Thin-Walled Structures最新文献_第3页

Nonlinear snap-through vibrations and energy harvesting for bistable piezoelectric composite laminated plate supported at four corners

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-23 DOI: 10.1016/j.tws.2025.112991

X.T. Guo , Y.F. Zhang , W. Zhang , A. Amer

The bistable piezoelectric composite laminates have two stable states, which can undergo the nonlinear large amplitude vibrations, namely the snap-through vibrations, are used to the broadband energy harvesting. This paper proposes a bistable energy harvester for the bistable piezoelectric composite laminates with the simply supporting of four corners. The nonlinear vibrations and energy harvesting are studied for the bistable piezoelectric composite laminates. It is determined that the piezoelectric layer attached to the asymmetric bistable four corner simply-support (FCSS) composite laminate still maintains two stable-states. The energy curves of the system have two potential wells, but it is not symmetric. The displacement bifurcation diagram, voltage bifurcation diagram and corresponding maximum Lyapunov exponent are simulated. The waveform, phase portrait and Poincaré map are utilized to illustrate the complex nonlinear dynamic phenomena of the bistable FCSS piezoelectric energy harvesters. The forward sweeps and backward sweeps are performed to identify all-around dynamic behaviors. The output voltage of the bistable piezoelectric FCSS energy harvester is evaluated. Analyzing the amplitude frequency response curves for the displacement and output voltage under different excitation amplitudes, the optimal frequency range of the bistable piezoelectric FCSS energy harvester is determined. As the excitation amplitude increases, the frequency bandwidth of the snap-through vibration also increases. Due to the soft spring characteristics and hysteresis effect of the system, a significant deviation is observed between the forward and backward frequency scans, indicating that during the backward frequency scan, the limit cycle vibration expands the frequency range of the double-well vibration. The vibration testing platform for piezoelectric testing is built and the voltage signal of the bistable piezoelectric FCSS composite laminate is tested.

双稳态压电复合材料层压板具有两种稳定状态，可发生非线性大振幅振动，即 "快穿 "振动，可用于宽带能量收集。本文针对四角简单支撑的双稳态压电复合材料层压板提出了一种双稳态能量收集器。研究了双稳态压电复合层压板的非线性振动和能量收集。结果表明，非对称双稳态四角简支（FCSS）复合层压板上的压电层仍能保持两个稳定状态。系统的能量曲线有两个势阱，但并不对称。模拟了位移分岔图、电压分岔图和相应的最大 Lyapunov 指数。利用波形、相位图和 Poincaré 图来说明双稳态 FCSS 压电能量收集器的复杂非线性动态现象。通过正向扫描和反向扫描来识别全方位的动态行为。评估了双稳态 FCSS 压电能量收集器的输出电压。通过分析不同激励幅值下位移和输出电压的幅频响应曲线，确定了双稳态压电 FCSS 能量收集器的最佳频率范围。随着激励振幅的增大，快通振动的频率带宽也随之增大。由于系统的软弹簧特性和滞后效应，正向和反向频率扫描之间出现了显著偏差，表明在反向频率扫描期间，极限循环振动扩大了双阱振动的频率范围。建立了用于压电测试的振动测试平台，并测试了双稳态压电 FCSS 复合层压板的电压信号。

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引用次数: 0

In situ chemical bonding at the 30 wt.% GF/PA6-A2024 aluminium alloy interface via ultrasonic-assisted injection moulding

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-23 DOI: 10.1016/j.tws.2025.112983

Baojia Cheng , Shumei Lou , Haoyu Wang , Fang Liu , Shukai Zhang , Yunwei He , Ruobing Sun , Leyao Xu , Xiping Li

In injection moulding processes with metal inserts, chemical bonds cannot be directly formed at the interface between polymers and metals without the application of special intermediate agents to form chemical bridges, which involves cumbersome steps and reduces production efficiency. This work successfully achieved in situ chemical bonding on a 30 wt.% GF/PA6-A2024 joint during the injection moulding process with the assistance of ultrasonic vibration. Effects of ultrasonic time and ultrasonic power on the interfacial bonding strength at different temperatures were analysed. The mechanism of in situ chemical bonding generated by ultrasonic-assisted injection moulding was explored in depth through experimental characterization combined with molecular dynamics. An appropriate ultrasonic energy (the product of ultrasonic time and ultrasonic power) can reduce the viscosity of the melted polymer and increase the surface free energy of the metal, resulting in rapid interfacial bonding. Notably, ultrasonic vibration can also cause a sharp increase in the interfacial temperature, converting molten PA6 into an oxygen-rich state and realizing in situ C‒O‒Al and hydrogen bonds at the interface under cavitation impact. With an ultrasonic time of 10 s and an ultrasonic power of 400 W, the normal-temperature tensile shear strength of 30 wt.% GF/PA6-A2024 reached 40.98 MPa, which is a 97.9% improvement over that without ultrasonic vibration. This work can help eliminate the need to apply intermediate agents, enabling in situ chemical bonding at the interface during the injection moulding process and providing an environmentally friendly and efficient method for enhancing the interfacial bonding strength of metal‒polymer joints.

