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【新文速递】2024年6月14日复合材料SCI期刊最新文章

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今日更新:Composite Structures 2 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 4 篇,Composites Science and Technology 2 篇

Composite Structures

Fretting fatigue crack initiation and propagation behaviours of Ti6Al4V alloy coated by functionally graded material

Can Wang, Qi Zhao, Yunlai Zhou, Dagang Wang, Lihua Wang, Magd Abdel Wahab

doi:10.1016/j.compstruct.2024.118285

功能分级材料涂层 Ti6Al4V 合金的摩擦疲劳裂纹萌发和扩展行为

Fretting fatigue pertains to the behaviour of engineering components undergoing cyclic loading while in contact with each other. This intricate contact-related phenomenon often results in premature failure compared to conventional fatigue issues. Moreover, when these components operate in high-temperature atmospheres and experience high wear conditions, such as the heat transfer tubes in the nuclear reactor, the application of Functionally Graded Material (FGM) coatings becomes essential. Consequently, it is imperative to investigate how FGM coatings influence the initiation and propagation behaviour of fretting fatigue cracks. This paper employs the Critical Plane (CP) Method to calculate the damage parameter. Additionally, Linear Elastic Fracture Mechanics (LEFM) criteria, specifically the Extended Maximum Tangential Stress (E-MTS) criterion, are utilized to examine how FGM coatings affect the paths of crack propagation in the presence of fretting conditions. Meanwhile, due to the unavailability of material properties for FGM coatings, the damage parameter and stress intensity factors are utilized to indirectly assess the effect of FGM coatings on crack initiation and propagation lifetime. The FGM coating significantly influences tangential stress, thereby affecting the length of the stick zone, while having minimal impact on the distribution of normal stress along the contact surface. Furthermore, it is observed that adjusting the descent ratio of FGM coatings and the elastic modulus of the first FGM coating layer provides a potential avenue for enhancing both crack initiation and propagation lifetimes.

摩擦疲劳是指工程部件在相互接触时承受循环载荷的行为。与传统的疲劳问题相比,这种错综复杂的接触相关现象往往会导致过早失效。此外,当这些部件在高温环境中工作并经历高磨损条件时,如核反应堆中的传热管,功能分级材料(FGM)涂层的应用就变得至关重要。因此,研究 FGM 涂层如何影响摩擦疲劳裂纹的起始和扩展行为势在必行。本文采用临界平面 (CP) 法计算损伤参数。此外,本文还利用线性弹性断裂力学(LEFM)准则,特别是扩展最大切向应力(E-MTS)准则,来研究 FGM 涂层如何影响存在微裂纹条件下的裂纹扩展路径。同时,由于无法获得 FGM 涂层的材料属性,因此利用损伤参数和应力强度因子来间接评估 FGM 涂层对裂纹起始和扩展寿命的影响。FGM 涂层对切向应力的影响很大,因此会影响粘滞区的长度,而对沿接触面的法向应力分布的影响却很小。此外,通过观察还发现,调整 FGM 涂层的下降率和第一层 FGM 涂层的弹性模量为提高裂纹萌生和扩展寿命提供了潜在的途径。


Three-dimensional aggregate modelling method and damage analysis of recycled aggregate concrete

Jingwei Ying, Yujun Jian, Xiaojie Gan, Baixi Chen, Jianzhuang Xiao

doi:10.1016/j.compstruct.2024.118286

再生骨料混凝土的三维骨料建模方法和损伤分析

A new aggregate placement algorithm has been developed that can automatically identify the remaining space after the aggregate is placed, and only new aggregates are placed in these spaces. This results in a reduction in the number of overlaps with existing aggregates, and the more aggregates placed, the higher the efficiency. This method is suitable for various types of concrete, such as ordinary aggregate concrete, recycled aggregate concrete (RAC), and fiber-reinforced concrete. Finite element analysis is applied to simulate stress and damage evolution in mesoscale models of concrete, taking into account the effects of actual aggregate slenderness ratio, concavity, flatness, asymmetry ratio, and compaction degree. The study reveals that tensile damage is the primary factor in concrete damage evolution up to peak stress, with both tensile and compressive damages influencing the post-peak behavior. In RAC, older Interfacial Transition Zones (ITZs) are found to be more susceptible to early damage than newer ones. Moreover, the model effectively illustrates the influence of recycled aggregate content and concavity on concrete’s mechanical properties. This mesoscale concrete modeling method, as developed in this study, holds potential for future research on various types of concrete.

