Irregular Cross-section Research Articles

Combination of LiDAR Detection and Green Integral Method for Calculating Irregular Cross-Section Geometric Properties of Deteriorated Components in Timber Historic Buildings

Timber components in historic buildings are susceptible to deterioration due to the complex external environment. The loss of material in these components and changes in their cross-section geometry significantly impact the stability and load-bearing capacity of historic buildings. A portable LiDAR device is utilized to acquire the cross-section geometry of the deteriorated components. The irregular cross-section profiles are extracted using point cloud slicing and the Alpha-Shape algorithm. Geometric characteristics such as cross-section area, moment of inertia, and moment of resistance are calculated using Green's integral method. The performance of this method is evaluated by measuring eight groups of deteriorated components with different cross-section characteristics and comparing it with five traditional methods.The results demonstrate that the proposed method improves the calculation accuracy by 1% to 21% relative to traditional methods, thereby enhancing reliability by 9% to 54%. Additionally, it reduces manual calculation workload and human error, while promoting calculation efficiency. The method exhibits excellent applicability and high efficiency, with an error below 3% when compared to the true value. This method proves valuable in evaluating the extent of deterioration in historic timber components and provides essential data for preventive conservation and restoration of historic timber buildings.

Evaluating possible glacial modification in the Martian tropics near Gale crater using a new U-shaped valley metric

Growing evidence supports the case for glacial processes within the equatorial regions of Mars. However, few examples of modeling or numerical analysis exist to support this hypothesis. Here we apply an automated method on valleys near Gale crater to extract morphometric data and analyze formative processes responsible for their current expression. The V-index utilized is a new robust method that is an alternative to traditional valley parabolic curve fits. This approach more easily characterizes irregular valley cross sections and thus aids in distinguishing between glacial and nonglacial forms. We applied this method along with standard power law and quadratic curve fits on valley cross sections along a 2300 km extent of the Martian tropics near Gale crater. Both V-index and power law b fit values suggest that the majority of the valleys are U-shaped and possibly created through glacial erosive processes. Further, V-index and power law b values plotted against elevation show a positive trend with higher V-index (glaciated) values associated with higher elevation. This suggests that an equilibrium-line altitude (ELA) may have existed at the time of valley formation. The timing of the formation of these U-shaped valleys is poorly defined. However, our initial crater statistics conducted within the study area suggest a young ∼1.05 (±0.25) Ga relative ages of the valley floors. Equatorial glaciers that produced these and other related glacial forms may be as old as the Hesperian to Amazonian transition (∼3 Ga) but more intriguingly may be associated with Amazonian equatorward migration of the Martian cryosphere during more recent periods of high obliquity oscillations.

Exploring eco-friendly pseudo stem fiber from the agricultural byproducts of the Alpinia purpurata plant

This study explored the potential of Alpinia purpurata pseudostems, an agricultural waste product, as a sustainable and eco-friendly source of natural fibers for the textile industry. The aim was to characterize the properties of natural cellulose fibers from the pseudostems of the Alpinia purpurata plant. The research employed water retting to extract the fibers, and the intrinsic fiber properties obtained were evaluated for their suitability in textile applications. The average length of an Alpinia purpurata fiber was 67.80 cm with a fineness value of 7.61 Tex. A bundle of Alpinia purpurata fibers was comprised of many elementary fibers. Alpinia purpurata had an irregular cross-section, with the lumen having a varied oval shape. The fibers exhibited tenacity and elongation values of 2.49 g/denier and 5.72 %, respectively, and a coefficient of friction value of 0.49. Additionally, Alpinia purpurata fibers were hygroscopic, with a moisture regain value of 11.97 %. The findings revealed that the fibers possessed notable tensile strength, moderate elongation, and high moisture regain, making them suitable for non-apparel textile products requiring durability and moisture management. While not the strongest among natural fibers, their sufficient strength and other advantageous properties demonstrated their viability for various applications. This work addressed a significant gap in the literature on the utilization of agricultural by-products, proposing Alpinia purpurata pseudostems as a sustainable alternative that aligned with environmentally responsible manufacturing practices and supported the circular economy. Future research was recommended to optimize processing techniques and explore broader applications.

