今日更新：International Journal of Solids and Structures 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 4 篇International Journal of Solids and StructuresVoltage-controlled non-axisymmetric vibrations of soft electro-active tubes with strain-stiffening effectFangzhou Zhu, Bin Wu, Michel Destrade, Huiming Wang, Ronghao Bao, Weiqiu Chendoi:10.1016/j.ijsolstr.2024.112671 具有应变加劲效应的软电活性管的压控非轴对称振动Material properties of soft electro-active (SEA) structures are significantly sensitive to external electro-mechanical biasing fields (such as pre-stretch and electric stimuli), which generate remarkable knock-on effects on their dynamic characteristics. In this work, we analyze the electrostatically tunable non-axisymmetric vibrations of an incompressible SEA cylindrical tube under the combination of a radially applied electric voltage and an axial pre-stretch. Following the theory of nonlinear electro-elasticity and the associated linearized theory for superimposed perturbations, we derive the nonlinear static response of the SEA tube to the inhomogeneous biasing fields for the Gent ideal dielectric model. Using the State Space Method, we efficiently obtain the frequency equations for voltage-controlled small-amplitude three-dimensional non-axisymmetric vibrations, covering a wide range of behaviors, from the purely radial breathing mode to torsional modes, axisymmetric longitudinal modes, and prismatic diffuse modes. We also perform an exhaustive numerical analysis to validate the proposed approach compared with the conventional displacement method, as well as to elucidate the influences of the applied voltage, axial pre-stretch, and strain-stiffening effect on the nonlinear static response and vibration behaviors of the SEA tube. The present study clearly indicates that manipulating electro-mechanical biasing fields is a feasible way to tune the small-amplitude vibration characteristics of an SEA tube. The results should benefit experimental work on, and design of, voltage-controlled resonant devices made of SEA tubes.软电活性(SEA)结构的材料性能对外部机电偏置场(如预拉伸和电刺 激)非常敏感，这对其动态特性产生了显著的连锁效应。在这项工作中，我们分析了不可压缩SEA圆柱管在径向施加电压和轴向预拉伸的组合下的静电可调非轴对称振动。根据非线性电弹性理论和相关的叠加扰动线性化理论，导出了根特理想介质模型下SEA管对非均匀偏置场的非线性静态响应。利用状态空间方法，我们有效地获得了电压控制的小幅度三维非轴对称振动的频率方程，涵盖了从纯径向呼吸模式到扭转模式、轴对称纵向模式和棱镜扩散模式的广泛行为。与传统的位移法相比，我们还进行了详尽的数值分析来验证所提出的方法，并阐明了施加电压、轴向预拉伸和应变加筋效应对SEA管的非线性静态响应和振动行为的影响。本研究清楚地表明，操纵机电偏置场是调节SEA管小振幅振动特性的可行方法。研究结果对SEA管压控谐振器件的实验工作和设计有一定的参考价值。International Journal of PlasticityA continuum scale chemo-mechanical model for multi-trap hydrogen transport in deformed polycrystalline metalsJinheung Park, Geonjin Shin, Hye-Jin Kim, Kijung Kim, Yoon Seung Chae, Seok Su Sohn, Myoung-Gyu Leedoi:10.1016/j.ijplas.2024.103890变形多晶金属中多阱氢输运的连续尺度化学-力学模型This study presents a coupled multi-trap hydrogen diffusion and crystal plasticity model within a thermodynamically consistent framework. The developed modeling scheme incorporates the hydrogen-enhanced localized plasticity (HELP) and hydrogen-enhanced strain-induced plasticity (HESIV) based on thermodynamic considerations. The theoretical formulations are implemented in the finite element method, which considers the concentration- and chemical potential-based balance equations. The validity of the coupled model is established through preliminary single element simulations under isothermal conditions, showcasing the predictability of evolution of hydrogen concentration and occupancies in the deformed microstructure of polycrystalline metal. Then, the developed computational approach is applied to two materials exhibiting hydrogen-induced hardening and softening behaviors in accordance with the HELP mechanism and vacancy-hydrogen complex (VaH) formation under isothermal condition. The model successfully reproduces the change of mechanical behavior induced by hydrogen in both materials. The effects of hydrogen diffusivity and the binding energy of defects on hydrogen transport are also investigated. Furthermore, the sensitivity of hydrogen diffusion to different trapping mechanisms, local equilibrium trapping and kinetics trapping, is examined. The proposed modeling framework can be applied to new material design strategies for developing metals resistant to hydrogen embrittlement.本研究在热力学一致的框架内提出了一个耦合的多阱氢扩散和晶体塑性模型。