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【新文速递】2024年12月10日固体力学SCI期刊最新文章

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今日更新:International Journal of Solids and Structures 1 篇,International Journal of Plasticity 3 篇

International Journal of Solids and Structures

Investigation of unidirectional vibration isolation and nonreciprocal design of axial elastic waves based on topological pumping theory

Zixun Lu, Hui Chern, Lingyun Yao

doi:10.1016/j.ijsolstr.2024.113192

基于拓扑抽运理论的轴向弹性波单向隔振与非倒易设计研究

In this work, a spiral structure (SS) based on the nonreciprocal waveguide theory of adiabatic evolution principle is designed, which can generate dynamic boundaries on a rotation shaft. The spatiotemporal topological pumping formed by SS can achieve nonreciprocal transmission of elastic waves in shaft, and the transmission can achieve unidirectional isolation of shaft vibration. Firstly, transfer matrix method (TMM) is used to theoretically derive the continuity at two-phase spiral periodic shaft structure (SPSS) medium. Then, finite element method (FEM) is utilized to calculate energy bands and frequency response functions of SPSS. Next, the calculations results obtained by FEM are used to analyze the influence of material parameters, geometric dimensions and other factors on band gap, and SPSS of rotation is used to confirm the variation of topological edge modes produced by spatiotemporal pumping. Finally, realistic shaft model and analytical parameters are combined to determine the dimensional parameters and materials of unidirectional vibration isolation shaft, vibration transmission characteristics of spiral shaft are obtained by numerical simulation, and its unidirectional vibration isolation performance is verified through experiment. The results show that SS can achieve spatiotemporal topological pumping function at a certain modulation speed, whenthe band gap is deflected in a specific frequency range, elastic waves can be transmitted unidirectional in deflected frequency range, the dynamic spiral shaft has a good unidirectional vibration isolation effect when the shaft is modulated in the reverse direction, and changing helical angular velocity can tune frequency range of nonreciprocal transmission of elastic waves. The design can provide a theoretical basis for engineering application of unidirectional vibration isolation bushing in wide frequency range.

本文基于绝热演化原理的非互易波导理论,设计了一种能在旋转轴上产生动态边界的螺旋结构(SS)。由SS形成的时空拓扑抽运可以实现弹性波在轴内的非互反传输,传输可以实现轴振动的单向隔离。首先,利用传递矩阵法(TMM)从理论上推导了两相螺旋周期轴结构(SPSS)介质的连续性。然后,利用有限元法(FEM)计算SPSS的能带和频响函数。其次,利用有限元法计算结果分析材料参数、几何尺寸等因素对带隙的影响,利用旋转SPSS软件确认时空抽运产生的拓扑边缘模态变化。最后,结合实际轴模型和解析参数确定单向隔振轴的尺寸参数和材料,通过数值模拟得到螺旋轴的振动传递特性,并通过实验验证其单向隔振性能。结果表明,在一定的调制速度下,SS可以实现时空拓扑抽运功能,当带隙在特定的频率范围内偏转时,弹性波可以在偏转的频率范围内单向传播,动态螺旋轴在反向调制时具有良好的单向隔振效果,改变螺旋角速度可以调节弹性波非互反传播的频率范围。该设计可为宽频率范围单向隔振衬套的工程应用提供理论依据。


International Journal of Plasticity

Role of thermal stress-driven dislocation and low-angle grain boundary migration in surface plastic deformation and grain orientation evolution of tungsten under thermal shock

Meng-Chong Ren, Yu-Fei Nie, Han-Qing Wang, Yue Yuan, Fan Feng, You-Yun Lian, Hao Yin, Long Cheng, Duo-Qi Shi, Guang-Hong Lu

doi:10.1016/j.ijplas.2024.104205

热应力驱动的位错和低角度晶界迁移在热冲击下钨表面塑性变形和晶粒取向演化中的作用

This study reveals that thermal fatigue loading (transient thermal shock), similar to that in fusion environments, can serve as a surface processing technique for BCC metals. Regions with a {110} grain orientation can be selectively achieved in varying sizes and locations on the sample surface. Furthermore, our experiments confirm that the specific localized orientation transformation obtained through this method exhibits certain high-temperature stability at 1573 K (above the recrystallization temperature of tungsten). The experiment employed a 0.25 GW/m² high-energy pulsed electron beam for 1 ms to cyclically load the tungsten surface, simulating edge localized mode events in fusion conditions. It was found that tungsten exhibited significant surface grain orientation transformation (distinct {110} grain orientation) under low strain (∼ 1%) after transient thermal shocks, a phenomenon rarely mentioned in studies of thermal shock on fusion reactor divertor materials. Microstructure characterization results suggest that this localized orientation transformation, induced by minor surface damage, primarily results from the generation, movement, and evolution of dislocations into subgrain and low-angle grain boundaries. The cyclic accumulation of the migration of kink-like subgrain/low-angle grain boundaries under transient thermal stress at high temperatures drives this process. Subsequently, crystal plasticity finite element method simulations based on dislocation slip were conducted to study the surface grain orientation transformation of tungsten under compressive thermal stress. This predictive capability provides valuable guidance for understanding the service conditions of fusion reactor divertor materials. Furthermore, we propose that cyclic transient thermal shocks can serve as an effective surface processing technique for metals, enabling the formation of specific localized grain orientations.

