Cross-sectional Shape Research Articles

Improving the local and distortional resistance of CFS trapezoidal self-supporting roof members

This paper reports the development, numerical implementation and application of a methodology to perform the multi-objective optimisation, with respect to local and distortional failures, of cold-formed steel (CFS) trapezoidal cross-section shapes used in members belonging to self-supporting roof systems and manufactured by bending the steel sheets with roll-forming machines. Initially, a brute-force approach is adopted to search for optimal unstiffened cross-section shapes of members subjected to positive (sagging) and negative (hogging) bending moments. Next, an optimisation procedure based on a Genetic Algorithm (GA) is employed to find stiffened cross-sections that (i) outperform the original (plain/unstiffened) ones, as far as the resistance against local and distortional failures is concerned, and (ii) can be fabricated with minimal additional cost, through the sole addition of small intermediate stiffeners, whose possible locations are pre-defined in accordance with a map of executable fold-line positions – the original cross-section typology, overall dimensions and wall angles are retained. The design approach adopted to estimate the member ultimate strengths is based on the Direct Strength Method (DSM), and Generalised Beam Theory (GBT) is used to calculate the elastic buckling stresses due to bending. The application and capabilities of the proposed methodology are illustrated, by means of numerical results presented in terms of cross-section families belonging to optimal Pareto Fronts – an excellent performance of the procedure was found in all cases.

Damped kink motions in a system of two solar coronal tubes with elliptic cross sections

Aims. This study is motivated by observations of coordinated transverse displacements in neighboring solar active region loops, addressing specifically how the behavior of kink motions in straight two-tube equilibria is impacted by tube interactions and tube cross-sectional shapes. Methods. We worked with linear, ideal, pressureless magnetohydrodynamics. Axially standing kink motions were examined as an initial value problem for transversely structured equilibria involving two identical, field-aligned, density-enhanced tubes with elliptic cross sections (elliptic tubes). Continuously nonuniform layers were implemented around both tube boundaries. We numerically followed the system response to external velocity drivers, largely focusing on the quasi-mode stage of internal flows to derive the pertinent periods and damping times. Results. The periods and damping times that we derive for two-circular-tube setups justify the available modal results found with the T-matrix approach. Regardless of cross-sectional shapes, our nonuniform layers feature the development of small-scale shears and energy accumulation around Alfvén resonances, indicative of resonant absorption and phase mixing. As with two-circular-tube systems, our configurational symmetries still make it possible to classify lower-order kink motions by the polarization and symmetric properties of the internal flows; hence, such motions are labeled as S​x and Ax. However, the periods and damping times for two-elliptic-tube setups further depend on cross-sectional aspect ratios, with Ax motions occasionally damped less rapidly than S​x motions. We find uncertainties up to ∼20% (∼50%) for the axial Alfvén time (the inhomogeneity lengthscale) if the periods (damping times) computed for two-elliptic-tube setups are seismologically inverted with canonical theories for isolated circular tubes. Conclusions. The effects of loop interactions and cross-sectional shapes need to be considered when the periods, and in particular the damping times, are seismologically exploited for coordinated transverse displacements in adjacent coronal loops.

A data-driven procedure for one-dimensional dynamic analysis of thin-walled beams with arbitrary cross-sections

This paper develops a one-dimensional dynamic model for thin-walled beams with arbitrary complex cross-sections in a data-driven way. In order to consider complicated deformations in the framework of a beam theory, a universal node system is first created to fit the deformed shape of a thin-walled cross-section, whether prismatic or curved, with or without symmetry. This helps to reduce the three-dimensional displacement field of the thin-walled beam to one dimension, and results in a preliminary higher-order beam model with limited precision loss. For the purpose of largely condense DOFs of the new model, a data-driven approach is proposed to identify cross-section deformation modes through the principal component analysis of free vibration deformation data of an unconstrained thin-walled beam. As a result, a compact set of core deformation modes are obtained and selected to update the preliminary model, leading to the refined higher-order beam model of high accuracy and efficiency. Examples are presented to illustrate the concrete implementation and check the effects of data-related controlling parameters of the proposed procedure. We also verify through numerical examples that the proposed model agrees well with plate/shell and other beam theories, and has remarkable advantages in physical interpretation, modeling simplicity and computation efficiency.

