Effect Of Cross-sectional Shape Research Articles

Finite element modelling of concrete-filled lean duplex stainless steel tubular stub columns

This paper presents a finite element (FE) study on concrete-filled lean duplex slender stainless steel tubular (CFDSST) stub columns of square and L-, T-, and +-shape (Non-Rectangular Sections or NRSs) sections under pure axial compression. The effect of cross-sectional shape and concrete compressive strength, by considering equal steel consumption (i.e. equal cross-sectional area) for all the square and NRSs sections have been reported. In CFDSST stub columns, the axial deformation (δ u ) at ultimate load (P u ) decreases with increasing concrete strengths, but increases as the sections changes from Square→L→T→+-shape. For normal concrete strength (≤40 MPa), NRSs appear to have similar or slightly enhanced P u , in comparison with the representaive square section. But in the case of a high strength concrete core (i.e. >40 MPa), NRSs are clearly at a disadvantage as far as the values of P u is concerned, however as the NRSs are lighter by 37%, they still offer an attractive option for the designers. The FE strengths over predicts the EN 1994-1-1 (2004) specification by about an average of 21, 19, 14, and 4% for the square, L, T, and +-shape sections, respectively.

Absorption threshold frequency of silicon nanowires: Effect of cross section shape

In the present work, the influence of cross sectional shape on threshold frequency of absorption in Silicon nanowires is investigated. For this purpose, we have considered Silicon nanowires with three different cross-sectional shapes like square, circular and triangular. We have used the effective mass approximation to obtain energy levels and wave functions of the structures. We have obtained absorption threshold frequency for two different cases, constant and variable effective mass. In the latter case, we have calculated the mass of electron and hole as a function of cross section. Also, we have used the tight binding approximation to obtain energy levels and thereby absorption threshold frequency. The results show that: (i) the threshold energy frequency for triangular quantum wire is higher than the square and circular cases, (ii) the electron effective mass increases by increasing the cross section area and approach to bulk value for large cross section area.

On the effect of cross sectional shape on incipient motion and deposition of sediments in fixed bed channels

Abstract The condition of incipient motion and deposition are of the essential issues for the study of sediment transport. This phenomenon is of great importance to hydraulic engineers for designing sewers, drainage, as well as other rigid boundary channels. This is a study carried out with the objectives of describing the effect of cross-sectional shape on incipient motion and deposition of particles in rigid boundary channels. In this research work, the experimental data given by Loveless (1992) and Mohammadi (2005) are used. On the basis of the critical velocity approach, a new incipient motion equation for a V-shaped bottom channel and incipient deposition of sediment particles equations for rigid boundary channels having circular, rectangular, and U-shaped cross sections are obtained. New equations were compared to the other incipient motion equations. The result shows that the cross-sectional shape is an important factor for defining the minimum velocity for no-deposit particles. This study also distinguishes incipient motion of particles from incipient deposition for particles. The results may be useful for designing fixed bed channels with a limited deposition condition.

Evaluation of Effect of Cross-Sectional Shape of Orthodontic Wires on Molar Movement Using Digital Image Correlation

Evaluation of Effect of Cross-Sectional Shape of Orthodontic Wires on Molar Movement Using Digital Image Correlation

20705 ハニカム構造を用いた超軽量宇宙用ロボットアームの研究

This paper proposes a novel lightweight robot arm for astronautical development by using honeycomb structure. Honeycomb structure is one of typical lightweight material and already used in astronoutical field mainly for large panels. Besides, Carbon-Fiber Reinforced Plastic (CFRP) is already known to be a lightweight and strong material. In this study, we propose to apply honeycomb structure with CFRP to realize lightweight and compact arm. A prototype using CFRP plates and aluminum honeycomb is produced and its mechanical property is investigated experimentally. The effect of cross-sectional shape and size of honeycomb core onto the mechanical property is also investigated. Moreover, theoretical analysis using FEM is under way.

