Effect Of Cross-sectional Shape Research Articles

Cross-sectional shape effect of stay-in-place formwork column on axial compressive behaviour

Experimental and numerical studies on the behavior of composite columns with prefabricated self-compacting mortar (SCM) stay-in-place (SIP) formwork and post-cast normal-strength core concrete were presented.The axial compression of twenty-eight reinforcement concrete (RC) composite columns having square or circular cross-section shapes, with formwork thicknesses of 10 mm or 15 mm, and confined with one or two layers of Carbon Fibre Reinforced Polymer (CFRP (, were tested. A finite element (FE) model was generated to simulate the stress–strain relationship, and failure mode of the column using ABAQUS software. The results show that square cross-section-shaped columns exhibited lower axial load and displacement capacities than their counterparts of equivalent circular cross-section-shaped columns. This behavior maintained consistent regardless of the use of the SCM-SIP formworks or the wrapping with CFRP fabrics. Among the various confinement systems compared in this study, the efficiency of the CFRP was the greatest. Good bonding with no peeling failure was observed between SCM-SIP formwork and core concrete, indicating the good integrity of the composite columns. Consistency between the FE model and experimental results was observed for both cross-section shapes, indicating the precise and plausible characteristics of the model to sensibly estimate the stress-strain behaviors.

Effects of cross-sectional shape on flow and heat transfer of the laminar flow of supercritical carbon dioxide inside horizontal microchannels

Supercritical carbon dioxide (sCO2) flow at the micro scale provides an excellent heat transfer solutions for a range of microelectronics cooling applications. The cross-sectional shape of the microchannel (in combination with the abruptly changing thermophysical properties of sCO2) affects the heat transfer and flow characteristics, but these effects are not well understood at constant wall temperatures as most of the previous studies were performed at constant surface heat fluxes. Current study numerically investigated, using CFD, the effects of different cross-sectional shapes, such as circle, equilateral triangle, semi-circle, and square, in zero gravity (space) and in terrestrial conditions, at constant wall temperatures.In all cases, the hydraulic diameter of the microchannel was 100 μm, the total length was 27 mm, and the heated length was 25 mm. A total of 216 cases were analyzed to predict the effects of surface temperature ranging from 310 to 330 K, pressures ranging from 8 to 10 MPa, and Reynolds numbers from 100 to 500 on the heat transfer and flow. It was revealed that the microchannel with triangular cross-section has the highest heat transfer rate, highest mass flow rate, and lowest pressure drop both in zero gravity and in terrestrial conditions. The total surface heat transfer rate for the triangular microchannel was about 49% higher than the circular microchannel at a pressure of 8 MPa, around 53% higher at 9 MPa, and about 55% higher at 10 MPa. However, the average surface heat transfer coefficient displayed a complex behavior, and it depends on the combination of surface temperature, Reynolds number, and operating pressure. The surface heat transfer rate and pressure drop were increased for all shapes at terrestrial conditions, emphasizing that the effects of buoyancy cannot be neglected. Overall, this study revealed a complex behavior of the flow of sCO2 inside microchannels of different cross-sectional shapes, and the triangular cross-section performed better than other shapes.

Investigation into the Effects of Cross-Sectional Shape and Size on the Light-Extraction Efficiency of GaN-Based Blue Nanorod Light-Emitting Diode Structures

We investigated the effect of cross-sectional shape and size on the light-extraction efficiency (LEE) of GaN-based blue nanorod light-emitting diode (LED) structures using numerical simulations based on finite-difference time-domain methods. For accurate determination, the LEE and far-field pattern (FFP) were evaluated by averaging them over emission spectra, polarization, and source positions inside the nanorod. The LEE decreased as rod size increased, owing to the nanorods’ increased ratio of cross-sectional area to sidewall area. We compared circular, square, triangular, and hexagonal cross-sectional shapes in this study. To date, nanorod LEDs with circular cross sections have been mainly demonstrated experimentally. However, circular shapes were found to show the lowest LEE, which is attributed to the coupling with whispering-gallery modes. For the total emission of the nanorod, the triangular cross section exhibited the highest LEE. When the angular dependence of the LEE was calculated using the FFP simulation results, the triangular and hexagonal shapes showed relatively high LEEs for direction emission. The simulation results presented in this study are expected to be useful in designing high-efficiency nanorod LED structures with optimum nanorod shape and dimensions.