我们开发了一种新的集料放置算法,可以自动识别集料放置后的剩余空间,并只在这些空间中放置新的集料。这样就减少了与现有骨料重叠的数量,而且骨料放得越多,效率就越高。这种方法适用于各种类型的混凝土,如普通骨料混凝土、再生骨料混凝土(RAC)和纤维增强混凝土。考虑到实际骨料细长比、凹度、平整度、不对称比和压实度的影响,应用有限元分析模拟混凝土中尺度模型的应力和损伤演变。研究结果表明,拉伸损伤是峰值应力前混凝土损伤演变的主要因素,拉伸和压缩损伤都会影响峰值后的行为。在 RAC 中,发现老的界面过渡区(ITZ)比新的界面过渡区更容易受到早期破坏的影响。此外,该模型还有效说明了再生骨料含量和凹度对混凝土力学性能的影响。本研究中开发的这种中尺度混凝土建模方法,为未来各类混凝土的研究提供了可能。


Composites Part A: Applied Science and Manufacturing

Fabrication and mechanical properties of a high-performance PEEK-PEI hybrid multilayered thermoplastic matrix composite reinforced with carbon fiber

Sebastian Andrés Toro, Carlos González, Juan P. Fernández-Blázquez, Alvaro Ridruejo

doi:10.1016/j.compositesa.2024.108308

用碳纤维增强的高性能 PEEK-PEI 混合多层热塑性基复合材料的制造和力学性能

This paper presents a method for manufacturing a hybrid matrix composite material reinforced with a woven carbon fiber that combines the properties of two thermoplastic polymers: PEEK (polyether-ether-ketone) and PEI (polyether-imide). The manufacturing process involves a multilayer architecture and a single hot-pressing consolidation step. Experimental tests—including uniaxial tensile tests, delamination tests in Mode I and impact tests at low velocities—were conducted to compare the resulting laminate with single matrix materials (PEEK/CF and PEI/CF).The improvements in strain to failure by 48 % in tensile tests with fiber orientation at ± 4 5 ∘ and in delamination force by 13 % in low velocity impact tests with respect to PEI/CF show that the heterogeneous matrix blend maintains the crystalline content and excellent elastoplastic response of PEEK while taking advantage of the affordability, lower processing temperature and toughness of PEI.

本文介绍了一种用编织碳纤维增强的混合基复合材料的制造方法,该材料结合了两种热塑性聚合物的特性:PEEK(聚醚醚酮)和 PEI(聚醚酰亚胺)。制造工艺包括多层结构和单一的热压固结步骤。实验测试包括单轴拉伸测试、模式 I 分层测试和低速冲击测试,以比较由此产生的层压材料与单基体材料(PEEK/CF 和 PEI/CF)。与 PEI/CF 相比,纤维取向为 ± 4 5 ∘ 的拉伸试验中的破坏应变提高了 48%,低速冲击试验中的分层力提高了 13%,这表明异质基质混合物保持了 PEEK 的结晶含量和优异的弹塑性响应,同时利用了 PEI 的经济性、较低的加工温度和韧性。


Composites Part B: Engineering

Structural fuses in composite structures:Engineered crack paths in carbon fibre-reinforced polymers