Mixing performance of a planar micromixer with circular obstructions in a curved microchannel

A numerical investigation of the mixing and fluid flow in a new design of passive micromixer employing several cylindrical obstructions within a curved microchannel is presented in this work. Mixing in the channels is analyzed using Navier–Stokes equations and the diffusion equation between two working fluids (water and ethanol) for Reynolds numbers from 0.1 to 60. The proposed micromixer shows far better mixing performance than a T-micromixer with circular obstructions and a simple curved micromixer. The effects of cross-sectional shape, height, and placement of the obstructions on mixing performance and the pressure drop of the proposed micromixer are evaluated.

Effect of Cross Sectional Shape of Polypropylene Fibers on Flexural Toughness of Composites and Fiber-to-Cement Matrix Adhesion

Cement based material are weak in flexure in comparison to compression. Fibers have been used for 100 years ago in an industrial process (i.e. Hatschek machine) to improve flexural and tensile strength of cement based materials. Many researches have been performed to define the best fiber condition such as fiber type, length, and diameter. A few investigations have been done on the effects of fiber cross section on fiber-cement bonding and flexural strength. In this research, polypropylene (PP) fibers which have diversity in cross section were selected and used as reinforcement in cementitious composites. Fibers characterized for cross sectional shape and average surface area. Flexural strength of the specimens at different fiber volume contents was evaluated. Also, the adhesion of the fibers (with different cross sections such as hollow, delta and circular) was measured using the pull-out test. Results showed that the cross section has an important effect on bonding of the fibers to cement matrix and flexural toughness of the specimens. It was observed that the hollow fiber that has the biggest lateral surface showed the highest pull-out load, and the delta fiber showed best flexural behavior.

Effect of Cross Sectional Shape on the Energy Absorbing Characteristics of a Tube under Quasi-Static Loading

In this study, numerical simulation of tubes of various cross section under axial compression is carried out using LS-DYNA. The effect of varying configurations of tube cross-section shape on the deformation response, collapse mode and energy absorption characteristics of tubes under quasi-static axial compression have been studied. The validation of the finite element tube model was made by comparison with the experimental results of the square tube subjected to quasi-static axial compression. Tabulated results are presented and plots have been included for the specific energy absorption for different cross sections. The study provides an insight on ways to increasing energy absorption of light weight aluminium tubes.

Three Dimensional Flow Simulation in Yarn Duct of Interlacers with Various Cross-Sectional Shapes

This goal of this paper was to determine the flow characteristics of compressible airflow in the yarn duct of an interlacer using numerical simulations to study the effects of cross-sectional shapes of yarn duct on the performance of interlacers. A CFD (Computational Fluid Dynamics) software package ANSYS CFX was used to calculate the flow patterns in the yarn duct. The relationship between the performance of the interlacer and the distribution of the velocity vector, the airflow speed and the particle trace of flow were examined in order to propose a better design of interlacers. From the results of the calculations, if the vortices on the middle cross-section of the yarn duct make the filaments revolve continuously, then a large number of entanglements can be achieved. The velocity at the central point of the yarn duct was the deciding factor as to a sufficient opening for the filaments. However, too high of a velocity makes the filaments stay on the wall, hindering them from entangling with each other.

Effect of cross-sectional shape on thermoelastic dissipation of micro/nano elastic beams

In spite of practical relevance, little effort has been made to analyze the effect of geometrical shape of cross-section on thermoelastic dissipation of micro/nano beams under different surface thermal condition. The present paper aims to study thermoelastic dissipation of micro/nano beams of elliptical, triangular or arbitrary rectangular cross-section with accurate satisfaction of the surface thermal condition. Detailed formulas are derived for quality (Q-) factor of beams of the above-mentioned cross-sections. Our results show that for all cross-section discussed, thermoelastic dissipation is a non-monotonic function of the absolute size of the cross-section provided the beam length is fixed, and the maximum dissipation appears at a specific size which is of the order of a few hundreds of nanometers for examples discussed. These results suggest that thermoelastic dissipation could increase with decreasing cross-sectional size within the micron scale, while it could decrease with decreasing cross-sectional size within the nano scale. In general, for all beams of the above-mentioned cross-sections, the Q-factor for isothermal surface is always higher than the Q-factor for adiabatic surface under otherwise identical conditions at micro/nano scales. The present analysis also indicates that, to achieve a high quality factor, beam resonators with elliptical or triangular cross-sections are best to operate at higher frequencies while beams of rectangular cross-sections are best to operate at lower frequencies.

