Thin-Walled Structures最新文献_第5页

Investigation on multi-mode coupling effects in wind-structure interaction of tension membrane structures using fully-coupled numerical simulation 利用全耦合数值模拟研究张拉膜结构风-结构相互作用中的多模式耦合效应

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-21 DOI: 10.1016/j.tws.2025.112993

Tian Li , Feixin Chen , Qingshan Yang , Bowen Yan , Yukio Tamura

Tension membrane structures may undergo significant wind-structure interactions (WSI), during which multi-mode coupling phenomenon can be commonly observed as the structural span, spatial tension, and openness increase. The lack of understanding of multi-mode coupling effects of tension membrane structures is a primary obstacle to establishing practical and feasible response estimation method for such structures considering WSI. In this research, the underlying mechanisms of multi-mode coupling effects in WSI of tension membrane structures are revealed based on numerical simulations. A one-way tensioned, open-type membrane structure is chosen to be the object because of its relatively idealized geometry for analysis of WSI mechanism, which is a simplified shape compared to typical membrane structures. Fully-coupled simulations are utilized to reproduce pre-existing aero-elastic experiment and well validated against the reference experimental results. Additionally, a modal identification method based on proper orthogonal decomposition (POD) technique is proposed for precisely decomposing the coupled vibrating modes. It is found that the multi-mode coupling phenomenon is initiated by the difference in the vortex-structure interaction between upper and lower sides of the membrane, due to the disparities in pneumatic shape between the two sides. Moreover, the modal jump and modal resonance are effectively examined and revealed through the proposed modal identification method. Energy transfer analysis shows that the modal jump is resulted by the negative aerodynamic damping, while the modal resonance, the main reason of the rapid amplification and instability of the membrane vibration, is triggered by the added mass. The findings in this study lay the foundation of establishing the response estimation method for tension membrane structures considering multi-mode coupling.

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引用次数: 0

Simplified mechanical model of stiffened panel structures based on laminate smeared stiffener method

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-20 DOI: 10.1016/j.tws.2024.112841

Chen Guo, Zheng Yang, Yanchao Yue, Wenxiao Li, Hantao Wu

Compared to flat panels, stiffened panels have a greater number of components and significant dimensional variations in different directions of these components. This often results in excessive mesh quantities and poor mesh quality during finite element analysis. Based on the relationship between deformation and generalized forces on the unit cells of the stiffened panel and laminated panel, this study has derived a simplified calculation method specifically for stiffened panels. The method transforms the stiffened panel into an equivalent three-layered orthogonal anisotropic laminated panel by adjusting the elastic and shear moduli of each layer of the laminated panel, significantly simplifying the model and improving computational efficiency. The equivalent laminated panel model can reproduce the tensile, compressive, shear, bending, and torsional deformations of the stiffened panel structure and can be used to calculate the deformation and buckling capacity of the original stiffened panel structure. This paper also provides static and buckling examples to verify the effectiveness and accuracy of the proposed method. In the static example, the maximum relative error of the deformation values calculated by the proposed method is 3.244 %. The average relative error of the first six orders of buckling loads in buckling Example 1 is 5.244 %. In comparison with the conventional method, the computation time of buckling Examples 1 and 2 is reduced by 22 % and 87 %, respectively.

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引用次数: 0

Additive manufacturing of crack-free large IN738LC parts through tailored substrate designs 通过定制基底设计快速成型制造无裂纹大型 IN738LC 零件

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-20 DOI: 10.1016/j.tws.2025.112979

Xufei Lu , Guohao Zhang , Michele Chiumenti , Miguel Cervera , Zhennan Wang , Bo Yao , Xin Lin

Additive Manufacturing (AM) is revolutionizing industrial production by enabling the direct fabrication of intricate geometries, far beyond the capabilities of traditional manufacturing methods. However, stress-induced cracking remains a significant challenge in AM, especially in hard-to-weld metallic materials like the Ni-based superalloy IN738LC. To address this issue, a novel substrate design has been developed for Laser Directed Energy Deposition (L-DED) to mitigate stress and prevent crack formation. This innovative substrate allows for more unrestricted thermal expansion and contraction of the deposited layers, a key factor in preventing stress accumulation that typically leads to cracking. To validate its effectiveness, IN738LC components were fabricated using both standard and designed substrates. In-situ temperature and displacement measurements were recorded throughout the L-DED process, and the data were used to calibrate a specialized thermo-mechanical finite element model tailored for AM. The simulations identified areas of high stress concentrations and potential cracking sites. With the standard substrate, cracks were observed to initiate, propagate and self-seal during the L-DED process. In contrast, the designed substrate completely eliminated stress accumulation, preventing any cracking. This novel approach successfully enabled the production of large-scale (over 220 mm) crack-free IN738LC components without the need for preheating, additional equipment, or modifications to the alloy composition—requirements that were previously considered essential. Moreover, the mechanical properties of the fabricated components were significantly improved, achieving a tensile strength of 1152.7 MPa and an elongation of 16.1 %, demonstrating the potential of this substrate design to advance the fabrication of industrial components.