所开发的模型方案结合了基于热力学考虑的氢增强局部塑性(HELP)和氢增强应变诱导塑性(HESIV)。理论公式在有限元法中实现，考虑了基于浓度和化学势的平衡方程。通过在等温条件下的初步单元素模拟，验证了耦合模型的有效性，显示了多晶金属变形微观结构中氢浓度和占比的演化可预测性。然后，将所建立的计算方法应用于两种具有氢致硬化和软化行为的材料，根据HELP机制和在等温条件下形成的空位-氢络合物(VaH)。该模型成功地再现了氢在两种材料中引起的力学行为变化。研究了氢扩散系数和缺陷结合能对氢输运的影响。此外，还研究了氢扩散对不同捕获机制(局部平衡捕获和动力学捕获)的敏感性。所提出的建模框架可以应用于开发抗氢脆金属的新材料设计策略。Thin-Walled StructuresLaser cleaning assisted wire arc additive manufacturing of aluminum alloy thin-wall through synchronous wire-powder depositionYunfei Meng, Zeyu Li, Ming Gao, Hui Chen, Xu Wu, Qianxi Yudoi:10.1016/j.tws.2024.111622激光清洗辅助同步线粉沉积铝合金薄壁线弧增材制造Due to the interference of ambient wind on arc burning and droplet transfer, wire arc additive manufacturing (WAAM) of aluminum alloy in field environment is hindered. The gas-slag joint protection by synchronous feeding of AlSi5 wire and mixed powder of 90Mg-5TiO2-5NaF (wt.%) was introduced. It was found the wind resistance for the stable deposition of thin-wall could be improved from 1.5 to 3.5 m/s. The added Mg benefited to refine the grain size by 21% and promote the formation of Mg2Si, which improved the mechanical properties by induced solid solution-precipitation strengthening effects. Furthermore, with the assistance of laser cleaning, the porosity of thin-wall deposited at ambient wind speed of 3.5 m/s was reduced from 54.9% to 28%. These improvements increased the ultimate tensile strength and elongation to 166 MPa and 3.7%, reaching 98.2% and 31% of the WAAM at indoor windless environment respectively.由于环境风对电弧燃烧和熔滴传递的干扰，阻碍了现场环境下铝合金丝弧增材制造。介绍了用90Mg-5TiO2-5NaF (wt.%)混合粉末同步进料AlSi5丝保护气渣接头的方法。结果表明，薄壁稳定沉积的抗风能力可由1.5 m/s提高到3.5 m/s。Mg的加入使晶粒细化21%，促进Mg2Si的形成，通过诱导固溶析出强化效应改善了合金的力学性能。此外，在激光清洗的帮助下，在3.5 m/s环境风速下沉积的薄壁孔隙率从54.9%降低到28%。这些改进使材料的极限抗拉强度和伸长率分别达到166 MPa和3.7%，分别达到室内无风环境下WAAM的98.2%和31%。A novel method to design gradient porous structures with conformal densityBin Liu, Xiaofeng Wei, Wei Cao, Ping Lu, Xiaofeng Wangdoi:10.1016/j.tws.2024.111623一种设计保形密度梯度多孔结构的新方法This work introduces a rapid modeling method for gradient porous structures with conformal density, aiming to address the challenges of transitional variation of porosity, and control of complex gradient variations in multiple directions. In comparison to other methods, this approach overcomes the limitations associated with coordinate systems and shape functions when designing complex gradient variations in multiple directions while achieving density variation with shape under different gradients. The method involves mapping the volumetric distance field to a density field using control functions. By adhering to the constraints of the density field, it employs a weighted random sampling method to attain gradient sites with shape-adaptive distribution. Voronoi polyhedron are then constructed based on these sites, and smooth Voronoi struts are generated using strut distance fields and improved Boolean operations. The boundary adaptation of the porous structure is subsequently achieved based on the volumetric distance field. By establishing the relationship between density and volumetric distance field values, the study illustrates the similarity between density variation in the structure and gradient variations in the control function, indicating the controllability of density variation with shape. Furthermore, the method enables the integration design of structural shape and mechanical properties through adjustments to the number of sites, radius size of struts, and gradient control functions. Finally, the method was validated through numerical simulation and experiments, demonstrating its controllability and effectiveness in generating random porous structures with conformal density gradients, providing important theoretical and practical support for research and application in related fields.本文介绍了一种具有保形密度的梯度多孔结构的快速建模方法，旨在解决孔隙度过渡变化和多方向复杂梯度变化控制的挑战。与其他方法相比，该方法克服了设计多方向复杂梯度变化时坐标系和形状函数的局限性，同时实现了不同梯度下密度随形状的变化。该方法包括使用控制函数将体积距离场映射到密度场。该算法遵循密度场的约束，采用加权随机抽样的方法获得具有形状自适应分布的梯度点。然后基于这些位点构建Voronoi多面体，并使用支柱距离场和改进的布尔运算生成平滑的Voronoi支柱。随后基于体积距离场实现了多孔结构的边界自适应。通过建立密度与体积距离场值之间的关系，说明了结构上的密度变化与控制函数上的梯度变化具有相似性，说明了密度变化对形状的可控性。此外，该方法还可以通过调整支杆的位置数量、半径大小和梯度控制函数，实现结构形状和力学性能的一体化设计。最后，通过数值模拟和实验验证了该方法的可控性和有效性，为相关领域的研究和应用提供了重要的理论和实践支持。