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Deflection (engineering)

About: Deflection (engineering) is a research topic. Over the lifetime, 30862 publications have been published within this topic receiving 298849 citations.


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Journal ArticleDOI
TL;DR: In this article, a numerical method for estimating the curvature, deflection and moment capacity of hybrid FRP/steel reinforced concrete beams is presented, where a sectional analysis is first carried out to predict the moment-curvature relationship from which beam deflection, moment capacity and curvature are then calculated.

132 citations

Journal ArticleDOI
TL;DR: The theoretically limited noise performance has been achieved in liquid for the first time and true atomic-resolution imaging of mica in water is demonstrated using the developed deflection sensor and the photothermal excitation system.
Abstract: I developed a wideband low-noise optical beam deflection sensor with a photothermal cantilever excitation system for liquid-environment atomic force microscopy The developed sensor has a 10 MHz bandwidth and 47 fm/Hz deflection noise density in water The theoretically limited noise performance (ie, the noise level limited only by the photodiode shot noise) has been achieved in liquid for the first time Owing to the wide bandwidth and the replaceable focus lens design, the sensor is applicable to cantilevers with various dimensions The deflection noise densities of less than 78 fm/Hz have been achieved in water for cantilevers with lengths from 35 to 125 μm The ideal amplitude and phase versus frequency curves without distortion are obtained with the developed photothermal excitation system The excitation system is applicable to relatively stiff cantilevers (>20 N/m) in liquid, making it possible to obtain true atomic-resolution images in liquid True atomic-resolution imaging of mica in water is

132 citations

Journal ArticleDOI
TL;DR: In this paper, an atomic force microscope equipped with a micromachined cantilever tip was used to evaluate the elasticity of the sample and the contact load dependence of the frequency, where contact stiffness of a non-spherical tip shape was derived from the Sneddon-Maugis formulation.
Abstract: In an atomic force microscope equipped with a micromachined cantilever tip, the cantilever vibration spectra in contact with the sample were found to be strongly dependent on the excitation power. However, if the excitation power is small enough, the resonance peak width decreases and the peak frequency increases to a certain limiting value. In this condition the tip-sample contact is kept linear, and satisfactory agreement between the measured and calculated frequency is obtained, assuming a constant contact stiffness; the agreement is further improved by taking into account the lateral stiffness. More quantitative information on the elasticity of the sample is obtained from the contact load dependence of the frequency, where contact stiffness of a non-spherical tip shape is derived from the Sneddon-Maugis formulation, and the tip shape index is estimated by an inverse analysis of the load-frequency relation. A further advantage of evaluating not only the vertical but also the lateral stiffness is demonstrated on a ground silicon wafer by simultaneous measurement of deflection and torsional vibration.

132 citations

Journal ArticleDOI
TL;DR: In this article, a simplified method of evaluating the fundamental frequency for the bending vibrations of cracked Euler-Bernouilli beams is presented based on the well-known approach of representing the crack in a beam through a hinge and an elastic spring, but here the transverse deflection of the cracked beam is constructed by adding polynomial functions to that of the uncracked beam.

132 citations

Journal ArticleDOI
TL;DR: By integrating interferometric deflection data from electrostatically actuated microcantilevers with a numerical finite difference model, the authors developed a step-by-step procedure to determine values of Young's modulus while simultaneously quantifying nonidealities.
Abstract: By integrating interferometric deflection data from electrostatically actuated microcantilevers with a numerical finite difference model, we have developed a step-by-step procedure to determine values of Young's modulus while simultaneously quantifying nonidealities. The central concept in the methodology is that nonidealities affect the long-range deflections of the beams, which can be determined to near nanometer accuracy. Beam take-off angle, curvature and support post compliance are systematically determined. Young's modulus is then the only unknown parameter, and is directly found. We find an average value of Young's modulus for polycrystalline silicon of 164.3 GPa and a standard deviation of 3.2 GPa (/spl plusmn/2%), reflecting data from three different support post designs. Systematic errors were assessed and may alter the average value by /spl plusmn/5%. An independent estimate from grain orientation measurements yielded 163.4-164.4 GPa (the Voigt and Reuss bounds), in agreement with the step-by-step procedure. Other features of the test procedure include that it is rapid, nondestructive, verifiable and requires only a small area on the test chip.

131 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202247
20211,006
20201,140
20191,262
20181,195
20171,215