Deciphering morphology patterns of environmental microfibers: Insights into source apportionment

Microfibers, a prevalent form of microplastics, undergo diverse environmental interactions resulting in varied morphological changes. These changes can offer insights into their environmental trajectories. Despite its importance, comprehensive studies on microfiber morphology are scarce. This study collected 233 microfibers from the East China Sea and South China Sea. Based on morphological features observed in microscopic images of microfibers, such as curvature, cross-sectional shapes, diameter variations, and crack shapes, we identified a general morphological pattern, classifying the environmental microfibers into three distinct morphological types. Our findings highlight noticeable differences in morphological metrics (e.g., length, diameter, and surface roughness) across three types, especially the diameter. Microfibers of Type I had an average diameter of 19.45 ± 4.93 μm, significantly smaller than Type II (263.00 ± 75.15 μm) and Type III (299.68 ± 85.62 μm). Within the three-dimensional (3D) space fully defined by these quantitative parameters, the clustering results of microfibers are also consistent with the proposed morphology pattern, with each category showing a potential correlation with specific chemical compositions. Type I microfibers correspond to synthetic cellulose, while 94.79 % of Types II and III are composed of polymers. Notably, we also validated the great applicability of the morphology categories to microfibers in diverse environmental compartments, including water and sediments in nearshore and offshore areas. This classification aids in the efficient determination of microfiber sources and the assessment of their ecological risks, marking a significant advancement in microfiber environmental studies.

Effect of Plate Thickness of Stainless Steel Core Plate Wall on Load Carrying Capacity under Pure Shear and Compression Shear Conditions

The shear walls have been employed as a lateral force opposing systems in numerous multistory buildings. The Stainless- Steel Core Plate Wall (SSCPW) is a recent and innovative addition to structural elements. The adoption of stainless steel over traditional steel has been driven by its advantageous properties, such as its lightweight nature, durability, and resistance to corrosion. The SSCPW comprises stainless-steel plates interconnected with orthogonally positioned stainless steel core tubes through welding. Depending on the specific orientations chosen, SSCPW can function as beams, columns, walls, floors and other essential structural components. Different cross-sectional shapes of SSCPWs are available, and this study focused on L- and T-shaped SSCPWs subjected to pure shear and compression shear conditions. The analysis and investigation of the impact of plate thickness on load-carrying capacities was conducted using ANSYS Workbench software. It was observed load-carrying capacity of SSCPW increases as the plate thickness increases. Plate thicknesses of 8, 12, 16 and 20 mm were chosen for modelling. Results show that SSCPW of plate thickness 20 mm has the maximum load-carrying capacity.

Estimation of pipe wall thickness variation during bending rolling

Abstract. The presented work examines the process of bending pipes using the cold rolling method. The main pa-rameters of bending that affect the change in wall thickness during the deformation process are analyzed. The influence of changing the shape of the cross-sectional shape, the increase in the pipe diameter, and the displacement of the neutral layer of bending, is identified. Theoretical values of thickening and thinning of the pipe wall are presented depending on the bending parameters. The authors provide theoretical and experimental data to assess the wall thickness variation. Data on the wall thickness of a bent pipe fitting with a diameter of 57 mm were obtained using two methods. The first method involves indirect measurements using an ultrasonic thickness gauge, while the second method involves direct measurements using a micrometer. A comparative analysis showed that the actual measurements of the wall thickness of the bent pipe fitting align with the theoretical values. Due to methodological discrepancies in the thickness measurements, it is recommended to use direct physical measurements to obtain more accurate results

Parameterization of Maxwell - Cremona Diagram for Determining Forces in Elements of a Scissors Truss

