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【新文速递】2024年8月14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,Journal of the Mechanics and Physics of Solids 2 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 6 篇

International Journal of Solids and Structures

A large deformation viscoelasticity theory for elastomeric materials and its numerical implementation in the open-source finite element program FEniCSx

Eric M. Stewart, Lallit Anand

doi:10.1016/j.ijsolstr.2024.113023

弹性材料的大变形粘弹性理论及其在开源有限元程序FEniCSx中的数值实现

Elastomeric solid materials typically exhibit a pronounced viscoelastic response. In this paper we consider a large deformation viscoelasticity theory for isotropic elastomeric materials which uses a multi-branch multiplicative decomposition of the deformation gradient. We then describe the numerical implementation of the theory in the open-source finite element program FEniCSx. Several example simulations which demonstrate the capability of the theory and its numerical implementation to model stress-relaxation, creep, stretch-rate sensitivity, hysteresis, damped inertial oscillations, and dynamic column buckling are shown. The source codes for these simulations are provided. The theory and the codes presented in this paper lay the foundation for future extensions of the theory and its numerical implementation to include the effects of coupling with thermal, electrical, and magnetic fields — extensions which are of central importance in modeling the response of soft-active materials.

弹性固体材料通常表现出明显的粘弹性响应。本文考虑了各向同性弹性体材料的大变形粘弹性理论,该理论采用变形梯度的多分支乘法分解。然后,我们描述了该理论在开源有限元程序FEniCSx中的数值实现。几个实例仿真表明,该理论及其数值实现能够模拟应力松弛、蠕变、拉伸率敏感性、迟滞、阻尼惯性振荡和动态柱屈曲。给出了这些模拟的源代码。本文提出的理论和代码为理论的未来扩展及其数值实现奠定了基础,以包括与热、电和磁场耦合的影响-这些扩展在模拟软活性材料的响应中是至关重要的。


Journal of the Mechanics and Physics of Solids

Stochastic process model for interfacial gap of purely normal elastic rough surface contact

Yang Xu, Junki Joe, Xiaobao Li, Yunong Zhou

doi:10.1016/j.jmps.2024.105823

纯法向弹性粗糙表面接触界面间隙的随机过程模型

In purely normal elastic rough surface contact problems, Persson’s theory of contact shows that the evolution of the probability density function (PDF) of contact pressure with the magnification is governed by a diffusion equation. However, there is no partial differential equation describing the evolution of the PDF of the interfacial gap. In this study, we derive a convection–diffusion equation in terms of the PDF of the interfacial gap based on stochastic process theory, as well as the initial and boundary conditions. A finite difference method is developed to numerically solve the partial differential equation. The predicted PDF of the interfacial gap agrees well with that by Green’s Function Molecular Dynamics (GFMD) and other variants of Persson’s theory of contact at high load ranges. At low load ranges, the obvious deviation between the present work and GFMD is attributed to the overestimated mean interfacial gap and oversimplified magnification-dependent diffusion coefficient used in the present model. As one of its direct application, we show that the present work can effectively solve the adhesive contact problem under the DMT limit. The current study provides an alternative methodology for determining the PDF of the interfacial gap and a unified framework for solving the complementary problem of random contact pressure and random interfacial gap based on stochastic process theory.

在纯法向弹性粗糙表面接触问题中,Persson接触理论表明,接触压力的概率密度函数(PDF)随放大倍数的演化由扩散方程控制。然而,目前还没有描述界面间隙的偏微分方程。本文基于随机过程理论,推导了基于界面间隙PDF的对流扩散方程,并给出了初始条件和边界条件。提出了一种数值求解偏微分方程的有限差分法。在高载荷范围内,界面间隙的预测PDF与格林函数分子动力学(GFMD)和佩尔松接触理论的其他变体相吻合。在低负荷范围内,本模型与GFMD之间的明显偏差是由于高估了平均界面间隙和过度简化了放大相关扩散系数。作为该方法的直接应用之一,本文的工作可以有效地解决DMT极限下的粘接问题。本研究提供了一种确定界面间隙PDF的替代方法,并基于随机过程理论为解决随机接触压力和随机界面间隙互补问题提供了统一的框架。


Simple and effective mechanical cloaking

Suzanne M. Fielding

doi:10.1016/j.jmps.2024.105824

简单有效的机械隐身

We show theoretically that essentially perfect elastostatic mechanical cloaking of a circular inclusion in a homogeneous surrounding medium can be achieved by means of a simple cloak comprising three concentric annuli, each formed of a homogeneous isotropic linear elastic material of prescribed shear modulus. Importantly, we find that the same combination of annuli will cloak any possible mode of imposed deformation or loading, for any randomly chosen admixture of imposed compression, pure shear and simple shear, without the need to re-design the cloak for different deformation modes. A full range of circular inclusions can be cloaked in this way, from soft to stiff. In consequence, we suggest that an inclusion of any arbitrary shape can also be cloaked, by first enveloping it in a stiff circle, then cloaking the combined structure with three annuli as described. Given that a single inclusion can be fully cloaked in this way, even at near field close to the cloaking perimeter, it also follows that multiple such neutral inclusions arranged with arbitrarily high packing fraction in a surrounding medium can also be cloaked. We confirm this by direct simulation. This indicates a possible route to fabricating composite materials with the same global mechanical response as a counterpart homogeneous material, and with uniform strain and stress fields outwith the cloaked inclusions.