M.Erfan Kazemi, Victor Medeau, Lorenzo Mencattelli, Emile Greenhalgh, Soraia Pimenta, James Finlayson, Silvestre T. Pinho

doi:10.1016/j.compositesb.2024.111604

复合材料结构中的结构熔丝:碳纤维增强聚合物中的工程裂纹路径

We designed engineered carbon fibre-reinforced polymer (CFRP) solutions for realising structural fuses in real CFRP composite components. We developed various concepts of engineered crack paths containing micro-cut patterns (MCPs) aiming to investigate how we can engage and trigger various damage propagation mechanisms both in-plane and through-the-thickness. To this end, we chose ultra-thin CFRP prepregs and engraved various designed MCPs / crack path combinations on them during layup with the help of a laser micro-machining system. Then, we manufactured CFRP specimens containing engineered crack paths and characterised them under a 3-point bending (3PB) test to evaluate their response in an out-of-plane loading scenario. We investigated various design parameters of the developed MCPs through 9 studies to understand how various parameters determine the damage propagation mechanisms and what effect they have on fracture properties. Following this, we performed fractography analysis to observe the failure mechanisms triggered by the implemented MCPs / crack path combinations in the tested specimens. The results demonstrate that carefully designed MCPs can tailor the failure load and energy dissipation, and moreover, provide significant control over the fracture locus and path.

我们设计了工程碳纤维增强聚合物(CFRP)解决方案,以实现实际 CFRP 复合材料部件的结构融合。我们开发了各种包含微切割图案(MCP)的工程裂纹路径概念,旨在研究如何在平面内和厚度内参与和触发各种损伤传播机制。为此,我们选择了超薄 CFRP 预浸料,并在铺层过程中借助激光微加工系统在上面雕刻出各种设计的 MCP/裂纹路径组合。然后,我们制造了包含工程裂纹路径的 CFRP 试样,并在三点弯曲 (3PB) 试验中对其进行了表征,以评估它们在平面外加载情况下的响应。我们通过 9 项研究调查了所开发 MCP 的各种设计参数,以了解各种参数如何决定损坏传播机制以及它们对断裂性能的影响。随后,我们进行了断口成像分析,以观察在测试试样中实施的 MCP/裂纹路径组合所引发的破坏机制。结果表明,精心设计的 MCP 可以调整破坏载荷和能量耗散,而且还能对断裂位置和路径进行有效控制。


Predicting Rapid Growth Behavior in Solidified Eutectic Ceramic Composites Using Infrared Thermal Imaging and Thermal Field Simulation During Laser Directed Energy Deposition

Zhonglin Shen, Haijun Su, Hao Jiang, Yuan Liu, Di Zhao, Yinuo Guo, Yang Cao, Minghui Yu, Peixin Yang, Xiang Li, Dong Dong, Min Guo, Zhuo Zhang

doi:10.1016/j.compositesb.2024.111619

利用红外热成像和热场模拟预测激光定向能沉积过程中凝固共晶陶瓷复合材料的快速生长行为

Cylindrical Al2O3/GdAlO3 binary in situ oxide eutectic ceramic composite, with a glossy surface and high relative density, has been fabricated using the laser directed energy deposition method (LDED) with optimized process parameters. In a novel and innovative approach, infrared thermal imaging and the finite element method (FEM) have been combined for the first time to capture the temperature field distribution across different regions of the molten pool during the LDED processing of the binary oxide eutectic ceramic composite, thereby synergistically obtaining the solidification characteristics. With an increase in the scanning rate, the temperature gradient within the molten pool decreases from 3.38 × 105 K/m to 1.62 × 105 K/m, while it shows minimal variation with fluctuations of the laser power. Under the conditions of high temperature gradients and rapid non-equilibrium solidification characteristic of LDED, the Al2O3/GdAlO3 (GAP) binary eutectic ceramic composites, which exhibit typical high melting entropy and faceted/non-faceted growth modes, exhibit complex and variable microstructure morphology. A combination of regular/irregular models, including JH (Jackson-Hunt), MK (Magnin-Kurz), GK (Guzik-Kopyciński) and TMK (Trivedi-Magnin-Kurz), is employed to investigate and predict the growth and transformation of microstructures. The JH and TMK models fairly predict the rod-like regular eutectic microstructure inside the colony and lamellar regular eutectic within adjacent layers, respectively. The "Chinese-script" irregular microstructure at the interface between the colony and the layers is consistent with the MK and GK models. The as-deposited eutectic ceramic composite presents ultra-fine microstructures, clear and strongly bonded phase interfaces with low strain energy, contributing to its microstructure stability after high temperature heat treatment at 1773 K for 200 hours, ans achieving a minimum microstructure coarsening rate of 0.0005 μm/h.

