今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 3 篇
Efficient computational homogenisation of 2D beams of heterogeneous elasticity using the patch scheme
Thien Tran-Duc, J.E. Bunder, A.J. Roberts
doi:10.1016/j.ijsolstr.2024.112719
使用补丁方案对异质弹性二维梁进行高效计算均质化
Modern ‘smart’ materials have complex heterogeneous microscale structure, often with unknown macroscale closure but one we need to realise for large scale engineering and science. The multiscale Equation-Free Patch Scheme empowers us to non-intrusively, efficiently, and accurately predict large scale, system level, solutions through computations on only small sparse patches of the given detailed microscale system. Here the microscale system is that of a 2D beam of heterogeneous elasticity, with either fixed-fixed, fixed-free, or periodic boundary conditions. We demonstrate that the described multiscale Patch Scheme simply, efficiently, and stably predicts the beam’s macroscale, with a controllable accuracy, at finite scale separation. Dynamical systems theory supports the scheme. This article points the way for others to use this innovative systematic non-intrusive approach, via a developing toolbox of functions, to model and compute accurately macroscale system-levels of general complex physical and engineering systems.
现代 "智能 "材料具有复杂的异质微观结构,通常具有未知的宏观封闭性,但我们需要实现大规模的工程和科学。多尺度无方程补丁方案使我们能够通过对给定详细微尺度系统的稀疏小补丁进行计算,非侵入式地高效、准确地预测大尺度系统级解决方案。这里的微尺度系统是具有固定-固定、无固定或周期性边界条件的异质弹性二维梁。我们证明,所描述的多尺度补丁方案可以简单、高效、稳定地预测梁的宏观尺度,并且在有限尺度分离的情况下精度可控。动力系统理论为该方案提供了支持。这篇文章为其他人使用这种创新的系统化非侵入式方法指明了方向,即通过一个开发中的函数工具箱,对一般复杂物理和工程系统的宏观系统级进行建模和精确计算。
Tailoring electromagnetic interference shielding effectiveness of SiO2-decorated MWCNT/polymer nanocomposites
Xiaodong Xia, Yang Liu, Juanjuan Zhang, Jianyang Luo, George J. Weng
doi:10.1016/j.mechmat.2024.104949
定制二氧化硅装饰的 MWCNT/聚合物纳米复合材料的电磁干扰屏蔽效果
While the decorated process has been demonstrated to be a highly efficient method to tailor the electrical conductivity of multi-walled carbon nanotube (MWCNT)-based nanocomposites, the corresponding influences on the agglomeration and electromagnetic interference (EMI) shielding behaviors still remain unknown. In this paper, the decoration-dependent EMI shielding behavior of progressively agglomerated SiO2@MWCNT/polymer nanocomposites is investigated through a hierarchical homogenization scheme of electromagnetic properties in the X-band. Various microstructural features including the MWCNT waviness, progressive agglomeration, hollow structure of MWCNT and decoration-dependent functional interfacial effects have been fully considered. The multiscale theoretical prediction of decorated EMI shielding effectiveness (SE) of progressively agglomerated SiO2@MWCNT/polymer nanocomposites agrees with the experiments along a wide range of decoration thickness. The SiO2 decorated interphase is demonstrated to tune both the nonuniform distribution of MWCNTs and the functional interface effects in the nanocomposites, and therefore tailor the decoration-dependent EMI shielding performance. The effective EMI SE is revealed to first enhance with the decoration thickness, but then decreases with it. The optimal decoration thickness for high EMI SE is obtained numerically. This research provides a guidance to tailor the X-band EMI shielding performance of progressively agglomerated SiO2@MWCNT/polymer nanocomposites by the decoration process.
