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Thin-Walled structures
Elsevier Science
Thin-Walled structures

Elsevier Science

0263-8231

Thin-Walled structures/Journal Thin-Walled structuresSCIISTP
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    Mechanical performance analysis method for ribbed H-section aluminum alloy members with initial curvature and torsion angle

    Sun G.Li B.Wu J.
    1.1-1.14页
    查看更多>>摘要：© 2024 Elsevier LtdIn this study, an experimental investigation was conducted on the axial compression performance of ribbed H-section aluminum alloy members with initial curvature and torsion angle under varying boundary conditions, including one end hinged with the other rigidly connected, and both ends rigidly connected. Ultimate bearing capacity and failure modes were identified under real loads and subsequently compared with previous findings from our research group on members with hinged ends. To account for initial imperfections introduced during processing and transportation, 3D scanning technology was utilized to capture the precise geometrical dimensions, constructing an accurate numerical simulation model. The experimental results were corroborated with numerical simulations, leading to the proposal of an analytical method for members with initial curvature and torsion angle. Furthermore, extensive parametric analysis elucidated the impact of initial curvature, torsion angle, and slenderness ratio on the ultimate bearing capacity, culminating in the formulation of the stability factor and calculated length factor based on numerical outcomes. The study discovered significant variances in bearing capacity under different boundary conditions, with one-end hinged and one-section rigidly connected, and two-end rigidly connected conditions exhibiting 1.4 and 2.1 times the capacity of the hinged-at-both-ends scenario. Under different boundary conditions, the axial compression members were subjected to flexural-torsional buckling failure. Moreover, when the ultimate bearing capacity was reached, the lower flange of the member and the web near the lower flange appeared obvious buckling phenomenon. The numerical analysis aligned well with experimental data, validating the simulation method's reliability and revealing the stress distribution and evolution during member failure. These findings offer vital theoretical insights and technical support for engineering design and practical applications.
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    • Elsevier

    A comprehensive study of beam modal functions in the free vibration analysis of cylindrical shells: Critical examination on the applicability to the clamped-free boundary condition

    Xu G.Zhu C.
    1.1-1.17页
    查看更多>>摘要：© 2024 Elsevier LtdOver the past few decades, approximate methods that can provide solutions of sufficient accuracy have received considerable attention in the free vibration analysis of cylindrical shells, where a great deal of studies adopted the beam modal functions as the trial functions for the axial mode shapes of cylindrical shells. Nevertheless, most studies were restricted to the application of single term beam modal function and failed to simulate elastic boundary conditions of cylindrical shells, while the accuracy of the corresponding methods has recently sparked significant controversy, especially for cylindrical shells under the clamped-free boundary condition. This paper presents a comparative study of three forms of beam modal functions in the free vibration analysis of cylindrical shells, one of which is proposed for the first time to simulate elastic boundary conditions of cylindrical shells. A unified model is developed using the general Rayleigh–Ritz method, incorporating the breathing modes with circumferential orders being zero, and four types of commonly used thin shell theories, namely the Donnell, Reissner, Love, and Sanders theories. From both perspectives of natural frequencies and mode shapes, numerical results are validated by comparison with those existing in the literature and those calculated from the finite element method (FEM). The results not only clarify the distinction of different forms of beam modal functions used in the Rayleigh-Ritz method, but also provide explanations for the controversy raised in recent studies. Furthermore, the unified formulations can be extended to vibration analysis of various forms of shell structures, and can also be helpful to the vibration analysis of beams and plates with elastic boundary conditions.
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    • Elsevier

    A systematical investigation on the impact of coupling crystal orientations on vibration characteristics of a single crystal superalloy cooling turbine blade

    Li H.T.Wang X.M.Cheng H.Sun S.Y....
    1.1-1.16页
    查看更多>>摘要：© 2024 Elsevier LtdRevealing the dispersion mechanism of vibration characteristic is significant for turbine blade that is one of the most important hot components of aero-engine. Thus, the aim of this article is to systematically address the influence of primary and secondary orientation deviations on the dynamic responses of a single crystal blade by theoretical analysis in combination with finite element numerical calculation. Besides, the relationship between the crystal orientation in engineering and material science is clarified by a mathematical approach. Primary orientations characterized by two deviation angles, each having 16 directions and secondary orientations with 11 deviation angles are defined by three angles measured by the Laue method. Good agreement on variation of structural eigenfrequency for the first bending or torsional mode is attained between theory analysis and numerical calculation. Numerical results show that the primary orientation deviation direction could cause significant dispersion of the natural frequencies for low and high order modes. The increasing deviation angle widens the dispersion, with the maximum variation ratio of 5.62% for the torsional mode. Importantly, the conjunction with the secondary orientation could further changes the dispersion of the natural frequencies, and the maximum variation of 6.5% is achieved for the torsional mode. This research may provide new perspectives for substantially improving the resonance margin of single crystal turbine blades, with potential applications in preventing high cycle fatigue failure, which is very meaningful to guide the design of the aero-engine.
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    • NETL
    • NSTL
    • Elsevier

