Cross-sectional Shape Research Articles

An analysis of tire radiation properties using dispersion diagrams

Road traffic noise created by tire/road interaction not only depends on the road surface properties and the tire tread pattern geometry, but also on the tire construction. Besides the footprint shape, the tire construction can also affect the radiation efficiency of the tire modes. Dispersion diagrams represent the circumferential mode number of a mode shape as a function of its natural frequency. Identification of key branches in the dispersion diagram for a tire can help in understanding tire noise radiation under working conditions. After performing a cluster analysis, where all points belonging to the same branch associated with a particular cross sectional mode shape deformation are identified, differences in tire specification are considered, and their respective dispersion diagrams are compared. First results reveal that by changing the tire stiffness (e.g. by increasing belt angle or inflation pressure) the shape and slope of the different branches are changing. Which branches remain unchanged, and which are most sensitive to these changes can reveal how differences in tire structural composition influence the modal wavelength and consequently the radiation efficiency of the different modes.

Sound environment design using flexible wood-based sound absorbers

A sound-absorbing material made of flexible wooden boards with air permeability was developed to improve the indoor sound environment of buildings. The flexible wood-based material has sound absorbing characteristics with the Helmholtz resonator by its air permeability. In other words, various sound absorption characteristics could be realized owing to the cross-sectional shape (flat or curved) and machining conditions (cut width, cut pitch, and plate thickness). In this paper, the application of flexible wood-based sound-absorbing materials to acoustic design in actual buildings (nursery schools and a church) where acoustic considerations are required is presented. In their application to a newly built nursery school, one of the considerations was to prevent the loss of design by installing sound-absorbing materials. In their application to acoustic renovation, the sound environment improvement effect was confirmed by measuring sounds before and after the installation, and it was also confirmed that the users were able to feel the improvement effect. These results will lead to the development of sound-absorbing wooden boards as an interior material and the promotion of the use of wood in buildings to contribute to the realization of a decarbonized society.

Dynamic analysis of a NiTi rotary file by using finite element analysis: Effect of cross-section and pitch length.

This study assessed stress distribution, maximum stress values and fatigue life of experimentally designed NiTi rotary files with different cross-sectional geometry and pitch length using finite element analysis (FEA). Four cross-sectional shapes (Convex triangle, S-shaped, Triple helix and Concave triangle) and two pitch lengths (2 mm and 3 mm) were tested in simulated root canals with curvatures of 30°, 45° and 60°. The FEA results indicated that convex triangle and triple helix geometries exhibited lower stress values compared to the S-shaped and concave triangle designs. Increasing the canal curvature angle resulted in higher stress values, with the S-shaped instrument showing the most significant increase (up to 12%). Instruments with shorter pitch lengths showed more even stress distribution enhancing fatigue life. The maximum stress was concentrated 5-8 mm from the tip, varying across cutting edges, with S-shaped sections experiencing the lowest forces but higher stress due to lower moments of inertia.

Assessment of photovoltaic system in existence of nanomaterial cooling flow

In this study, a photovoltaic (PV) system was enhanced through the combination of a cooling duct utilizing a nanofluid composed of water and Al₂O₃ nanoparticles, aimed at optimizing thermal regulation and improving electrical efficiency. A novel approach was introduced by systematically examining the effects of channel cross-sectional shapes and fin arrangements on heat dissipation. Using a single-phase simulation model, the thermal performance of the nanofluid was evaluated across various nanoparticle shapes, providing new insights into the relationship between geometry and nanofluid cooling efficacy. The results demonstrated that altering the cross-sectional shape generally reduced thermal performance, but strategic fin configurations significantly enhanced heat transfer. The optimal design, featuring eight shorter fins arranged around an eight-lobed pipe, resulted in a 4.3% improvement in thermal performance. Additionally, blade-shaped nanoparticles were identified as the most effective, enhancing heat absorption by 1.15% compared to pure water. This research presents the first combination of advanced nanofluid cooling with a detailed analysis of geometric factors (cross-section and fin design) in PV systems. The findings provide practical guidelines for improving heat management in PV cells, ultimately leading to increased electrical efficiency and an extended operational lifespan. These insights hold promising implications for the design of more efficient solar energy systems and could inform future thermal management solutions in renewable energy applications.