虽然装饰工艺已被证明是一种定制多壁碳纳米管(MWCNT)基纳米复合材料导电性的高效方法,但其对团聚和电磁干扰(EMI)屏蔽行为的相应影响仍然未知。本文通过 X 波段电磁特性的分层均质化方案,研究了逐渐团聚的 SiO2@MWCNT/聚合物纳米复合材料与装饰相关的电磁干扰屏蔽行为。充分考虑了各种微观结构特征,包括 MWCNT 的波浪状、渐进团聚、MWCNT 的中空结构以及与装饰相关的功能界面效应。对渐进团聚的 SiO2@MWCNT/ 聚合物纳米复合材料的装饰电磁干扰屏蔽效能(SE)进行的多尺度理论预测与实验结果在较宽的装饰厚度范围内相吻合。事实证明,SiO2 装饰的中间相可以调整纳米复合材料中 MWCNT 的不均匀分布和功能界面效应,从而定制与装饰相关的 EMI 屏蔽性能。结果表明,有效的 EMI SE 首先会随着装饰厚度的增加而增加,但随后会随着装饰厚度的增加而减少。通过数值计算得到了实现高 EMI SE 的最佳装饰厚度。这项研究为通过装饰工艺定制逐步团聚的 SiO2@MWCNT/ 聚合物纳米复合材料的 X 波段 EMI 屏蔽性能提供了指导。
A forming limit framework accounting for various failure mechanisms: localization, ductile and cleavage fracture
Fuhui Shen, Yannik Sparrer, Jing Rao, Markus Könemann, Sebastian Münstermann, Junhe Lian
doi:10.1016/j.ijplas.2024.103921
考虑到各种破坏机制的成形极限框架:局部破坏、韧性破坏和劈裂破坏
The forming limits and failure properties of three distinct advanced high-strength steels (AHSS) have been investigated under various stress states in tensile tests with optimized specimen geometries. In addition to the commonly observed failure patterns governed by localized necking and ductile fracture for two of the AHSS, after substantial plastic deformation at room temperature, cleavage fracture occurs for a large range of stress states in a laboratory quenching and partitioning steel with superior tensile properties. The competition between failure patterns, encompassing ductile and cleavage fractures with and without necking, is governed by the mechanical properties of materials and the stress states, as a transition of failure mechanisms occurs with increasing triaxiality. The forming limit framework is, therefore, further extended to seamlessly integrate cleavage fracture in this study, where the competition between various failure mechanisms is demonstrated using three AHSS in the space of critical strain and principal stress. These findings shed light on the importance of considering cleavage fracture strength as a parameter besides the strength-ductility synergy in advanced high-strength metallic materials, and the proposed framework also gives a more comprehensive guide in designing and conducting the sheet metal forming processes.
在采用优化试样几何形状的拉伸试验中,研究了三种不同的高级高强度钢(AHSS)在各种应力状态下的成型极限和破坏特性。除了两种 AHSS 常见的局部缩颈和韧性断裂失效模式外,一种具有优异拉伸性能的实验室淬火分区钢在室温下发生大量塑性变形后,在很大的应力状态范围内出现了劈裂断裂。材料的机械性能和应力状态决定了破坏模式之间的竞争,包括韧性断裂和劈裂断裂(有无缩颈),因为随着三轴度的增加,破坏机制会发生转变。因此,本研究进一步扩展了成形极限框架,以无缝整合劈裂断裂,并使用临界应变和主应力空间中的三种 AHSS 证明了各种破坏机制之间的竞争。这些发现揭示了在先进高强度金属材料中将劈裂断裂强度作为强度-电导率协同作用之外的一个参数考虑的重要性,所提出的框架也为设计和实施金属板材成形工艺提供了更全面的指导。
Upper-bound Vibration Response Spectrum Computation for Deployable Membrane Structures with Uncertainty Effects
Takashi Iwasa, Shuuta Fujibayashi, Nobuhisa Katsumata, Ken Higuchi
doi:10.1016/j.tws.2024.111706
具有不确定性效应的可部署膜结构的上界振动响应谱计算
Real-time monitoring technology is essential for establishing a control technology for large-sized membrane space structures. However, numerous measurement points are necessary to capture the maximum vibration response, which renders the real-time monitoring technology impractical. Thus, this study proposed an upper-bound vibration spectrum computation approach using a few measurement points samples on a deployable membrane structure. The proposed method exhibits characteristics of applying the standardized upper-bound spectrum, including uncertainty effects for the computations. The experiment results indicated that the upper-bound spectrum calculated from only 30 measured data points appropriately covered the measured spectra, thus confirming the effectiveness of the proposed method.
实时监测技术对于建立大型膜空间结构的控制技术至关重要。然而,要捕捉最大振动响应,必须要有大量的测量点,这使得实时监测技术变得不切实际。因此,本研究提出了一种利用可展开膜结构上的少量测量点样本进行上限振动频谱计算的方法。所提出的方法具有应用标准化上界频谱的特点,包括计算的不确定性影响。实验结果表明,仅用 30 个测量数据点计算出的上限值频谱恰当地覆盖了测量频谱,从而证实了所提方法的有效性。
Influence of Diverse Boundary Conditions on SH and P-SV Wave Dynamics in Micropolar Plates
Satish Kumar, Vikas Sharma
doi:10.1016/j.tws.2024.111708
不同边界条件对微极性板块中 SH 波和 P-SV 波动力学的影响
Studying wave propagation characteristics in plates is vital for comprehending the material dynamics to enhance the strength of structures and for optimizing the effectiveness of non-destructive testing devices. Micropolar elasticity displays microcontinuum behavior by integrating rotational and coupling effects through displacements and micro-rotations. The present study thoroughly investigates horizontally polarized shear waves (SH) within a thin micropolar plate by employing diverse boundary conditions namely stress-free, clamped, and mixed conditions. Shear horizontal waves propagate within a plate by shearing the material along the surface, excluding any motion in perpendicular direction. Moreover, for a more comprehensive grasp of wave behavior in a micropolar plate, the study investigates P-SV type waves under plain strain conditions. Analytical techniques are utilized to derive the dispersion relations for SH and P-SV type waves in a micropolar plate. Graphical representations are provided to showcase the impacts of various micropolar parameters such as coupling number, characteristic length, and plate thickness on the phase velocities of SH and P-SV type waves. The study also includes a dispersion analysis of the multimode aspect of SH and P-SV waves. This thorough investigation can significantly augment the comprehension of wave propagation phenomena within plate-like structures.
