今日更新:International Journal of Solids and Structures 1 篇,Thin-Walled Structures 12 篇
Simulating loading–unloading hysteretic behaviors of nematic-genesis polydomain nematic elastomers
Yuzhen Chen, Songshan Zhao, Hongyu Li, Yongzhong Huo
doi:10.1016/j.ijsolstr.2024.113039
向列成因多域向列弹性体加载-卸载滞回特性模拟
Nematic elastomers (NEs) are lightly cross-linked elastomers with nematic mesogens integrated in their polymer networks. Combination of large deformation capability with nematic-isotropic phase transition enables NEs to be the most promising soft materials for impact attenuation, actuation and soft robotics. In this paper, we focus on nematic-genesis polydomain NEs (N-PNEs) where mesogens are cross-linked at nematic states. N-PNEs are capable of absorbing and dissipating energy and easy to synthesize. We present a Voronoi diagram-baseed finite element model for specimen-scale N-PNEs, and investigate the cyclic tensile and compressive behaviors of N-PNEs at different strain rates. Our simulations reveal a smooth polydomain-monodomain transition during loading, accompanied by a full recovery of polydomain texture after the load is removed, indicating a memory effect of initial disordered mesogen alignment. The predicted behaviors align well with experimental observations, which validates our model. Furthermore, we assess the energy absorption and dissipation capabilities of N-PNEs compared to monodomain NEs, identifying conditions where N-PNEs exhibit superior performance. This study not only enhances our understanding of polydomain-monodomain transitions in N-PNEs, but also lays the groundwork for the development of N-PNE-based energy absorbers
向列弹性体(NEs)是轻交联弹性体与向列介元集成在其聚合物网络。大变形能力和向列各向同性相变的结合使NEs成为最有前途的软材料,用于冲击衰减,驱动和软机器人。在本文中,我们重点研究了向列发生多结构域内链(N-PNEs),其中中显子在向列状态交联。n - pne具有吸收和耗散能量的特点,易于合成。提出了基于Voronoi图的N-PNEs试样有限元模型,研究了N-PNEs在不同应变速率下的循环拉伸和压缩行为。我们的模拟结果显示,加载过程中多域-单域平滑过渡,加载去除后多域纹理完全恢复,表明初始无序介观排列存在记忆效应。预测的行为与实验观察吻合得很好,这验证了我们的模型。此外,我们评估了n - pne与单畴网元相比的能量吸收和耗散能力,确定了n - pne表现出优越性能的条件。该研究不仅加深了我们对n- pne中多畴-单畴跃迁的理解,而且为开发基于n- pne的能量吸收剂奠定了基础
Seismic performance of an innovative self-centering and repairable connection with SMA bolts in modular steel construction
En-Feng Deng, You-Peng Du, Jun-Dong Gao, Zhe Zhang, Yan-Bo Wang
doi:10.1016/j.tws.2024.112377
模块化钢结构中创新性自定心可修复SMA螺栓连接的抗震性能
Modular steel construction (MSC) is widely noticed and adopted in the building industry for its benefits of short construction period, low carbon emission, and great flexibility. The performance of inter-module connections, including the strength, toughness and ductility, is the focus of maintaining the load transfer mechanism and overall stability of modular structures. The structure with favorably designed connections can dissipate expected energy under cyclic loading with reduced structural damage. A self-centering and repairable connection (SRC) is herein proposed, with the benefits of a distinct load transmission path and easy assembly. Four full-size specimens were fabricated and tested under low-cycle loading, and the tested specimens were subsequently repaired by replacing angle cleats. The failure mode and bearing capacity of both SRC and repaired SRC specimens were investigated. Several seismic performance indices of the specimens, including hysteresis curves, strength and stiffness degradation, energy dissipation capacity, self-centering and repairable ability, were obtained. Furthermore, the performance of the SRC was comprehensively assessed according to Eurocode 3 Part 1-8, Chinese code GB 50011-2010, and American code AISC 341-16. In addition, an accurate finite element model (FEM) of the SRC was created and verified using experimental results. The developed FEM was used to investigate the effects of critical parameters, including angle cleat thickness and grade, vertical bolt diameter, and SMA bolt number and diameter, on the seismic performance of SRCs. Both experimental and FEM results show that only the replaceable angle cleats experienced the noticed plastic deformation for SRC specimens under cyclic loading, and SMA bolts provided the required self-centering force. It can be hence concluded that the proposed SRC can achieve the expected self-centering and recovery function.