在使用金属嵌件的注塑成型工艺中，如果不使用特殊的中间剂形成化学桥，就无法在聚合物和金属之间的界面上直接形成化学键，这涉及到繁琐的步骤并降低了生产效率。这项研究利用超声波振动，在注塑成型过程中成功实现了 30 wt.% GF/PA6-A2024 接头的原位化学键合。分析了超声波时间和超声波功率对不同温度下界面结合强度的影响。通过实验表征结合分子动力学，深入探讨了超声波辅助注塑成型产生的原位化学键合机理。适当的超声波能量（超声波时间和超声波功率的乘积）可以降低熔化聚合物的粘度，增加金属的表面自由能，从而快速形成界面粘结。值得注意的是，超声波振动还能使界面温度急剧升高，使熔融 PA6 转变为富氧状态，并在空化冲击下实现界面上的原位 C-O-Al 键和氢键。在超声时间为 10 s、超声功率为 400 W 的条件下，30 wt.% GF/PA6-A2024 的常温拉伸剪切强度达到了 40.98 MPa，比没有超声振动时提高了 97.9%。这项工作有助于消除使用中间剂的需要，在注塑成型过程中实现界面原位化学键合，为提高金属聚合物接头的界面键合强度提供了一种环保、高效的方法。

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引用次数: 0

Plate buckling in the framework of a modified RRD concept from shell buckling

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-23 DOI: 10.1016/j.tws.2025.112992

R. Timmers, M. Ladinek, R. Lang

The Eurocode EN 1993-1-5 rules the proof against plate buckling of unstiffened and stiffened plated structures. Alternatively, the proof can be carried out numerically using the new Eurocode prEN 1993-1-14. However, the numerical proof with the Finite-Element Method (FEM) can be very time-consuming due to the high modelling effort and the verification and validation process of the model. This is where the Reference Resistance Design (RRD) concept from shell buckling, ruled in EN 1993-1-6, comes in. The idea of the RRD concept is to perform numerical simulations and obtain generalized capacity curves based on these resistances. As the application of the RRD concept to plate buckling problems is new, the question arises of whether the RRD concept can map the different coupled stability phenomena, like local and global plate buckling, post-critical behaviour, column-like behaviour, torsional buckling of open stiffeners, etc. Therefore, extensive numerical studies were carried out on the typical case of longitudinally stiffened plates with flat stiffeners. The numerical resistances were used as the basis for determining the RRD parameters of the generalized capacity curves. It was found that the RRD concept is suitable for mapping the complex load-bearing behaviour of stiffened plated elements. Nevertheless, larger deviations were found for the current version of the RRD concept, which is why a modified version is proposed. The obtained RRD parameters are given as supplemental text files to this paper. The RRD concept appears to be a simple alternative to the proofs from EN 1993-1-5. The time-consuming determination of the RRD parameters is a significant disadvantage, but the RRD concept can be very helpful in cases not covered by EN 1993-1-5.

欧洲规范 EN 1993-1-5 规定了非加固和加固板结构的板屈曲证明。另外，也可以使用新的欧洲规范 prEN 1993-1-14 进行数值证明。然而，使用有限元法（FEM）进行数值证明非常耗时，因为模型的建模工作以及验证和确认过程都很繁重。这就是 EN 1993-1-6 中规定的壳体屈曲参考阻力设计 (RRD) 概念的由来。RRD 概念的理念是进行数值模拟，并根据这些阻力获得通用的承载能力曲线。由于将 RRD 概念应用于板屈曲问题是一项新技术，因此出现的问题是 RRD 概念能否映射不同的耦合稳定性现象，如局部和整体板屈曲、临界后行为、柱状行为、开放式加劲件的扭转屈曲等。因此，我们对带有平面加强筋的纵向加强板的典型情况进行了广泛的数值研究。数值阻力被用作确定广义承载力曲线 RRD 参数的基础。研究发现，RRD 概念适用于绘制加劲板构件的复杂承载行为。然而，当前版本的 RRD 概念存在较大偏差，因此提出了一个修改版本。获得的 RRD 参数作为本文的补充文本文件。RRD 概念似乎是 EN 1993-1-5 证明的一个简单替代方案。RRD 参数的确定非常耗时，这是一个明显的缺点，但 RRD 概念对 EN 1993-1-5 未涵盖的情况非常有帮助。