本研究表明,热疲劳加载(瞬态热冲击),类似于熔合环境,可以作为BCC金属的表面加工技术。具有{110}晶粒取向的区域可以选择性地在样品表面的不同尺寸和位置上实现。此外,我们的实验证实,通过该方法获得的特定局部取向转变在1573 K(高于钨的再结晶温度)时具有一定的高温稳定性。实验采用0.25 GW/m²高能脉冲电子束循环加载钨表面,模拟聚变条件下的边缘局域模式事件。发现钨在瞬态热冲击后的低应变(~ 1%)下表现出明显的表面晶粒取向转变(明显的{110}晶粒取向),这一现象在聚变反应堆转向器材料的热冲击研究中很少提及。微观结构表征结果表明,这种由轻微表面损伤引起的局部取向转变主要是由位错在亚晶界和低角度晶界的产生、移动和演化引起的。高温瞬态热应力作用下扭结状亚晶/低角度晶界迁移的循环积累驱动了这一过程。随后,采用基于位错滑移的晶体塑性有限元模拟方法,研究了压缩热应力作用下钨的表面晶粒取向转变。这种预测能力为理解聚变反应堆导流器材料的使用状况提供了有价值的指导。此外,我们提出循环瞬态热冲击可以作为一种有效的金属表面加工技术,使特定局部晶粒取向的形成成为可能。


Unusual hardening mediated by {10-12} twins of strongly textured titanium at cryogenic temperature

Yu Zhang, Danyang Li, Guowei Zhou, Luyang Tao, Zhuangzhuang Liu, Guohua Fan, Hao Wu

doi:10.1016/j.ijplas.2024.104206

在低温下,强织构钛的{10-12}孪晶介导了异常硬化

{10-12} twinning is an important deformation mechanism for hexagonal metals; however, its characteristically low critical stress and resulting high twin activity often lead to rapid strain localization and premature failure. Therefore, this study aims to strategically delay {10-12} twinning at the initial deformation stage to prevent the strain localization, and concurrently seeks to reactivate {10-12} twinning at the large deformation stage to facilitate continuous hardening. Guided by these dual objectives, we selected rolled titanium as the model material and designed the loading direction to minimize the Schmid factor of {10-12} twinning, and then introduced cryogenic temperatures as low as 77 K to apply GPa-grade stress, thereby enabling continuous strengthening until the reactivation of {10-12} twinning. Under these specified conditions, the rolled titanium exhibited markedly enhanced mechanical properties; the ultimate strength increased from 618 MPa to 1634 MPa, while the true strain was increased by approximately 0.15 when the temperature was reduced from 298 K to 77 K. More importantly, an unusual strain hardening behavior was experimentally observed at a true strain of 0.16, at which {10-12} twins started to behave as the predominant twinning mechanism. Quantitative analysis further indicated that the large majority of the strain hardening capacity was attributed to high-density {10-12} twins. The present study therefore highlighted the pivotal role of {10-12} twins and offers a novel viewpoint for designing and achieving distinctive mechanical properties through the manipulation of deformation twinning.

{10-12}孪晶是六方金属的重要变形机制;然而,其低临界应力的特点和由此产生的高孪晶活性往往导致快速应变局部化和过早失效。因此,本研究旨在在初始变形阶段有策略地延迟{10-12}孪晶,以防止应变局部化,同时在大变形阶段重新激活{10-12}孪晶,以促进连续硬化。在这两个目标的指导下,我们选择轧制钛作为模型材料,并设计加载方向以最小化{10-12}孪晶的施密德因子,然后引入低至77 K的低温施加gpa级应力,从而实现持续强化,直到{10-12}孪晶重新激活。在此条件下,轧制钛的力学性能得到了显著提高;当温度从298 K降低到77 K时,合金的极限强度从618 MPa提高到1634 MPa,而真应变提高了约0.15。更重要的是,在0.16的真应变下,实验观察到不寻常的应变硬化行为,此时{10-12}孪晶开始表现为主要的孪晶机制。定量分析进一步表明,绝大多数应变硬化能力归因于高密度{10-12}孪晶。因此,本研究强调了{10-12}孪晶的关键作用,并为通过变形孪晶的操纵来设计和实现独特的机械性能提供了一个新的观点。


Temperature-dependent microscopic deformation mechanisms and performance enhancement prospects in high-cycle fatigue of nickel-based single crystal superalloys