模块化钢结构以其工期短、碳排放低、灵活性大等优点在建筑行业得到广泛关注和采用。模块间连接的强度、韧性和延性等性能是维持模块化结构荷载传递机制和整体稳定性的关键。在循环荷载作用下,连接设计合理的结构可以耗散预期能量,降低结构损伤。本文提出了一种自定心可修连接(SRC),具有负载传递路径清晰、装配方便等优点。制作了4个全尺寸试件,在低周载荷下进行了试验,并对试件进行了补角修复。研究了修复后和修复后试件的破坏模式和承载力。得到了试件的滞回曲线、强度和刚度退化、耗能能力、自定心和可修复能力等抗震性能指标。根据欧洲规范3第1-8部分、中国规范GB 50011-2010和美国规范AISC 341-16对混凝土混凝土的性能进行了综合评价。此外,还建立了结构的精确有限元模型,并用实验结果进行了验证。采用所开发的有限元方法,研究了角缝厚度和等级、垂直螺栓直径、SMA螺栓数量和直径等关键参数对混凝土抗震性能的影响。试验和有限元分析结果均表明,在循环荷载作用下,SRC试件只有可替换角夹角产生了明显的塑性变形,SMA螺栓提供了所需的自定心力。由此可以得出结论,所提出的SRC能够实现预期的自定心和恢复功能。
A novel method for fully penetrated U-rib-to-deck joints: single-sided oscillating laser arc hybrid welding
Yuantai Li, Shaoning Geng, Chu Han, Jun Jin, Ping Jiang
doi:10.1016/j.tws.2024.112378
一种新型的u型肋-甲板全渗透连接方法:单面振荡激光电弧混合焊接
U-rib-to-deck (RTD) joints represent one of the most critical and vulnerable welding details of orthotropic steel decks. Aiming for full penetration and high-level service performance, a novel method with single-sided oscillating laser-arc hybrid welding (OLAHW) technique was proposed for the RTD joint. The weld formation, microstructure and mechanical properties were extensively investigated. The results indicated that the porosity and lack of fusion (LoF) defects effectively suppressed with the beam oscillation during LAHW process. The OLAHW technique has good spatial accessibility with larger laser beam incidence angle of 20°. Beam oscillation led to an increase in acicular ferrite in the fusion zone (FZ) while simultaneously a reduction of martensite in the heat effected zone (HAZ). This was related to the cooling time, and the thermal simulation results revealed that the OLAHW sample demonstrated comparable cooling times in both the Laser-FZ and arc-FZ. Consequently, beam oscillation can generated more homogeneous microstructures and microhardness. Although the microhardness of the OLAHW sample in the FZ was increased compared to the conventional arc welding (CAW) and LAHW sample, the highest microhardness value remained within acceptable limits (380 HV). Moreover, the ultimate tensile strength of the OLAHW weld sample increased by 7% compared to the CAW weld sample. The application of the OLAHW technique demonstrates its feasibility for engineering applications in orthotropic steel decks manufacturing.