我们从理论上证明,在均匀的周围介质中,圆形包裹体的基本完美的弹性静力机械斗篷可以通过由三个同心环组成的简单斗篷来实现,每个环由规定剪切模量的均匀各向同性线弹性材料组成。重要的是,我们发现相同的环空组合可以覆盖任何可能的施加变形或加载模式,对于任意随机选择的施加压缩、纯剪切和简单剪切的混合,而无需针对不同的变形模式重新设计斗篷。用这种方法可以覆盖从柔软到坚硬的各种圆形内含物。因此,我们建议,任何任意形状的内含物也可以被掩盖,首先将其包裹在一个刚性的圆圈中,然后用三个环空来掩盖所描述的组合结构。考虑到单个包裹体可以以这种方式被完全包裹,即使在接近包裹周长的近场,也可以得出在周围介质中以任意高堆积分数排列的多个这样的中性包裹体也可以被包裹。我们通过直接模拟证实了这一点。这表明了一种制造复合材料的可能途径,该复合材料具有与对应的均质材料相同的整体力学响应,并且具有均匀的应变和应力场。


Mechanics of Materials

ANALYSIS OF THE MECHANICAL BEHAVIOR OF POROUS MATERIALS CONTAINING TWO POPULATIONS OF VOIDS UNDER DYNAMIC SPHERICAL LOADING

Mohammed El Ansi, Cédric Sartori, Christophe Czarnota

doi:10.1016/j.mechmat.2024.105112

含两类孔洞的多孔材料在动态球面载荷下的力学行为分析

A computational homogenization analysis is performed on three-dimensional representative volume elements (RVE) that contain two distinct populations of voids, to demonstrate the influence of the interaction between cavities. RVEs are constructed as cubic elastic perfectly-plastic matrices embedding two families of spherical voids, and subjected to dynamic loading under homogeneous kinematic boundary conditions. Multiple microstructure models are considered by varying the number, position, and size of voids to evaluate the micro-inertia contribution to the overall macroscopic stress. Velocity fields within numerical RVEs are investigated to reveal the interaction of voids and their key role in the dynamic macroscopic response of the porous material. Based on numerical simulation results, a homogenization analytical model considering void interaction is proposed to describe the mechanical behavior under dynamic loadings. This model relies on adjusting the strain rate level at the boundary of unit cells composing the porous material. Comparison between our numerical and analytical results with those obtained using the classical Taylor homogenization scheme highlights the limitations of the Taylor model in the case of porous materials under dynamic loading.

对包含两种不同空洞种群的三维代表性体积元(RVE)进行了计算均匀化分析,以证明空洞之间相互作用的影响。rve被构造为嵌入两族球面空隙的三次弹性完全塑性矩阵,并在均匀运动边界条件下承受动载荷。通过改变孔隙的数量、位置和大小,考虑多种微观结构模型,以评估微惯性对总体宏观应力的贡献。研究了数值rve内的速度场,揭示了孔隙的相互作用及其在多孔材料动态宏观响应中的关键作用。基于数值模拟结果,提出了考虑空隙相互作用的均匀化分析模型来描述动载荷作用下的力学行为。该模型依赖于在构成多孔材料的单元胞的边界处调整应变率水平。本文的数值和解析结果与经典Taylor均质格式的结果进行了比较,突出了Taylor模型在多孔材料动载情况下的局限性。


International Journal of Plasticity

Direct application of elasto-visco-plastic self-consistent crystal plasticity model to U-draw bending and springback of dual-phase high strength steel