Analytical solutions for thermo-elastic damping of rotational ring resonators incorporating thermal relaxations and elastic small scales

At the micro and nanoscales, thermo-elastic damping is regarded as one of the most crucial factors for promoting energy dissipation in vibrating structures. The thermo-elastic damping of a thin rotational ring resonator is explored in this paper based on three phase lag heat conduction model for thermal relaxations and nonclassical elasticity for small scale effects. Solving the heat conduction equation for radial direction heat flow and zero heat flux boundary conditions yields the temperature spread across ring cross-section. The equation takes into account only the rotating narrow ring’s in-plane vibrations. For the frequency dependent thermo-elastic damping, the combined nonlocal thermo-elasto-dynamic equations are solved. The present model is validated with the experimental and finite element data. The thermo-elastic damping of rotating rings has been found to be over predicted by classical elasticity. For a particular small scale factor, as rotational speed rises by 80%, the equivalent thermo-elastic damping of the ring resonator reduces by 43%. In addition, the effects of cross-sectional shape, nonlocal scale factor, rotating speed, modenumber, ambient temperature, and substance on thermo-elastic damping are thoroughly explored in this work. The results presented here are useful to build and construct future nanoscale resonant sensors and radio-frequency devices.

Mechanical response of twisted multifilament artificial muscles upon thermal actuation

Recently-developed twisted multifilament artificial muscles are an intelligent material or device storing energy and outputing work under external stimuli. These muscles are fabricated by a twist-insertion procedure and share a two-step process in triggering rotation or contraction, that is volumetric expansion and tension-torsion coupling. The energy conversion efficiency of thermal actuation for the artificial muscles made of carbon nanotubes has attracted increasing attention due to the giant tensile stroke, record energy density, and easy controllability. In the present paper, the thermal actuation processes of artificial muscles are modeled by numerical simulations, in which the energy conversion efficiency is expressed as the ratio of work output to heat input. The Cosserat curve theory is introduced to analyze the geometric effect of cross-sectional shapes on the tensile TMFAM. The abilities of axial elastic deformation and stretching stable for the CNTBs with typical shapes are quantified. The work output and energy conversion efficiency are then evaluated, offering the opportunity to elevate the mechanical properties of artificial muscles. The strategy to improve the muscle performance is also outlined through their dependence on the geometrical and material parameters.

Practical Machine Learning Application for Predicting Axial Capacity of Composite Concrete-Filled Steel Tube Columns Considering Effect of Cross-Sectional Shapes

Practical Machine Learning Application for Predicting Axial Capacity of Composite Concrete-Filled Steel Tube Columns Considering Effect of Cross-Sectional Shapes

Effect of fire-induced restraint forces on fire behavior of reinforced and prestressed concrete beams

This paper presents results from a set of numerical studies on the effect of fire-induced restraint forces on the response of prestressed concrete (PC) beams. The main parameters studied are the effect of cross-sectional shape, support conditions, and level of prestress. The numerical studies are conducted using a validated three-dimensional (3D) finite-element (FE) based numerical model which accounts for critical governing factors such as magnitude and location of restraint forces, cracking and crushing of concrete, material, and geometric nonlinearity, and spalling. Especially, the model accounts for varying fire-induced restraint forces throughout fire exposure using a new efficient spring idealization framework for connections. The effect of fire-induced restraint forces on the fire response of PC beams is compared with equivalent RC beams to identify key differences in the fire behavior of PC and RC beams. Results from the advanced numerical studies show that significant restraint forces develop in PC and RC beams under fire exposure and these forces vary with fire exposure duration. Further the results show that the fire-induced restraint forces significantly alter the structural response of the beam.

Study the influence of anchoring parameters on asteroid drilling anchoring with discrete element simulation

Asteroid exploration has become a research hotspot, and anchoring probes to asteroids is essential for in situ scientific detections. The influence of ultrasonic drilling force-closure anchoring parameters on the anchoring performance and its influence mechanism are studied based on discrete element simulation. An anchoring simulation model is established after calibrating virtual asteroid soil, and its validity is verified by anchoring experiments. Discrete element simulations are performed to study the effect of cross-sectional shape and longitudinal cross-sectional shape of anchoring rods on anchoring force. The internal influence mechanism of anchor configurations on the anchoring force is analyzed by extracting the number of stressed particles in the simulation area. The anchoring force has a positive correlation with the cross-sectional area. The rotation of non-circular anchors causes fluctuations in the anchoring force. The effect of the anchored material strength on the anchoring force is studied with the calibrated virtual asteroid soil. The relationship between anchoring force and anchoring parameters is studied, and the optimal anchoring angle is 54° for anchored material strength of 100 kPa. Finally, the variation of the anchoring force with the direction of external force is studied. This work can guide the anchor configuration design and the anchoring condition parameter optimization.