u型肋-甲板(RTD)接头是正交异性钢甲板最关键、最脆弱的焊接部位之一。以全熔透和高使用性能为目标,提出了单面振荡激光-电弧复合焊接(OLAHW)方法。对焊缝成形、显微组织和力学性能进行了广泛的研究。结果表明,在law过程中,梁的振荡有效地抑制了多孔性和不熔合缺陷。OLAHW技术具有较好的空间可达性,光束入射角可达20°。束流振荡导致熔合区针状铁素体增加,热影响区马氏体减少。这与冷却时间有关,热模拟结果表明,OLAHW样品在Laser-FZ和arc-FZ中都表现出相当的冷却时间。因此,梁振荡可以产生更均匀的显微组织和显微硬度。与传统电弧焊(CAW)和LAHW试样相比,FZ中OLAHW试样的显微硬度有所提高,但最高显微硬度值仍在可接受范围内(380 HV)。此外,与CAW相比,OLAHW焊缝试样的极限抗拉强度提高了7%。OLAHW技术在正交各向异性钢甲板制造中的工程应用证明了其可行性。
Microstructure and mechanical properties of GH4169 thin-walled parts fabricated by ultrasonic vibration assisted laser directed energy deposition/milling hybrid process
Heng Zhou, Yongqiang Yang, Changjun Han, Linqing Liu, Zhongwei Yan, Yang Wei, Renwu Jiang, Xiaoqi Chen, Di Wang
doi:10.1016/j.tws.2024.112349
超声振动辅助激光定向能沉积/铣削复合工艺制备GH4169薄壁件的组织与力学性能
Ultrasonic vibration (UV) was employed for the first time to assist laser directed energy deposition/milling hybrid process (LMHP) in fabricating GH4169 thin-walled parts. The effects of building strategy, including UV-assistance, milling rounds, and building heights, on the thermal history, printability, microstructure, and mechanical properties of the fabricated thin-walled parts were systematically investigated. The thermal history analysis revealed that the UV-assistance resulted in a reduction in the average temperature of the laser scanning area, an increase in pore defects, and compromised surface finish due to an enlarged molten pool and enhanced heat transfer. Moreover, the thin-walled parts exhibited refined grain structure, equiaxed crystallization, homogenized element distribution, decreased proportion of the Laves phase, and increased strength with UV-assistance. Notably, the grain size was significantly reduced from a millimetre scale to 86.2 μm, while the average yield strength increased from 489.1 MPa to 523.6 MPa and the average ultimate tensile strength increased from 747.1 MPa to 830.4 MPa. Furthermore, introducing more hybrid-processed interfaces within a certain distance allowed for further grain refinement, enhanced strength, and decreased elongation in the GH4169 thin-walled part. This work is anticipated to provide a comprehensive understanding of the thin-walled parts fabricated by UV-assisted LMHP with high surface quality and superior mechanical properties.
首次利用超声振动(UV)辅助激光定向能沉积/铣削混合工艺(LMHP)加工GH4169薄壁件。系统地研究了制造策略,包括uv辅助,铣削圆和制造高度,对制造薄壁零件的热历史,可打印性,微观结构和机械性能的影响。热历史分析表明,uv辅助导致激光扫描区域的平均温度降低,孔隙缺陷增加,由于熔池扩大和传热增强,表面光洁度降低。在紫外辅助下,薄壁件晶粒组织细化,晶化等轴,元素分布均匀,Laves相比例减少,强度提高。晶粒尺寸从mm级明显减小到86.2 μm,平均屈服强度从489.1 MPa提高到523.6 MPa,平均极限抗拉强度从747.1 MPa提高到830.4 MPa。此外,在一定距离内引入更多的混合加工界面,可以进一步细化GH4169薄壁件的晶粒,提高强度,降低伸长率。这项工作有望为紫外辅助LMHP制造具有高表面质量和优异机械性能的薄壁零件提供全面的了解。
Influence of overlap rate and ultrasonic compaction on mechanical performance for additive manufacturing of continuous carbon fiber reinforced polylactic acid composites
Yaxing Song, Congze Fan, Wenzhe Song, Jinghua Zheng, Yiwei Chen, Zhongde Shan
doi:10.1016/j.tws.2024.112374
重叠率和超声压实对增材制造连续碳纤维增强聚乳酸复合材料力学性能的影响
The additive manufacturing (AM) technology of continuous fiber reinforced thermoplastic composites (CFRTPCs) is gaining attention in the composites industry due to its excellent mechanical performance, potential designability and light-weight structures. Process parameters of AM have a significant impact on mechanical performance and forming accuracy. There is still a Lack of clear design basis for hatch spacing as structural parameter. This study focused on the effect of overlap rate on AM performance of continuous carbon fiber (CCF)/polylactic acid (PLA) composites through the mechanical test, surface morphology, defects characterization and failure analysis, and investigated the adaptability of ultrasonic compaction post-treatment to overlap rate settings. The results indicated that proper overlap state between filaments was beneficial for mechanical properties. The optimal interlaminar shear strength (ILSS) increased to 22.72 MPa by 56% and tensile strength improved by 17.5% to 721.65 MPa at various overlap rates. Surface roughness remained stable at approximately 33 μm. Ultrasonic compaction achieved a maximum ILSS up to 24.84 MPa with improvement of 10.26%, and tensile strength reached to 736.76 MPa with 2.09% improvement, showing excellent adaptability to overlap rate design. Research findings will improve understanding of digital adjustment mechanisms for printing parameters and provide design guidance for high-performance AM technology of CFRTPCs.