Choosing the Design of a Radial-Shear Rolling Mill for Obtaining a Screw Profile

The purpose of this work is a comparative analysis of the workpiece shape, and parameters of the stress-strain state during deformation on two radial-shear rolling mills with different roll configurations to determine the most suitable scheme for obtaining a screw reinforcement profile. During the FEM simulation of the radial-shear rolling process in the DEFORM program, a comparison of the workpiece shape change after rolling, equivalent strain, damage index, and Lode–Nadai index was carried out. Steel 10 (analogue of AISI 1010) was chosen as material workpiece. The analysis of the obtained data revealed that the most rational choice for the implementation of the reinforcement profile production process is the radial-shear rolling mill RSR 10-30. Subsequent modeling of the combined process of radial-shear rolling and twisting in a screw matrix showed that when using rolls of RSR 10-30 mill, the screw profile of the workpiece is formed successfully, whereas using rolls of the SVP-08 mill, the formation of a screw profile is impossible due to jamming due to an irregular cross-section shape. A laboratory experiment confirmed the possibility of forming a screw reinforcement profile at RSR 10-30 mill, and an assessment of the geometric parameters of the final workpiece showed full compliance with the dimensions of the profiles obtained during modeling and experiment.

Tumor contour irregularity on preoperative CT predicts prognosis in renal cell carcinoma: a multi-institutional study

Radiology-based prognostic biomarkers play a crucial role in patient counseling, enhancing surveillance, and designing clinical trials effectively. This study aims to assess the predictive significance of preoperative CT-based tumor contour irregularity in determining clinical outcomes among patients with renal cell carcinoma (RCC). We conducted a retrospective multi-institutional review involving 2218 patients pathologically diagnosed with RCC. The training and internal validation sets included patients at Zhongshan Hospital between January 2009 and August 2019. The external test set comprised patients from the First Affiliated Hospital, Zhejiang University School of Medicine (January 2016 to January 2018), the Xiamen Branch of Zhongshan Hospital (November 2017 to June 2023), and the Cancer Imaging Archive. The contour irregularity degree (CID), quantified as the ratio of irregular cross-sections to the total tumor cross-sections, was analyzed for its prognostic relevance across different subgroups of RCC patients. A novel CID-based scoring system was developed, and its predictive efficacy was evaluated and compared with existing prognostic models. The CID exhibited significant discriminatory power in predicting overall survival (OS), recurrence-free survival (RFS), and disease-specific survival (DSS) among patients with RCC tumors measuring 3cm or larger (all p<0.001). Multivariate analyses confirmed the CID as an independent prognostic indicator. Notably, the CID augmented prognostic stratification among RCC patients within distinct risk subgroups delineated by SSIGN models and ISUP grades. The CID-based nomogram (C-Model) demonstrated robust predictive performance, with C-index values of 0.88 (95%CI: 0.84-0.92) in the training set, 0.92 (95%CI: 0.88-0.98) in the internal validation set, and 0.86 (95%CI: 0.81-0.90) in the external test set, surpassing existing prognostic models. Routine imaging-based assessment of the CID serves as an independent prognostic factor, offering incremental prognostic value to existing models in RCC patients with tumors measuring 3cm or larger. This study was funded by grants from National Natural Science Foundation of China; Shanghai Municipal Health Commission; China National Key R&D Program and Science and Technology Commission of Shanghai Municipality.