Fiber Cross Sectional Shape: A Persuadable Feature for Assessment of Acoustic Noise Control Property of Some Natural Fibers and Its Geometrical Modeling

ABSTRACT The effects of cross-sectional shape, fiber density, and porosity of flax, jute, okra, sisal, and wool fibrous assemblies on noise absorption coefficient have been investigated. The shape was described in terms of its shape factor and the depth of grooves on the fiber’s surface. The number of lobes on the surface of the fiber, which is attributed to intrinsic variability, was utilized to construct the governing equation of shape factors. The shape factor tends to increase as the number of lobes increases. Shapes such as hexalobal (jute), pentalobal (flax), tetralobal (okra), trilobal (sisal), and circular (wool) affected noise control performance. The technique for order performance by similarity to ideal solution (TOPSIS) was used to rank the fibers for noise control performance based on five attributes namely, cross-sectional area, shape eccentricity, shape factor, bulk density, and porosity for validation. The technique confirmed the rank of the absorption performance of the fiber measured by transfer matrix method in impedance tube (ISO 10,534–2). Okra rendered the best noise absorption for its multilobal shape, low density, and spatial arrangement. Wool having regular cross-sections resulted in much lower noise absorption performance.

Analysis of Concrete-filled Lean Duplex Stainless Steel Columns Using ANSYS

Abstract: The Lean Duplex Stainless Steel (LDSS) which is a category of stainless steel is becoming popular as a structural member because of its increased corrosion resistance and durability compared with that of steel. LDSS offers relatively cheaper cost (as compared to austenitic stainless steel), higher strength, acceptable weld ability, and fracture toughness properties, etc. When concrete is filled inside the stainless steel hollow section the load-carrying capacity of this section increases. The aim of this study is to understand the buckling behaviour of concrete-filled stainless steel columns of L, T, and + shaped cross-sections using ANSYS. The LDSS columns having equal material cross-sectional areas with varying thickness are analysed in the current study. This paper gains an understanding of different cross-sectional shape effects under varying thickness.

Visualization and Assessment of Hang-Up Phenomena Using Vertical Transparent Ore-Pass Models

Limestone is one of the most important mineral resources, and it is only one mineral that can be fully supplied by domestic producers. Generally, a certain amount of ores is stored in the ore passes temporally after blasting excavation, and extraction is carried out from the bottom of the ore pass. However, the hang-up phenomena in the ore passes sometimes occurred and some cases are recently reported. Once the hang-up phenomena in the ore passes occur, it will cause serious problems. In this study, ore flow experiments in the vertical ore passes were conducted using ore pass models which was composed of transparent acrylic tubes, and the conditions of hang-ups were discussed. Since the ore passes were assembled with transparent tubes, it was also possible to observe the hang-up phenomenon directly. To discuss the effect of cross-sectional shapes of ore passes, two kinds of ore-passes, that is, circular and square shapes of cross-sections, are prepared. Using various sizes of ores, the relation between ore size and cross-sectional area was also discussed. It was found that the hang-up phenomenon almost did not occur when the ratio of ore pass size to the mean grain size of ores exceeds the value of 5. It was also found that the circular-shaped ore passes were a little preferable to avoid ore pass hang-ups compared with the square ore pass. The same procedure was applied to the mixed ores which two types of ores with different mean diameters are mixed. In this case, also, the results were almost the same as the results obtained by single-size ores. 3D-DEM analysis was also conducted, and the validity of the experiments was discussed.

Mathematical modeling of forced oscillations of manometric tubular springs

Difficult working conditions, as well as vibrations of technological process units and unstable load intensity impose high demands on overpressure monitoring devices that ensure the required measurement accuracy and trouble-free operation of equipment. The use of pressure gauges today is a mandatory requirement for monitoring overpressure. The main type of pressure gauges uses manometric tubular springs (MTP) as elastic sensing elements. Therefore, the issue of calculating the motion of the MTP under the influence of external variable loads, in particular variable internal pressure, is relevant. Issues related to the influence of internal pressure pulsations and external periodically changing external forces remain unexplored. For successful operation, the strength and frequency characteristics of vibrations of tubular springs were previously investigated, the effects of cross-sectional shapes and basic geometric dimensions on their vibration characteristics were considered, and the process of vibration damping by liquid was analyzed. The paper presents a mathematical model of forced oscillations of the MTP based on Lagrange equations of the second kind. The MTP is considered as a mechanical system with two degrees of freedom, that is, defined by two generalized coordinates. They are a relative change in the main angle of the tube and an increase in the small semi-axis of the cross section. The model allows us to determine the nature of the movement of the MTP under the influence of periodically changing internal pressure. To implement it, a program has been developed in MATLAB, which makes it possible to determine the required characteristics of pressure monitoring devices that exclude the possibility of resonance. With the help of the developed program, the influence of geometric characteristics and internal pressure pulsations on the movements of the free end of the MTP is estimated. The presented model can be successfully used for dynamic calculations of manometric tubes, since it is a classical approach to solving problems of vibrations of mechanical systems. In addition, it will allow you to calculate the parameters of tubular elastic elements used in various mechanisms as power elements.