Jiachen Xu, Xinbao Zhao, Jishan Chen, Pengfei Wang, Hao Liu, Wanshun Xia, Quanzhao Yue, Yuefeng Gu, Ze Zhang

doi:10.1016/j.ijplas.2024.104207

镍基单晶高温合金高周疲劳温度相关显微变形机制及性能增强前景

Given the limited systematic analysis of microstructural deformation mechanisms in high-cycle fatigue, this study investigates the high-cycle fatigue failure of a fourth-generation nickel-based single crystal superalloy across temperatures of 700°C, 850°C, and 980°C. The results indicate that the alloy exhibits optimal performance at 980°C, followed by 700 °C and then 850°C. At 700°C, stacking fault locks and Lomer-Cottrell dislocations were identified, whereas, at 850°C, elongated stacking fault shearing and typical cross-slip were observed. Notably, at 980°C, intense dislocation activity was detected, including Kear-Wilsdorf locks, dislocation pile-up, and entanglement. The observed changes in microstructural mechanisms with increasing temperature are attributed to elevated stacking fault energy and critical shear stress, alongside reduced critical stress for various dislocation movements. Furthermore, the types of Lomer-Cottrell dislocation and Kear-Wilsdorf lock were accurately identified. In conclusion, the dominant micro-deformation mechanisms—stacking fault locks, Lomer-Cottrell dislocations, and dislocation hardening behaviors such as Kear-Wilsdorf locks—significantly enhance high-cycle fatigue performance. This research addresses the scarcity of studies on microscopic deformation mechanisms in single crystal high-cycle fatigue and provides valuable insights for optimizing the high-cycle fatigue performance of nickel-based superalloys.