Bohye Jeon, Shin-Yeong Lee, Jinwoo Lee, Youngung Jeong

doi:10.1016/j.ijplas.2024.104098

弹粘塑性自洽结晶塑性模型在双相高强钢u形拉伸弯曲回弹中的直接应用

The incremental elasto-visco-plastic self-consistent polycrystal model (ΔEVPSC) was utilized to describe the constitutive behavior of dual-phase 980 (DP980) steel. A simple baseline modeling approach was chosen: the hardening behavior of each constituent phase in the DP980 steel was described by a simple Voce hardening law without explicitly considering the back stress; and it was assumed that using the same single crystal elastic modulus for ferrite and martensite is sufficiently representative. The adequacy of this baseline modeling approach was evaluated by comparing various mechanical experimental data with model predictions in terms of the stress vs. strain curves obtained from uniaxial tension, tension-compression, and loading-unloading-loading (LUL) tests. Additionally, the evolution of experimental lattice strain data reported in literature was used to validate the phase-specific Voce hardening parameters. Despite its minimalistic modeling description, the baseline ΔEVPSC model successfully captured key features: 1) the Bauschinger effect, 2) the decrease in chord modulus, and 3) the non-linearity in the stress vs. strain curves resulting from the LUL test. All three mentioned characteristics are crucial for accurate prediction of springback in sheet metals. The ΔEVPSC model, interfaced with a finite element solver (Abaqus/standard) as the user material subroutine, was employed to simulate the Numisheet93 benchmark problem. The strip of DP980 was first U-drawn followed by springback. The model-predicted springback profile aligned well with the experimental results only when stress relaxation was properly considered, resulting in improved predictive accuracy compared to predictions based on a distortional plasticity model.

增量弹塑性自洽多晶体模型(ΔEVPSC)用于描述双相 980(DP980)钢的构成行为。我们选择了一种简单的基准建模方法:DP980 钢中各组成相的硬化行为由简单的 Voce 硬化定律来描述,而不明确考虑背应力;并且假定对铁素体和马氏体使用相同的单晶弹性模量具有足够的代表性。通过比较单轴拉伸、拉伸-压缩和加载-卸载-加载(LUL)试验获得的应力与应变曲线,将各种力学实验数据与模型预测进行比较,以评估这种基线建模方法的适当性。此外,文献中报道的实验晶格应变数据的演变也用于验证特定相位的 Voce 硬化参数。尽管建模描述非常简单,但基线 ΔEVPSC 模型成功地捕捉到了以下关键特征: 1)鲍辛格效应;2)弦模量下降;3)LUL 试验产生的应力与应变曲线的非线性。上述三个特征对于准确预测金属板材的回弹至关重要。ΔEVPSC 模型作为用户材料子程序与有限元求解器(Abaqus/标准)连接,用于模拟 Numisheet93 基准问题。首先对 DP980 带材进行 U 型拉伸,然后进行回弹。只有在适当考虑应力松弛的情况下,模型预测的回弹曲线才能与实验结果很好地吻合,从而与基于变形塑性模型的预测相比提高了预测精度。


Thin-Walled Structures

Flexural performance and damage mechanisms of stitched composites under different stitch patterns and densities by acoustic emission

Shengqiang Jiang, Tai Zeng, Ming Mei, Zhihao Chen, Lei Wen, Jielin Huang, Yujia He, Xu Li

doi:10.1016/j.tws.2024.112323

不同针法和针法密度下缝合复合材料的弯曲性能及损伤机制

The flexural performance of standard composites has been extensively studied; however, the response of stitched composites with different stitch patterns and densities has received little attention and is not well understood. This study systematically explored the flexural performance of stitched composites with different stitch patterns and densities. The stitches weakened the flexural strength while improving the residual strength of the composites, particularly under a high stitch density. In addition, the stitch threads in the longitudinal stitch pattern preferably resisted the deformation of the bottom side of the specimen, showing superior flexural strength compared with the diagonal and transversal stitch patterns. However, the stitch threads in the diagonal and transverse stitch patterns impeded crack propagation and enhanced the residual strength of the composites. In addition, acoustic emission was used to confirm that the acoustic emission signals and the first moment of rapid increase in cumulative acoustic emission energy were detected earlier under a high stitch density, suggesting that the increase in stitch defects promotes damage initiation and severe damage. The durations with high values and a continuous increase in the cumulative acoustic emission energy after brittle failure indicated that the stitched composites experienced non-catastrophic failure.

标准复合材料的抗弯性能得到了广泛的研究;然而,不同针法和密度的缝合复合材料的响应很少受到关注,也没有得到很好的理解。本研究系统地探讨了不同缝型和密度的复合材料的弯曲性能。针脚削弱了抗弯强度,同时提高了复合材料的残余强度,特别是在高针脚密度下。此外,纵缝图案中的缝线较好地抵抗了试样底面的变形,与斜缝和横缝图案相比,显示出更高的抗弯强度。然而,斜缝和横缝方式的缝线阻碍了裂纹扩展,提高了复合材料的残余强度。此外,声发射实验证实,在高针脚密度下,声发射信号和累积声发射能量快速增加的第一时刻提前被检测到,表明针脚缺陷的增加促进了损伤的发生和严重损伤。高值持续时间和脆性破坏后累积声发射能量的持续增加表明缝合复合材料发生了非灾难性破坏。


A modified quasi-3D theory and mixed beam element method for static behaviour analysis of functionally graded beams

