects of vacuum on the mechanical properties of these three materials. In addition, time-temperature-superposition, as a technique for accelerating vacuum induced changes in mechanical properties, is discussed with reference to the three materials tested in the subject program.
Ward, T. C.↗
A passive pendulum wobble damper for a low spin rate Jupiter flyby spacecraft
When the spacecraft has a low spin rate and precise pointing requirements, the wobble angle must be damped in a time period equivalent to a very few wobble cycles. The design, analysis, and test of a passive pendulum wobble damper are described.
Fowler, R. C.↗
Periodic solutions of a spring-pendulum system.
A study has been made of a dynamical system composed of a pendulum and a harmonic oscillator, in order to show the remarkable resemblance with many classical celestial mechanics problems, in particular, the restricted three-body problem. It is shown that the well-known investigations of periodic orbits can be applied to the present dynamics problem.
Broucke, R.↗
Testing and evaluation of the LES-6 pulsed plasma thruster by means of a torsion pendulum system
Performance characteristics of the LES-6 pulsed plasma thruster over a range of input conditions were investigated by means of a torsion pendulum system. Parameters of particular interest included the impulse bit and time average thrust (and their repeatability), specific impulse, mass ablated per discharge, specific thrust, energy per unit area, efficiency, and variation of performance with ignition command rate. Intermittency of the thruster as affected by input energy and igniter resistance were also investigated. Comparative experimental data correlation with the data presented. The results of these tests indicate that the LES-6 thruster, with some identifiable design improvements, represents an attractive reaction control thruster for attitude contol applications on long-life spacecraft requiring small metered impulse bits for precise pointing control of science instruments.
Hamidian, J. P.↗
Vertical-plane pendulum absorbers for minimizing helicopter vibratory loads
The use of pendulum dynamic absorbers mounted on the blade root and operating in the vertical plane to minimize helicopter vibratory loads was discussed. A qualitative description was given of the concept of the dynamic absorbers and some results of analytical studies showing the degree of reduction in vibratory loads attainable are presented. Operational experience of vertical plane dynamic absorbers on the OH-6A helicopter is also discussed.
Amer, K. B.↗
A high-sensitivity torsional pendulum for polymeric films and fibres
A free oscillation torsion pendulum is described, which has been designed to measure accurately the dynamic shear modulus and logarithmic decrement of polymeric thin films and fibers, at frequencies of 0.1 to 10 Hz and a temperature range of 4.2 to 450 K. The instrument can also provide in situ tensile deformations of up to 5%. The specimen geometry necessary to obtain reliable modulus measurements with thin films is discussed, and typical data are presented which exhibit hitherto unreported relaxation processes, discernible by this instrument.
Aghili-Kermani, H.↗
A classification of large amplitude oscillations of a spring-pendulum system
We present a detailed classification of large amplitude oscillations of a non-integrable autonomous system with two degrees of freedom: the spring pendulum system. The classification is made with the method of invariant curves. The results show the importance of three types of motion: periodic, quasi-periodic and semi-ergodic. The numerical results are given for nine different values of the energy constant.
Broucke, R.↗
Aeroelastic analysis for helicopter rotors with blade appended pendulum vibration absorbers. Mathematical derivations and program user's manual
Mathematical development is presented for the expanded capabilities of the United Technologies Research Center (UTRC) G400 Rotor Aeroelastic Analysis. This expanded analysis, G400PA, simulates the dynamics of teetered rotors, blade pendulum vibration absorbers and the higher harmonic excitations resulting from prescribed vibratory hub motions and higher harmonic blade pitch control. Formulations are also presented for calculating the rotor impedance matrix appropriate to these higher harmonic blade excitations. This impedance matrix and the associated vibratory hub loads are intended as the rotor blade characteristics elements for use in the Simplified Coupled Rotor/Fuselage Vibration Analysis (SIMVIB). Sections are included presenting updates to the development of the original G400 theory, and material appropriate to the user of the G400PA computer program. This material includes: (1) a general descriptionof the tructuring of the G400PA FORTRAN coding, (2) a detaild description of the required input data and other useful information for successfully running the program, and (3) a detailed description of the output results.
Bielawa, R. L.↗
Control of the constrained planar simple inverted pendulum
Control of a constrained planar inverted pendulum by eigenstructure assignment is considered. Linear feedback is used to stabilize and decouple the system in such a way that specified subspaces of the state space are invariant for the closed-loop system. The effectiveness of the feedback law is tested by digital computer simulation. Pre-compensation by an inverse plant is used to improve performance.
Bavarian, B.↗
Learning control of inverted pendulum system by neural network driven fuzzy reasoning: The learning function of NN-driven fuzzy reasoning under changes of reasoning environment
Whereas conventional fuzzy reasonings are associated with tuning problems, which are lack of membership functions and inference rule designs, a neural network driven fuzzy reasoning (NDF) capable of determining membership functions by neural network is formulated. In the antecedent parts of the neural network driven fuzzy reasoning, the optimum membership function is determined by a neural network, while in the consequent parts, an amount of control for each rule is determined by other plural neural networks. By introducing an algorithm of neural network driven fuzzy reasoning, inference rules for making a pendulum stand up from its lowest suspended point are determined for verifying the usefulness of the algorithm.
Hayashi, Isao↗
A Study of the "toss Factor" in the Impact Testing of Cermets by the Izod Pendulum Test
The test method presented shows that the "toss energy" contributed by the apparatus for brittle materials is negligible. The total toss energy is considered to consist of two components. (a) recovered stored elastic energy and (b) kinetic energy contributed directly by the apparatus. The results were verified by high-speed motion pictures of the test in operation. From these photographs, velocities of tossed specimens were obtained and toss energy computed. In addition, impact energies of some titanium carbide base cermets and high-temperature alloys, as measured by the low-capacity Izod pendulum test, compare well with impact energies measured by the NACA drop test.
ALLOYS, HEAT-RESISTING↗