Atomistic simulation on the shape dependence of the melting behavior of V nanowire

The modified analytical embedded atom method (MAEAM) has been used to study the cross-sectional shape dependence of the melting of vanadium nanowire (NW). The results indicate that the effect of the shape on the melting behavior is apparent. For the prefect crystal, the calculated thermodynamic properties including the melting temperature and the latent heat of melting, which are evidently higher than those of the NWs, are in good agreement with the previously corresponding value. For NWs, by monitoring the temperature dependence of the potential energy and heat capacity, the melting temperature of Tr-, Te-, and Cr-NW has been accurately determined to be 1730 K, 1790 K, and 1760 K, respectively. The melting temperature discrepancy of NWs predicates that the shape effect is prominent. On the basis of the obtained melting point of NW, we study the temperature dependence of the atomic fraction of all shells to explore the effect of cross-sectional shape on the melting behavior. Compared with the melting transition of three NWs, it is found that the melting behavior of triangular nanowire (Tr-NW) with the relatively larger shape factor is significantly different from that of other shape NW. Finally, the cross-sectional shape dependent melting mechanism of NWs is further studied by displaying the atomic snapshots at some given temperatures.

Effect of cross-sectional shape on the behaviour of cationic dyeable poly(ethylene terephthalate) fibres

The effects of cross-sectional shape on the properties of cationic dyeable poly(ethylene terephthalate) fibres were investigated. Three different cross sections, namely tetra channel, snowflake and hollow, were used. Tensile test results showed that the hollow cross section has the highest breaking strength, while the snowflake has the lowest. In terms of thermal properties, no significant difference was observed. However, some differences in their morphology and surface topography were seen. According to birefringence studies, the hollow cross section has the highest overall orientation, while tetra has the lowest. In addition to this, hollow cross section gives the highest roughness value.

Effects of Cross Sectional Shape and Material Strength on Torsional Buckling Behavior

Effects of Cross Sectional Shape and Material Strength on Torsional Buckling Behavior

Effect of Cross Sectional Shape and Material Properties on Impact Deformation Behavior of Ultra High Strength Steel Members

Effect of Cross Sectional Shape and Material Properties on Impact Deformation Behavior of Ultra High Strength Steel Members

Effect of cross sectional shape during condensation in a single square minichannel

The objective of this work is to present new condensation heat transfer coefficients measured inside a single square cross section minichannel, having a 1.18 mm side length, and compare them to the ones previously measured in a circular minichannel. Tests have been performed with R134a at 40 °C saturation temperature, at mass velocity ranging between 200 and 800 kg m −2 s −1. As compared to the heat transfer coefficients measured in the circular cross section channel, for the same hydraulic diameter, in the square minichannel the authors find a heat transfer enhancement at the lowest value of mass velocity, which must be due to the effect of surface tension. No heat transfer coefficient increase has been found at the highest values of the mass velocity where condensation is shear stress dominated.

Cross-sectional shape effect of a diffuser micropump on flow rates

Presented is the effect of cross-sectional shapes in a diffuser micropump using a hetero-shaped fluidic channel. The hetero-shaped fluidic channel consists of two regions with different cross-sectional shapes: a semi-cylindrical shape for the inlet and a rectangular shape for the outlet. The semi-cylindrical-shaped channel can produce almost zero dead volume in a closed state; thus, the flow rate of the micropump should be enhanced. To evaluate the effect of the cross-sectional shape, both hetero-shaped and homo-shaped micropumps were fabricated with the same cross-sectional area. The flow rate of both micropumps was evaluated in terms of frequency and duty ratio. The experimental comparison demonstrated that the hetero-shaped micropump is generally superior to the homo-shaped one with regards to flow rate. The ratio of the maximum flow rate between the two types was more than five for the experiments performed in this study. The acquired maximum flow rate of the hetero-shaped micropump was 38.76 nl/min, which is ten times larger than that of the homo-shaped micropump in identical conditions (frequency: 3 Hz; duty ratio: 50%). Moreover, the hetero-shaped micropump performed the valve function without additional devices.