连续纤维增强热塑性复合材料(cfrtpc)的增材制造(AM)技术因其优异的力学性能、可设计性和结构轻量化而受到复合材料行业的关注。增材制造的工艺参数对机械性能和成形精度有重要影响。舱口间距作为结构参数,目前还缺乏明确的设计依据。本研究通过力学测试、表面形貌、缺陷表征和失效分析,重点研究了重叠率对连续碳纤维(CCF)/聚乳酸(PLA)复合材料增材制造性能的影响,并研究了超声压实后处理对重叠率设置的适应性。结果表明,适当的丝间重叠状态有利于提高材料的力学性能。在不同重叠率下,最佳层间剪切强度(ILSS)提高56%,达到22.72 MPa,抗拉强度提高17.5%,达到721.65 MPa。表面粗糙度稳定在33 μm左右。超声压实的最大ILSS达到24.84 MPa,提高了10.26%,抗拉强度达到736.76 MPa,提高了2.09%,对重叠率设计具有良好的适应性。研究结果将提高对打印参数数字调节机制的理解,并为高性能碳纤维复合材料增材制造技术提供设计指导。
Nonlinear thermo-electro-mechanical responses and active control of functionally graded piezoelectric plates subjected to strong electric fields
Yu Zhang, Xuankai Guo, Yufan Wu, Yangyang Zhang, He Zhang, Chaofeng Lü
doi:10.1016/j.tws.2024.112375
强电场作用下功能梯度压电板的非线性热-电-机械响应及主动控制
Functionally graded piezoelectric plates (FGPPs) are often exposed to extreme thermal environments and subjected to large amplitude excitation and strong electric fields. Accurately predicting the nonlinear behaviors of FGPPs under large thermo-electro-mechanical loads remains a considerable challenge. This paper proposes a comprehensive nonlinear coupled analysis model that considers geometric nonlinearity, piezoelectric nonlinearity, and the temperature dependence of piezoelectric parameters. The total Lagrangian incremental finite element equations for FGPPs under thermo-electro-mechanical loads are derived using Hamilton's principle, by employing the first-order shear deformation theory and the von Kármán nonlinear strain-displacement relationship. The accuracy of the model is validated through comparative studies. Based on this multi-nonlinear model, we further investigate the effects of geometric nonlinearity, piezoelectric nonlinearity, and temperature dependence on the nonlinear static bending, dynamic responses, and active control of FGPPs. This study demonstrates that considering these factors enables accurate prediction of the static, dynamic, and active control behaviors of FGPPs.