利用激光定向能沉积法(LDED)和优化的工艺参数,制造出了表面光亮、相对密度高的圆柱形 Al2O3/GdAlO3 二元原位氧化共晶陶瓷复合材料。在二元氧化物共晶陶瓷复合材料的 LDED 加工过程中,红外热成像和有限元法(FEM)首次结合起来捕捉熔池不同区域的温度场分布,从而协同获得凝固特性。随着扫描速率的增加,熔池内的温度梯度从 3.38 × 105 K/m 减小到 1.62 × 105 K/m,而其随激光功率波动的变化极小。在 LDED 特有的高温梯度和快速非平衡凝固条件下,Al2O3/GdAlO3(GAP)二元共晶陶瓷复合材料表现出典型的高熔熵和面状/非面状生长模式,并呈现出复杂多变的微观结构形态。我们采用了规则/不规则模型组合,包括 JH(Jackson-Hunt)、MK(Magnin-Kurz)、GK(Guzik-Kopyciński)和 TMK(Trivedi-Magnin-Kurz),来研究和预测微结构的生长和转变。JH 和 TMK 模型分别较好地预测了菌落内部的棒状规则共晶微观结构和相邻层内的片状规则共晶微观结构。菌落和层之间界面的 "中国式 "不规则微观结构与 MK 和 GK 模型一致。沉积后的共晶陶瓷复合材料呈现出超精细的微观结构,相界面清晰且结合牢固,应变能较低,这有助于其在 1773 K 高温热处理 200 小时后的微观结构稳定性,并实现了 0.0005 μm/h 的最小微观结构粗化率。


Selective localization of carbonized polymer dots in amorphous phase towards high breakdown strength and energy density of PVDF-based dielectric composites

Zhen-jie Lu, Wen-jin Hu, Xiao-dong Qi, De-xiang Sun, Yong Wang, Jing-hui Yang

doi:10.1016/j.compositesb.2024.111627

 

非晶相中碳化聚合物点的选择性定位,实现基于 PVDF 的电介质复合材料的高击穿强度和能量密度

In a general way, there is a contradictory between dielectric constant () and breakdown strength () in dielectric materials, and improving the discharge energy density () of dielectric polymers has become a great challenge. The semicrystalline ferroelectric polymer polyvinylidene fluoride (PVDF) is favored for its high , but its relatively weak  in amorphous regions makes it still difficult to obtain appreciable . In response to the fact that the current method of introducing rigid chain amorphous polymers into the amorphous regions of PVDF has limited capability to enhance its , in this work, due to the crystallization induced phase separation, carbonated polymer dots (CPDs) as well as PMMA were introduced into the amorphous region of PVDF, and CPDs/PVDF/PMMA composites were prepared towards high  and . It is confirmed that, CPDs significantly increase the entanglement density of molecular chains in amorphous regions of PVDF; in addition, CPDs rely on their inorganic carbon cores with unique electrical properties to resist carrier migration in amorphous regions of PVDF under high electric fields. In brief, CPDs are used as a reinforcing agent for the amorphous region of PVDF to further enhance its  and . The composite loaded with 0.1 wt% CPDs exhibits the superior  of 12.4 J/cm3 at the  of 652.0 MV/m. This work provides new understanding on the dielectric response of ultrasmall-sized CPDs on polymer dielectrics, which could help us design new dielectric polymer composites with suppressed segmental motions for high breakdown strength and high energy density applications.