Effects of cross-section shape on fast electron beams excited plasmons in the surface of nanowire pairs

In this paper,we investigate the gap plasmon excitation by swift electron beams in nanowire pairs, in particular, with different cross-section shapes (including circular, wedge and irregular shape). For all these nanowire pairs, our results show that fast electron beams can efficiently excite low-order monopole-monopole gap plasmons, which possess long propagation distance and well spatial localization. Furthermore, in contrast to high-order plasmons, the excited gap plasmons do not depend highly on cross-section shape of nanowire pairs through comparing the merit parameters in these three kinds of waveguides. Besides, the excited gap mode will be more confined in nanowire pairs with wedge cross-section. Our study will be helpful for the experiments of gap plasmon generation using electron microscope.

Cross sectional shape effects on the performance of post-heated reinforced concrete columns wrapped with FRP composites

Abstract An experimental study was conducted to examine how the cross sectional shape affects the strength and ductility of post-heated reinforced concrete columns wrapped with unidirectional fibre reinforced polymer (FRP). Seventeen columns were tested under axial compression. The main variables investigated were the cross sectional shape of the columns, the presence of heat damage and the type of FRP used for repair. The columns were placed into three groups defined by columns without being subjected to heat, post-heated columns and post-heated and repaired columns. The test results showed that the load carrying capacity of post-heated FRP wrapped columns was significantly affected by the column’s original cross sectional shape. For circular sections the strength of post-heated columns was restored up to, or greater than, its original pre-heated strength. However, the strength of post-heated GFRP or CFRP wrapped square columns was recovered to some extent but not to the level of its original pre-heated strength. It was also found that the increase in the ductility of circular columns was more pronounced compared to square columns after wrapping with FRP. For all damaged columns the use of FRP did not restore the column’s stiffness which was lost due to damage caused by heating.

Theoretical Study on Thermoelectric Properties of Ge Nanowires Based on Electronic Band Structures

Theoretical studies on the thermoelectric properties of Ge nanowires (NWs) in terms of the Seebeck coefficient, electrical conductance, and power factor are carried out under different combinations of parameters. As orientation affects power factor, [100] Ge NWs have better performance than NWs along [111] and [110] in general. For extremely small (1-nm) NWs, the effect of cross-sectional shape also plays an important role on the thermoelectric properties of Ge NWs due to quantum confinement effects. The thermoelectric properties vary strongly depending on the band structure of the Ge NWs of different sizes, cross-sectional shapes, and orientations. Comparing the results between 1-nm triangular Ge and Si NWs in terms of power factor, p-type Ge NWs outperform Si NWs, while n-type Si NWs outperform Ge NWs due to the higher numbers of subband valleys contributing to electron transport.

Cross-sectional shape effect for enhanced Raman spectroscopy on polymer-based microstructures

We prepare various polymer-based microstructures for gold colloid detection in a Raman system. Several surface treatment techniques as well as chip configurations are discussed with an emphasis on their strengths and limitations. First, the optimum focus space is found for the experiment. Next, surface treatment effects for the Raman signal on the polymer-based substrate are compared. Finally, the Raman intensity of three channel configurations is compared along the cross sectional direction. There results demonstrate that a triangle shape provides the highest intensity for the same microstructure depth. A signal-enhanced mechanism on the difference cross sectional surface is also discussed in this research. Optimal shape designs based on polymer-based configurations are proposed for Raman detection in microchannels. This can give rise to several interesting applications, including trapping viruses from samples, and enzymatic reaction from enzymatic immuno-assay systems for real-time monitoring.