Elucidating the mechanism of overcuring in microchannels fabricated via vat photopolymerization (VPP) for precise microfluidic chip printing

Vat Photopolymerization (VPP) technology is highly regarded for precision micromachining applications like microfluidic chip fabrication, owing to its fine resolution, adaptability, and rapid prototyping capabilities. However, the challenge of resin over-curing resulting from UV energy penetration poses a significant obstacle in microchannel printing. This study addresses this challenge by investigating the intricate relationship between resin properties and over-curing. Diverse microfluidic chips were printed utilizing VPP technology, and the overall cross-sectional over-curing characteristics of the channels were systematically examined. A novel combination of the classical UV light curing model and computational Fluid-Structure Interaction (FSI) model with the VPP printing process was proposed to examine the complex hydrodynamics and exfoliation dynamics within VPP-printed microchannels. The simulation results suggest that resins with higher viscosities and surface roughness are better suited for microchannel printing. Subsequent experiments using five different resins verified these findings and showed that the microchannels obtained with resins of lower viscosity and surface roughness resins have an irregular trapezoidal cross-section, which is uncontrollable and unpredictable and seriously affects the microchannel printing accuracy. Conversely, resins with higher viscosity and surface roughness have an ideal rectangular cross-section, which can be compensated by the model further refined printing to print microchannel. Finally, microfluidic chips were printed using "high precision 8 K resin" and "8 K-clay resin" with higher viscosity and surface roughness. The results proved that the microchannels printed by these resins had the desired rectangular cross-section, which was consistent with the "DLP light-curing" model. This study elucidates, for the first time, the intricate interplay between resin properties, printing structure, and microchannel over-curing, and this provides a solid groundwork for advancing high-precision microfluidic chip fabrication via DLP printing.

Numerical study on ultrasonic detection of cracks in metallic structures with variable cross-sectional thickness

The metal structures are widely used in aerospace engineering, especially in joints and spars. The safety of these parts is important to ensure the safe service of the whole structures. The ultrasonic wave is a traditional technique to detect cracks in metals. However, it is usually difficult to find all the cracks because of its difficulty in variable directions of the crack and the irregular shapes of the metals. This paper aims to address the challenge of detecting cracks in metallic structures with varying cross-sectional thicknesses using ultrasonic methods. The research investigates the behavior of ultrasonic longitudinal and transverse waves as they propagate through aluminum plates with variable cross sections. Additionally, it examines how cracks in different orientations influence these wave types. The theoretical analyses are performed which explore the reflection of oblique incidence waves and the diffraction of ultrasonic waves when they encounter semi-infinite cracks. Subsequently, numerical simulations are performed to validate the theoretical findings and to detect both horizontal and vertical cracks within metal plates of varying cross-sectional thicknesses. The findings indicate that both longitudinal and transverse waves are effective in identifying the location of damage caused by horizontal cracks. However, when it comes to vertical cracks, only transverse waves are successful in detecting their precise location. From the research of this paper, transverse ultrasonic wave is suggested to detect cracks in metal structures with irregular cross sections.

Cyclic behaviour of circular CFT-SG columns under axial tension-compression: Novel FE modelling and design methods

The ultra-high concrete-filled steel tubular (CFT) power transmission tower is popularly applied in engineering practice, which may be under a typical cyclic axial tension-compression loading condition due to the dynamic wind load. Nonetheless, the CFT columns of the tower may be accompanied by significant gap defects due to the influence of structural feature, material property, and service environment. Hence, to figure out the performance of circular CFT columns with spherical-cap gaps (CFT-SG) subjected to cyclic axial tension-compression, this paper investigates a constitutive relationship for the gapped core concrete, which is verified by several existing experiments. A novel numerical modelling approach for simulating the irregular cross-section of the circular CFT-SG columns under cyclic axial load was following established based on the triangulation method and code programming. The influence of important parameters such as gap ratio, material strength, and diameter to thickness ratio on the hysteresis characteristics, load-bearing capacity, elastic stiffness, energy dissipation and ductility of circular CFT-SG columns under cyclic axial tension-compression force is studied. Moreover, the restoring force model of the circular CFT-SG columns under cyclic axial tension-compression is finally presented. Research results declare that the compressive bearing capacity, stiffness, ductility, and energy dissipation of circular CFT-SG columns under cyclic axial tension-compression are gradually weakened with the increment in the gap ratio. The numerical modelling approach and restoring force model proposed in this article can accurately evaluate the hysteresis performance of circular CFT-SG columns subjected to cyclic axial tension-compression.

