Experimental determination of the dynamic properties of a bridge substructure

1971 ◽  
Vol 61 (6) ◽  
pp. 1529-1548
Author(s):  
R. Shepherd ◽  
A. W. Charleson
Keyword(s):  
Steady State ◽  
Experimental Determination ◽  
Vibration Amplitude ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Viscous Damping ◽  
Equivalent Viscous Damping ◽  
Vibration Tests ◽  
Bridge Substructures

abstract As part of an investigation of the dynamic properties of bridge substructures, a series of steady-state vibration tests were undertaken on a multispan continuous deck bridge at several stages during construction. In this paper the method of testing is outlined and the measured natural frequencies and derived values of equivalent viscous damping are presented. The results confirm that the bridge does behave in a manner reasonably consistent with the design assumptions. At the small values of vibration amplitude generated, an equivalent viscous damping of the order of 4 per cent of critical was determined for the completed bridge.

An Experimental Determination of the Relationship between Lift and Aerodynamic Power in Calliphora Erythrocephala and Phormia Regina

1972 ◽  
Vol 56 (1) ◽  
pp. 31-36
Author(s):  
JAMES WOOD
Keyword(s):  
Steady State ◽  
Experimental Determination ◽  
Insect Flight ◽  
Phormia Regina ◽  
Calliphora Erythrocephala ◽  
The Relationship

Lift and aerodynamic power were calculated for Calliphora and Phormia using assumptions which maximized and minimized the ratio of aerodynamic power to lift. The ratios of aerodynamic power to lift calculated by these methods, which do not rely on the assumption that steady-state aerodynamics applies to insect flight, are in agreement with results calculated by others using steady-state aerodynamics.

Experimental Determination of Bearing Dynamic Properties

1984 ◽  
pp. 417-420 ◽  
Author(s):  
Z. A. Parszewski
Keyword(s):  
Experimental Determination ◽  
Dynamic Properties

Dynamic Properties of a Circuit Breaker with Friction-Based Seismic Dampers

1996 ◽  
Vol 12 (2) ◽  
pp. 297-314 ◽  
Author(s):  
R. Kar ◽  
J. H. Rainer ◽  
A. C. Lefrançois
Keyword(s):  
Design Parameter ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Circuit Breaker ◽  
Ground Acceleration ◽  
Discrete Parameter ◽  
Wide Range ◽  
Sf6 Circuit Breaker ◽  
Energy Dissipated

The design parameter of 1.05 g peak seismic ground acceleration for a 300 kV SF6 circuit breaker necessitated the provision of supplemental friction-based dampers. This paper describes the dampers and the dynamic properties of the circuit breaker as obtained from a series of pull-release tests with increasing force amplitudes. These tests permitted a determination of a wide range of damping ratios and natural frequencies as a function of displacements. A comparison is also presented between the measured and the calculated damping ratios and frequencies, using common engineering approximation of the energy dissipated per cycle for damping, and a discrete parameter and linearized stiffness approach for the calculation of natural frequency. Reasonable comparisons were achieved between the measured and calculated values.

Experimental determination of the coefficient in the steady state current equation for spherical segment microelectrodes

1989 ◽  
Vol 61 (11) ◽  
pp. 1305-1308 ◽  
Author(s):  
Zbigniew. Stojek ◽  
Janet. Osteryoung
Keyword(s):  
Steady State ◽  
Experimental Determination ◽  
Spherical Segment ◽  
Steady State Current ◽  
Current Equation

Experimental Determination of Oscillatory Lift and Moment Distributions on Fully Submerged Flexible Hydrofoils

1963 ◽  
Vol 7 (04) ◽  
pp. 24-41
Author(s):  
Guido E. Ransleben ◽  
H. Norman Abramson
Keyword(s):  
Steady State ◽  
Wind Tunnel ◽  
Aspect Ratio ◽  
Experimental Determination ◽  
Theoretical Predictions ◽  
Wind Tunnel Data

Measured span wise distributions of steady state and oscillatory lift and moment on fully submerged cantilever hydrofoils are presented. The hydrofoils were of aspect ratio 5 rectangular platform, and were towed at speeds sufficiently low to avoid cavitation. The data are compared with theoretical predictions and wind-tunnel data previously obtained at higher values of reduced velocity.

Experimental Determination of the Complete Dynamical Properties of a Two-Degree-Of-Freedom Model Having Nearly Coincident Natural Frequencies

1967 ◽  
Vol 9 (5) ◽  
pp. 402-413 ◽  
Author(s):  
R. W. Traill-Nash ◽  
G. Long ◽  
C. M. Bailey
Keyword(s):  
Experimental Investigation ◽  
Experimental Determination ◽  
Natural Frequencies ◽  
Degree Of Freedom ◽  
Influence Coefficients ◽  
Stiffness Properties ◽  
Modes Of Vibration ◽  
Dynamical Properties ◽  
Two Degree Of Freedom

Existing techniques of resonance testing have shown a marked inability to find the principal modes, natural frequencies and levels of damping in a structure which possesses two or more close natural frequencies (1)§. This paper describes an experimental investigation on a two-degree-of-freedom model of a technique which makes use of dynamical influence coefficients (or receptances) measured at a number of stations on the structure (2) (3) (4) (5). The measured coefficients are used to calculate natural frequencies and modes of vibration, and the mass, damping and stiffness properties of the system. Several model configurations having different natural frequency separations were tested and no special difficulty resulted when natural frequencies were close or even coincident.

The experimental determination of trajectories in geometrically similar plastic flows

1978 ◽  
Vol 13 (1) ◽  
pp. 29-34 ◽  
Author(s):  
R N Roth
Keyword(s):  
Steady State ◽  
Experimental Determination ◽  
Experimental Method ◽  
Quasi Steady State ◽  
Experimental Accuracy ◽  
Geometric Similarity ◽  
Orthogonal Grid ◽  
Wedge Indentation ◽  
Strain Wedge

A new experimental method is presented for determining trajectories of flow for non-steady-state processes which exhibit geometric similarity (quasi-steady-state processes (1)∗). One process that is normally regarded as quasi-steady-state (plane strain wedge indentation) is investigated using this method. It is shown that this process satisfies the requirements of geometric similarity within experimental accuracy. Results are presented for wedge angles of 30°, 60° and 90° and a range of indentation depths up to approximately 3 mm. Finally, it is suggested how this method can be combined with well-known orthogonal-grid techniques to provide information for the calculation of effective strains throughout the deforming region.

Experimental determination of adhesion and slip areas in rolling contact

1970 ◽  
Vol 5 (3) ◽  
pp. 193-199 ◽  
Author(s):  
E Ollerton ◽  
R Pigott
Keyword(s):  
Steady State ◽  
Experimental Determination ◽  
Experimental Technique ◽  
Contact Area ◽  
Rapid Determination ◽  
Glass Plate ◽  
Rolling Contact ◽  
Ground Glass ◽  
Steady State Rolling

An experimental technique has been developed to allow the rapid determination of adhesion and slip areas in steady-state rolling contact. The technique consists in rolling solid black-rubber toroids on a ground-glass plate under carefully controlled conditions. It enables the division of the contact area into slip and adhesion areas to be observed and photographed whilst rolling is taking place. A loading frame was devised to enable rolling with longitudinal shearing traction, rolling with transverse creep, and rolling with spin to be investigated either separately or in combinations. The results of the experiments have been compared with existing theories, and some conclusions as to the accuracy of the theories have been made.

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