鉴于对高周疲劳中微观组织变形机制的系统分析有限,本研究研究了第四代镍基单晶高温合金在700°C、850°C和980°C下的高周疲劳失效。结果表明,该合金在980℃时性能最佳,其次是700℃和850℃。在700°C时,发现了层错锁和lomo - cottrell位错,而在850°C时,发现了拉长的层错剪切和典型的交叉滑动。值得注意的是,在980°C时,检测到强烈的位错活动,包括基尔-威尔斯多夫锁、位错堆积和纠缠。观察到的显微组织机制随温度升高的变化归因于层错能和临界剪应力的升高,以及各种位错运动的临界应力的降低。此外,准确地识别了lomo - cottrell位错和Kear-Wilsdorf锁的类型。综上所述,主要的微变形机制——层错锁、lomo - cottrell位错和位错硬化行为(如Kear-Wilsdorf锁)——显著提高了高周疲劳性能。该研究解决了单晶高周疲劳微观变形机制研究的不足,为优化镍基高温合金高周疲劳性能提供了有价值的见解。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemDeform振动疲劳电子UG理论材料
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首次发布时间:2024-12-18
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【新文速递】2024年12月4日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Thin-Walled Structures 8 篇International Journal of Solids and StructuresExperimental and numerical analysis of mixed mode bending of adhesive-bonded and hybrid honeycomb core sandwich structuresA. Kumar, P.J. Saikia, R.Ganesh Narayanan, N. Muthudoi:10.1016/j.ijsolstr.2024.113177粘接与杂化蜂窝芯夹层结构混合模态弯曲试验与数值分析This study investigates the potential of a hybrid joining method, called friction stir spot welding with disc and adhesive bonding (FSSW_D_AB), for bonding honeycomb core sandwich structures, offering an alternative to traditional adhesive bonding (AB) sandwich structures. The research focuses on the manufacturing of these hybrid joints and evaluating their performance compared to conventional adhesive bonding (AB) methods. Mixed Mode Bending (MMB) tests were performed to assess the mechanical behaviour of the joints under different loading conditions. Additionally, numerical analysis using cohesive zone modeling (CZM) was performed using both a honeycomb core with a cohesive layer and the homogenized core with an equivalent cohesive layer. The study reveals that the hybrid joining method significantly enhances the performance of honeycomb sandwich structures. The good agreement between the numerical predictions and the experimental results for all types of joints showed the usefulness of the proposed numerical model. However, the FEM-based stress and damage analyses of the joints provided crucial results on normal and shear stress distributions and delamination.本研究探讨了一种混合连接方法的潜力,称为搅拌摩擦点焊与圆盘和粘合剂粘合(FSSW_D_AB),用于粘合蜂窝芯夹层结构,为传统的粘合剂粘合(AB)夹层结构提供了一种替代方案。研究重点是这些混合接头的制造,并与传统的粘接(AB)方法相比,评估其性能。通过混合模态弯曲(MMB)试验,评估了不同加载条件下节点的力学性能。此外,利用粘聚区模型(CZM)对蜂窝核进行了数值分析,其中蜂窝核有粘聚层,蜂窝核有等效粘聚层。研究表明,混合连接方法显著提高了蜂窝夹层结构的性能。所有类型节理的数值预测结果与实验结果吻合较好,表明了所建数值模型的有效性。然而,基于有限元的关节应力和损伤分析提供了重要的法向和剪切应力分布和分层结果。Journal of the Mechanics and Physics of SolidsRupture Mechanics of Blood Clot Fibrin Fibers: A Coarse-Grained Model StudyBeikang Gu, Jixin Hou, Nicholas Filla, He Li, Xianqiao Wangdoi:10.1016/j.jmps.2024.105998血凝块纤维蛋白纤维破裂力学:粗粒度模型研究Thrombosis, when occurring undesirably, disrupts normal blood flow and poses significant medical challenges. As the skeleton of blood clots, fibrin fibers play a vital role in the formation and fragmentation of blood clots. Thus, studying the deformation and fracture characteristics of fibrin fiber networks is the key factor to solve a series of health problems caused by thrombosis. This study employs a coarse-grained model of fibrin fibers to investigate the rupture dynamics of fibrin fiber networks. We propose a new method for generating biomimetic fibrin fiber networks to simulate their spatial geometry in blood clots. We examine the mechanical characteristics and rupture behaviors of fibrin fiber networks under various conditions, including fiber junction density, fiber tortuosity, fiber strength, and the strain limit of single fiber rupture in both tension and simple shear cases. Our findings indicate that the stress-strain relationship of the fibrin fiber network follows a similar pattern to that of individual fibers, characterized by a shortened entropy stretching phase and an extended transition phase. Fiber junction density, fiber strength, and single fiber rupture limit predominantly influence the stress of the network, while fiber tortuosity governs the strain behavior. The availability of more fibers in shear cases to bear the load results in delayed rupture compared to tension cases. With consideration of different factors of fibrin fibers in networks, this work provides a more realistic description of the mechanical deformation process in fibrin fiber networks, offering new insights into their rupture and failure mechanisms. These findings could inspire novel approaches and methodologies for understanding the fracture of fibrin networks during a surgical thrombectomy.当不希望发生血栓时,它会破坏正常的血液流动,并带来重大的医疗挑战。纤维蛋白纤维作为血凝块的骨架,在血凝块的形成和破碎中起着至关重要的作用。因此,研究纤维蛋白纤维网络的变形和断裂特性是解决血栓形成引起的一系列健康问题的关键因素。本研究采用粗粒度的纤维蛋白纤维模型来研究纤维蛋白纤维网络的断裂动力学。我们提出了一种生成仿生纤维蛋白纤维网络的新方法来模拟其在血凝块中的空间几何形状。