功能梯度压电板(FGPPs)经常暴露在极端的热环境中,并受到大振幅激励和强电场的作用。准确预测FGPPs在大热机电负荷下的非线性行为仍然是一个相当大的挑战。本文提出了一种综合考虑几何非线性、压电非线性和压电参数温度依赖性的非线性耦合分析模型。利用Hamilton原理,利用一阶剪切变形理论和von Kármán非线性应变-位移关系,推导了热电-机械载荷作用下FGPPs的总拉格朗日增量有限元方程。通过对比研究验证了模型的准确性。基于该多非线性模型,我们进一步研究了几何非线性、压电非线性和温度依赖对FGPPs非线性静态弯曲、动态响应和主动控制的影响。该研究表明,考虑这些因素可以准确预测FGPPs的静态、动态和主动控制行为。
Behavior of randomly pitted Q690 high-strength steel H-section members under eccentric compression
Lei Zhong, Chen Jia, Yongsong Shao, Xiaohan Sang, Zhibo Dong
doi:10.1016/j.tws.2024.112369
Q690高强钢h型钢随机点蚀构件偏心受压性能
Six Q690 high-strength steel H-section specimens with pits were tested under eccentric compression loads. The results showed that the pits changed the failure modes of the members under eccentric compression by inducing local buckling, which resulted in a significant reduction in the ultimate resistance, reaching 31.7% when the volume loss ratio was 15%. A numerical study was then conducted, which revealed that the ultimate resistance loss ratio varied with the volume loss ratio and the eccentricity ratio, but not with the slenderness ratio. Finally, the existing rules for determining the ultimate resistance were modified by using the equivalent residual thickness, and the applicability of the modification was assessed.
对6个Q690高强钢带坑h型钢试件进行了偏心压缩试验。结果表明:凹坑通过诱导局部屈曲改变构件偏心受压破坏模式,使构件的极限阻力显著降低,当体积损失比为15%时,极限阻力降低31.7%;数值研究表明,极限阻力损失比随体积损失比和偏心比的变化而变化,但与长细比无关。最后,利用等效残余厚度对现有的极限抗力确定规则进行了修正,并对修正后的适用性进行了评价。
A cable finite element formulation based on exact tension field for static nonlinear analysis of cable structures
Wenxiong Li, Qikun Huang, Suiyin Chen
doi:10.1016/j.tws.2024.112371
基于精确张力场的索结构静力非线性有限元分析
This paper presents a numerically exact cable finite element model for static nonlinear analysis of cable structures. The model derives the exact expression of the tension field using the geometrically exact beam theory coupled with the fundamental mechanical characteristics of cables. The equations for the cable elements are formulated by addressing the equilibrium conditions at the element boundaries and ensuring compatibility within the elements. Unlike previous studies that typically provide explicit expressions for cable models, this study develops a formulation that emphasizes numerical precision and broad applicability. It achieves this by deriving linearized equations with implicit expressions incorporating integrals. The present model accurately computes internal forces and deformation states, and determines the unstrained length of the cable. Additionally, it accounts for the variability in cross-sectional stiffness along the cable's length. The paper discusses solution implementations using the complete tangent matrix and element internal iterations. The effectiveness of the proposed cable elements is demonstrated through numerical examples.