Comparative Study on Thermos-Hydraulic Performance of Different Cross Section Shapes of Microchannels with Supercritical CO2 Fluid

The influence of the cross section shape of microchannels on the thermos-hydraulic performance of the supercritical CO2 fluid is an important issue in the design of industrial compact heat exchangers, but few studies have been conducted about this issue. In this paper, comparative studies of the flow and heat transfer performance of SCO2 fluid in horizontal microchannels with circular, semicircular, rectangle, and trapezoidal cross sections were conducted numerically. The comparison is based on the same hydraulic diameter and length for all channel types and is carried out under the same mass flux, outlet pressure, and wall heat flux. The fluid bulk temperature in this analysis ranges from 285 K to 375 K, which covers the pseudocritical point of SCO2. The results show that the circular channel has the highest average heat convection coefficient, while the trapezoidal channel has the worst convective heat transfer performance under the same hydraulic diameter and boundary conditions. The results also indicate that the effect of cross section shape on the heat convection coefficient is significantly greater than that on the channel pressure drop, and the existence of the corner region in the cross section, especially the acute angle, will weaken the heat transfer performance.

FRACTAL ANALYSIS OF NON-NEWTON FLUID GROUTING IN SOIL COMPOSED OF ARBITRARY CROSS-SECTIONAL CAPILLARIES

The fractal theory has been applied to understand the transport law for the non-Newton Herschel–Bulkley (H-B) fluid grouting in fractal soil consisting of a bunch of arbitrary cross-sectional tortuous capillaries. The fractal models for the average flow velocity, starting pressure gradient and effective permeability are the functions of the cross-sectional geometric factors of capillaries, minimum and maximum cross-sectional area of capillaries, porosity, fractal dimensions and characteristic parameters of H-B fluid. The proposed models are verified by comparing with the available models, and then the effects of cross-sectional shapes of capillaries and the characteristic parameters of H-B fluid on the average flow velocity, starting pressure gradient and effective permeability are also analyzed. The results show that the present models relate the characteristics of H-B fluid to the microstructure of soil, and both are the most important factors in determining the grouting effect.

Investigation of aerodynamic performance ofpitch-control wind turbine with polygonal towers

Wind turbines are commonly used power generation systems around the world and their application is becoming increasingly widespread. Traditionally, they have been mounted on circular towers, but their recent upsizing has exposed weaknesses of these structures, including problems related to manufacturing and insufficient strength. Thus, the concept of site-assembled modular towers with polygonal cross-sections has been proposed, but their aerodynamic performances have not been properly investigated. In the present study, the aerodynamic performances of a wind turbine with seven polygonal towers were investigated. Wind tunnel tests have shown that the forces on the upper structure (rotor and nacelle) are larger than those on the tower, which makes the effect of cross-sectional shape of tower relatively small. Drag forces decrease with increasing number of sides of the tower, and lift forces on the square helical tower are quite small. For the power spectra, there are peaks in high reduced frequency for oblique wind directions at azimuth angles of 60° and 90°, which were considered to result from vortices that were formed and shed behind the blade in front of the tower.

Effect of fibre cross-sectional shape on bending behaviour of yarns and fabrics; part I

To study the effect of fibre cross-sectional shapes on the bending behaviour of continuous multifilament polyethylene terephthalate (PET) yarns and corresponding fabrics, a circular cross-sectional shape has been taken as reference shape. To mimic the natural fibres in different ways, the cross-sectional shape is an important parameter in this regard. Different cross-sectional shapes like circular, trilobal, rectangular, plus, double flange dumble shape, octagonal, hexalobal, square and trilobal plus or Y-shape were selected for the study. The linear density of single filament and yarn were kept constant (i.e. 76/48/0) in all cross-sectional shapes. The area of cross section was approximately constant for all shapes. The theoretical bending rigidity was calculated for all cross-sectional shapes about its neutral axis. The experimental BR ratio concerning reference circular cross section of fibre was compared with the theoretical BR ratio. It is assumed that individual filament is free to bend in fibre assembly having zero twists. All yarns were converted to fabric having constant areal density. The yarn bending behaviour is compared with fabric bending behaviour to study the effect of cross-sectional shapes on bending behaviour.

