Increase In Taper Ratio Research Articles

Vibration and resonance reliability analysis of non-uniform beam with randomly varying boundary conditions based on Kriging model

In order to prevent the function failure of the structure due to resonance in the working process. The vibration responses and resonance reliability of non-uniform beam (NUB) with randomly varying boundary conditions (RVBCs) are investigated in this paper. The natural frequencies calculated by Adomian decomposition method (ADM) are used to establish the sample space, based on which the Kriging model is obtained through learning. The influences of boundary support spring stiffness (BSSS) and taper ratio on natural frequencies, vibration responses, and resonance reliability are then studied. The numerical results show that within the range of studied parameters, when the BSSS of the NUB change simultaneously during vibration, the influences and trends of the BSSS on each order’s natural frequency are different and challenging to predict. Due to the geometric nonuniformity of the NUB, the influence of the spring at the left end with a smaller cross-section on the resonance failure probability is more significant than that on the other side. With the increase in taper ratio, the amplitude, maximum strain, and resonance failure probability increase first and then decrease. The method can also be used to solve the vibration characteristics and resonance reliability of NUBs with randomly varying elastic modulus, density and dimensions, which can provide a reference for the data monitoring and use maintenance of the non-uniform beam in vibration.

The Role of Tapered Light-Diffusing Fibers in Plasmonic Sensor Configurations.

In this work, we experimentally analyzed the effect of tapering in light-diffusing optical fibers (LDFs) when employed as surface plasmon resonance (SPR)-based sensors. Although tapering is commonly adopted to enhance the performance of plasmonic optical fiber sensors, we have demonstrated that in the case of plasmonic sensors based on LDFs, the tapering produces a significant worsening of the bulk sensitivity (roughly 60% in the worst case), against a slight decrease in the full width at half maximum (FWHM) of the SPR spectra. Furthermore, we have demonstrated that these aspects become more pronounced when the taper ratio increases. Secondly, we have established that a possible alternative exists in using the tapered LDF as a modal filter after the sensible region. In such a case, we have determined that a good trade-off between the loss in sensitivity and the FWHM decrease could be reached.

Experimental Characterization of Plasmonic Sensors Based on Lab-Built Tapered Plastic Optical Fibers

In this work, we have compared several configurations of surface plasmon resonance (SPR) sensors based on D-shaped tapered plastic optical fibers (TPOFs). Particularly, the TPOFs used to obtain the SPR sensors are made by a lab-built system based on two motorized linear positioning stages and a heating plate. Preliminarily, a comparative analysis has been carried out between two different configurations, one with and one without a thin buffer layer deposited between the core of TPOFs and the gold film. After this preliminary step, we have used the simpler configuration, obtained without the buffer layer, to realize different SPR D-shaped TPOF sensors. This study could be of interest in SPR D-shaped multimode plastic optical fiber (POF) sensors because, without the tapers, the performances decrease when the POF’s diameter decreases, whereas the performances improve in SPR D-shaped tapered POF sensors, where the diameter decreases in the D-shaped sensing area. The performances of the SPR sensors based on different taper ratios have been analyzed and compared. The SPR-TPOF sensors have been tested using water–glycerin mixtures with refractive indices ranging from 1.332 to 1.381 RIU. According to the theory, the experimental results have demonstrated that, as the taper ratio increases, the sensitivity of the SPR sensor increases as well, while on the contrary the signal-to-noise ratio (SNR) decreases.

Vibration control of super-tall buildings using combination of tapering method and TMD system

Modern super-tall buildings are highly sensitive to wind-induced vibrations due to their high flexibility and low inherent damping. Tapering the cross-section of buildings is an aerodynamic modification to control wind-induced vibrations. Tuned mass damper (TMD) is another control system to mitigate structural vibrations. In the present study, the effect of using the tapering method together with the TMD system on the wind-induced vibration control of super-tall buildings is investigated. A numerical example of super-tall buildings is presented, and the wind-induced responses are computed for four different conditions, including: tapered and non-tapered super-tall buildings with and without TMD system. The along-wind and crosswind responses are computed using the frequency domain analysis for different values of taper and TMD mass ratio. The results indicate that for tapered buildings, the natural frequency of the structure increases as taper ratio increases and since the acceleration is proportional to the square of the natural frequency, tapering method cannot effectively reduce the acceleration response. TMD has higher acceleration control performance than the displacement. By using the two control strategies together, both the displacement and acceleration responses can be effectively suppressed, and this method would be helpful in satisfying the occupant comfort and safety criteria of super-tall building.

Experimental studies on the sensitivity of the propagating and localized surface plasmon resonance-based tapered fiber optic refractive index sensors.

In the present study, the sensitivities of the fiber optic propagating surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR)-based refractive index sensors have been evaluated experimentally for a tapered probe of different taper ratio. The tapering of the fiber probe has been carried out via a heating and stretching technique. The SPR probe has been fabricated by coating a thin film of silver over the core of the tapered optical fiber, while the LSPR probe has been prepared by the coating of the gold nanoparticles over the core of the tapered optical fiber. The increase in the taper ratio increases the sensitivity of both kinds of the probes. The experimentally obtained sensitivity has been compared with the sensitivity of the SPR-based fiber optic refractive index sensors fabricated using various techniques and reported in the literature.