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引用次数: 0

Design, fabrication and mechanical properties of multi-dimensional graded-amplitude gyroid structures

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-23 DOI: 10.1016/j.tws.2025.113002

Xiaofei Ma, Ce Guo, Yuxuan Wang, Jingyu Shen, Xiao Wang

Graded Triply periodic minimal surface (TPMS) lattice structures have gained significant attention due to their ability to enhance the mechanical and energy-absorbing properties of uniform structures. However, current studies have focused primarily on the graded design of topological constants, relative density, size, and wall thickness and there has been less research on the design of graded-amplitude TPMS structures. Inspired by some biological gradient structures, this study presents a method for designing multi-dimensional graded-amplitude structures based on a Gyroid structure. A graded-amplitude Gyroid structure was fabricated using stainless steel 316L powder by selective laser melting (SLM). The mechanical properties of the structures were investigated using quasi-static compression tests and numerical simulation methods. The findings indicate that the manufacturing accuracy of SLM fabrication is affected by the variation in the structure amplitude. A smaller amplitude results in more particles adhering to the structure surface. Additionally, a graded-amplitude can alter the angle between the structure surface and the loading direction, which affects the mechanical properties and energy absorption capacity of the structure. The specific energy absorption of the three-dimensional gradient structure with amplitude variation range of 0-1 reaches 33.98 J/g, which is 35.76 % higher than that of the uniform structure. Furthermore, graded-amplitude can change the deformation pattern of the structure. The one-dimensional gradient structures with amplitude variations ranging from 0 to 2 displays deformation in a layer-by-layer manner. Moreover, one-dimensional and two-dimensional gradient structures display significant anisotropic properties, whereas three-dimensional gradient structures exhibit approximately orthogonal isotropic characteristics. Finally, a parametric analysis shows that the low-dimensional graded-amplitude structure has better mechanical properties and energy absorption characteristics when the amplitude variation range is greater than 1 but worse when the amplitude variation range is less than 1. This graded-amplitude design method offers new design freedom for porous structures and new ideas for developing energy-absorbing devices.

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引用次数: 0

Structural performance and section classification of austenitic stainless steel welded I-section flexural members 奥氏体不锈钢焊接工字形弯曲构件的结构性能和截面分类

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-22 DOI: 10.1016/j.tws.2025.112958

Junwei Fan , Lu Yang , Keyang Ning

This study investigates the structural performance and section classification of austenitic stainless steel welded I-section flexural members subjected to monotonic and cyclic loading. Finite element models of the stainless steel welded I-section beams were developed using the finite element software ABAQUS, and the validity of the finite element model was verified based on existing experimental research on stainless steel welded I-section member. A comprehensive series of parametric analyses were conducted using the validated finite element model to evaluate the load-bearing capacity and rotation capacity of the stainless steel flexural members under different loading conditions. Additionally, the rationality of the width-to-thickness ratio limits for different section classes, as outlined in the European stainless steel standard EN 1993-1-4 and the Chinese steel structure design standard GB 50017-2017, was assessed. The results indicate that there is a significant correlation between the effect of the width-to-thickness ratio of different components of the section on the section load-carrying capacity and rotation capacity. For austenitic stainless steel welded I-section flexural members, the section classification limits outlined in EN 1993-1-4 are conservative, whereas those in GB 50017-2017 are conservative for certain sections but may be unsafe for others. Furthermore, the loading conditions significantly affect structural performance and should be considered in the section classification. Consequently, an innovative section classification method was proposed, considering the correlation of section components, and new width-to-thickness ratio limits for austenitic stainless steel I-section flexural members were established for various section classes under both monotonic and cyclic loading.