Experimental investigation on axial compressive performance of rectangular multi-cell stocky concrete-filled steel tubes stiffened with PBL

An experimental investigation on the structural performance of rectangular multi-cell stocky concrete-filled steel tubes (CFSTs) stocky stiffened with perfobond leiste (PBL) under compression. Compression tests were conducted on 12 stocky CFSTs, varying concrete strengths, number of cells, and cross-section shapes. The tests discussed the failure process, load-deformation behaviours, section capacities, ductility factors, and core concrete enhancement factors of the specimens. It was found that all the 12 tested CFSTs experienced local bucking, and owing to the inclusion of PBL, the short sides of the steel tubes exhibited double-wave bulging, while the long sides showed multiple-wave bulging. With the enhancement of concrete strength from 29.4 to 65.1MPa, the section capacity exhibited a significant increase of 18–30%. As the cell number increased from 1 to 3, the section capacity increased by 1.35–1.59 times. When the cross-section of triple-cell CFSTs changed from the I-shape to the L-shape, the section capacity only increased by 3–9%. Moreover, the enhancement factor of the core concrete and the confinement factor showed a significant correlation. The comparison between test capacities and predicted capacities using the methods given in design codes ANSI/AISC 360-16, EN 1994-1-1, and GB 50936-2014, as well as proposed by Zhang, revealed that the capacity ratios of predicted values to experimental values ranged from 0.63 to 0.89, indicating an overly conservative prediction. Considering the confinement factor, a modified design method, based on Zhang’s method was proposed, to more accurately predict the section compressive capacity of rectangular multi-cell stocky CFSTs stiffened with PBL.

Multiple-arc cylinder under flow: Vortex-induced vibration and energy harvesting

The shape of a cylindrical cross-section affects the vibrational performance. The vortex-induced vibration (VIV) phenomena of multiple-arc cylinders were numerically investigated to assess their impact on hydrodynamic energy harvesting and potential vibration suppression across a flow velocity range of 0.2 m/s to 1.4 m/s (1.767×104<Re<1.237×105). The study involves five types of multiple-arc cylinders: 4-arc, 8-arc, 16-arc, 24-arc, and circular cylinders. The accuracy of the numerical method was validated through comparison with experimental data. Specifically, increasing the number of arcs generally enhances overall energy conversion efficiency. Then, the VIV response and energy conversion results of the 24-arc cylinder are similar to those of the circular cylinder with maximum efficiency. Notably, the 4-arc cylinder achieves a global maximum amplitude of 0.074 m (A*=0.83) and a power output of 4.4 W with the new P+T mode, making it the most effective configuration for flow velocities between 0.7 and 0.9 m/s. For vibration suppression of multiple-arc cylinders, the appropriate arc structure effectively reduces amplitudes. The small vortices generated by the arc structures disrupt the separation of normal vortices from the boundary layer, leading to approximately a 50% reduction in amplitude responses for 8-arc and 16-arc cylinders.

Impact of liquid crossflow on the discharge coefficient of a gas jet hole on a flat plate

This study combines the experimental and numerical simulation methods to deeply analyze the impact of liquid crossflow on the discharge coefficient of a gas jet hole on a flat plate. Experiments were conducted to examine the influence of momentum flux ratio and theoretical momentum flux ratio on the discharge coefficient under various crossflow Reynolds numbers. It was found that the variation of the discharge coefficient with the theoretical momentum flux ratio clearly reflects the impact of the crossflow boundary layer velocity profile on the discharge coefficient. The rapid growth of velocity in the boundary layer near the wall in the direction normal to the wall surface, or the decrease in the thickness of the boundary layer, both enhance the shearing effect of the crossflow, leading to a decrease in the discharge coefficient. Analysis of the cavity morphology at the hole exit captured by high-speed camera revealed that the averaged profile of the gas–liquid boundary on the symmetrical plane of the jet below the hole can be approximated as a straight line within the scale of the hole diameter, and the sine of the angle between this line and the upper wall surface is roughly equivalent to the normalized discharge coefficient. This relationship was physically interpreted through the analysis of effective and equivalent flow cross-sectional shapes derived from numerical simulation at different crossflow Reynolds numbers and theoretical momentum flux ratios. Additionally, this paper introduces an innovative method for predicting jet flow rate based on image processing technology. A notable feature of this method is that it does not require the measurement of the pressure inside the gas chamber.