一般来说,介电材料的介电常数()和击穿强度()之间存在矛盾,提高介电聚合物的放电能量密度()已成为一个巨大的挑战。半结晶铁电聚合物聚偏二氟乙烯(PVDF)因其较高的介电常数()和击穿强度()而备受青睐,但由于其在无定形区的击穿强度相对较弱,因此仍难以获得可观的介电常数()和击穿强度()。针对目前在 PVDF 非晶区引入刚性链非晶态聚合物的方法对提高其Ⅴ-Ⅴ性能的作用有限这一事实,在这项工作中,由于结晶引起的相分离,在 PVDF 非晶区引入了碳化聚合物点(CPDs)和 PMMA,并制备出了具有高Ⅴ-Ⅴ性能的 CPDs/PVDF/PMMA 复合材料。研究证实,CPDs 能显著提高 PVDF 非晶区分子链的缠结密度;此外,CPDs 还能依靠其无机碳核的独特电学特性,在高电场下抵抗 PVDF 非晶区的载流子迁移。简而言之,CPD 可用作 PVDF 无定形区的增强剂,以进一步增强其性能。负载了 0.1 wt% CPDs 的复合材料在 652.0 MV/m 的电场中表现出 12.4 J/cm3 的优异性能。这项研究对超小尺寸 CPD 在聚合物电介质上的介电响应有了新的认识,有助于我们设计出具有抑制分段运动的新型聚合物电介质复合材料,以实现高击穿强度和高能量密度应用。


Composites Science and Technology

Layer-by-layer reconstruction of fatigue damages in composites from thermal images by a Residual U-Net

Benedict von Houwald, Ali Sarhadi, Christian Eitzinger, Martin A. Eder

doi:10.1016/j.compscitech.2024.110712

 

利用残余 U-Net 通过热图像逐层重建复合材料中的疲劳损伤

In this paper a deep learning model is used to fully reconstruct the 3D distribution of arbitrarily shaped subsurface fatigue damages in a fiber/epoxy composite from synthetic thermal surface images. Synthetic thermal surface images (TIs) of self-heating damage hotspots are produced by thermal finite element analysis which are consequently used to train a Residual U-Net based on recent architectures designed for image segmentation. Different augmentation techniques are employed to mitigate the computational cost of generating training data through thermal finite element analysis. The Residual U-Net model accurately reconstructed – layer by layer – the ground truths and thereby enabling the quantitative assessment of location, size, shape, depth and gradient of an internal fatigue damage distribution. Moreover, the Residual U-Net achieved good predictions for a comparatively small training set sizes.

本文采用深度学习模型,从合成热表面图像中全面重建纤维/环氧树脂复合材料中任意形状的次表面疲劳损伤的三维分布。自加热损伤热点的合成热表面图像(TI)是通过热有限元分析生成的,因此可用于训练基于最新图像分割架构设计的残差 U-网络。我们采用了不同的增强技术,以降低通过热有限元分析生成训练数据的计算成本。残差 U-Net 模型逐层准确地重建了地面真相,从而能够对内部疲劳损伤分布的位置、大小、形状、深度和梯度进行定量评估。此外,残余 U-Net 还能在相对较小的训练集中实现良好的预测。


Multiscale analysis of the compressive behaviour of polymer-based composites reinforced by hybrid Al2O3/Al fibres

Hao Tang, Jiaqi Xu, Aleksey B. Rogov, Constantinos Soutis, Aleksey Yerokhin

doi:10.1016/j.compscitech.2024.110718

 

用 Al2O3/Al 混合纤维增强聚合物基复合材料抗压性能的多尺度分析

Metal fibre reinforcements to polymer matrix composites (PMCs) bolster architectural flexibility and functionality affordably but feature a relatively weak interfacial bonding if not surface treated. This work demonstrates that Plasma Electrolytic Oxidation is promising to prepare woven hybrid Al2O3/Al reinforcements for PMCs. The compressive behaviour (a critical design parameter in structural design) of PMCs reinforced by ∼9 to 13 vol% γ-Al2O3/Al fibres with different oxide-to-metal ratios (∼20-50 vol%) is evaluated. The majority of fibres with the oxide ratio of 20% failed in micro-buckling mode at interlacing points. Compared to Al reinforcements, the hybrid Al2O3/Al fibres increased the specific compressive strength (σc/ρ) and modulus (Ec/ρ) of the composite by ∼15% and ∼58%, respectively. Oxide shells thicker than 15-20 μm limited further enhancement due to fibre failure by shear-induced rupture. Thinner shells on Al reinforcements are recommended for PMCs used to manufacture structural components in mechanical engineering applications.