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引用次数: 0

Creep behaviour and modelling of adhesively bonded CFRP-steel joints

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-20 DOI: 10.1016/j.tws.2025.112981

Songbo Wang , Yanchen Fu , Jun Su , Zhuo Duan , Siyuan Yang

The performance of adhesively bonded joints is vital to the effectiveness of carbon fibre-reinforced polymer (CFRP) strengthening in steel structures. This study investigates the creep of CFRP-steel joints employing a combination of experimental testing and numerical analysis. A total of 10 characterisation tests were conducted on the strengthening adhesive to assess its thermal stability and viscoelastic creep properties. The findings revealed a significant increase in the creep rate as the temperature approached the adhesive's glass transition temperature (63.9 °C). Based on these results, a viscoelastic constitutive model, formulated using a Prony series, was developed and applied in the numerical analysis of the creep performance of CFRP-steel joints. Additionally, 6 sustained loading tests were performed on individual CFRP-steel joints, measuring creep displacement over periods of 7 and 12 days, which were used to validate the model's predictions. The experimental and numerical results showed a strong correlation, with a minimum R² value of 0.883. Extended numerical simulations, encompassing 60 scenarios, demonstrated that increasing the adhesive layer thickness significantly influences creep displacement, while variations in bond length have a relatively minor effect. After 30 days, a joint with a bond length of 13.5 mm and an adhesive thickness of 3.0 mm was predicted to exhibit a creep displacement of 62.5 μm, emphasising the importance of accounting for creep in design. The numerical modelling method based on material characterisation can be applicable for studying creep in various engineering adhesively bonded joints and offers valuable insights for optimising CFRP-steel joint designs in practical applications.

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引用次数: 0

Response mechanisms and energy absorption properties of hybrid sheet TPMS lattices under static and dynamic loading

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-20 DOI: 10.1016/j.tws.2025.112980

Zihao Li , Shiqiang Li , Jiajing Liu , Zhifang Liu , Jianyin Lei , Zhihua Wang

Triple Periodic Minimal Surface (TPMS) is widely used in many fields as a porous structure with light weight and high energy absorption efficiency. Based on uniform sheet TPMS lattices, a Gyroid-IWP Hybrid (GIH) sheet TPMS lattice was designed by internal cylindrical Gyroid lattice and external cubic IWP lattice. Specimens were fabricated by selective laser melting (SLM) technique and subjected to quasi-static compression and direct-impact Hopkinson bar (DIHB) experiments. The experimental results show that the hybrid GIH lattices exhibit more significant strain-hardening effects and higher energy absorption capacities than the uniform Gyroid and IWP lattices. And the GIH-I lattice (the lattice is compressed along the axis of the cylindrical Gyroid region) exhibits a relatively uniform deformation pattern. While the localized collapse of the GIH-II lattice (the lattice is compressed perpendicular to the axis of the cylindrical Gyroid region) firstly occurs in the IWP region at the two ends of the lattice, and then symmetrically collapses and deforms towards the intermediate transition layer. Finite element simulation was used to investigate the inner deformation mechanisms and energy absorption characteristics during the deformation processes. The effects of normalized hybrid diameters of the internal Gyroid region and the width of transition layer on the mechanical properties of the GIH lattice are also investigated. The results indicated that the GIH-I lattice has better impact resistance at low and medium strain rates, while the GIH-II lattice exhibits superior mechanical properties at higher strain rates. The GIH-II lattice not only has the smallest initial peak stress, but also exhibits significant multi-stage platform energy absorption. In addition, compared with the Linear Gyroid-IWP Hybrid (LGIH) lattices, the GIH lattices designed in this paper have obvious advantages under dynamic impact loading, which can provide a better design idea for engineering applications.