Three-dimensional dynamics of detonation cells in linearly diverging channels: experimental analysis of the cross-sectional shape and a detonation-shock dynamics interpretation

Three-dimensional dynamics of detonation cells in linearly diverging channels: experimental analysis of the cross-sectional shape and a detonation-shock dynamics interpretation

Simulation of thermoelectric-photovoltaic system integrated with various shapes of cooling ducts filled with nanomaterial

Incorporating thermoelectric (TE) modules into photovoltaic/thermal (PVT) systems can markedly increase energy output by improving the overall efficiency of energy conversion. This research focused on the design and simulation of a PVT system integrated with a TE module, utilizing ANSYS Fluent. The study assessed four different tube cross-sectional shapes—circular, square, elliptical, and triangular—all with the same cross-sectional areas. Moreover, the investigation included the impact of Cu-alumina/H2O hybrid nanofluid at a 0.024 % volume concentration, fluid inlet velocity (ui), and solar radiation (G) on PV temperature (TPV) and the overall productivity. The outputs showed that the triangular configuration considerably reduced TPV compared to the other shapes. This configuration also generated the highest thermal power, reaching 130.84 W. Additionally, at ui = 0.19 m/s, the unit's thermal efficiency and overall electrical efficiency increased by 0.93 % and 0.22 %, respectively.

Effective Press Folding Line Process as Producing Smart Intersection in Square Steel Pipe Structures by Using Crushed Cross Section Compactly

As a cross section of square steel pipe is crushed, the upper plate and the lower plate deform inward, and the side plates deform outward from the original square cross section shape. When the press folding line process as deformation induction is applied, the upper plate and the lower plate keep flat, and the side plates are compactly folded inward. This deformation pattern is safe without causing any harm to the surrounding area, and makes it possible to improve impact energy absorption performance by folding side plates as overlapping. Moreover, square steel pipe structures include places as pipes intersect and places to avoid interference with other parts (piping, wiring, fork claws, etc.). In such cases, the current method is to create an opening by cutting off. At that time, the structural strength will decrease, so reinforcing materials are often installed as a countermeasure. On the other hand, if the opening is processed by laterally impact crushing using the press folding line process proposed in this paper, a crushed part will remain, suppressing the decrease in structural strength, and this can be handled without adding reinforcing material to be a smart intersection. This paper shows the findings based on experimental data, FEM (Finite Element Method) results on processing conditions for inward deforming side plates of square steel pipes and evaluation of impact energy absorption performance in laterally impact crushing.

Bandgap Control of Local Resonance Sandwich Meta-Plate with Cantilevered Archimedean Spiral Beam-Mass Resonators

In order to attenuate the various low-frequency vibrations that may cause structural fatigue and damage, impact human health and affect work efficiency, this paper presents a novel local resonance metamaterial sandwich meta-plate structure containing a cantilever spiral beam-mass resonator, and investigates vibration reduction effects of it within the obtained low-frequency bandgap range. For this purpose, a theoretical model of the low-frequency resonator being composed by a cantilever Archimedean spiral beam and cylindrical mass is established. The natural frequency of it is calculated by solving the Euler-Lagrange equation of the resonator. The accuracy and reliability of the theoretical model are verified through COMSOL simulation. The stress distribution of five types of cantilever spiral beam mass resonators (i.e. Archimedes spiral, triangle spiral, square spiral, pentagon spiral and hexagon spiral) and different cross-sectional shapes (rectangular, square, circular, diamond and triangular) are analyzed. Then, a unit cell model of a sandwich meta-plate with a cantilever Archimedean spiral beam resonator is selected. Hamilton’s principle is used to deduce the bandgap range under infinite periods, and the theoretical solutions are also verified. The parameter optimization of the substrate plate and resonator are also studied. Moreover, the effects of the various structural variables on the bandgap range are systematically explored. Finally, the dynamic responses of the sandwich meta-plate composed of [Formula: see text]-unit cells under different excitation frequencies, boundary conditions and structural damping are analyzed.

Multistability of a long droplet in a capillary tube under transverse body force

Bistable states for a sufficiently large amount of liquid can appear in an eccentric capillary due to the eccentricity effect under zero gravity (J. Fluid Mech, vol. 863, 2019, pp. 364–385). A transverse body force, which can lead to rich physical phenomena of a droplet, may lead to multistable states (bistability, tristability and the likes) of a sufficiently large amount of liquid in a capillary. We theoretically investigate this situation in a circular or annular capillary tube under a transverse body force. The results show that there can be tristable (bistable) states in an annular (circular) capillary tube: an occluding configuration and two (one) non-occluding configurations. In the annular tube, for one of the non-occluding configurations, the gas–liquid interface in the middle cross-section of the droplet meets both the inner and outer walls of the tube (bridging configuration); for the other non-occluding configuration, the gas–liquid interface in the middle cross-section of the droplet does not meet the inner wall (non-bridging configuration). The multistability is dependent on the Bond number, the contact angle and the cross-sectional shape. The multistability cannot occur for a zero or very large Bond number. A hydrophilic condition (the contact angle smaller than 90°) contributes to the non-occluding non-bridging configuration, while the hydrophobic condition (the contact angle larger than 90°) contributes to the non-occluding bridging configuration (only for the annular capillary). For the annular capillary with a not-so-large contact angle, increasing the inner-to-outer radius ratio can lead to a larger range of Bond numbers, in which the multistability occurs.