Wenxiong Li, Zhiwei Liu, Suiyin Chen

doi:10.1016/j.tws.2024.112316

功能梯度梁静力性能分析的修正准三维理论和混合梁单元法

This paper develops a modified quasi-3D theory and the mixed beam element model for static analysis of functionally graded beams. The modified quasi-3D theory encompasses two innovations. Firstly, the accurate distribution of transverse shear stress is derived from the differential equilibrium equation that describes the relationship between stresses, rather than the traditional one derived from geometric relations and constitutive equations. Secondly, the effect of distributed loads associated with transverse stretching deformation, a factor typically overlooked in the existing quasi-3D theory-based beam models, is involved. In the development of beam finite element model, the mixed variational principle is firstly utilized to formulate the model of a quasi-3D theory-based beam element, where generalized displacements and internal forces are treated as two types of independent field quantities. Two numerical examples are conducted to investigate the validity and accuracy of the proposed theory and beam element. Numerical results indicate that the proposed mixed beam element can accurately predict the stress distributions over the cross-section and produce accurate displacement solutions. Meanwhile, it is noted that the effect of distributed loads related to the transverse stretching deformation should be correctly considered in the analysis of functionally graded beams based on quasi-3D theory.

本文提出了一种改进的准三维理论和混合梁单元模型,用于功能梯度梁的静力分析。修正后的准三维理论包含两个创新。首先,从描述应力关系的微分平衡方程中推导出横向剪应力的精确分布,而不是传统的从几何关系和本构方程中推导出横向剪应力的精确分布。其次,考虑了与横向拉伸变形相关的分布荷载的影响,这是现有基于准三维理论的梁模型中通常忽略的一个因素。在梁有限元模型的建立中,首先利用混合变分原理建立了准三维理论梁单元模型,将广义位移和内力作为两类独立的场量。通过两个算例验证了所提理论和梁单元的有效性和准确性。数值结果表明,所提出的混合梁单元能够准确地预测截面上的应力分布,并得到准确的位移解。同时指出,在基于准三维理论的功能梯度梁分析中,应正确考虑与横向拉伸变形相关的分布荷载的影响。


Synergistic improvement of the compression-after-impact performance of composite laminates by multi-scale CNF/Z-pin reinforcement

Guozhi Zhao, Mengjia Li, Yuan Zhao, Jiajia Zheng, Ying Gao, Xin Chen, Zhipeng Dai, Puhui Chen

doi:10.1016/j.tws.2024.112332

多尺度CNF/Z-pin增强对复合材料层合板冲击后压缩性能的协同改善

This paper investigated the effects of carbon nanofibers (CNF), Z-pin, and multi-scale CNF/Z-pin on the compression-after-impact (CAI) properties and damage morphology of laminates after 10 J, 30 J, and 50 J impact. The deformation and strain field variations of the laminate during the CAI process were clearly characterized by 3D-Digital Image Correlation (DIC). The process from local buckling to the global failure of the laminate was clearly revealed. The mechanical response results showed that the CAI strength of unreinforced, CNF, Z-pin and CNF/Z-pin-reinforced laminates increased in order after impact with the same energy. After 50 J impact, the CAI strength of CNF, Z-pin and CNF/Z-pin-reinforced laminates was increased by 18.6%, 28.7% and 36.4%, respectively, compared to unreinforced laminates. By constructing a simulation model to analyze damage and mechanical response, the model's effectiveness was verified. Additionally, the damage morphology, damage mechanism, and synergistic toughening mechanism between CNF and Z-pin in CAI specimens were revealed from optical photographs and scanning electron microscopy (SEM).

研究了碳纳米纤维(CNF)、Z-pin和多尺度CNF/Z-pin对复合材料在10 J、30 J和50 J冲击后压缩性能和损伤形貌的影响。三维数字图像相关技术(DIC)清晰地表征了复合材料在CAI过程中的变形场和应变场变化。揭示了层合板从局部屈曲到整体破坏的过程。力学响应结果表明,在相同能量的冲击下,未加筋、CNF、Z-pin和CNF/Z-pin加筋层合板的CAI强度依次增大。经50j冲击后,CNF、Z-pin和CNF/Z-pin增强层合板的CAI强度分别比未增强层合板提高18.6%、28.7%和36.4%。通过建立仿真模型分析损伤和力学响应,验证了该模型的有效性。此外,通过光学照片和扫描电镜(SEM)揭示了CNF与Z-pin在CAI试样中的损伤形态、损伤机理以及协同增韧机理。


Influence of welding sequences and boundary conditions on residual stress and residual deformation in DH36 steel T-joint fillet welds