我们研究了纤维蛋白纤维网络在不同条件下的力学特性和断裂行为,包括纤维结密度、纤维弯曲度、纤维强度以及单纤维在拉伸和简单剪切情况下断裂的应变极限。我们的研究结果表明,纤维蛋白纤维网络的应力-应变关系遵循与单个纤维相似的模式,其特征是熵拉伸阶段缩短,过渡阶段延长。纤维结密度、纤维强度和单纤维断裂极限主要影响网络的应力,而纤维弯曲度主要影响网络的应变行为。与拉伸情况相比,更多的纤维在剪切情况下承受载荷导致延迟断裂。考虑到纤维蛋白纤维在网络中的不同影响因素,本研究更真实地描述了纤维蛋白纤维网络的力学变形过程,为纤维蛋白纤维网络的断裂破坏机制提供了新的认识。这些发现可以激发新的方法和方法来理解外科血栓切除术中纤维蛋白网络的断裂。Thin-Walled StructuresMulti-crack damage identification and quantification using Lamb wave-based structural health monitoringXianping Zeng, Jiajia Yan, Qijian Liu, Bowen Zhao, Xinlin Qingdoi:10.1016/j.tws.2024.112782基于Lamb波的结构健康监测多裂纹损伤识别与量化The simultaneous presence of multi-crack damage in a structural component is a crucial issue affecting system safety. To address the accurate and quantitative monitoring of multi-crack damage in an aeronautical structure, an innovative multi-crack damage localization, orientation and quantification algorithm using Lamb wave-based structural health monitoring is presented in this paper. An improved Hausdorff distance-based weighted average imaging methodology is introduced for precise multi-crack damage position identifications. To account for the critical role of crack orientation in damage quantification, a cross-orthogonality-based method is developed, enabling orientation detection at arbitrary positions and angles while simplifying the problem into a mathematical formulation. A wave scattering sources-based quantification algorithm incorporating the estimated position and orientation information is further proposed to estimate the multi-crack lengths. Additionally, a singular elliptic trajectories removal scheme is presented to suppress useless ambient noise and enhance the damage information discriminability. Experiments on the aircraft wing-box structure of a real airplane are implemented to substantiate the proposed techniques. Due to the outstanding properties, such as flexibility, electrically stabilized and applicability to complex structures, the sensor layer with built-in PZT sensor network surface-installed on the monitored structure is adopted to generate and receive Lamb wave signal. The results manifest that the proposed monitoring algorithm, without prior information or calibration required, is effective and straightforward for detecting multi-crack damage. This study can also provide a feasible technique for accurately locating and quantitatively identifying cracks in some concealed parts or inside the structure.结构构件同时存在多裂纹损伤是影响系统安全的关键问题。为解决航空结构多裂纹损伤的精确定量监测问题,提出了一种基于Lamb波的结构健康监测多裂纹损伤定位、定位和量化的创新算法。提出了一种改进的基于Hausdorff距离的加权平均成像方法,用于多裂纹损伤位置的精确识别。考虑到裂纹方向在损伤量化中的关键作用,提出了一种基于交叉正交性的方法,可以在任意位置和角度进行方向检测,同时将问题简化为数学公式。在此基础上,提出了一种结合估计的位置和方位信息的基于波散射源的多裂纹长度量化算法。此外,提出了一种奇异椭圆轨迹去除方案,以抑制无用的环境噪声,提高损伤信息的可分辨性。最后对某型飞机的翼箱结构进行了实验验证。由于传感器具有柔韧性、电稳定性和适用于复杂结构等突出特性,因此采用内置PZT传感器网络的传感器层,将其表面安装在被监测结构上,产生和接收兰姆波信号。结果表明,该监测算法在不需要先验信息和校正的情况下,对多裂纹损伤的检测是有效和直接的。该研究也为某些隐蔽处或结构内部的裂缝精确定位和定量识别提供了一种可行的技术。Energy absorption properties of dimpled circular tubes: Experimental and numerical studiesChang Zhou Fu, Yi Zhang, Xing Chi Teng, Wei Zhong Jiang, Xi Hai Ni, Xiang Sun, Xin Rendoi:10.1016/j.tws.2024.112785凹形圆管的能量吸收特性:实验与数值研究As an exemplary energy absorption structure, thin-walled metallic tubes have been extensively studied. Introducing dimple defects into the tube wall can induce the desired deformation in thin-walled metallic tubes to enhance their energy absorption performance. Existing research has only discussed dimpled tubes with relatively thin wall thicknesses and shallow dimples, which is insufficient to meet the demands of widespread applications. This study introduces two novel tubular structures by incorporating predefined dimples into the walls of smooth tubes. Through finite element simulation and experiment, the influence of wall thickness, dimple aspect ratio, and the orientation of the dimples on the energy absorption capacity of the structures is parametrically analyzed. A comparison with traditional smooth tubes is also conducted. The results indicate that the wall thickness, dimple aspect ratio, and orientation of the dimples have significant effects on reducing the initial peak force, enhancing specific energy absorption, and improving structural stability. By appropriately selecting geometric parameters, energy absorption tubular structures adaptable to various application scenarios can be designed. The two novel tubular structures proposed provide new design insights for the study of energy absorption in thin-walled metallic tubes.作为一种典型的吸能结构,薄壁金属管得到了广泛的研究。在薄壁金属管的管壁上引入韧窝缺陷可以引起所需的变形,从而提高薄壁金属管的吸能性能。现有的研究只讨论了壁厚相对较薄、微窝较浅的微窝管,不足以满足广泛应用的要求。本研究引入了两种新型管状结构,通过在光滑管的壁上加入预定义的凹窝。通过有限元模拟和实验,参数化分析了壁厚、凹痕长径比和凹痕方向对结构吸能能力的影响。并与传统光滑管进行了比较。结果表明,壁厚、凹窝长径比和凹窝取向对减小初始峰值力、提高比能吸收、提高结构稳定性有显著影响。