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引用次数: 0

Experimental investigation and predictive model on tensile behavior of corroded high-strength steel and butt-welded connections

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-20 DOI: 10.1016/j.tws.2025.112982

Man-Tai Chen , Yang Pan , Fengming Ren , Huan Cao , Mianheng Lai , Jingjing Zhang

High-strength steel structures have emerged as an optimal choice for ocean engineering applications, offering enhanced performance, durability and construction efficiency in both coastal infrastructure and offshore installations. However, the aggressive nature of marine environments poses significant challenges to the long-term integrity and safety of these structures due to corrosion. While understanding the degradation of steel material properties is essential, equally critical is the evaluation of welded connections, as joints typically represent critical vulnerabilities in corroded steel structures. This study focuses on experimentally evaluating the residual tensile properties of HG785 high-strength steel and butt-welded connections after exposure to corrosion. Test specimens, comprising both base metal and butt-welded configurations, underwent accelerated deterioration using neutral salt spray exposure, simulating the harsh conditions characteristic of coastal settings. The experimental program incorporated six distinct exposure durations to assess progressive corrosion damage. Surface degradation patterns were precisely documented using 3D laser measurement technology, enabling detailed geometric analysis of the corroded specimens. Through comprehensive tensile testing, the remaining tensile properties of the deteriorated specimens, including load-strain relationships, strength parameters and ductility metrics were evaluated. The findings led to the development of two-stage predictive models that quantify the residual tensile properties of both the corroded HG785 high-strength steel base material and butt-welded connections.

高强度钢结构已成为海洋工程应用的最佳选择，可为沿海基础设施和海上设施提供更高的性能、耐用性和施工效率。然而，海洋环境的腐蚀性给这些结构的长期完整性和安全性带来了巨大挑战。虽然了解钢材料性能的退化至关重要，但同样重要的是对焊接连接的评估，因为接头通常是腐蚀钢结构的关键薄弱环节。本研究的重点是通过实验评估 HG785 高强度钢和对焊连接件在受到腐蚀后的残余拉伸性能。测试试样包括基体金属和对焊结构，通过中性盐雾暴露进行加速劣化，模拟沿海地区特有的恶劣条件。实验项目包括六种不同的暴露持续时间，以评估渐进式腐蚀损伤。利用三维激光测量技术精确记录了表面退化模式，从而能够对腐蚀试样进行详细的几何分析。通过全面的拉伸测试，评估了退化试样的其余拉伸特性，包括载荷-应变关系、强度参数和延展性指标。研究结果促成了两阶段预测模型的开发，该模型可量化已腐蚀的 HG785 高强度钢基材和对焊连接件的剩余拉伸性能。

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引用次数: 0

Fillet effects on hemispherical shell resonators: Analytical insights for enhanced structural integrity 半球壳谐振器的圆角效应：增强结构完整性的分析见解

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-19 DOI: 10.1016/j.tws.2025.112965

Lingxia Liu , Qixing Liu , Shuangxi Shi , Fengming Li

This study investigates the impact of fillet geometry on the dynamic and thermoelastic damping (TED) properties of hemispherical shell resonators, commonly used in composite structural applications. Fillets are often applied to reduce stress concentrations and improve structural integrity, but their influence on the mechanical behavior and thermoelastic quality factor (Q_TED) of resonators has not been thoroughly examined. An analytical approach is presented to evaluate the free vibration and TED characteristics of filleted hemispherical shells. The model incorporates variations in shell thickness to represent fillet effects and applies the first-order shear deformation theory (FSDT) for theoretical derivation. Mode shapes are described using a combination of Jacobi polynomials and Fourier series, and the equations of motion are derived using Hamilton's principle and the assumed mode method. The analytical model for the Q_TED is developed by calculating the dissipated energy and the maximum elastic potential energy of the shell. The accuracy of the model is validated through comparison with existing literature and finite element method (FEM) simulations. Numerical examples highlight the effect of fillet geometry on the vibration modes and Q_TED characteristics, offering insights into the optimization of fillet design for improved performance in hemispherical shell resonators.

本研究探讨了圆角几何形状对半球形壳体谐振器动态和热弹性阻尼（TED）特性的影响，这种谐振器通常用于复合结构应用中。圆角通常用于减少应力集中和改善结构完整性，但其对谐振器机械行为和热弹性品质因数（QTED）的影响尚未得到深入研究。本文提出了一种分析方法，用于评估滤波半球形壳体的自由振动和 TED 特性。该模型结合了壳体厚度的变化来表示圆角效应，并应用一阶剪切变形理论（FSDT）进行理论推导。采用雅可比多项式和傅里叶级数相结合的方法来描述模态形状，并利用汉密尔顿原理和假定模态法推导出运动方程。通过计算耗散能量和壳体的最大弹性势能，建立了 QTED 的分析模型。通过与现有文献和有限元法（FEM）模拟进行比较，验证了模型的准确性。数值示例强调了圆角几何形状对振动模式和 QTED 特性的影响，为优化圆角设计以提高半球形壳体谐振器的性能提供了启示。