本文提出了一种用于索结构静力非线性分析的数值精确的索有限元模型。该模型采用几何精确梁理论,结合索的基本力学特性,推导出张力场的精确表达式。通过解决单元边界处的平衡条件并确保单元之间的兼容性,制定了电缆单元的方程。与以往的研究通常为电缆模型提供显式表达式不同,本研究开发了一个强调数值精度和广泛适用性的公式。它通过推导包含积分的隐式表达式的线性化方程来实现这一点。该模型准确地计算了索的内力和变形状态,并确定了索的非应变长度。此外,它还考虑了沿电缆长度的截面刚度的变化。本文讨论了使用完全切矩阵和元素内部迭代的求解实现。通过数值算例验证了所提索单元的有效性。
Clockwise vs Anti-Clockwise Chiral Metamaterials: Influence of Base Tessellation Symmetry and Rotational Direction of Chiralisation on Mechanical Properties
Luke Mizzi, Luigi Grasselli, Andrea Spaggiari
doi:10.1016/j.tws.2024.112381
顺时针与逆时针手性超材料:基镶嵌对称性和手性化旋转方向对力学性能的影响
Chiral honeycombs are a class of auxetic metamaterials which are characterised by a lack of plane symmetry. Besides the traditional chiral honeycombs based on regular monohedral tessellations such as the hexachiral and tetrachiral honeycombs, a vast range of auxetic chiral metamaterials may be produced through the ‘chiralisation’ of Euclidean tessellations made from polyhedral tilings and/or irregular monohedral polygons. In this work, we show for the first time, how the direction of the geometric chiral transformation, i.e. clockwise vs anti-clockwise chiralisation, has an influence on the mechanical properties and deformation modes of the resultant chiral metamaterial systems. This influence, which is a result of the intrinsic absence of axial symmetry in the original base tessellation, can lead to the production of two unique and distinct chiral metamaterial configurations with completely different mechanical properties originating from a single base tessellation. In this work we demonstrate and quantify, through a wide range of numerical simulations and experimental tests on additively-manufactured prototypes, the effect of the direction of chiralisation on two tessellations: a Florent pentagonal system with hexagonal rotational symmetry and a hexagonal monohedral tessellation with trigonal rotational symmetry. The results obtained show that the clockwise and anti-clockwise chiral structures exhibit significantly different mechanical properties and deformation modes, highlighting the increased versatility of this relatively novel class of chiral metamaterials.
手性蜂窝是一类以缺乏平面对称性为特征的辅助超材料。除了传统的基于规则单面镶嵌的手性蜂巢,如六手性和四手性蜂巢,大量的非手性超材料可以通过由多面体瓷砖和/或不规则单面多边形制成的欧几里得镶嵌的“手性化”来生产。在这项工作中,我们首次展示了几何手性变换的方向,即顺时针和逆时针手性化,如何影响所得手性超材料系统的机械性能和变形模式。这种影响是原始基镶嵌中固有的轴对称缺失的结果,可以导致产生两种独特的、截然不同的手性超材料构型,它们具有源自单一基镶嵌的完全不同的机械性能。在这项工作中,我们通过广泛的数值模拟和加性制造原型的实验测试,证明并量化了手化方向对两种镶嵌的影响:具有六边形旋转对称的Florent五边形系统和具有三角形旋转对称的六边形单面体镶嵌。结果表明,顺时针和逆时针的手性结构表现出明显不同的力学性能和变形模式,突出了这类相对新颖的手性超材料的多功能性。
Spatial tuning of the positive and negative Poisson's ratio of metamaterials through gradient design
XiangLong Zhou, Xian Liu, AiGuo Zhao, Chuang Liu, HengAn Wu
doi:10.1016/j.tws.2024.112382
基于梯度设计的超材料正、负泊松比的空间调谐
The design of negative Poisson's ratio materials has received much attention in recent years. However, there are few focus on tuning spatial negative and positive Poisson's ratio behavior, which has potential applications in engineering such as mimicking the mechanics behavior of natural tissue. In this study, a two-dimensional rectangular perforated material is used as an example, and the positive-negative Poisson's ratio (PPR-NPR) behavior is successfully obtained by gradient design. Deep learning combined with meta-heuristic algorithms is used to material design for targeted deformation behaviors, enabling precise control over material deformation, customization of constitutive models, and constrained single-objective material optimization. The gradient design is expected to be extended to different configurations to realize the tunable positive-negative Poisson's ratio of the materials, which will provide broader possibilities for the design and fabrication of new negative Poisson's ratio materials.