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引用次数: 0

Active nonlinear vibration control of space membrane structure based on deep reinforcement learning 基于深度强化学习的空间膜结构主动非线性振动控制

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-22 DOI: 10.1016/j.tws.2025.112987

Xiang Liu , Guoping Cai

To maintain the working performance of membrane spacecraft, active nonlinear vibration control of space membrane structure is a bottleneck problem of great value and research interest. The traditional model-based vibration control method usually requires a fine dynamic model which is very hard to establish in practice especially when it comes to large-amplitude nonlinear vibration. In this paper, a model-free active vibration control method for space membrane structure based on deep reinforcement learning (DRL) is presented. The proper orthogonal decomposition (POD) modal coordinates obtained from the nonlinear vibration of the space membrane structure caused by attitude maneuvering are selected as the observations. Two stayed cables are used as vibration control actuators, and the control action is applied by adjusting the tension forces in the cable actuators. A DRL agent is trained by using the deep deterministic policy gradient (DDPG) algorithm to suppress the nonlinear vibration of the space membrane structure. Simulation results show that the convergence rate of the training process for the DDPG agent can be improved significantly by choosing the low-order POD modal coordinates as observations, the DRL-based active controller can suppress the nonlinear vibration of the space membrane structure under attitude maneuvering effectively, and the DRL-based vibration controller can even out-perform the model-based controller for some cases.

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引用次数: 0

Thin-walled single and multi-cell CFRP composite tubes in uniform torsion–Local shear and distortional-torsional instability

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-22 DOI: 10.1016/j.tws.2025.112998

J. Loughlan , N.B. Yidris

The buckling performance of thin-walled single and multi-cell CFRP composite tubes in uniform torsion is examined in this paper using both the finite strip and finite element methods of analysis. Due consideration is given in the paper to the influence on performance of flexural anisotropy or the bend-twist coupling characteristics of the composite material. The paper highlights the importance of realising the significance of the applied torque direction on buckling performance. Markedly different stability levels are shown to be in existence for the clockwise and anticlockwise torsional loading cases of the thin-walled multi-cell CFRP composite tubes. This situation is, of course, not realised in isotropic metal construction or in specially orthotropic CFRP composite construction since such material systems are devoid of the effects of material flexural anisotropy and thus the significance of the applied torque direction in this case is no longer appropriate.

本文采用有限条带和有限元分析方法研究了薄壁单孔和多孔 CFRP 复合管在均匀扭转情况下的屈曲性能。文中适当考虑了复合材料的弯曲各向异性或弯曲-扭转耦合特性对性能的影响。论文强调了认识到施加扭矩方向对屈曲性能影响的重要性。研究表明，薄壁多孔 CFRP 复合材料管在顺时针和逆时针扭转加载情况下存在明显不同的稳定性水平。当然，这种情况在各向同性的金属结构或特别正交的 CFRP 复合材料结构中是无法实现的，因为这类材料系统不存在材料挠曲各向异性的影响，因此在这种情况下施加扭矩方向的重要性不再适用。

引用次数: 0

Design and kinematic analysis of origami honeycomb metamaterials with one-DOF radial motion

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-22 DOI: 10.1016/j.tws.2025.112978

Haojie Huang, Jinlong Jiang, Yongquan Li

Rigid origami offers innovative approaches for designing metamaterials with unique mechanical properties. This paper proposes a new family of one-degree-of-freedom (one-DOF) radial-motion honeycomb metamaterials based on a novel rigid origami pattern. First, metamaterial cells based on this pattern were designed and assembled into origami honeycomb structures. The synchronized one-DOF radial motion exhibited by these cells was verified through both circulation laws and an improved Denavit–Hartenberg (D–H) parametric method. The conditions for avoiding physical interference between metamaterial cells and the scalability and geometric kinematic properties of such cells were then investigated. The Poisson's ratios of the metamaterials were analyzed under both linear and nonlinear material properties, with the results showing constant negative Poisson's ratios in all three directions. It was shown that, when nonlinear effects were considered, the negative Poisson's ratio increased with the elastic modulus of the material. Finally, potential engineering applications of the origami honeycomb structure were evaluated, including a novel honeycomb concrete composite structure with potential applications in high axial load environments such as buildings and bridge pillars.