An analysis of changing patterns of the values of member forces in a scissors truss, depending on the position of connections of its lower chords to the upper chords, is performed. Exploring effective truss structure designs in terms of balanced combination of maximum strength and minimum weight is a sustainable approach to a more rational use of building materials and the development of green construction. This determines the relevance of this area of research. The analysis of configurations of the truss under study was performed using the parameterized Maxwell - Cremona diagram. Such diagram is a visually informative tool in presenting the calculation results and it fully reflects the relationship between the member forces and the parameters of the structure. The research process was performed using the MS Excel spreadsheet editor. This eventually developed into a software tool for finding effective scissors truss designs, which has full potential for further improvement and development. Thus, the functionality of the tool can be easily expanded to designing scissors trusses made of various structural materials, as well as with various crosssectional shapes of its elements. The proposed approach to the calculation of such structures can serve as a basis for parameterization of trusses with other types of web.

Numerical analysis of thermal-hydraulic comprehensive performance of composite corrugated tubes with different cross-section shapes

Composite corrugation is a structure transformed from traditional corrugation to improve the thermal-hydraulic comprehensive performance (THCP) of corrugated tubes. However, compared to simple corrugations, the mechanism by which composite corrugations enhance THCP is still unclear. Therefore, in this work, numerical simulations are performed within the Reynolds number (Re) range of 5000–20,000 to evaluate the mechanism of composite corrugation strengthening THCP. The distributions of flow velocity, streamline, turbulent kinetic energy (TKE), pressure, and normalized force are used to reveal the differences in the effects of simple and composite corrugations on THCP. In addition, the influence of composite corrugation cross-sections and distribution forms on THCP has been explored in detail. The results indicate that increasing the impingement of the fluid on the tube wall, disrupting the fluid boundary layer, and expanding the range of secondary flow are the main mechanisms by which composite corrugations further strengthen THCP compared to simple corrugations (CT-SC). The THCP of composite corrugation (CT-CC-A-F) can be increased by 31.5% at Re = 20,000 compared to CT-SC. Composite corrugations with different cross-sections cause differences in THCP due to their varying effects on the distribution of secondary flow and the impingement of the fluid on the tube wall. The difference in the influence of composite corrugation distribution forms on THCP is still caused by the difference in the impingement of the fluid on the tube wall. This work can provide a reference for the design of composite corrugations to achieve better THCP.

Investigation of forming process and deformation mechanisms of 3D warp interlock fabric

This article introduces a modeling method aimed at predicting the internal geometric structure of 3D warp interlock fabric. Inspired by the digital element method, the method employs truss elements to model the yarns as fiber bundles, and considers their material properties. This technique allows for predicting the microstructure of 3D woven fabric based on simple input characteristics. By varying the elastic modulus of virtual fibers, the friction coefficient between fibers, and the tension load at the ends of yarns, and designing compression molding molds to compress the fabric into shape, the virtual fiber fabric predicted the influence of variables on the fabric. The study found that the structure of the samples obtained through CT scanning is generally consistent with the structure of the virtual fiber fabric. The elastic modulus has a relatively minor impact on the fabric structure, whereas the friction coefficient and tension load significantly affect the cross-sectional shape of the yarns. During compression molding, deformation within the mold leads to interlayer fabric slippage and changes in the cross-sectional shape of the fabric. This suggests the feasibility and applicability of virtual simulation testing methods for analyzing the behavior of various types of 3D woven fabrics.

Study on ultimate capacity and design method of cold-formed steel equal lipped angle components under axial compression

This study focuses on evaluating the load-bearing capacity of cold-formed steel (CFS) equal lipped angle components. It delves into the structural behavior and design methods, taking into account various edge conditions and buckling modes. By considering the key parameters, which are component length, component thickness, total lip length, and lip bending angle, a total of 555 numerical models are developed for a systematic analysis on the components with two types of cross-sectional shapes. Since the coefficients within the direct strength method (DSM) inadequately capture the ultimate load-bearing capacity of lipped angle components, we introduce a design methodology rooted in the DSM framework to address global and global-local coupling buckling modes while imposing constraints to prevent local-distortion coupling buckling modes. The machine learning models (XGBoost, BPNN, and 1D-CNN) are adopted to predict the structural behavior of the two types of lipped angle components. These models can integrate the analysis of the components with two types of cross-section shapes in predictions of ultimate load capacity, axial deformation, and buckling modes. Meanwhile, the prediction accuracy of the machine learning models surpasses that of the analytical design methodology, offering more accurate prediction for ultimate load capacity, axial deformation and buckling modes.