负泊松比材料的设计近年来受到了广泛的关注。然而,目前很少有人关注调节空间负、正泊松比行为,这在工程上有潜在的应用,如模拟自然组织的力学行为。本研究以二维矩形多孔材料为例,通过梯度设计成功获得了正-负泊松比(PPR-NPR)行为。将深度学习与元启发式算法相结合,用于材料变形行为的目标设计,实现对材料变形的精确控制、本构模型的定制和约束单目标材料优化。梯度设计有望扩展到不同的构型,实现材料正负泊松比的可调,这将为新型负泊松比材料的设计和制造提供更广阔的可能性。
Experimental and numerical study of aluminium alloy angle-section stub columns
Yao Sun, Zining Wang, Jun Xia, Fernando R. Sarquis, Luciano R.O. de Lima
doi:10.1016/j.tws.2024.112361
铝合金角截面短柱的试验与数值研究
This paper reports experimental and numerical studies on the behaviour and compression resistances of aluminium alloy angle-section stub columns. A testing programme was firstly carried out, including material coupon tests and stub column tests. Both equal-leg and unequal-leg angle-sections were considered in the testing programme. The member lengths of the angle-section stub column specimens were selected based on a preliminary elastic buckling analysis prior to testing, in which their predominant failure buckling mode was analytically found to be torsional buckling. The torsional buckling failure mode was also clearly observed in the testing programme, indicating that angle-section stub columns exhibit different failure mode from their hollow-section and T-section counterparts that are susceptible to local buckling. Upon completion of the testing programme, a numerical modelling programme was conducted, where finite-element models were developed and validated against the test results. The validated models were then adopted to conduct parametric studies to generate more numerical data. The obtained test and numerical data were used to perform a design analysis, where the relevant design rules in the European, American, Australian/New Zealand and Chinese standards were evaluated. The analysis results indicate that both the European and Australian/New Zealand standards result in conservative resistance predictions for angle-section stub columns with low and high torsional slendernesses. Meanwhile, they offer unsafe resistance predictions for some angle-section stub columns with intermediate torsional slendernesses. In contrast, the American and Chinese standards yield a high level of design conservatism over the full range of torsional slendernesses.
本文报道了铝合金角截面短柱的性能和抗压性能的试验和数值研究。首先进行了一套试验方案,包括材料粘结试验和短柱试验。在试验方案中考虑了等腿角截面和不等腿角截面。基于试验前的初步弹性屈曲分析,选择了角截面短柱试件的构件长度,分析发现其主要破坏屈曲模式为扭转屈曲。在试验程序中也清楚地观察到扭转屈曲破坏模式,表明角截面短柱的破坏模式与容易发生局部屈曲的空心截面和t形截面短柱不同。在完成测试程序后,进行了数值模拟程序,开发了有限元素模型,并根据测试结果进行了验证。然后采用验证过的模型进行参数化研究,得到更多的数值数据。获得的试验和数值数据用于进行设计分析,其中评估了欧洲,美国,澳大利亚/新西兰和中国标准的相关设计规则。分析结果表明,无论是欧洲标准还是澳大利亚/新西兰标准,对低扭长和高扭长角截面短柱的阻力预测都较为保守。同时,对一些具有中等扭转细长度的角截面短柱提供了不安全抗力预测。相比之下,美国和中国的标准在整个扭转细长度范围内产生了高水平的设计保守性。
Long-Term Relaxation Analysis of Steel Cables Based on Viscoelastic Model
Yue Feng, Xingfei Yuan, Weijia Zhang, Manyu Deng
doi:10.1016/j.tws.2024.112363
基于粘弹性模型的钢索长期松弛分析
Steel cables, renowned for their lightweight and high-strength properties, stand as ubiquitous building materials in large-span structures. Serving as crucial load-bearing elements, cables endure sustained tension throughout the structure's lifecycle. To further investigate the long-term relaxation characteristics of steel cables and provide more theoretical basis for structural relaxation calculations, this paper introduces a long-term relaxation constitutive model for steel cables, formulated through theoretical derivation, experimental validation, and data fitting techniques to establish time-dependent constitutive relationships. By employing the Bingham and Kelvin viscoelastic models, a relaxation model for steel cables is presented and optimized accordingly. Experimental investigations involve long-term tests on steel cables with three different sizes and detailed fitting analysis on collected internal force relaxation data. The findings emphasize the indispensability of structural relaxation behavior and the significance of altering internal forces, particularly in large-span cable-strut structures. The developed numerical model enables accurate simulation and prediction of long-term time-dependent performance in such structures, serving as a springboard for future studies in this domain.