Tumor margin irregularity degree is an important preoperative predictor of adverse pathology for clinical T1/2 renal cell carcinoma and the construction of predictive model.

To explore the critical role of the tumor margin irregularity degree (TMID) of renal tumors in predicting adverse pathology of patients with clinical T1/2 (cT1/2) renal cell carcinoma (RCC). A total of 821 patients with cT1/2 RCC undergoing nephrectomy in the Second Hospital of Tianjin Medical University between January 2017 and December 2020 were reviewed. The tumor margin irregularity (TMI) was classified into renal mass with locally raised protrusion and smooth margin called 'lobular', sharply and unsmooth nodular margin called 'spiculation', blurred margins between tumor and renal parenchyma or a completely irregular and non-elliptical shape. The ratio between the number of irregular cross-sections (X) and the number of total cross-sections from top to bottom occupied (Y) was defined as TMID (X/Y). The logistic regression was performed to determine the independent predictors of adverse pathology, and the Kaplan-Meier curve and log-rank test were used to analyze the survival outcomes. Among 821 cT1/2 RCC patients, 245 (29.8%) had adverse pathology. The results of the univariate and multivariate logistic regressions showed that the age, tumor size, hemoglobin, and TMID were the independent predictors of adverse pathology. Incorporation of TMID could increase the discrimination of the predictive model with the area under curve (AUC) of ROC curves increasing from 0.725 to 0.808. Patients with adverse pathology or higher TMID both had significantly shorter recurrence-free survival (RFS). The nomogram model incorporated with TMID for predicting adverse pathology could increase its discrimination, calibration, and clinical application values, compared with the models without TMID.

CFD Study of Pressure Distribution on Recessed Faces of a Diamond C-Shaped Building

A building situated in the flow path of the wind is subjected to differential velocity and pressure distribution around the envelope. Wind effects are influenced by and vary for each individual shape of a tall building. Tall building structures are considered as cantilever structures with fixed ends at the ground. Wind velocity acting along the height of the building makes the velocity and pressure distribution more complex; as the height of the building structure increases, wind velocity increases. This study discusses the effect of the wind on an irregular cross-section shape. The present study was conducted numerically with a building model placed in a virtual wind tunnel using the ANSYS (CFX 2020 Academic Version) software tool. Wind effects are investigated on a building model situated in a terrain category-II defined in IS: 875 (Part 3): 2015; wind scale model of 1:100 and turbulence intensity are at 5% and power law index α is considered to be 0.143. The validation and verification of the study were made by comparing pressure coefficients on different faces of a rectangular model of similar floor area and height as that taken for a C-plan dia-mond-shaped model under similar boundary conditions, wind environment, and solver setting of numerical setups. The values of surface pressures generated on the recessed faces of the model and wind flow patterns within the recessed cavity were studied at wind incident angles 0°, 30°, 60°, 105°, 135°, and 180°. The critical suction on all the recessed faces was observed to be at a 105° angle of wind attack.

A Case Study on Simulation of Urban Inundation by Inland Flooding and River Flooding

Urban flooding can occur due to a combination of factors such as insufficient drainage capacity in stormwater systems, inland flooding from elevated river levels, and river flooding. This study proposes a method for analyzing urban inundation resulting from these complex phenomena using XP-SWMM. This is essentially a model capable of calculating the flow of drainage systems in urban watersheds and analyzing surface inundation. Moreover, it can accommodate irregular channel cross-sections and bridges, enabling river flooding modeling. However, it has limitations in terms of replicating the actual flooding patterns of rivers due to its representation of rivers through one-dimensional links and nodes. This study implemented virtual control structures to reflect the flooding effects caused by river flooding. This approach was applied to the Dongcheon watershed in Busan, where two instances of river and inland flooding coincided in July 2020. The results indicated the appropriateness of the approach.