Hongtao Ding, Wenyue Zhang, Zhengyi Zhang, Didi Yin, Wentao He, De Xie

doi:10.1016/j.tws.2024.112337

焊接顺序和边界条件对DH36钢t形角焊缝残余应力和残余变形的影响

This paper aims to investigate the influence of welding sequences and boundary conditions on welding-induced residual stress and residual deformation of DH36 steel T-joint fillet welds through experimental and numerical methods. A series of typical experiments of successive and simultaneous double-sided welding conditions are conducted to explore both the magnitude and distribution of temperature field, residual stress and residual deformation. Meanwhile, thermal elastic-plastic finite element analysis based on a double ellipsoidal heat source model is performed to investigate the heat transfer and deformation mechanism during the welding process. The influencing factors are further explored to determine and quantify the residual stress and residual deformation induced by different welding sequences and boundary conditions. There is generally well agreement between the experimental and numerical results in terms of temperature field, residual stress, residual deformation and molten pool morphology. The results show that the welding sequences have an important influence on the magnitude and distribution of residual stress and residual deformation. Continuous simultaneous double-sided welding can significantly reduce residual stress and residual deformation to obtain better-quality welds. Boundary conditions have a significant effect on the distribution and magnitude of residual deformation and little effects on residual stress. Tightening the ends of the flange plate with bolts during the welding process can significantly reduce the deformation.

本文旨在通过实验和数值方法研究焊接顺序和边界条件对DH36钢t型接头角焊缝焊接残余应力和残余变形的影响。通过一系列典型的连续和同步双面焊接试验,探讨了温度场、残余应力和残余变形的大小和分布。同时,基于双椭球热源模型进行了热弹塑性有限元分析,研究了焊接过程中的传热和变形机理。进一步探讨了影响因素,确定和量化了不同焊接顺序和边界条件引起的残余应力和残余变形。在温度场、残余应力、残余变形和熔池形貌等方面,实验结果与数值结果基本吻合。结果表明,焊接顺序对残余应力和残余变形的大小和分布有重要影响。双面连续同时焊接可显著降低残余应力和残余变形,获得更好的焊缝质量。边界条件对残余变形的分布和大小有显著影响,对残余应力影响不大。在焊接过程中,用螺栓拧紧法兰板的两端,可以显著减少变形。


A novel multi-spot structure for joining aluminum and steel dissimilar thin-walled tubes by magnetic pulse crimping

Dayong Wang, Gongcheng Peng, Shaoluo Wang, Hao Jiang, Binbin Zhou, Guangyao Li, Junjia Cui

doi:10.1016/j.tws.2024.112338

一种新型多点磁脉冲压接铝与钢异种薄壁管的结构

Lightweight manufacture for dissimilar thin-walled tube structures without additional liner support has always been a challenge. A novel magnetic pulse multi-spot joining structure was proposed for the non-weight gain mechanical connection of 6061 aluminum to SPCC (Steel Plate Cold-rolled Common) steel thin-walled tubes. Mechanical properties, microscopic features, and joining mechanism of the magnetic pulse crimping (MPC) joints were explored based on simulation and experiments. Under the geometric conditions of flyer tube with an outer diameter of 30 mm and a thickness of 1 mm, the optimal preformed groove depth and discharge energy for the MPC joints were 2 mm and 16 kJ, respectively. The corresponding maximum tensile and torsional strength were 10.6 kN and 131.2 N·m, respectively. The corresponding relative thinning rate of aluminum outer tube was 13%. The failure forms of the MPC joints were all pull out and torsion out failures. During the high-speed joining of aluminum tube to steel tube, stress concentration phenomena occurred successively at the circumferential bottom fillet, axial bottom fillet, and axial upper edge of the groove. This was due to a certain height difference between the circumferential and axial directions of the groove. It was related to induction distance, discharge energy, skin effect, proximity effect, and tip effect in the coupled field. The yielding and instability of the groove in the steel inner tube would lead to a decrease in the fitting area of the aluminum outer tube filled groove and the relative thinning rate of the aluminum outer tube. This caused a decrease in the mechanical interlocking force at the groove, which was detrimental to the mechanical properties of the MPC joints. This article provides a new approach and data support for the lightweight manufacture of dissimilar thin-walled tube structures.

没有额外衬垫支撑的不同薄壁管结构的轻量化制造一直是一个挑战。提出了一种新型磁脉冲多点连接结构,用于6061铝合金与SPCC薄壁钢管的无增重机械连接。通过仿真和实验对磁脉冲压接接头的力学性能、微观特征及连接机理进行了探讨。在外径为30 mm、厚度为1 mm的飞管几何条件下,MPC接头的最佳预制槽深和放电能量分别为2 mm和16 kJ。其最大抗拉强度为10.6 kN,最大抗扭强度为131.2 N·m。铝外管相应的相对减薄率为13%。MPC接头的破坏形式均为拉拔和扭拔破坏。铝管与钢管高速连接过程中,在槽的周向底圆角、轴向底圆角、轴向上边缘依次出现应力集中现象。这是由于槽的周向和轴向之间存在一定的高度差。这与耦合场中的感应距离、放电能量、趋肤效应、接近效应和尖端效应有关。钢内管槽的屈服和失稳会导致铝外管填充槽的拟合面积减小,铝外管的相对变薄率降低。这导致凹槽处的机械联锁力降低,不利于MPC接头的力学性能。本文为异种薄壁管结构的轻量化制造提供了新的途径和数据支持。