Visualized study and performance evaluation on a micro-grooved vapor chamber

The evaporation resistance and capillary flow both dominates the heat transfer performance of aluminum vapor chamber (VC) with micro-grooved wicks (MGW). This study presents the visualization experiments for three MGW VC samples with different cross-sectional shapes, including semicircular (MGW-S), V-shaped (MGW-V) and trapezoidal (MGW-T). The characterization of capillary rise dynamics is evaluated and compared by depicting the transient liquid front in vertical installation while the thermal spreading capability is examined horizontally at the quasi-steady state. Results show that the MGW-T exhibits the highest capillary pressure, and higher capillary rise rate can be obtained when applying acetone as working medium. As the groove shape impacting on the rate of bubble generation and detachment during evaporation process, the MGW-S obtains the lowest average thermal resistance. However, compared to the uniformly generated bubbles of acetone, it is revealed that ethanol might result in the slug or puddle at the evaporation area, which shortens the flow length of vapor and increases the average thermal resistance. When conducting under incremental heat loads, the boiling phenomenon of the working liquid becomes increasingly turbulent, and the average thermal resistance can be minimized from 2.6 K/W to the level lower than 1 K/W. As the result, when using acetone with filling ratio of 30%, the average thermal resistance of the MGW-T reaches 0.92 K/W under heat load of 60 W.

Design, Manufacturing, and Analysis of Periodic Three-Dimensional Cellular Materials for Energy Absorption Applications: A Critical Review.

Cellular materials offer industries the ability to close gaps in the material selection design space with properties not otherwise achievable by bulk, monolithic counterparts. Their superior specific strength, stiffness, and energy absorption, as well as their multi-functionality, makes them desirable for a wide range of applications. The objective of this paper is to compile and present a review of the open literature focusing on the energy absorption of periodic three-dimensional cellular materials. The review begins with the methodical cataloging of qualitative and quantitative elements from 100 papers in the available literature and then provides readers with a thorough overview of the state of this research field, discussing areas such as parent material(s), manufacturing methods, cell topologies, cross-section shapes for truss topologies, analysis methods, loading types, and test strain rates. Based on these collected data, areas of great and limited research are identified and future avenues of interest are suggested for the continued maturation and growth of this field, such as the development of a consistent naming and classification system for topologies; the creation of test standards considering additive manufacturing processes; further investigation of non-uniform and non-cylindrical struts on the performance of truss lattices; and further investigation into the performance of lattice materials under the impact of non-flat surfaces and projectiles. Finally, the numerical energy absorption (by mass and by volume) data of 76 papers are presented across multiple property selection charts, highlighting various materials, manufacturing methods, and topology groups. While there are noticeable differences at certain densities, the graphs show that the categorical differences within those groups have large overlap in terms of energy absorption performance and can be referenced to identify areas for further investigation and to help in the preliminary design process by researchers and industry professionals alike.

The use of a swept frequency alternating current potential difference method for identifying local geometric features within prismatic conductors

Potential difference methods are widely accepted as means to detect and monitor cracks in safety critical components. This paper investigates the capability of the potential difference method that uses a swept frequency alternating current excitation (i.e. skin effect with varying current penetration depths) in identifying conductor shapes and features through experiments and finite element analysis. The study focused on samples with the size of 55 mm × 100 mm2 and surface features with opening widths vary from 11% to 42% to the sample size. The method has been investigated by finite element analysis with the capability to distinguish cross-sectional shapes of non-magnetic conductors due to prominent current crowding on surfaces, in which the potential differences measured from a SS316 conductor of triangular cross-sectional shape are higher to those of a circular shape by 77% at 300 kHz. The detection capability of the method has also be confirmed, which is attributed to the impact of feature openings on skin effect. At 50 kHz, potential differences measured across features with the same cross-sectional area of 9 mm2 on EN1A samples rise by 130% as the opening width increase from 11% to 42% to the sample size.