研究板材中的波传播特性对于理解材料动力学以提高结构强度和优化无损检测设备的有效性至关重要。微极性弹性通过位移和微旋转整合了旋转和耦合效应,从而显示出微连续行为。本研究通过采用不同的边界条件,即无应力、夹紧和混合条件,深入研究了薄微波板内的水平极化剪切波(SH)。剪切水平波是通过沿表面剪切材料而在板内传播的,不包括任何垂直方向的运动。此外,为了更全面地掌握微极板中的波行为,研究还探讨了平应变条件下的 P-SV 型波。研究利用分析技术推导出微极板中 SH 波和 P-SV 波的频散关系。研究用图表展示了各种微波参数(如耦合数、特征长度和板厚度)对 SH 波和 P-SV 波相速的影响。研究还包括 SH 波和 P-SV 波多模方面的频散分析。这一深入研究可极大地增强对板状结构内波传播现象的理解。
A multistable composite hinge structure
Chenmin Zhao, Xinyu Lin, Bing Wang, Juncheng Zhu, Chenglong Guan, Shuncong Zhong
doi:10.1016/j.tws.2024.111709
多稳复合铰链结构
A composite tape-spring (CTS) structure is a thin-walled open slit tube with fibres oriented at ±45°, which is stable in both extended and coiled configurations. The governing factors of its bistability include composite constitutive behaviour, initial geometrical proportions, and geometrically non-linear structural behaviour. Its bistable principle can be employed to produce a flexible multistable hinge structure with tailorable stability. This is achieved by introducing variable stiffness design within a cylindrical shell structure, where folding stability is dependent on central functional patch region, and then connected to linking ploy regions. Thus, a novel multistable composite hinge structure can be designed with positive Gaussian curvature deformation, and its multistability is highly tailorable: a lengthy one-dimensional mechanical arm can be designed to coil and fold multiple times to enable large folding ratio. An analytical model was established based on the strain energy principle, in order to determine effects from functional tape length; the typical structural stability and stable configurations were then predicted with respect to regional length of the functional layer. It is found that the stability of a multistable composite hinge structure is dependent on geometry and combination of both the functional patch region, and connecting ploy region; the stable criteria are then proposed and show good agreement with experimental observations and FE analysis. These enrich the diversities of functional deployable structures to benefit novel requirements for various deployable mechanisms, and enable customised design, as well as smart driving for flexible and multifunctional mechanical composite hinge applications.
复合胶带弹簧(CTS)结构是一种纤维方向为±45°的薄壁开缝管,在伸展和盘绕两种配置下都很稳定。其双稳态性的制约因素包括复合材料的构成行为、初始几何比例和几何非线性结构行为。其双稳态原理可用于制造具有可定制稳定性的柔性多稳态铰链结构。这是通过在圆柱形壳体结构中引入可变刚度设计来实现的,其中折叠稳定性取决于中心功能补丁区域,然后连接到连接犁区域。因此,可以设计出一种具有正高斯曲率变形的新型多稳态复合铰链结构,而且其多稳态性具有很强的可定制性:可以设计出一个冗长的一维机械臂,使其可以多次卷绕和折叠,从而实现较大的折叠率。根据应变能原理建立了一个分析模型,以确定功能带长度的影响;然后预测了与功能层区域长度有关的典型结构稳定性和稳定构型。研究发现,多稳态复合铰链结构的稳定性取决于功能贴片区域和连接杆区域的几何形状和组合;随后提出了稳定标准,并与实验观察和 FE 分析结果表明了良好的一致性。这些研究丰富了功能性可展开结构的多样性,从而满足了各种可展开机构的新要求,实现了定制化设计以及灵活和多功能机械复合材料铰链应用的智能驱动。