A Design Method for Continuous Fiber-Reinforced Composite Patches

Tianchi Zhang, Jiahao Liu, Xiaosheng Cheng, Ce Guo, Hongqing Dai, Ning Dai

doi:10.1016/j.tws.2024.112336

连续纤维增强复合材料贴片的设计方法

The urgent need for lightweight and high-strength patches in the field of aircraft structural repair has propelled continuous fiber-reinforced thermoset composites into a research hotspot. However, constrained by manufacturing processes, the designs of composite repair structures primarily focus on external shape and ply layup. These approaches presently lack design methods for the internal fiber adaptability of patches driven by in-service loads. In this paper, we proposed a method for fiber distribution and orientation design based on maximum normal stress. The composite simulation model was established based on fracture toughness. The influence of tensile-shear coupling effects on the mechanical response of composites and the fiber orientation design were examined in the study. The orientation-density coupling effects on the enhancement of patch strength were also analyzed. Furthermore, additive manufacturing technology was employed to fabricate thermoset composite patches. The results show that the composite patches designed in this paper exhibit a 10.50% improvement in strength compared to traditional unidirectional patches.

飞机结构维修领域对轻量化、高强贴片的迫切需求使得连续纤维增强热固性复合材料成为研究热点。然而,受制造工艺的限制,复合材料修复结构的设计主要集中在外部形状和层数上。这些方法目前缺乏对在用负载驱动的贴片内部光纤适应性的设计方法。本文提出了一种基于最大 法向应力的纤维分布和取向设计方法。建立了基于断裂韧性的复合仿真模型。研究了拉伸-剪切耦合效应对复合材料力学响应和纤维取向设计的影响。分析了取向-密度耦合对贴片强度增强的影响。采用增材制造技术制备热固性复合材料贴片。结果表明,与传统的单向贴片相比,本文设计的复合贴片强度提高了10.50%。