Tunable viscoelastic size-based particle separation in straight microchannels with triangular cross-sections

In recent years, viscoelastic particle manipulation within microfluidic systems has received much attention due to the ease with which micron-sized objects may be maneuvered and isolated on the basis of size. While several factors, including both fluid and particle properties, regulate the precise locations and trajectories of micron-sized species flowing along a microchannel, the role of channel cross-section shape is critical, since it directly influences the fluid velocity profile and thus the direction and magnitude of hydrodynamic forces. It is therefore surprising that this parameter has not been comprehensively investigated for cell-based separations, especially since most viscoelastic microfluidic systems are only able to efficiently sperate cells over limited size ranges. To address this shortcoming, we present a viscoelastic microfluidic system integrating a triangular cross-section microchannel, for efficient and tunable size-based separations of micron-sized species. We find that particle focusing patterns can be controlled by simple variation of volumetric flow rates, which allows for the efficient separation of particles and cells of variable size. To showcase the efficacy of the approach, we present a size-based separation of various blood components, including white blood cells, platelets, and rare cells. By quantifying the number of particles collected at the outlets, we achieve recovery efficiencies of over 98%.

Photonuclear experiments: from the bremsstrahlung to the Compton backward scattering photons

The features of the methods for obtaining the information on photonuclear reaction cross sections using the beams of bremsstrahlung and quasimonoenergetic photons from the annihilation in flight of relativistic positrons with which such the absolute majority of such kind data was obtained in the nucleus excitation energy up to ∼40 MeV are discussed. It was shown that significant disagreements between the results of such experiments in cross sections absolute values and shapes are due to both methods definite shortcomings which to a certain extent can be overcome by using the beams of the photons from the processes of Compton backward scattering.

Effects of fuselage shape on helicopter aerodynamic performance in case of intermeshing-rotor interference

To study the influence of fuselage shape on the aerodynamic performance of a helicopter under the interference of an intermeshing-rotor, a numerical simulation method of flow field under the forward flight state of Synchropter is established based on the lattice Boltzmann method. Firstly, the Maryland helicopter was calculated to verify the scientific validity of the method. Then, the simplified S-97 fuselage was used as the object of analysis to analyze the aerodynamic data such as surface pressure, friction, and lift resistance of the fuselage with different head curvature, cross-section shapes, and transition segments under Synchropter interference with different attack angles in forward flight. The results show that increasing the radius of curvature of the nose can reduce the total drag of the fuselage; the fuselage with a circular cross-section shape has better aerodynamic characteristics of lift resistance, and the fuselage with rhombic cross-section shape has better transverse stability; the transition section with backward position, smaller upward dihedral angle, and smooth transition can avoid serious airflow separation and achieve the purpose of drag reduction.

The effect of elastic and plastic stresses on the electrical resistivity of conductive materials

The mobility sector has been responsible for large emissions of harmful greenhouse gases worldwide for years. E-mobility can contribute to a reduction of these emissions. For a faster spread and acceptance of electric vehicles, the achievable range and thus the efficiency of the individual components in the drive and charging train is essential. In addition to the battery and the electric machine, losses in the cables and bus bars are playing an increasingly important role. The cross-sectional shape, material and manufacturing technology of these conductive materials depends on the voltage and power to be transmitted and may still change in the future, especially in the field of fast charging and increased voltage.The aim of this work is to investigate the influence of the mechanical stress condition of copper, brass and aluminium materials on their electrical conductivity. The conductivity is measured by means of 4-wire measurements under defined tensile and compressive loads. The effects of elastic and plastic strains are taken into account. The findings can be used for an optimized manufacturing strategy for conductive components for future applications.