Theoretical and Numerical Estimation of Vibroacoustic Behavior of Clamped Free Parabolic Tapered Annular Circular Plate with Different Arrangement of Stiffener Patches

This paper compares the vibroacoustic behavior of a tapered annular circular plate having different parabolic varying thickness with different combinations of rectangular and concentric stiffener patches keeping the mass of the plate and the patch constant for a clamped-free boundary condition. Both numerical and analytical methods are used to solve the plate. The finite element method (FEM) is used to determine the vibration characteristic and both Rayleigh integral and FEM is used to determine the acoustic behavior of the plate. It is observed that a Case II plate with parabolic decreasing–increasing thickness variation for a plate with different stiffener patches shows reduction in frequency parameter in comparison to other cases. For acoustic response, the variation of peak sound power level for different combinations of stiffener patches is investigated with different taper ratios. It is investigated that Case II plate with parabolic decreasing–increasing thickness variation for an unloaded tapered plate as well as case II plate with 2 rectangular and 4 concentric stiffeners patches shows the maximum sound power level among all variations. However, it is shown that the Case III plate with parabolically increasing–decreasing thickness variation with different combinations of rectangular and concentric stiffeners patches is least prone to acoustic radiation. Furthermore, it is shown that at low forcing frequency, average radiation efficiency with different combinations of stiffeners patches remains the same, but at higher forcing frequency a higher taper ratio causes higher radiation efficiency, and the radiation peak shifts towards the lower frequency and alters its stiffness as the taper ratio increases. Finally, the design options for peak sound power actuation and reduction for different combinations of stiffener patches with different taper ratios are suggested.

Buckling Analysis of Belly Shaped Composite Column

The study of Non prismatic column is designed to minimize the volume of material in the column by changing its shape, the column is subject to both buckling and strength constraints under axial compression load. The belly column is designed as Encased Composite column to improve the strength and ductility of column. The effective use of material through optimal shape of the column. Five models have been created in ANSYS WORKBENCH and all the columns having the same volume of materials, fixed end conditions and length of column. The behaviour of non-prismatic column is always based on tapering ratio and the slenderness ratio of the column. As the taper ratio increases, the elastic buckling load increases and stress decreases in the mean while the maximum stress occurs in the prismatic column compared with the non-prismatic column. As a result of this analysis Equivalent stress, Equivalent elastic strain, Total Deformation and Buckling load Deformation was observed and hence Stress-Strain graphs, Load -Deformation graphs and Mode-Load multiplier graph had been plotted.

Structural behavior of non-prismatic mono-symmetric beam

This paper attempts to understand the structural behavior of non prismatic channel beams subjected to bending through finite element(FE) analysis. The present study aims at shedding some light on how tapered channel beams behave by studying the effect of taper ratio on structural behavior. As a weight reduction is always desired in aerospace structures beams are tapered in order to obtain highest structural efficiency. FE analysis has been performed to study the effect of taper ratio on linear deflection, lateral torsional buckling, non-linear parameters and dynamic parameters. Taper ratio tends to affect the mechanics of tapered beams innocuously and adversely. Consequently it becomes important to understand and document the mechanics of channel tapered beams. Channel beams generally have low torsional rigidity due to the off-shear loading. The effect of loading type and location of applied load have been studied for flange taper, web taper and symmetric taper for different conditions. Among these, as the taper ratio is increased, the torsional angular deflection increases but begins to decrease when the beam is web tapered and symmetrically tapered for a mid web loaded beam. But when loaded through the shear center, an increase in the torsional angular deflection can be observed with increase in taper ratio. This indicates that a flange taper could cause an increase in torsional angular deflection with an increase in taper ratio.

Response Time Analysis of a Few Selected Tapered Porous Clad Fiber Gas Sensors

A comparative study has been carried out on the detection of gases with the use of attenuated total internal reflection spectroscopy in a multimode step index, based on parabolic, linear, and exponential-linear tapered fibers with porous cladding. Using geometric optics, an expression has been derived for the time dependent evanescent absorbance as the gas diffuses through the cladding. It has been shown that the relative evanescent absorbance depends on the taper profile and taper ratio. For a given taper profile, as the taper ratio increases, the response time of the sensor decreases. Further, the sensor with the exponential-linear taper profile has less response time than those with the parabolic and linear profiles in cases of a particular taper ratio.

Gas sensor response time analysis for tapered porous-clad fibers

Abstract The detection of gases with the use of ATR spectroscopy in a multimode step-index-tapered fiber with porous cladding has been described. Geometrical optics has been used to derive an expression for the time-dependent evanescent absorbance as the gas diffuses through the cladding. The ratio of the radii of core and cladding has been assumed to be constant throughout the length of the taper. It has been shown that the relative evanescent absorbance depends on the taper ratio. As the taper ratio increases, the response time of the sensor decreases.

Dynamics of Neutrally Buoyant Inflated Viscoelastic Tapered Cantilevers Used in Underwater Applications

The paper investigates statics and dynamics of neutrally buoyant inflated viscoelastic tapered cantilevers used as structural members in underwater platforms. In the beginning, the static flexural behavior of the beam is studied using the three-parameter viscoelastic solid model which yields material properties for the mylar-polyethylene-mylar plastic film used. Results of a detailed experimental program are also presented to substantiate validity of the analytical model. This is followed by free vibration analyses of the inflated cantilevers in the ocean environment. The elementary beam theory is used to predict their natural frequencies. Finally, the dynamical response of the uniform and tapered cantilevers to root excitation, at the fundamental wave frequency and its second harmonic, is studied. The governing nonlinear equations are analyzed by taking two terms of the assumed Fourier series solution. Results suggest that for the case of the simple harmonic excitation, the nonlinear hydrodynamic drag introduces no superharmonic components into the response. For low forcing frequencies typical of the ocean environment, an increase in taper ratio tends to reduce the tip amplitudes. However, for frequencies above the fundamental, the response characteristics are completely reversed. The analysis provides valuable information concerning the system parameters leading to critical response and hence should prove useful in the design of such inflatable members.