来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveOpticalSystem断裂复合材料非线性隐身光学增材焊接裂纹理论材料分子动力学螺栓
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首次发布时间:2024-11-21
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【新文速递】2024年8月18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,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 1 篇International Journal of Solids and StructuresInfluence of elasto-plastic behaviour of thin films on circular buckling structuresK. Meng, G. Parry, M.A. Hurier, C. Tromas, C. Coupeaudoi:10.1016/j.ijsolstr.2024.113032薄膜弹塑性对圆形屈曲结构的影响We report on circular buckles experimentally observed by optical and atomic force microscopy on gold ductile thin films deposited by physical vapor deposition on silicon wafers. It is shown that, whatever the radius blister dimensions, their maximum deflections are higher than those expected by the elastic theory. It suggests that plastic events may take place in the film, impacting on the blister morphology as a result. Based on nanoindentation experiments carried out on our gold films, a proper plastic hardening law has been determined by calculations using the finite elements method. The influence of this elasto-plastic behavior on the buckled circular profiles has been then numerically studied, compared to the experimental observations and discussed.本文报道了用光学和原子力显微镜在物理气相沉积在硅片上的金延展性薄膜上实验观察到的圆形屈曲。结果表明,无论气泡半径大小如何,其最大挠度都高于弹性理论所期望的挠度。这表明塑料事件可能在薄膜中发生,从而影响水疱形态。在对金薄膜进行纳米压痕实验的基础上,采用有限元法计算确定了合适的塑性硬化规律。然后对这种弹塑性行为对屈曲圆形型材的影响进行了数值研究,并与实验结果进行了比较和讨论。Journal of the Mechanics and Physics of SolidsA regularized variational mechanics theory for modeling the evolution of brittle crack networks in composite materials with sharp interfacesKaushik Vijaykumar, Benjamin E. Grossman-Ponemon, Yang Wan, Pooya Yousefi, Christopher J. Larsen, Haneesh Kesaridoi:10.1016/j.jmps.2024.105772具有尖锐界面的复合材料脆性裂纹网络演化的正则变分力学理论In the design of structural materials, there is traditionally a tradeoff between achieving high strength and achieving high toughness. Nature offers creative solutions to this problem in the form of structural biomaterials (SBs), intelligent arrangements of mineral and organic phases which possess greater strength and toughness than the constituents. The micro-architecture of SBs like nacre and sea sponge spicules are characterized by weak organic interfaces between brittle mineral phases. To better understand the toughening mechanisms in SBs requires simulation techniques which can resolve arbitrary interface and bulk fracture patterns.In this work, we present a modified regularization of Variational Fracture Theory (VFT) that allows for simulation of fracture in materials and structures with weak interfaces. The core of our approach is widen the weak interfaces on a length scale proportional to that of the diffuse damage field, and assign a reduced fracture toughness therein. We show that in 2D the modified regularized functionals Γ-converge to that for sharp cracks. The resulting thin weak interfaces have fracture toughness which depends on the bulk material fracture toughness, the widened interface fracture toughness, and the widened interface length scale. We next apply our modified regularization within a computer implementation of regularized VFT, which we term RVFTI. We assess the performance of RVFTI in 2D by reproducing the effective interface fracture toughness predicted by the Γ-convergence theory and simulating crack trapping at a bi-material interface. We then use RVFTI to study toughening in SB-inspired microarchitectures, namely layered materials and materials with wavy interfaces.在结构材料的设计中,传统上需要在实现高强度和高韧性之间做出权衡。大自然以结构生物材料(SBs)的形式为这一问题提供了创造性的解决方案,SBs 是矿物和有机相的智能排列,具有比成分更高的强度和韧性。珍珠质和海绵体等 SB 的微观结构特点是脆性矿物相之间的有机界面较弱。要更好地了解 SB 的增韧机制,就需要能解析任意界面和整体断裂模式的模拟技术。在这项工作中,我们提出了一种修正的变分断裂理论(VFT)正则化方法,可以模拟具有弱界面的材料和结构的断裂。我们方法的核心是在与弥散损伤场成正比的长度尺度上拓宽弱界面,并在其中赋予降低的断裂韧性。我们的研究表明,在二维情况下,修正后的正则化函数与尖锐裂缝的正则化函数Γ-趋同。由此产生的薄弱界面的断裂韧性取决于块体材料断裂韧性、加宽界面断裂韧性和加宽界面长度尺度。接下来,我们在正则化 VFT 的计算机实现中应用了修改后的正则化,我们称之为 RVFTI。我们通过再现Γ-收敛理论预测的有效界面断裂韧性并模拟双材料界面的裂纹捕获,评估了 RVFTI 在二维中的性能。然后,我们使用 RVFTI 研究 SB 启发的微结构(即层状材料和具有波浪形界面的材料)中的增韧问题。Mechanics of MaterialsAn analytical and experimental investigation into overall dissipation of flexural mode in a periodically damped beamSouryadeep Biswas, Arnab Banerjee, Kamal K. Beradoi:10.1016/j.mechmat.2024.105113周期阻尼梁挠曲模态总耗散的分析与实验研究This study presents an innovative analytical model to estimate the overall energy dissipation in damped Euler–Bernoulli beams with uniform and non-uniform (stepped) cross-sections. The novelty lies in proposing a closed-form expression for an envelope function that closely matches the energy dissipation profile obtained from the time-domain response. Importantly, the study unveils a non-intuitive finding, which states that the rate of energy decay predominantly depends on the configuration (orientation) of the stepped beam. Both strain rate-dependent viscous damping and velocity-dependent viscous damping components are considered in the governing equations. An analytical formulation is developed to obtain the wave-number-dependent damped frequencies and damping