Extraction and Physicochemical and Thermomechanical Characterizations of Water Hyacinth Fibers Eichhornia crassipes

The presence of floating plants is becoming an uncontrollable issue on the banks of Douala, Cameroon, notably in the city of Bonaberi, where the water hyacinth is expanding incredibly quickly. The aim of this study is to evaluate the mechanical and physicochemical performance of water hyacinth fibers for pulp manufacture. To this end, tensile tests on fiber bundles in accordance with ISO 13934-1:2013, thermogravimetric analysis (TGA), chemical composition evaluation in accordance with ASTM 1972 and 1977, and absorption rate were carried out. The results obtained indicate that the fiber is composed of a variety of fibrils with irregular cross-sections, with an average diameter ranging from 0.02 to 0.09 mm. The fibers absorb 42.03% of their weight in water, and their density ranges from 1.23 to 1.45 g/cm3. According to mechanical tests, the fiber has a maximum tensile strength of around 0.64 MPa, a specific modulus of 6.45 MPa/g/cm3, and an elongation at break of 1.8%. For the chemical characteristics of the fiber, cellulose, hemicellulose, and lignin contents are 68.3%, 11.3%, and 7.4%, respectively, while pectin and ash content concentrations are 4.8% and 7.8%, respectively. Thus, in order to determine whether the plant is suitable for making pulp and paper, this investigation was conducted to examine its fiber properties. It was found that the water hyacinth fibers were superior to flax straw and jute fibers in all qualities, but not as good as silk cotton and bagasse fibers. Given the information above, water hyacinth has been recognized as a potential raw material for the pulp and paper industries, though.

Study on the mechanism of local compression bruising in kiwifruit based on FEM

AbstractThis study focuses on the relationship between local compression and local bruise volume of kiwifruits by means of finite element method (FEM). The effects of four indenter shapes and three compression directions on the local kiwifruit bruise were considered. The local bruise volume and the irregular cross section area of kiwifruit were calculated. Multi‐scale kiwifruit 3D modelling based on irregular cross‐sectional area computed by slice‐integration method. Local compression bruise was simulated by FEM. The results of the local bruise test show that the contact force and the bruise volume of kiwifruit are positive linear correlation. Comparing the simulation with the experimental, the mean absolute percentage error (MAPE) of the reconstructed model is 0.0394, and the R2 of contact force–bruise volume curve is 0.8203. The maximum equivalent forces and abrasions occur in the 0° and 90° loading directions with the square indenter has been showed by FEM results.Practical applicationsSe‐enriched kiwifruit has high nutrition and economic value. Kiwifruits are often influenced by a variety of factors and processes from harvest to consumption time. Cleaning, transport, and various processing operations including peeling and slicing in the kiwifruit industry are responsible for local bruise to kiwifruit. Therefore, understanding the mechanism of local bruise caused by local contact force of kiwifruit plays an important role in reducing kiwifruit waste in the postharvest stage. Local bruise mechanisms can be used in harvesting and post‐harvest mechanical design and product transportation and positioning equipment.

Theoretical and experimental investigations on the stability performance of concrete-filled steel tubular X-column with regard to the flexural rigidity variation

The concrete-filled steel tube (CFST) X-column comprises two intersecting steel tubes filled with concrete, having irregular cross-sections that vary along its length, leading to variation in its flexural rigidity. This poses a challenge in terms of its buckling instability, a vital consideration in engineering practices. Hence, this study aims to investigate the stability performance of slender CFST X-columns. Firstly, the flexural rigidity of the two common types of CFST X-columns (through-type and reinforced-type) was calculated, and utilizing the stationary potential energy principle the elastic buckling loads of the both types of CFST X-columns were determined. The results indicated that the elastic buckling loads primarily depend on the position and length of the cross area. Next, the stability factors for both cases were calculated, and a formula for determining the stability bearing capacity of the CFST X-column was proposed. Finally, an experimental investigation of the stability behavior of CFST X-columns was conducted to validate these theoretical findings. The test specimens underwent a comprehensive analysis of their load-carrying process, and the instability failure mode as well as the deformation development were obtained. The experimental results demonstrated that within the given range of slenderness ratio, the specimens experienced elastic-plastic instability under axial compression. The calculated stability bearing capacity derived from the theoretical analysis closely matched the experimental results, indicating the reliability of the proposed theoretical analysis method. This provides valuable reference for the practical application of this novel component in engineering projects.