通过合理选择几何参数,可以设计出适应各种应用场景的吸能管状结构。提出的两种新型管状结构为薄壁金属管的能量吸收研究提供了新的设计思路。Simulation and cross-section design of steel beams under moment gradientsZichang Yang, Xin Meng, Fiona Walport, Leroy Gardnerdoi:10.1016/j.tws.2024.112786弯矩梯度作用下钢梁的模拟与截面设计A systematic study into the effect of moment gradients on the cross-section resistance of hot-rolled steel square hollow section (SHS), rectangular hollow section (RHS) and I-section beams has been conducted and is presented in this paper. Finite element (FE) models were first developed and validated against test results from the literature; parametric studies covering different steel grades, cross-section geometries and moment distributions were then carried out. It was found that cross-section bending resistances increase with increasing moment gradient in the low to intermediate range, despite the necessary rise in the level of co-existent shear. Under high moment gradients, the negative impact of the high co-existent shear outweighs the positive influence of the moment gradient, and cross-section bending resistances fall. It was found that the benefits from moment gradients vary with the cross-section slenderness and the aspect ratio of the cross-section, and increase when intermediate web stiffeners are present. A new design method that captures the observed behaviour is devised, featuring a new parameter to describe the local moment gradient in beams under different loading conditions. The proposed design equations are shown to be more accurate than existing provisions in EC3 and to meet the reliability requirements set out in EN 1990. The new method is therefore deemed to be suitable for implementation within the EC3 framework.本文系统地研究了弯矩梯度对热轧钢方空心截面、矩形空心截面和工字钢截面梁截面阻力的影响。首先开发了有限元(FE)模型并根据文献中的测试结果进行了验证;参数化研究涵盖了不同的钢种、截面几何形状和弯矩分布。结果表明,在低至中弯矩梯度范围内,截面抗弯阻力随弯矩梯度的增大而增大,尽管共存剪切水平有必要提高。在高弯矩梯度下,高共存剪力的负面影响大于弯矩梯度的正面影响,截面抗弯阻力下降。结果表明,弯矩梯度的效益随截面长细比和截面长径比的变化而变化,当存在中间腹板加强筋时,弯矩梯度的效益增加。设计了一种新的设计方法来捕捉观察到的行为,采用新的参数来描述不同荷载条件下梁的局部弯矩梯度。所提出的设计方程被证明比EC3中现有的规定更准确,并满足en1990中规定的可靠性要求。因此,新方法被认为适合在EC3框架内实现。Axisymmetric thermal post-buckling of the eccentric annular sector plate made of Gori-metamaterials: Introducing DNN-RF algorithm for solving the post-buckling problemsPeyman Mehrabi, Mina Mortazavi, Harry Fardoi:10.1016/j.tws.2024.112795偏心环形扇形板轴对称热后屈曲:引入DNN-RF算法求解后屈曲问题Composite eccentric annular sector plates are frequently utilized in engineering. This structure is crucial in the manufacturing, aircraft, nuclear, and construction industries due to its asymmetrical geometry. So, in this work for the first time, thermal-post buckling analysis of the composite eccentric annular sector plate made of graphene origami enriched auxetic metamaterial (GOEAM) is presented. To improve the stability of this kind of structure, the GOEAM composite eccentric annular sector plate is surrounded by an auxetic concrete foundation. To estimate the nonlinear thermal buckling information of the presented structure using a hybrid machine learning algorithm, a dataset is needed. Due to the lack of thermal post-buckling datasets for the presented composite eccentric annular sector plate, a mathematical simulation is presented. In the mathematical simulation (MS) section, quasi-3D refined theory (Q3D-RT), Von-Karman nonlinearity, minimum total potential energy principle, and Haber-Schaim formulations are used to generate the governing and boundary equations of the GOEAM annular sector plates surrounded by auxetic concrete foundation. After extracting the governing equations, they are solved via the transformed differential quadrature method (TDQM) with the aid of differential quadrature (DQ) weighting coefficients. After obtaining the datasets using MS, in the artificial intelligence domain, the results for future research of thermal post-buckling of the GOEAM composite eccentric annular sector plate surrounded by the auxetic concrete foundation are tested, trained, and validated. So, with the presented datasets of thermal post-buckling of the GOEAM composite eccentric annular sector plate surrounded by auxetic concrete foundation, this kind of structure using a machine learning algorithm can be simulated in other complex situations.复合偏心环形扇形板在工程中应用较多。由于其不对称的几何形状,这种结构在制造业,飞机,核能和建筑业中至关重要。因此,本文首次对石墨烯折纸富氧超材料(GOEAM)制备的偏心环形扇形复合材料板进行了热后屈曲分析。为了提高这类结构的稳定性,在GOEAM复合偏心环形扇形板的周围设置了减量混凝土基础。为了利用混合机器学习算法估计结构的非线性热屈曲信息,需要一个数据集。由于所提出的复合材料偏心环形扇形板缺乏屈曲后的热数据集,提出了数学模拟。在数学模拟(MS)部分,采用准三维精细理论(Q3D-RT)、Von-Karman非线性、最小总势能原理和Haber-Schaim公式,生成了被混凝土基础包围的GOEAM环形扇形板的控制方程和边界方程。提取控制方程后,借助微分正交(DQ)加权系数,采用变换微分正交法求解控制方程。利用MS获取数据集后,在人工智能领域对GOEAM复合材料偏心环形扇形板的失稳后热屈曲研究结果进行了测试、训练和验证。因此,利用本文提出的GOEAM复合材料偏心环形扇形板被混凝土基础包围的热后屈曲数据集,可以利用机器学习算法对这种结构进行其他复杂情况的模拟。