Inverse design of 3D curved ducts using a 3D-upgraded ball-spine algorithm

ABSTRACT Achieving a unique solution for the 3D inverse design of a curved duct is a challenging problem in aerodynamic design. The centre-line curvature, and cross-sections’ area and shape of a 3D curved duct influence the wall pressure distribution. All the previous developments on the ball-spine method were limited to 2D and quasi-3D ducts, in which only the upper and lower lines of the symmetry plane were modified based on the target pressure distribution. In the present work, the ball-spine method was three-dimensionally developed for the design of curved ducts while considering the effects of cross-sectional shape and area. To validate the method, all the nodes of a 3D duct wall were iteratively corrected under the modified ball-spine method to reach the target geometry. The effects of the ball movement directions (spines) and the grid generation scheme in achieving the unique solution in inverse design were evaluated. The results showed that the new method converges to a unique solution only if the streamline-based grids are applied for the flow numerical solution, and the horizontal spines are considered as the directions for the displacement of the nodes. Finally, the wall pressure distribution of a high-deflected 3D S-shaped diffuser was three-dimensionally modified to reduce the separation, secondary flow, and flow distortion.

Experimental and numerical investigation of the effect of cross-section shape on damaged self-compacting concrete columns

This paper experimentally and numerically (using the finite element analysis) examines cross-section shape effects on damaged SCC short columns enhanced with CFRP sheet wrapping. The impact of various strengthening techniques on the structural behaviour of columns was investigated, with the convergence between the experimental and numerical results verified numerically in ABAQUS. The experimental strengthening process included partial or full wrapping in CFRP sheets, with specimens in the first group enhanced with three or five CFRP sheets of 100 mm width and those in the latter group enveloped in CFRP sheet to the full column height. The numerical results agreed well with the experimental results and demonstrated that the square cross-section SCC short column exhibited higher strength capacity than other shapes.

Influence of cross-section shape on structure and properties of Lyocell fibers

Three kinds of Lyocell fibers with different cross-sections including circular, H-shape, and Y-shape (abbreviated as O-, H-, and Y-Lyocell) were prepared by a dry-jet wet spinning method. The effects of cross-sectional shape on structure and properties of Lyocell fibers were evaluated. The results showed H-Lyocell and Y-Lyocell exhibited triangular and dumbbell cross-sections, respectively, due to die swell. Both non-roundness factor and crystallinity of different cross-sectional Lyocell fibers were in the order of H-Lyocell > Y-Lyocell > O-Lyocell. All cross-sectional Lyocell fibers showed similar values of fineness and tensile strength. The profiled Lyocell fibers were superior to circular Lyocell fibers in terms of luster, dyeing properties, and moisture regain. The dye uptake and fixation rate of Lyocell fibers were influenced by shape in the order H-Lyocell > Y-Lyocell > O-Lyocell; while for luster and moisture regain the order was Y-Lyocell > H-Lyocell > O-Lyocell. Profiled Lyocell fibers are expected to open broader prospects in different textile or composite fields due to their various advantages versus conventional circular Lyocell fibers.

The effects of cross-sectional shapes on the axial performance of concrete-filled steel tube columns

Concrete-filled steel tubular (CFST) columns have been used in the construction of modern structures such as high-rise buildings and bridges as well as infrastructures as they provide better structural performance than conventional reinforced concrete or steel members. Different shapes of CFST columns may be needed to satisfy the architectural and aesthetic criteria. In the study, three dimensional FE simulations of circular, square, hexagonal, and octagonal CFST stub columns under axial compression were developed and verified through the experimental test data from the perspectives of full load-displacement histories, ultimate axial strengths, and failure modes. The verified FE models were used to investigate and compare the structural performance of CFST columns with different cross-section shapes by evaluating the overall load-deformation curves, interaction stress-deformation responses, and composite actions of the column. The extent of the ultimate-axial-strength enhancement due to enhanced steel yield strength and concrete compressive strength was evaluated through the parametric studies. At last, the accuracy of available design models in predicting the ultimate axial strengths of CFST columns were investigated. Research results showed that the behaviors of hexagonal and octagonal CFST columns were generally similar to that of the square CFST column as their overall structural performance was relatively improved.