Theoretical derivation of hydraulic geometry equations for a gravel bed river channel

The geomorphic relations of hydraulic geometry at-a-station and downstream, expressed as power laws, are derived for a straight, single thread, gravel river channel. The cross-section has a plane central bed, narrow or wide, flanked by curved sides or banks. The analysis employs mechanistic formulae for fixed and mobile bed flow resistance, downchannel bedslope, bedload transport and the novel introduction of bedload ratings all expressed as power laws. Steady uniform flow and equilibrium bedload transport conditions are assumed to occur above the central section. Water discharge and sediment size are assumed to be the only known variables. Exponents of the relations of hydraulic geometry are fixed and are consistent with reported theoretical estimates and field measurements. Coefficients are also explicitly derived and are consistent with field measurements and vary owing to the presence of independent variables in their definition. Here aspect ratio has the major influence. The derived equations can provide coarse estimates for the design of canal and river control works. Conditional separate relations between both width and depth, and bed material size or bed slope are also determined for the occurrence of at-many-stations hydraulic geometry. To improve generality, future work should consider the hydraulic geometry of straight gravel channels with bedload transport, but having an irregular cross-section.

Modeling unsteady and steady 1D hydrodynamics under different hydraulic conceptualizations: Model/Software development and case studies

The stage-discharge relationship is affected by hysteresis, especially in 1D river cross-sections with very mild slopes, and/or where backwater effects occur. To model these cases, hydraulic property (HP) estimations (e.g., hydraulic radius and conveyance) are usually required as closed-form functions of stage. However, these are typically unavailable for complex cross-sections with overbanks. For no sediment-laden flows, we created the HydroHP - 1D tool to solve the 1D Saint Venant Equations aided by the cross-section HP stored in tables. It also simulates irregular and composite hydraulic cross-sections, allows hydrodynamic simulation using the single-channel method (SCM), and proposes the divided channel method (DCM) for steady and unsteady flow analysis. A wide range of applications in rivers such as the Little Washita River and the Upper Negro River, and comparisons with NOAA normal depth solver, HEC-RAS, and with an analytical solution shows a promising scenario of applying HydroHP - 1D to estimate 1D steady and unsteady hydrodynamics.

Motor unit placement in a realistic muscle cross section model: performance of a new algorithm and effects of muscle architecture on surface EMG power spectral components

Objetive. Surface electromyogram (sEMG) characteristics are strongly dependent on the spatial localization of motor units (MU). Thus, the definition of the muscle architecture is a crucial step in the simulation of sEMG. Muscles cross section or even the shape of the MU territories is not a regular geometric figure. Moreover, MU may have different fibre densities, and its distribution may not be random but follow a spatial regionalization by type. Despite these prior conditions, the method for MU placement in a muscle model should be able to achieve constant muscle fibre density, which is a generally accepted property of any muscle. Approach. An algorithm was developed that meets the previously established requirements for the distribution of MU in a muscle model. The algorithm considers the muscle cross section and MU territories as bitmaps and encodes the muscle fibre density distribution by pixel brightness. This allowed the use of digital image processing techniques to optimally distribute the MU. The impact of the different muscle architectures on sEMG was investigated using one of the most accepted models of motor unit pool recruitment combined with a model of MU action potential simulation. element-citationitalic Main results. The algorithm produced a completely regionalized architecture with constant muscle fibre density in a muscle with both an irregular cross-section and elliptic MU territory. Significance. In addition to the improvement in the realism of the muscle simulations, the algorithm allowed the investigation of the influence of the spatial distribution of MU on the sEMG power spectrum, thus helping to explain the existing inability to detect changes in motor unit recruitment strategies through the spectral analysis of interference patterns.