Digital Twin-based Online Structural Optimization? Yes, It's Possible!Xiwang He, Liangliang Yang, Zhuangzhuang Gong, Yong Pang, Jianji Li, Ziyun Kan, Xueguan Songdoi:10.1016/j.tws.2024.112796基于数字孪生的在线结构优化?是的,这是可能的!In structural design, simulation technology has been extensively applied. However, simulation-based offline optimization methods encounter two primary limitations: (1) they typically optimize parameters based on a structure's mechanical properties under extreme, static conditions, and (2) they involve complex, time-consuming performance calculations. To address these challenges, this paper introduces a structural online optimization framework driven by shape-performance integrated digital twins (SPI-DTs), which breaks the connection barrier between the real-time dynamics of digital twins and the offline characteristics of traditional optimization under dynamic operating conditions. Initially, the structure's remaining life is calculated online using real-time performance data from the digital twin, with the constraint stress and equivalent load derived via the static load equivalent method. A hierarchical radial basis function is then proposed, which integrates multi-source data for rapid calculation of the structure's target performance under the equivalent load. Finally, structural optimization parameters, determined through topology optimization, are solved using the multi-objective genetic algorithm. The feasibility of the proposed method is demonstrated through typical case studies: the wing cantilever beam and a three-dimensional flat plate. The results show that the weight of the wing cantilever beam case based on size optimization is reduced by 12.07%, and the weight of the flat plate case based on combined topology optimization and size optimization is reduced by 66.66%. In conclusion, the proposed framework offers a viable approach to achieving lightweight design and extending the operational life of structures under real-world conditions.在结构设计中,仿真技术得到了广泛的应用。然而,基于仿真的离线优化方法遇到两个主要限制:(1)它们通常基于极端静态条件下结构的力学性能来优化参数;(2)它们涉及复杂且耗时的性能计算。为了解决这些问题,本文引入了一种基于形状-性能集成数字孪生(spi - dt)驱动的结构在线优化框架,打破了数字孪生的实时动态与动态工况下传统优化的离线特性之间的联系障碍。首先,使用来自数字孪生的实时性能数据在线计算结构的剩余寿命,并通过静载荷等效方法导出约束应力和等效载荷。然后提出了一种分层径向基函数,该函数集成了多源数据,可以快速计算等效荷载下结构的目标性能。最后,通过拓扑优化确定结构优化参数,利用多目标遗传算法求解。通过机翼悬臂梁和三维平板的典型算例验证了该方法的可行性。结果表明,基于尺寸优化的机翼悬臂梁壳体重量减轻了12.07%,基于拓扑优化和尺寸优化相结合的平板壳体重量减轻了66.66%。总之,提出的框架为实现轻量化设计和延长结构在现实条件下的使用寿命提供了一种可行的方法。Electrothermally actuated lattice metamaterials with remarkable shear deformationKai Zhang, Jinyu Ji, Yixing Huang, Hao Wang, Dengbao Xiao, Xiao Kang, Xiaogang Guodoi:10.1016/j.tws.2024.112797具有显著剪切变形的电热驱动晶格超材料Active metamaterials with specific deformation responses present great promise in fields such as multifunctional antennas, stretchable electronic devices and reconfigurable soft robots, due to their ability to switch between different operational states within a single system. However, the previous researches on active metamaterials with shear deformation responses exhibit two issues: inability to further enhance the shear deformation magnitude of the active metamaterials and inability to achieve precise customized design of the metamaterials, such as realizing simple shear deformation. Moreover, the inverse design of active metamaterials is challenging because theoretical models describing the finite deformation of active metamaterials under external-field actuation are lacking. To address the aforementioned issues, this study reports a design strategy for the electrothermally actuated lattice metamaterials to realize remarkable shear deformation with the maximum shear angle exceeding 26° and the capability to precisely achieve desired mechanical responses of the active metamaterials. The shear angle of the electrothermally actuated lattice metamaterials reported in this paper has increased by approximately 82% compared to that achieved in previous studies. Theoretical models for the electrothermally actuated metamaterials are established to describe the shear deformation behaviors. The theoretical models are demonstrated through both qualitative and quantitative comparisons with finite element analyses (FEAs) and experimental results. Theoretical models provide detailed predictions of the configuration after electric heating and offer analytical solutions for crucial mechanical quantities, such as the effective strains and shear angle for the electrothermally actuated lattice metamaterials exhibiting shear deformations. Moreover, experimental results and FEA calculations show that the simple shear deformation mode can be realized in the active metamaterials through the design strategies proposed in this paper, while it cannot be achieved in previous researches. This demonstrates the capability of the design strategies proposed in this paper to precisely realize required mechanical responses of the active metamaterials.