Identification of the effective crane hook's cross-section by incorporating finite element method and programming language

The crane hook is a widely utilized component in several industries for the purpose of lifting things. The crane hook must possess the capacity to withstand the intended load without encountering any complications, hence ensuring the safety of both personnel and the objects being lifted. The process of analysis is crucial for the effective utilization of a crane hook. The primary aim of this study was to determine the most efficient cross-sectional crane hook among five distinct geometric profiles. This was achieved through the application of finite element analysis using Solidworks software. Subsequently, the identified cross-sectional profile was further examined using the Python programming language, taking into account the classical equation of a curved beam. The five cross-sectional shapes seen in the study were circular, rectangular, trapezoidal, I-shaped, and T-shaped. For the purposes of this investigation, the chosen material for each cross-sectional crane hook model was 34CrMo4 steel. Despite the identical boundary constraints imposed on all the chosen cross-sectional crane hook profiles, it was observed that the trapezoidal cross-sectional crane hook exhibited superior performance compared to the others. The trapezoidal cross-sectional crane hook model exhibited a Von Mises stress of 203 MPa, with a corresponding factor of safety of 3.20. Further experimentation was conducted using Python to examine the trapezoidal profile. The results indicated that an increased level of parallelism in the inner side of the trapezoidal shape corresponded to a higher factor of safety. Hence, it is advisable to maintain the trapezoidal cross-sectional profile of the crane hook, with due consideration given to maximizing the length of the inner parallel side. The enhancement of design leads to a decrease in the likelihood of failure and the occurrence of undesirable accidents.

Effect of Taper and Pitch on Nickle-Titanium File with Variable Cross Section to Its Cyclic Fatigue (In Silico Study)

The geometric design of an endodontic file includes cross-sectional shape, taper, and pitch. NiTi endodontic files of OneCurve (MicroMega) are made of two variations of cross-sectional shape, that is, double-s shaped and triple helix. Various kinds of modifications were made to increase the resistance of the NiTi endodontic files from fracture. Cyclic fatigue is the most common factor that causes a fracture of the endodontic file. Objective: The purpose of this study was to obtain a NiTi endodontic file design that has the best cyclic resistance value based on its taper size and number of pitch. Methods: This study used OneCurve endodontic file size 25.06, then scanned with MicroCT Scan and modified the geometric design. The number of file modifications was nine. Taper size modifications were 4%, 6%, and 8%; the number of pitch modifications was reduced by three, fixed, and added by three. Cyclic fatigue measurement simulations were carried out using the finite element method three times each. The result data were analyzed using a two-way ANOVA test and then continued with LSD. Results: The results of the statistical test showed that there was an effect of the size of the taper on the cyclic fatigue values. Endodontic files with a size of a taper 4% had the lowest cyclic fatigue value. Conclusion: The conclusion of this research was that the taper size affects the value of cyclic fatigue in continuous endodontic files made of nickel-titanium with variable cross sections. The number of pitch did not show a significant effect on the cyclic value.

COMPARASION PLASTIC BEHAVIOR OF BOX GRIDER BRIDGE WITH MULTIPLE BOX AND CELLULAR BOX CROSS SECTIONS

This study compares plastic deformation behavior in box girder bridges with multiple boxes and cellular box cross-sections. The cross-section's shape significantly influences the girder's post-yield behavior despite being designed to have the exact yield moment. Steel's stress-strain relationship undergoes linear behavior until the yield stress is reached, followed by strain hardening. This study aims to assess the impact of strain hardening on the plastic behavior of girder box bridges.Two types of box girder sections, multiple box and cellular box, are designed with equivalent yield moments. The analysis is conducted with and without strain hardening calculations to evaluate plastic moment, inelastic area length, shape factor, and moment-curvature relationship. The design and analysis follow RSNI T-03-2005 standards using SAP 2000 v.15.Results indicate that multiple box sections exhibit more prominent plastic moments and inelastic area lengths than cellular box sections. Strain hardening calculations show significant increases in plastic moments for both section types. Graphical comparisons highlight the differences in moment-curvature relationships between models with and without strain hardening. Understanding the impact of strain hardening on plastic behavior provides valuable insights for designing and assessing box girder bridges, ensuring structural safety and performance under load conditions.