ratios using the free-wave approach. The coefficient of energy decay, governing the envelope function, is expressed in terms of the damping ratios, natural frequencies, mode participation factors, and the ratio of flexural rigidities. Moreover, this study presents the experimental validation of the analytical formulation by estimating the settling times from free vibration tests on 3D-printed stepped beams with different configurations and further quantifies the damping coefficients of the stepped beam by applying the nonlinear least squares method to fit the peaks in the experimentally acquired acceleration response. The close agreement between analytical and experimental results establishes the accuracy and applicability of the proposed model for transient vibration mitigation.本文提出了一种新颖的分析模型来估计均匀截面和非均匀截面(阶梯)阻尼欧拉-伯努利梁的总能量耗散。新颖之处在于提出了一个封闭形式的包络函数表达式,该表达式与从时域响应中获得的能量耗散曲线密切匹配。重要的是,这项研究揭示了一个非直觉的发现,即能量衰减的速率主要取决于阶梯梁的结构(方向)。控制方程中考虑了应变率相关的粘性阻尼分量和速度相关的粘性阻尼分量。利用自由波法推导出了与波数相关的阻尼频率和阻尼比的解析公式。控制包络函数的能量衰减系数用阻尼比、固有频率、模态参与系数和弯曲刚度比来表示。此外,通过对不同构型的3d打印阶梯梁进行自由振动试验,估计其沉降时间,对解析公式进行了实验验证,并利用非线性最小二乘法对实验得到的加速度响应峰进行拟合,进一步量化了阶梯梁的阻尼系数。分析结果与实验结果吻合较好,证明了该模型对瞬态振动抑制的准确性和适用性。International Journal of PlasticityUncovering all possible dislocation locks in face-centered cubic materialsD. Bajaj, D.L. Chendoi:10.1016/j.ijplas.2024.104101 揭示面心立方材料中所有可能的位错锁Dislocation reactions and locks play an important role in the plastic deformation and mechanical behavior of crystalline materials. Various types of dislocation locks in face-centered cubic (FCC) materials have been reported in the literature pertaining to material-specific molecular-dynamic simulations and high-resolution transmission electron microscopy observations. However, it is unknown how many dislocation locks are possible, and how immobile all the dislocation locks are, with respect to each other. Here we present a discrete mathematics-based approach to reveal all possible dislocation locks in the FCC crystal structure. Totally eight types of dislocation locks are uncovered, resulting from all possible reactions of mobile/glissile (namely, perfect and Shockley partial) dislocations with (a) non-coplanar Burgers vectors which reside on two slip planes intersecting at both obtuse and acute angles and (b) coplanar Burgers vectors. We redefine the degree of dislocation lock immobility based on misorientations between non-close-packed lock planes and close-packed {111} slip planes. The subsequently derived sequences for the dislocation lock immobility and formation tendency are rationalized by the reported experimental and dislocation-dynamics simulation results.位错反应和锁在晶体材料的塑性变形和力学行为中起着重要的作用。面心立方(FCC)材料中各种类型的位错锁已经在与材料特异性分子动力学模拟和高分辨率透射电子显微镜观察相关的文献中得到了报道。然而,目前尚不清楚可能有多少位错锁,以及所有位错锁相对于彼此的不动程度。在这里,我们提出了一种基于离散数学的方法来揭示FCC晶体结构中所有可能的位错锁。共有八种类型的位错锁被发现,这是由所有可能的移动/滑动位错(即完全位错和肖克利部分位错)与(a)位于以钝角和锐角相交的两个滑移面上的非共面Burgers矢量和(b)共面Burgers矢量的反应造成的。我们基于非密实锁面和密实{111}滑移面之间的取向偏差重新定义了位错锁不动的程度。本文的实验结果和位错动力学模拟结果使推导出的位错锁不动性和形成倾向的序列更为合理。Thin-Walled StructuresA methodology for evaluating damage in thin-walled cylindrical shells using bounded ultrasonic beam scatteringJiangcheng Cai, Mingxi Dengdoi:10.1016/j.tws.2024.112352用有界超声波束散射评估薄壁圆柱壳损伤的方法This paper introduces an ultrasonic detection methodology specifically designed to assess damage in thin-walled cylindrical shells, which crucially relies on the interaction between a bounded ultrasonic beam and a thin-walled cylindrical shell immersed in fluid, considering both water-filled and air-filled cavities. Initially, we derive the scattered sound field expression for a bounded ultrasonic beam obliquely striking the shell. Subsequently, through finite element simulations and experimental verification, we observe that when the incident bounded beam is emitted at the critical angles defined in this study, early damage significantly enhances the received sound pressure amplitude detected by a symmetrically positioned receiver. Notably, a mere 5% decrease in the shell's elastic modulus leads to a notable 233.69% increase in the area under the amplitude-frequency curve of the received sound pressure for water-filled cavities and a remarkable 642.85% surge in area for air-filled cavities. Experimental data further validates the sensitivity of this method towards varying corrosion damage states. This approach combines the reliability of linear ultrasonic methods with the enhanced sensitivity of nonlinear ultrasonic techniques, offering a significant advancement over traditional ultrasonic detection methods for inspecting cylindrical shells. The proposed assessment method holds immense potential in providing novel insights for inspecting cylindrical shells in practical applications.本文介绍了一种专门用于评估薄壁圆柱壳损伤的超声检测方法,该方法主要依赖于有界超声束与浸入流体中的薄壁圆柱壳之间的相互作用,同时考虑了充水腔和充气腔。首先推导了有界超声波束斜击壳时的散射声场表达式。随后,通过有限元模拟和实验验证,我们观察到,当入射有界光束以本文定义的临界角发射时,早期损伤显著增强了对称定位接收机检测到的接收声压幅值。值得注意的是,当壳的弹性模量减小5%时,充水空腔的声压幅频曲线下面积显著增大233.69%,充气空腔的声压幅频曲线下面积显著增大642.85%。实验数据进一步验证了该方法对不同腐蚀损伤状态的敏感性。该方法结合了线性超声方法的可靠性和非线性超声技术的增强灵敏度,与传统的超声检测方法相比,在检测圆柱壳方面有了显著的进步。所提出的评估方法在实际应用中为检测圆柱壳提供新的见解方面具有巨大的潜力。来源:复合材料力学仿真Composites FEM

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