具有特定变形响应的活性超材料在多功能天线、可拉伸电子设备和可重构软机器人等领域表现出巨大的前景,因为它们能够在单个系统中在不同的工作状态之间切换。然而,以往对具有剪切变形响应的活性超材料的研究存在两个问题:无法进一步提高活性超材料的剪切变形幅度;无法实现对超材料的精确定制设计,如实现简单的剪切变形。此外,由于缺乏描述外场驱动下活性超材料有限变形的理论模型,因此活性超材料的反设计具有挑战性。针对上述问题,本研究提出了一种电热驱动晶格超材料的设计策略,实现了最大剪切角超过26°的显著剪切变形,并能够精确实现活性超材料所期望的力学响应。本文报道的电热驱动晶格超材料的剪切角比以往的研究结果提高了约82%。建立了电热致动超材料的理论模型来描述其剪切变形行为。通过与有限元分析和实验结果的定性和定量比较,对理论模型进行了验证。理论模型提供了电加热后结构的详细预测,并提供了关键力学量的解析解决方案,例如电热驱动晶格超材料表现出剪切变形的有效应变和剪切角。此外,实验结果和有限元计算表明,通过本文提出的设计策略,可以在活性超材料中实现简单的剪切变形模式,而这是以往研究无法实现的。这证明了本文提出的设计策略能够精确地实现活性超材料所需的力学响应。Dual-nozzle 3D printing of fiber composites for fabrication of compliant lever-type vibration isolators with wide stopbandKoichi Mizukami, Kota Nakamuradoi:10.1016/j.tws.2024.112799双喷嘴3D打印纤维复合材料制造柔性宽阻带杠杆式隔振器This study proposes fiber-composite lever-type vibration isolators with a wide stopband around the antiresonance frequency. The proposed mechanisms were 3D-printed monolithic structures with compliant butterfly hinges that mimic an ideal pinned support for the lever. Continuous carbon fiber and short carbon fiber regions were combined to achieve a wide low-frequency stopband. A rigid link model was developed to derive analytical solutions for the resonance and antiresonance frequencies of the proposed mechanisms. Frequency response analysis and modal analysis were performed to examine designs for widening the stopband using the finite element method. The print path-dependent anisotropy of short fiber-reinforced plastic was reflected in the finite element model. A dual-nozzle fiber-composite 3D printer was used to fabricate the proposed lever-type mechanisms. The measured vibration transmissibilities of the 3D-printed samples showed a similar improvement of the stopband width to the numerical analysis results, demonstrating that suitable designs of continuous fiber placement and hinge shape widened the stopband.本文提出了一种具有宽阻带的纤维复合材料杠杆式隔振器。所提出的机构是3d打印的整体结构,具有柔顺的蝶式铰链,模仿杠杆的理想固定支撑。连续碳纤维区和短碳纤维区相结合,实现了宽低频阻带。建立了刚性连杆模型,推导出了所提机构共振频率和反 共振频率的解析解。采用有限元法进行了频率响应分析和模态分析,以检验加宽阻带的设计。在有限元模型中反映了短纤维增强塑料打印路径相关的各向异性。利用双喷嘴纤维复合材料3D打印机制造了所提出的杠杆式机构。3d打印样品的振动透射率测量结果显示出与数值分析结果相似的阻带宽度改善,表明适当的连续纤维放置和铰链形状设计拓宽了阻带。Optimizing mass transfer performance in triply periodic minimal surface porous scaffolds through isosurface offsetKun Li, Chunlin Zuo, Ruobing Liao, Haisong Liang, Xuan Liang, David Z. Zhang, Lawrence E. Murr, Huajun Caodoi:10.1016/j.tws.2024.112800利用等面偏移优化三周期最小表面多孔支架的传质性能Efficient bone tissue regeneration remains a critical challenge in orthopedic medicine, with scaffold mass transfer capabilities playing a pivotal role. Triply periodic minimal surface (TPMS) scaffolds have emerged as promising candidates due to their unique structure characterized by smooth, continuous surfaces with zero mean curvature and high specific surface area. However, optimizing their mass transfer performance to meet the diverse needs of bone tissues at different anatomical sites has been a persistent challenge. This study addresses this gap by investigating the effects of isosurface offset on mass transfer performance in three TPMS scaffolds (Fisher-Koch S, Gyroid, and Split-P) using computational fluid dynamics (CFD). The results showed that isosurface offset significantly increased the effective scaffold permeability range (by 116.8%, 5.3%, and 64.3% for F, G, and S scaffolds, respectively) and improved the wall shear stress (WSS) distribution, enhancing the area that effectively stimulates cell proliferation (by 25.2%, 8.7%, and 14.3% increase, respectively). Additionally, it was found that porosity, specific surface area, the ratio of maximum pore size to tortuosity, and curvature significantly influenced the permeability and WSS distribution of the scaffolds. Finally, permeation experiments using porous scaffolds fabricated by laser powder bed fusion (LPBF) technology were performed to validate the simulation results. This study provides new insights into the design of TPMS porous scaffolds and customized bone implants, enhancing their application prospects in bone tissue engineering.高效的骨组织再生仍然是骨科医学的关键挑战,支架的质量传递能力起着关键作用。三周期最小表面(TPMS)支架由于其具有光滑、连续、平均曲率为零和高比表面积的独特结构而成为有希望的候选材料。然而,优化其传质性能以满足不同解剖部位骨组织的不同需求一直是一个持续的挑战。本研究利用计算流体动力学(CFD)研究了三种TPMS支架(Fisher-Koch S、Gyroid和Split-P)的等面偏移对传质性能的影响,从而解决了这一空白。结果表明,等面偏移显著增加了F、G和S支架的有效通透性范围(分别增加116.8%、5.3%和64.3%),改善了壁剪切应力(WSS)分布,增加了有效刺 激细胞增殖的面积(分别增加25.2%、8.7%和14.3%)。此外,孔隙率、比表面积、最大孔径与弯曲度之比和曲率对支架的渗透性和WSS分布有显著影响。最后,利用激光粉末床熔融(LPBF)技术制备多孔支架进行渗透实验,验证模拟结果。本研究为TPMS多孔支架和定制骨植入物的设计提供了新的思路,增强了其在骨组织工程中的应用前景。

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