Development of an ultrasound-based metric of muscle functional capacity for use in patients with neuromuscular disease.

Spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD) are progressive neuromuscular disorders characterized by severe muscle weakness and functional decline (Pillen et al., Muscle Nerve 2008; 37(6):679-693). With new therapeutics, objective methods with increased sensitivity are needed to assess muscle function. Ultrasound imaging is a promising approach for assessing muscle fat and fibrosis in neuromuscular disorders. This study builds on prior work by combining ultrasound-based measurements of muscle size, shape, and quality, relating these measures to muscle strength, and proposing a multivariable image-based estimate of muscle function. Maximum voluntary elbow flexion torque of 36 participants (SMA, DMD, and healthy controls) was measured by hand-held dynamometry and elbow flexor muscles were imaged using ultrasound. Muscle size (cross-sectional area, maximum Feret diameter or width, and thickness), quality (echogenicity, texture anisotropy index), and cross-sectional shape (diameter ratio) were measured. Multivariable regression was used to select ultrasound measurements that predict elbow flexion torque. Significant differences were observed in muscle size (decreased), shape (thinned), and quality (decreased) with increased disease severity and compared to healthy participants. CSA (brachioradialis R2 = 0.51), maximum Feret diameter (biceps R2 = 0.49, brachioradialis R2 = 0.58) and echogenicity (brachioradialis R2 = 0.61) were most correlated with torque production. Multivariable regression models identified that muscle size (CSA, maximum Feret diameter) and quality (echogenicity) were both essential to predict elbow flexion torque (R2 = 0.65). A multivariable approach combining muscle size and quality improves strength predictions over single variable approaches. These methods present a promising avenue for the development of sensitive and functionally relevant biomarkers of neuromuscular disease.

Buckling analysis of functionally graded nanobeams via surface stress-driven model

The manuscript investigates the buckling behaviour of Bernoulli-Euler nanobeams composed of Functionally-Graded (FG) materials with different cross-sectional shapes. This analysis is conducted using the surface stress-driven model of elasticity. The nonlocal governing equations for the elastostatic buckling problem are derived employing the principle of virtual work. The study also includes a parametric investigation, presenting and discussing the main results while varying the nonlocal parameter, material gradient index, the cross-sectional shapes and the constraints at the ends of the FG nanobeams. Critical loads are numerically calculated and compared with those obtained by other authors using the classical stress-driven model elasticity.

Analysis of strength and resistance to loss of stability of thin-walled channel columns with non-standard cross-sectional shape

Analysis of strength and resistance to loss of stability of thin-walled channel columns with non-standard cross-sectional shape

Improvement of mixing efficiency in twisted micromixers: The impact of cross-sectional shape and eccentricity ratio

Microfluidic mixers with twisted geometries show promise for high mixing efficiency, especially at elevated flow rates. However, there is a lack of understanding regarding the optimal geometrical parameters to enhance mixing across various Reynolds numbers. This study aimed to explore the influence of pitch number, cross-section geometry, and eccentricity ratio on the performance of the twisted micromixer. The flow field in these micromixers was solved numerically and the mixing index and pressure drop were calculated for Reynolds numbers of 1 to 400. Twisted micromixers with rectangular cross-sections and aspect ratios of 0.5 and 2 outperformed those with square cross-sections by up to 34% in mixing efficiency, exceeding 90% efficiency for Reynolds numbers from 1 to 400. Moreover, the eccentricity ratio (ER) was studied for the first time in twisted micromixers in this study and demonstrated a critical role in improving the mixing performance. For low to intermediate Reynolds numbers, the highest ER of 0.75 showed the best performance, while for high Reynolds numbers, an ER of 0.5 was optimal. These insights offer valuable direction for designing high-performance micromixers for advanced microfluidic systems.

