Measuring strain response mode shapes with a continuous-scan LDV

2000 ◽  
Author(s):  
Anthony B. Stanbridge ◽  
Milena Martarelli ◽  
David J. Ewins
Keyword(s):  
Response Mode ◽  
Mode Shapes ◽  
Strain Response

scholarly journals Measuring Strain Response Mode Shapes with a Continuous-Scan LDV

2002 ◽  
Vol 9 (1-2) ◽  
pp. 19-27 ◽  
Author(s):  
Anthony B. Stanbridge ◽  
Milena Martarelli ◽  
David J. Ewins
Keyword(s):  
Mode Shape ◽  
Response Mode ◽  
Mode Shapes ◽  
Stress And Strain ◽  
Governing Equations ◽  
Convenient Means ◽  
Straight Line ◽  
Polynomial Series ◽  
Spatial Derivatives ◽  
Derivatives Of

A continuous-scan LDV is a convenient means for measuring the response mode shape (ODS) of a vibrating surface, particularly in view of the fact that the ODS is automatically derived as a spatial polynomial series. Second spatial derivatives of the deflection equations are therefore easily derived, and these should, in principle, give curvature equations from which, for a beam or plate of known cross-section, stresses and strains can be obtained directly. Unfortunately, the stress and strain distributions depend critically on higher terms in the original ODS series, which are not accurately measured. This problem can be avoided by a method described here, which enables accurate stress and strain distributions to be derived, from a straight-line LDV scan along a uniform beam, using only five terms in the mode-shape polynomial series. A similar technique could be applied to uniform plates but the analysis and the governing equations are rather more complicated.

Deciding the Adequacy of a Set of Tests for an Specific Assessment Situation. Decision-making Strategies

1996 ◽  
Vol 12 (1) ◽  
pp. 14-22
Author(s):  
R. Esteve ◽  
A. Godoy
Keyword(s):  
Decision Making ◽  
Time Pressure ◽  
Response Mode ◽  
Information Load ◽  
Variable Pattern ◽  
Mode Effects ◽  
Moderator Effects ◽  
Specific Assessment ◽  
Information Board ◽  
Decision Importance

The aim of the present paper was to test the effects of response mode (choice vs. judgment) on decision-making strategies when subjects were faced with the task of deciding the adequacy of a set of tests for a specific assessment situation. Compared with choice, judgment was predicted to lead to more information sought, more time spent on the task, a less variable pattern of search, and a greater amount of interdimensional search. Three variables hypothesized as potential moderators of the response mode effects are also studied: time pressure, information load and decision importance. Using an information board, 300 subjects made decisions (choices and judgments) on tests for a concrete assessment situation, under high or low time pressure, high or low information load, and high or low decision importance. Response mode produced strong effects on all measures of decision behavior except for pattern of search. Moderator effects occurred for time pressure and information load.

Tire Vibrations

1977 ◽  
Vol 5 (4) ◽  
pp. 202-225 ◽  
Author(s):  
G. R. Potts ◽  
C. A. Bell ◽  
L. T. Charek ◽  
T. K. Roy
Keyword(s):  
Natural Frequencies ◽  
Standing Waves ◽  
Resonant Mode ◽  
Mode Shapes ◽  
Resonant Vibrations ◽  
Resonant Frequencies ◽  
Radial Tire ◽  
Analysis Techniques ◽  
Thin Ring ◽  
Good Agreement

Abstract Natural frequencies and vibrating motions are determined in terms of the material and geometric properties of a radial tire modeled as a thin ring on an elastic foundation. Experimental checks of resonant frequencies show good agreement. Forced vibration solutions obtained are shown to consist of a superposition of resonant vibrations, each rotating around the tire at a rate depending on the mode number and the tire rotational speed. Theoretical rolling speeds that are upper bounds at which standing waves occur are determined and checked experimentally. Digital Fourier transform, transfer function, and modal analysis techniques used to determine the resonant mode shapes of a radial tire reveal that antiresonances are the primary transmitters of vibration to the tire axle.

Experimental Characterization of Mechanical Behavior of Cord-Rubber Composites

1982 ◽  
Vol 10 (1) ◽  
pp. 37-54 ◽  
Author(s):  
M. Kumar ◽  
C. W. Bert
Keyword(s):  
Response Characteristic ◽  
Cord Compression ◽  
Complete Characterization ◽  
Strain Response ◽  
Strain Gages ◽  
Experimental Characterization ◽  
Rubber Composites ◽  
Stress Strain ◽  
Strain Data

Abstract Unidirectional cord-rubber specimens in the form of tensile coupons and sandwich beams were used. Using specimens with the cords oriented at 0°, 45°, and 90° to the loading direction and appropriate data reduction, we were able to obtain complete characterization for the in-plane stress-strain response of single-ply, unidirectional cord-rubber composites. All strains were measured by means of liquid mercury strain gages, for which the nonlinear strain response characteristic was obtained by calibration. Stress-strain data were obtained for the cases of both cord tension and cord compression. Materials investigated were aramid-rubber, polyester-rubber, and steel-rubber.

Effect of Bass Bar Tension on Modal Parameters of a Violin's Top Plate

2015 ◽  
Vol 39 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Ewa B. Skrodzka ◽  
Bogumił B.J. Linde ◽  
Antoni Krupa
Keyword(s):  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Normal Value ◽  
Modal Damping

Abstract Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1-).

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