    Mechanical behaviour of rigid-flexible combined structures: Aluminium-inflated membrane beams for application in floating photovoltaic platform

    Ye Y.Gan J.Wu W.Wang S....
    1.1-1.15页
    查看更多>>摘要：© 2024This study aims to investigate the bending and failure behaviour of aluminium-inflated membrane beams for their applications in floating photovoltaic platforms. Four-point bending tests are conducted for a range of inflated pressures and two different deck heights to assess their effect on structural stiffness and ultimate bearing capacity. Meanwhile, the surface-based fluid cavity method is employed to develop the finite element model with the material properties determined by independent coupon-level tests. The bearing capacity of the aluminium-inflated membrane beam is positively correlated with the internal pressure and deck height. The midspan strain distribution is similar to those of the traditional four-point bending beam with the upper part undergoing compression and the lower part experiencing tension, however, the structural behaviour at the failure stage is different. Failure typically occurs due to localised depressions at the loading points on the aluminium deck, ultimately leading to structural failure. The numerical model closely matches the experimental data for the initial inflated and bending configurations, exhibiting a deviation of only 0.10 % to 0.46 % in diameter and 0.32 % to 5.57 % in equivalent bending stiffness. A parametric study shows that the loading properties of the beam are more sensitive to the internal pressure than the deck height and thickness.
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    • NETL
    • NSTL
    • Elsevier

    Thermal performance analysis and optimization of air-supported membrane building envelope based on numerical simulation

    Huang C.Sun Y.Wang H.Pang M....
    1.1-1.15页
    查看更多>>摘要：© 2024Air-supported membrane (ASM) envelopes offer an effective solution for creating large interior spaces for buildings with lower energy consumption and carbon emissions. However, there is little research on the thermal performance of ASM envelopes, particularly regarding the natural convection within the air interlayer and its impact on thermal resistance. To address this gap, this study developed a numerical model of ASM envelopes and validated it through experiments. Subsequently, a numerical investigation was conducted to analyze natural convection and thermal resistance while considering factors such as indoor-outdoor temperature difference, membrane emissivity and air interlayer thickness. Results indicated that with the emissivity increased from 0.2 to 1, the thermal resistance of the air interlayer and the envelope decreased by 32.35 % and 9.13 %, respectively. Besides, the thickness of air interlayer also had evident effect on thermal resistance. When it increased from 5 mm to 35 mm, the thermal resistance of the air interlayer and the envelope increased by 156.19 % and 14.74 %, and further results in the heat transfer decreased by 13.85 %. However, the convective heat transfer would remain constant when the thickness exceeded 35 mm. This study provided valuable reference for optimizing the design of ASM envelopes and accurately calculating their thermal resistance.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Combined bending-torsion and compression-bending-torsion behaviours of reinforced concrete-filled thin-walled corrugated steel tubes

    Fang Y.Wang Y.Yang H.
    1.1-1.22页
    查看更多>>摘要：© 2024Reinforced concrete-filled thin-walled galvanized corrugated steel tube (RCFCST) is a novel composite member that has application potential in extremely corrosive environments and seismic activity regions. A series of preliminary works have been conducted on its compressive, flexural, shear, and torsional behaviour. However, the combined loading condition is almost inevitable in practice. The correlations between the flexural and torsional behaviour of RCFCSTs are unique due to the special spiral corrugated profile, which is unclear and needs to be addressed. This paper, therefore, presents an experimental investigation of the RCFCST under combined bending-torsion and compression-bending-torsion loads, encompassing the main test variables of torsion-to-bending ratios, torsional directions, and axial compression ratios. The loading set-up and instruments have been introduced in detail. The failure modes, lateral load versus lateral displacement curves, bending moment versus flexural lateral displacement curves, torsion moment versus torsional angle curves, and strain distributions are carefully addressed. The working mechanisms of the RCFCST under monotonic combined loads are discussed, with a particular explanation of the dependent behaviour on the torsion-to-bending ratios and torsional directions. The applicability of the existing design methods for the bearing capacity of RCFCST specimens under combined loads is examined carefully, with specific design suggestions proposed.
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    • NETL
    • NSTL
    • Elsevier

    On the imperfection sensitivity and design of buckling critical wind turbine towers

    Wagner H.N.R.Huhne C.
    1.1-1.16页
    查看更多>>摘要：© 2024Wind turbine towers pose major challenges for design engineers due to their complex geometry, nonlinear material behavior and imperfection sensitivity. In service, these thin-walled shells are burdened by a combination of complex load cases and prone to buckling. In fact, one of the main design drivers of wind turbine towers is stability failure for which often the design recommendation of the EN-1993–1–6 are used. Recently an international shell buckling exercise was caried out by the team behind the EN-1993–1–6 design standard. Within this exercise 29 teams from academia and industry were asked to perform a series of linear and non-linear finite element simulations of an 8-MW multi-strake steel wind turbine support tower segment. In general, the linear and nonlinear analyzes posed no challenge for the shell buckling experts from around the world. However, the imperfection sensitivity analysis results scattered significantly among the participants. In addition, there was little consensus as to whether the given tower design is actually safe. The authors, whose background is aerospace engineering, participated in this exercise and show in this article how they overcome the challenges of this typical civil engineering problem. Among linear and non-linear analyzes the authors show the results of state-of-the-art shell buckling concepts which were developed for aerospace shells like interstage tanks and adapters but are also applicable to wind turbine towers.
      原文链接:
    • NETL
    • NSTL
    • Elsevier