Shear Force of Interior Beam–Column Joints under Symmetrical Loading with Two Transverse Forces on the Beam †

The beam-to-column connection is a particularly vulnerable element in frame structures under seismic action and is often responsible for building damages. Experimental investigations carried out over the past six decades on shear strength in frame joints have not led to the establishment of a uniform procedure in the design codes of different countries. The reason lies probably in the varied nature of the investigated parameters and in the varied configurations of beam–column connections. A good knowledge of the forces passing through the frame joints in the beam–beam and column–column direction would allow both their adequate computation in new buildings and the verification of existing ones without requiring experimental studies. In the design codes of the leading countries in seismic engineering, the shear force is determined by the capacitive method, considering only the area of the longitudinal reinforcement of the beam passing through the column. This method shows us how much shear force the beam reinforcement can take, but not what the magnitude of the resulting forces actually is as a result of the acting loads. In addition, the method of the codes does not indicate the contribution of the concrete to the total magnitude of the shear force in the beam–column connection. In the proposed mathematical model for calculating the forces that leave the beam, the full dimensions of the cross-section of the beam were taken into account. The material properties and cross-sectional shape were also taken into account. A determining factor for the magnitude of forces entering the beam–column joint is the acting load on the beam. In this paper, the load of two transverse forces was considered. The forces are applied in different possible positions, while remaining symmetrically located on the beam. The calculations are based on Menabrea’s theorem to determine the hyperstatic unknowns. The results of the proposed method for the considered beam show that the magnitude of the shear force differs from that accepted in the literature and the norms by 2% to 27%, depending on the stage of development of the crack. In comparison, the Eurocode-recommended method shows differences in the order of 27% to 40% for the adopted beam under static loads.

Electromechanical properties and piezoelectric potentials of one-dimensional GaN nanostructures: A bond relaxation investigation

From the viewpoint of atomic bond relaxation, an analytical approach was put forward to elucidate the physical origins of crystal size and cross-sectional shape dependency of piezoelectric potentials in GaN nanowires and nanotubes. It is demonstrated that (i) size-induced increase in piezoelectric potential is attributed to the coupling effect of the rising piezoelectric coefficient and both the reducing dielectric constant and elastic constant caused by the surface atomic coordination number loss, bond energy perturbation, and surface-to-volume ratio rising; (ii) as the number of sides for polygonal nanowires or nanotubes with the same equivalent radius decreases, the surface-to-volume ratio rises, and the piezoelectric potential increases; and (iii) the nanotubes can generate a piezoelectric potential higher than their nanowire counterparts due to their larger surface-to-volume ratios. The proposed formulation offers a scientific basis for the fabrication, optimization, and modulation of one-dimensional GaN-based piezoelectric nanometer devices.

Comparative analysis of the influence of different shapes of shaft sections on dust transportation

Large amounts of dust are generated during digging operations in underground mines, and the transportation of dust is affected by the shape of the roadway section. In order to know the dust transportation law of different cross-section shapes when digging. Fluent software was used to simulate the distribution of wind flow field, dust transportation trajectory, and dust quality concentration in roadways with semicircular arch, three-centered arch, rectangle and trapezium, and then analyze and compare the influence of four cross-section shapes on dust transportation, and use gray correlation analysis to investigate the correlation between the time needed to reduce the dust quality concentration of the roadway to the safe value and the ventilation air volume and air supply distance. The results of the study show that the wind speed in the roadway is in the following order from high to low: rectangle &amp;gt; trapezium &amp;gt; three-centered arch &amp;gt; semicircular arch. Dust particles of each size rubbed each other after blasting, and there were fewer dust particles with larger sizes in the three-centered arch roadway. Both the air supply distance and ventilation air volume impact the dust removal effect; when the air supply distances are 5 m and 10 m, the three-centered arch has a better dust removal effect; when the air supply distances are 15 m and 20 m, the effect is better in the rectangular roadway and trapezoidal roadway; and when the ventilation air volume is increased, it is the three-centered arch. Through the gray correlation analysis, it can be seen that in order to improve the construction environment in the roadway after blasting, the rectangular section can be chosen when considering the air supply distance, and the three-centered arch can be chosen when considering the ventilation air volume.

A Review of the Properties of Different Concrete-Filled Steel Tube Columns

This paper mainly analyzes different types of concrete-filled steel tube columns to compare different parameters such as loading angle, eccentricity, different steel pipe thickness, different strength grades of concrete, different cross-sectional shapes, etc., and elaborates the changes of mechanical properties of the specimens under the influence of different parameters. The formulas of axial compression and flexural bearing capacity of different concrete-filled steel tube columns and the bearing capacity of concrete-filled steel filled steel tubes after fire were proposed, and the interaction of various materials in the components was studied in depth. The proposed studies are summarized.