Experimental and numerical study of corrugated steel-plain concrete composite structures under contact explosionsSiyuan Yu, Guokai Zhang, Zhen Wang, Ju Liu, Shuxin Deng, Xianzhao Song, Mingyang Wangdoi:10.1016/j.tws.2024.111624接触爆炸作用下波纹钢-素混凝土组合结构的试验与数值研究This paper investigates the dynamic response and blast resistance of corrugated steel-plain concrete (CSPC) composite structures subjected to contact blast. A series of explosive tests were conducted to investigate the acceleration, deformation, and damage patterns of CSPC plates under varying blast loads and arrangements of shear connectors, and these findings were compared with reinforced concrete (RC) plates. The results suggested that CSPC plates exhibited superior ductility and blast resistance, and effectively mitigated concrete collapse. The CSPC slab primarily underwent elastic deformation when the TNT charge was small, with the rebound deformation of the concrete and steel plates acting as a significant mode of energy dissipation. As for larger TNT charges, the maximum deformation of the plate progressively increased, especially when exceeding 0.3 kg, the deformation rebound ratio decreased significantly, and the plastic deformation increased. For further increased explosive loads, the concrete and steel plates exhibited a pronounced strain rate effect with a slowed growth rate of deformation. By examining different configurations of shear connectors, it was discovered that the adhesive strength between concrete and steel plates was closely related to the energy dissipation mode, and the elastic recovery capability and deformation resistance of the CSPC structure significantly deteriorated when the shear connectors were shorter, sparser or thinner. A numerical model based on LS-DYNA was designed to further analyze the blast resistance characteristics of CSPC plates. An engineering collapse coefficient Kz was established to predict the failure level of the CSPC plates. This paper provides useful insights for the optimal design and damage assessment of CSPC composite structures.研究了波纹钢-素混凝土组合结构在接触爆破作用下的动力响应和抗爆性能。通过一系列爆炸试验，研究了CSPC板在不同爆炸荷载和剪切连接件布置下的加速度、变形和损伤模式，并将这些结果与钢筋混凝土(RC)板进行了比较。结果表明，CSPC板具有良好的延性和抗震性，能有效地减缓混凝土的倒塌。当TNT装药较小时，CSPC板主要发生弹性变形，混凝土和钢板的回弹变形是重要的耗能方式。较大TNT装药时，板的最大变形逐渐增大，特别是超过0.3 kg时，变形回弹比明显减小，塑性变形增大。当爆炸荷载进一步增大时，混凝土和钢板表现出明显的应变速率效应，变形增长速度减慢。通过对不同剪力连接件配置的考察，发现混凝土与钢板之间的粘接强度与耗能方式密切相关，剪力连接件越短、越稀疏、越薄，CSPC结构的弹性恢复能力和抗变形能力明显下降。设计了基于LS-DYNA的数值模型，进一步分析了CSPC板的耐爆特性。建立了CSPC板的工程破坏系数Kz来预测CSPC板的破坏程度。本文为CSPC复合材料结构的优化设计和损伤评估提供了有益的见解。Comparison of free vibration behaviors for simply supported and clamped T-shaped thin plate resting on Winkler elastic foundationHao-Jie Jiang, Qing-Zhao Guo, Xiao-Gui Wang, Ning-Hua Gaodoi:10.1016/j.tws.2024.111621温克勒弹性基础上简支与夹紧t型薄板自由振动特性比较The analysis of free vibration problems for thin plates is essential for the design of various structural systems. However, it is difficult to find analytical solutions due to the complexity of mathematical computing. Based on the symplectic superposition method, the T-shaped thin plate on the Winkler elastic foundation is divided into four sub-plates and are solved by using the symplectic eigen expansion method, and the modes and frequencies are studied. The method begins directly with the fundamental equations and undergoes a rigorous mathematical derivation without assuming the form of the solution beforehand. This approach helps circumvent the drawbacks associated with traditional semi-inverse solution methods. In addition, the theoretical calculation model and finite element analysis model of T-shaped thin plates on elastic foundation are established by using Mathematic software and ABAQUS software in present paper. It proves that the symplectic superposition method converges very fast and has a good consistency with the finite element simulation results. Results show that the boundary condition, foundation stiffness and aspect ratio have great influences on vibration frequency and mode shape for T-shaped structures.薄板自由振动问题的分析对各种结构体系的设计至关重要。然而，由于数学计算的复杂性，很难找到解析解。基于辛叠加法，将温克勒弹性基础上的t型薄板划分为4个子板，采用辛本征展开法进行求解，研究了其模态和频率。该方法直接从基本方程开始，经过严格的数学推导，而无需事先假设解的形式。这种方法有助于克服与传统半逆解方法相关的缺点。此外，本文还利用数学软件和ABAQUS软件建立了弹性基础上t型薄板的理论计算模型和有限元分析模型。结果表明，辛叠加法收敛速度快，与有限元仿真结果有较好的一致性。结果表明，边界条件、基础刚度和展弦比对t型结构的振动频率和振型有较大影响。来源：复合材料力学仿真Composites FEM