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引用次数: 0

Mechanics of curved chiral beam based three-dimensional metamaterial

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-22 DOI: 10.1016/j.tws.2025.112995

Minghao Li , Zizhen Qi , Chenyang Jiang , Rong Chen , Yuliang Lin , Xiangcheng Li , Yuwu Zhang

Flexible metamaterials with low modulus but progressively enhanced compressive resistance have shown huge potential in flexible protection applications for personnel and sensitive equipment. Ascribed to the specific mechanical properties such as negative Poisson's ratios and significant compressibility, the chiral microstructural configurations have attracted great interests in energy absorption and can therefore be customized for specific designs. However, the more advanced design is still desired. In this paper, a three-dimensional curved chiral beam based lattice (3D-CCBL) was proposed by replacing the conventional straight trusses with curved chiral beams, aiming to achieve novel metamaterial with excellent flexibility and tailorable mechanical properties. Two types of 3D-CCBL specimens, with arc angles ranging from 120° to 210° were fabricated using the selective laser sintering (SLS) additive manufacturing technique. The compressive characteristics of 3D-CCBL were thoroughly investigated via experiments and simulations, considering the effects of anisotropy and relative density. In addition, a theoretical model was derived to predict the compressive modulus and plateau stress of 3D-CCBL, which achieved satisfactory agreement with both experimental measurements and numerical predictions. It is indicated that both types of 3D-CCBL mainly exhibited a bending-dominated deformation mode, although type II of 3D-CCBL possessed better energy-absorbing capacity and resistance to instability. The energy-absorbing capacity of 3D-CCBL can be enhanced by appropriately decreasing the arc angle, whereas the small angles would be more likely lead to instability. This paper provides a framework for guiding the design of three-dimensional flexible and ultra-lightweight metamaterials and promotes their applications in the fields of flexible protections.

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引用次数: 0

Experiments and simulations on the impact resistance of superelastic shape memory alloy reinforced composites

IF 5.7 1区工程技术 Q1 ENGINEERING, CIVIL

Thin-Walled Structures

Pub Date : 2025-01-22 DOI: 10.1016/j.tws.2025.112977

Liangdi Wang , Jun Wang , Yingjie Xu , Yanlong Liu , Xuebei Teng , Jihong Zhu , Weihong Zhang

Carbon fiber reinforced polymer (CFRP) composites are highly valued for their excellent specific strength and stiffness. However, CFRP is vulnerable to impact damage, which is often unavoidable in practical applications. This study investigates the enhancement of impact resistance in CFRP composites through the incorporation of superelastic shape memory alloy (SMA) wires into the CFRP matrix. Unidirectional and bidirectional SMA-reinforced CFRP laminates were fabricated and subjected to low-velocity impact testing. The surface and internal interlaminar damage patterns of the laminates were observed through a combination of visual inspection and ultrasonic C-scan imaging. The impact response of the laminates was analyzed by examining the time-varying curves of impact force and impact point displacement. The results indicate that SMA-reinforced CFRP (SMA-CFRP) demonstrates shallower delamination cracks and reduced interlaminar damage after impact. The maximum impact force of the unidirectional and bidirectional SMA-reinforced CFRP increased by 26.1 % and 29.5 %, respectively, indicating a significant enhancement in the matrix stiffness after the incorporation of SMA. The mechanical mechanisms behind the improved impact resistance were further investigated through simulation analysis, the importance of SMA phase transformation in the energy absorption process during impact was highlighted. The results of the parametric analysis indicate that reducing the spacing or introducing pre-stress of SMA wires contributes to a slight improvement in impact resistance. This study offers new insights for the design and optimization of impact-resistant composites.

碳纤维增强聚合物（CFRP）复合材料因其出色的比强度和刚度而备受推崇。然而，CFRP 很容易受到冲击损坏，这在实际应用中往往是不可避免的。本研究探讨了通过在 CFRP 基体中加入超弹性形状记忆合金（SMA）丝来增强 CFRP 复合材料的抗冲击性。研究人员制作了单向和双向 SMA 增强 CFRP 层压板，并对其进行了低速冲击测试。通过目视检查和超声波 C 扫描成像相结合的方法，观察了层压板的表面和内部层间损伤模式。通过检查冲击力和冲击点位移的时变曲线，分析了层压板的冲击响应。结果表明，SMA 增强 CFRP（SMA-CFRP）在受到冲击后会出现较浅的分层裂缝，层间损伤也会减少。单向和双向 SMA 增强 CFRP 的最大冲击力分别增加了 26.1% 和 29.5%，表明加入 SMA 后基体刚度显著增强。通过模拟分析进一步研究了抗冲击性能提高背后的力学机理，突出了 SMA 相变在冲击过程中能量吸收过程中的重要性。参数分析结果表明，减小 SMA 线的间距或引入预应力可略微提高抗冲击性。这项研究为抗冲击复合材料的设计和优化提供了新的见解。

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引用次数: 0