Kinematic modeling with Micro-CT slice auxiliary calibration for 2.5D woven SiO2f/SiO2 composites

An algorithm combining Micro-CT slice auxiliary calibration and kinematic modeling method is proposed to automatically generate yarns with irregular cross-sections and central paths for 2.5D woven SiO2f/SiO2 composites. The initial boundary conditions of the kinematic modelling simulation are calibrated by extracting the yarn positions from the corresponding Micro-CT slices. The simulation parameters with the real physical meanings are also determined in the kinematic modelling calculation. An explicit contact algorithm for truss elements in the kinematic modelling simulation with the calibration boundary conditions is employed to calculate nodal displacement. The virtual geometry of 2.5D woven SiO2f/SiO2 composites including detailed geometry information such as irregular yarn cross-section and yarn waviness or crimp can be reconstructed, which are in good agreement with the yarn geometry structures observed in Micro-CT scanning slices. The reconstructed geometry model can reflect the change of textile configurations during weaving and solidification process. The developed high-fidelity modelling method can also be used to reconstruct the geometry model of other textile composites with complex meso-structures.

Performance of Corrugated-Plate-Shaped Bridge Piers under Uniaxial Loading

The current research examines the seismic performance of irregular cross-section of bridge piers that has rarely been investigated. Preceded by a successful validation, the study was numerically conducted by ABAQUS/Explicit program containing a comprehensive series of FE bridge piers under unidirectional cyclic loading and axial dead load. Three corrugated shapes with a net depth of 60, 80 and 146 mm mainly formed the cross-sectional configuration of concrete-filled steel bridge piers. The aim was to examine the load-bearing capacity, ductility and buckling mode of such models and compare their behavior with traditional circular-shaped steel columns. Afterwards, a parametric study involved the grade of concrete (20, 30, and 40 MPa), corrugation geometry (C60, C80, and C146 mm), radius-to-thickness ratio (0.131, 0.149, and 0.116), and axial force ratio (10%, 15%, 20% and 30%). FE results suggested that concrete-filled corrugated-shaped columns revealed nearly 50% more load-bearing capacity and ductility as compared to circular-section columns. The damage configuration among corrugated-shaped columns was seen less severe than circular-section columns, where the local buckling in the latter one was premature and concentrated in particular zone. The findings herein urge to consider implementing corrugated-shaped piers in structures due to their significant addition in strength, ductility, and failure control.

The hot gas forming process of ultra-large aluminum tubular parts with irregular cross-sections: Experimentation and application

For many transportation sectors, high-strength aluminum alloy tube parts are the suitable structure to accomplish both structural and material lightweight. The following paper presents systematic experimentation on the hot gas forming of ultra-large aluminum alloy tubular parts comprising analysis of the process parameters and the hot deformation behavior of AA6011 tube, full-scale hot gas forming tests, and property assessment. First, hot uniaxial tensile tests using Digital Image Correlation (DIC) method at various temperatures and strain rates were conducted to systematically analyze the hot flow behavior and assist in selecting appropriate process parameters. Then, full- scale hot gas forming tests of AA6011 tubes with different diameters were conducted enabling the 5 m long integral tubular part to be formed for the first time. Desired characteristics such as thickness distribution, mechanical properties, and grain microstructure were comprehensively examined. It is demonstrated that the hot-formed component displays a homogeneous strength distribution and an improvement in ultimate tensile strength of between 28.2 % and 44.7 % over the raw material. The maximum thinning ratio was calculated to be 0.225 for a specific cross-section, further meeting the thinning requirement. In addition, dynamic recrystallization was discovered on the straight walls of particular cross-section No. 9 with a significant bulging deformation, i.e. 9.45 %. Such a cross-section displayed a relatively greater thickness reduction and the resulting dislocations triggered the occurrence of dynamic recrystallization, as evidenced by the EBSD observations at typical locations.