钢索以其轻质、高强的特性而闻名,在大跨度结构中是无处不在的建筑材料。作为关键的承重元件,电缆在整个结构的生命周期中承受持续的张力。为了进一步研究钢索的长期松弛特性,为结构松弛计算提供更多的理论依据,本文通过理论推导、实验验证和数据拟合技术,建立了钢索的长期松弛本构模型,建立了随时间变化的本构关系。采用Bingham粘弹性模型和Kelvin粘弹性模型,建立了钢索的松弛模型,并对模型进行了优化。实验研究包括对三种不同尺寸的钢索进行长期试验,并对收集到的内力松弛数据进行详细的拟合分析。研究结果强调了结构松弛行为的必要性和改变内力的重要性,特别是在大跨度索杆结构中。所开发的数值模型能够准确模拟和预测此类结构的长期随时间变化的性能,为该领域的未来研究提供了跳板。
Buckling and vibro-acoustic behavior analysis of laminated immersed cylindrical shells with hydrostatic pressure based on Chebyshev-Fourier spectral approach
Tiangui Ye, Tiantong Zhao, Yukun Chen, Guoyong Jin, Yuehua Chen, Zhigang Liu
doi:10.1016/j.tws.2024.112376
基于切比雪夫-傅立叶谱方法的静水压力下层合沉圆柱壳屈曲及振声特性分析
The buckling and vibroacoustic behaviour of laminated cylindrical shell structures is vital for the safety and operational efficiency of underwater vehicles. This paper introduces a Chebyshev-Fourier spectral approach for the comprehensive analysis of buckling and vibro-acoustic behaviour in water-immersed laminated cylindrical shells under external hydrostatic pressure. The approach combines Chebyshev polynomials and Fourier series to approximate the displacement of shell and acoustic pressure of the fluid-structure-interaction (FSI) surface in cylindrical coordinates. An approximate solution is used in the axial direction, while an analytical solution is used in the circumferential direction, allowing for the analysis of different circumferential wave numbers n. The influence of external fluid pressure is characterized through the Helmholtz boundary integral equation, while the effect of hydrostatic pressure is deduced using linear elastic theory. From a theoretical derivation standpoint, hydrostatic pressure leads to a reduction in equivalent stiffness, while the external fluid contributes to an increase in the effective mass matrix. Validated against established literature analysis, the study finds that hydrostatic pressure decreases the natural frequencies, though the impact is less significant for lower circumferential wave numbers. For these lower wave numbers, the overall radiated sound power remains largely independent of external hydrostatic pressure, regardless of being in air or water. However, at higher circumferential wave numbers, the effect is more pronounced. This study not only advances the theoretical framework for analysing submerged cylindrical shells but also provides crucial insights into designing more robust structures for underwater applications.
层合柱壳结构的屈曲和声振特性对水下航行器的安全性和运行效率至关重要。本文介绍了一种切比雪夫-傅立叶谱方法,用于综合分析水浸层合圆柱壳在静水压力作用下的屈曲和振动声行为。该方法将切比雪夫多项式和傅立叶级数结合起来,在柱坐标系下近似求解壳的位移和流固耦合表面的声压。轴向采用近似解,周向采用解析解,可对不同周向波数n进行分析。外部流体压力的影响通过亥姆霍兹边界积分方程表征,静水压力的影响采用线弹性理论推导。从理论推导的角度来看,静水压力导致等效刚度的减小,而外部流体有助于有效质量矩阵的增加。通过对已有文献分析的验证,该研究发现静水压力降低了固有频率,尽管对较低的周向波数的影响不太显著。对于这些较低的波数,无论在空气中还是在水中,总的辐射声功率在很大程度上与外部静水压力无关。然而,在较高的周向波数下,这种效应更为明显。这项研究不仅推进了分析水下圆柱壳的理论框架,而且为设计更坚固的水下应用结构提供了重要的见解。