Effects Of Thickness Distribution Research Articles

Voltammetric and electrochemical impedance analysis of poly(bisphenol A) supported poly(3,4-ethylenedioxythiophene) layers deposited on gold – the effects of thickness distribution, overoxidation and non-stationarity

The present study describes the preparation and electrochemical characterization of poly(bisphenol A) (poly(BPA)) supported poly(3,4-ethylenedioxythiophene) (PEDOT) modified gold electrodes.Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the electrochemistry of the Au | PEDOT | 0.1 mol/dm3 H2SO4(aq.) and Au | [poly(BPA)/PEDOT] | 0.1 mol/dm3 H2SO4(aq.) electrodes before and after overoxidation. Scanning electron microscopy (SEM) was used for the study of the structure/morphology of the polymer coatings.Similarly to overoxidized PEDOT modified electrodes, time evolution of the electrochemical properties of the poly(BPA)/PEDOT films could be observed after overoxidation. The four-dimensional (4D) analysis method (i.e., a post-experimental mathematical/analytical procedure to overcome the problems caused by non-stationarity) and complex nonlinear least-squares (CNLS) fitting has been used for the estimation of the impedance parameters corresponding to different time instants after overoxidation of the [poly(BPA)/PEDOT] film.The deviations of the impedance responses from the purely capacitive behavior predicted at low frequencies by the theoretical models could be well explained solely by the assumption of uneven film thickness. It has been found that the impedance model, which takes into account the film thickness distribution gives a good description of the impedance data, both before and after overoxidation.According to the results, after the electrochemical deposition of poly(BPA) on the PEDOT layer the resulting [poly(BPA)/PEDOT] modified electrode becomes more resistant against the negative effects of overoxidation.

Experimental and numerical investigation of dynamic plastic behavior of tube with different thickness distribution under axial impact

In this study, the dynamic behavior of uniform thickness, stepped thickness and functionally graded thickness tubes under axial impact are investigated experimentally and numerically. A striking mass has been used to impact tubes. Experimental tests are performed by using gas gun and numerical results are obtained by FE simulation. The effect of thickness distribution on shortening, energy absorption, axial force and buckling shape of tubes are investigated. It is found that a change in thickness distribution of tube can convert the buckling shape from buckling with mild folds to progressive buckling and vice versa. In addition, it is found that stepped thickness tube can be an approximate of functionally graded thickness tube which in this case almost, their behavior is identical. This study reveals that stepped thickness and functionally graded thickness tubes in comparison with uniform thickness tube absorb the same energy with more shortening and less peak load or less mean load; thus, they are better energy absorption specimens. With comparing experimental and numerical results, it is found that there is a good agreement between them.

558 和鐘の肉厚分布と表面の模様が振動特性に及ぼす影響(機械力学・振動,人体のコンピュータモデルの作成とその応用,特別講演)

558 和鐘の肉厚分布と表面の模様が振動特性に及ぼす影響(機械力学・振動,人体のコンピュータモデルの作成とその応用,特別講演)

Effect of Thickness Distribution on Performance of S‐Cambered Profiles

A fully reversible axial flow pump‐turbine is a device that can work as a turbine and as a pump for both forward and reverse directions of flow. These machines find applications in tidal power plants. Double‐cambered S‐shaped profiles are known to be better suited for the blades of such machines; however, information on the aerodynamic characteristics of S‐cambered profiles is very limited. The effect of thickness distribution on the performance of S‐shaped airfoils is considered in this paper. The results obtained from an extensive experimental aerodynamic investigation of three S‐cambered profiles with different thickness distributions are presented. Göttingen 775 and NACA 0010‐66 basic thickness distributions were used to obtain these profiles. The profiles were tested in a wind tunnel in forward and reverse directions of flow. The variation of lift and drag coefficients and that of lift‐to‐drag ratio with angle of attack were obtained. The study showed that among the profiles tested the profile with Göttingen 775 thickness distribution having a maximum thickness at 30% chord is best suited for fully reversible axial pump‐turbine application from the point view of high lift‐to‐drag ratio.

Free vibration of circular cylindrical shells with axially varying thickness

A semi-analytical finite element analysis is presented for determining the natural frequencies of thin circular isotropic cylindrical shells with variable thickness. Love's first approximation shell theory is used to solve the problem. The effect of thickness distribution on natural frequencies was determined for two boundary conditions; viz., simply supported-simply supported and clamped-clamped with different length to radius ratios. The thickness distribution was assumed to be linear and quadratic along the axial direction.