    Shear performance prediction for corrugated steel web girders based on machine-learning algorithms

    Liu Y.Ji W.Li J.Liu S....
    1.1-1.16页
    查看更多>>摘要：© 2024This study aimed to predict the shear strength of corrugated steel web girders (CSWGs) by developing a new method based on four machine-learning (ML) algorithms, namely the support vector machine, artificial neural network, random forest, and XGBoost. Based on the acquired experimental and numerical data, a database containing 552 samples was constructed to train and test the ML models. A five-fold cross-validation approach was adopted during training to prevent model overfitting. A RandomizedSearchCV was used to optimize the hyperparameters of each model. The performance of the trained models was evaluated using four performance metrics, and the results revealed that the coefficients of determination (R2) of all ML models exceeded 0.97 when used on both training and validation sets, demonstrating the excellent performance of the ML models in predicting the shear strength of CSWGs. Additionally, the implemented ML models outperformed existing design codes and empirical formulae. The XGBoost model yielded the best prediction results with an R2 of 0.999, mean absolute error of 44.98 kN, root-mean-square error of 66.67 kN, and mean absolute percentage error of 2.1 %. By using the Shapley additive explanation to derive a visual, quantitative explanation of the XGBoost model, the yield strength, web thickness, and web height were identified as the most critical factors affecting the shear strength of CSWGs, and their average absolute Shapley values accounted for approximately 91.45 % of the total value. The ML models implemented in this study provide a promising new approach for pre-designing and verifying the stability of CSWGs.
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    • NETL
    • NSTL
    • Elsevier

    Microstructure and mechanical properties of Mg-Nd-Zn-Zr alloy fabricated by TIG-based wire – Arc directed energy deposition with pulsed current

    Wu K.Zhang X.Wang W.Liang J....
    1.1-1.15页
    查看更多>>摘要：© 2024 Elsevier LtdIn this study, the Mg-Nd-Zn-Zr alloy thin-wall specimens were prepared by tungsten inert gas (TIG) based wire-arc directed energy deposition (WA-DED) with different pulsed currents. The arc characteristics of different pulsed current frequents were observed. The microstructures, and mechanical properties of as-deposited (AD), 5 Hz, 10 Hz, 15 Hz, and 20 Hz specimens were systematically analyzed and evaluated. The uniformly equiaxed crystals with random grain orientations and intergranular network Mg-Nd-Zn eutectics were found in the WA-DED fabricated Mg-Nd-Zn-Zr alloy thin-wall specimens. No significant voids were found. The microstructures were regulated, and the mechanical properties were improved by adjusting the pulsed current frequency. The 10 Hz specimen had the optimal microstructure with an average grain size of 10.35 μm. Concurrently, the 10 Hz specimen exhibits excellent strength-ductility synergy and isotropic, benefiting from the finely equiaxed crystals. The average microhardness of the 10 Hz specimen was 68.51 HV0.2, and the ultimate tensile strengths in the building and traveling directions were 223 MPa and 229.7 MPa, respectively, and the yield strengths in the building and traveling directions were 138.3 MPa and 145.3 MPa, respectively. Notably, the elongations in the building and traveling directions of the 10 Hz specimen were 16.8 % and 17.4 %, respectively. The local strain evolution and fracture surfaces of AD and 10 Hz specimens in the building and traveling directions were observed. The mechanisms of grain refinement and mechanical properties improvement were revealed.
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    • NSTL
    • Elsevier

    Numerical study on the effects of alloying variations on the crushing behaviour of an aluminium profile

    Fernandez M.Costas M.Hopperstad O.S.Morin D....
    1.1-1.14页
    查看更多>>摘要：© 2024The effects of variations in the chemical composition of an aluminium alloy AA6005 on the axial crushing and bending behaviour of a double chamber extruded profile are investigated by shell-based finite element analyses. A novel sequential modelling method, including nanostructure modelling, virtual tensile testing and localisation analyses, is used to determine the yield strength, work-hardening, and ductility of several variants of the AA6005 alloy. The data obtained from the models are used to calibrate the parameters of an isotropic elastic–plastic constitutive model and an uncoupled damage criterion. Explicit finite element analyses of axial crushing and three-point bending of the double chamber extruded profile are conducted for all variants of the AA6005 alloy in temper T6. By comparing the results of the finite element analyses with existing experimental data, the results reveal how variations in the chemical composition significantly influence the structural integrity of the extruded aluminium profile in axial crushing and bending.
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    • NETL
    • NSTL
    • Elsevier