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引用次数: 0

Principal Stress Lines (PSLs)-guided discrete topology designs for self-similar porous infills in shell structures with fractal geometry

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-18 DOI: 10.1016/j.tws.2025.112915

Jiayi Zhu , Jie Xu , Xiaoqiang Zhou , Liang Gao , Jie Gao

Although the optimization design for engineering structures to improve mechanical performance has gained a wide of discussions in recent years, the potential in the industry design and the considerations of structural aesthetics are extensively limited. In the current work, the main intention is to propose a new design method for shell structures, where the generation of the Principal Stress Lines (PSLs) and the fractal geometry are seamlessly coupled to achieve self-similar porous infill designs. Firstly, the implementation algorithm for shell structures with the NURBS (Non-uniform Rational B-splines)-based isogeometric analysis (IGA) is developed to generate the dense distribution of the PSLs in the whole domain, and the main transmission paths of the imposed loads are extracted to be the discrete topology designs for shell structures, which are applied to determine the overall layout of the stiffeners, namely primarily bearing-load bars, in the domain to improve structural performance. Secondly, the fractal geometry with several principles is considered to develop the numerical flowchart of the self-similar porous infill designs in shell structures, where the above stiffeners determine the layout compactness of porous unit cells in unique local regions. The Variable Period Voronoi Tessellations (VPVT), which are the self-similar generation mechanisms using the iterated function system, are employed to maintain structural manufacturability and a higher aesthetic appeal. Finally, several numerical examples with multiple loads and conditions, particular the engineering structure of the satellite fairing, are discussed to demonstrate the effectiveness and superiority of the proposed design method.

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引用次数: 0

Analytical analysis of traveling wave vibration for rotating bi-directional dual-functionally graded carbon nanotube reinforced composite stepped thin cylindrical shells

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-17 DOI: 10.1016/j.tws.2025.112956

Ziqiang Xu , Yu Wang , Jingyu Zhai , Bing Han , Ziyi Wang , Xuehui Li

In this paper, considering both carbon nanotubes and the matrix are distributed axially and radially, the traveling wave vibration for the bi-directional dual-functionally graded carbon nanotube reinforced composite stepped thin cylindrical shells is researched. To begin with, the effective material properties of stepped shells are obtained by the improved law of mixtures. In the meantime, the energy expressions of the shell are derived by considering the centrifugal and the Coriolis effect generated from rotation on the basis of the first-order shear deformation theory. Through varying the stiffness value of the artificial spring, the boundary constraints on the shell and the connections between each segment are simulated in the actual working conditions. Furthermore, the Gegenbauer-Ritz method, a novel analytical approach derived from the conventional Ritz method, is chosen to analyze this model and its validity is verified through comparisons with the existing literature and the finite element method. Ultimately, the influences of the carbon nanotubes distribution types, rotating speed, and other parameters on traveling wave vibration of the rotating stepped shells under classical and elastic boundary conditions are discussed in axial and radial directions, respectively. It is shown that gradually increasing the content of carbon nanotubes towards the weak areas of the components can effectively enhance their stiffness to maximize service life. Meanwhile, when the length-to-radius ratio is large, the axial type is superior to the radial type for the reinforcement of the overall stiffness of the shell.

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引用次数: 0

Testing and modelling of residual stresses within Q690 high strength steel press-braked round-ended oval hollow section

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-17 DOI: 10.1016/j.tws.2025.112974

Jun-Zhi Liu , Heng Zhang , Jiachen Guo , Xiaowei Ma , Junbo Chen , Fei Xu

This research explores the material properties and residual stresses of Q690 high-strength steel (HSS) round-ended oval hollow sections (ROHS), fabricated from steel plates after press-braking and welding. It aims to fill the existing knowledge gap concerning the mechanical properties of this novel section profile. Four Q690 HSS press-braked ROHS were examined, employing both transverse bending and longitudinal welding techniques. In addition to the material properties investigation, membrane and bending residual stresses in the longitudinal direction were assessed. The wire cutting method was utilised to create testing strips, resulting in 60 strips with more than720 strain measurements taken. Complementing the experimental tests, an integrated sequentially-coupled thermo-mechanical analysis was performed by developing an advanced lumped line finite element (FE) model. Solid element was used in simulating both cold-forming and welding process, and birth and death techniques was used to replicate the multi-pass welding and the melting of the welding rod. As a result, an explicit residual stress distribution in the longitudinal direction along the perimeter, resulting from cold-forming process and welding, was established. The collected experimental and simulation results elucidated the levels and distribution characteristics of the residual stresses, leading to the development and proposal of predictive models for residual stresses of the press-braked ROHS containing two different fabrication routes.

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引用次数: 0