在聚合物基复合材料(PMC)中加入金属纤维增强材料可提高结构的灵活性和功能性,但如果不进行表面处理,界面结合力会相对较弱。这项研究表明,等离子电解氧化法有望为 PMC 制备出 Al2O3/Al 混合编织增强材料。研究评估了由不同氧化物金属比(20-50%)的 9 至 13 Vol% γ-Al2O3/Al 纤维增强的 PMC 的抗压性能(结构设计中的关键设计参数)。大多数氧化物比率为 20% 的纤维在交错点处以微屈曲模式失效。与铝增强材料相比,Al2O3/铝混合纤维使复合材料的抗压强度(σc/ρ)和模量(Ec/ρ)分别提高了 15% 和 58%。厚度超过 15-20 μm 的氧化壳限制了进一步的增强,因为纤维会因剪切力而断裂。建议在机械工程应用中用于制造结构部件的聚甲基丙烯酸甲酯上使用更薄的铝加固壳。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystem疲劳断裂复合材料UGUM裂纹电场材料多尺度控制
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【新文速递】2024年6月19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 2 篇,International Journal of Plasticity 2 篇,Thin-Walled Structures 2 篇International Journal of Solids and StructuresHamiltonian/Stroh formalism for reversible poroelasticity (and thermoelasticity)Andrea Nobilidoi:10.1016/j.ijsolstr.2024.112935可逆孔弹性(和热弹性)的哈密顿/斯特罗形式主义Stroh’s sextic formalism represents the equilibrium equations of anisotropic elasticity in a particularly attractive form, that is most suitable for studying interface-dominated multilayered solids, composite materials and time-harmonic problems. Taking advantage of the fact that the Stroh formalism really amounts to the canonical form of the equations in the Hamiltonian sense, the case of Biot’s reversible (i.e. no fluid dissipation) poroelasticity is here addressed, in the absence of a fluid pressure gradient. This framework is the same as thermoelasticity of perfect conductors. Two Hamiltonian formulations are developed: the first describes both the solid and the fluid phases and it exhibits, besides energy conservation, momentum conservation, as a result of pressure uniformity (perfectly drained conditions). The second is restricted to the solid skeleton and perfectly parallels anisotropic elasticity, where the Stroh matrices refer to the effective stress tensor. The case of weak fluid-solid coupling is also considered and it produces a perturbation from anisotropic elasticity with the same structure as incompressibility, although in an “opposing” manner. This comparison suggests that the incompressibility limit introduced by Biot should be revised. The energy conservation integral and the edge impedance matrix are also illustrated.斯特罗的六元形式主义以一种特别有吸引力的形式表示各向异性弹性的平衡方程,最适合研究界面主导的多层固体、复合材料和时谐问题。利用 Stroh 公式实际上等同于哈密顿方程的典型形式这一事实,在没有流体压力梯度的情况下,本文讨论了 Biot 可逆(即无流体耗散)孔弹性的情况。这一框架与完美导体的热弹性相同。提出了两种哈密顿公式:第一种同时描述了固体和流体相,由于压力均匀性(完全排水条件),除了能量守恒外,还表现出动量守恒。第二种仅限于固体骨架,完全平行于各向异性弹性,其中 Stroh 矩阵指的是有效应力张量。我们还考虑了流固弱耦合的情况,它产生了各向异性弹性的扰动,其结构与不可压缩性相同,但方式 "相反"。这种比较表明,应修改 Biot 引入的不可压缩性限制。此外,还说明了能量守恒积分和边缘阻抗矩阵。Journal of the Mechanics and Physics of SolidsA unified discontinuous Galerkin formulation for interfacial multiphysics modeling of thermo-chemically driven fractureDaniel Pickard, Raúl Radovitzkydoi:10.1016/j.jmps.2024.105748用于热化学驱动断裂界面多物理场建模的统一非连续伽勒金公式Many engineering and natural materials exhibit coupled thermo-chemo-mechanical phenomena, which can result in embrittlement and fracture. These fractures, in turn, can alter the subsequent thermal, chemical, and mechanical response. We present a theoretical formulation and computational framework for the analysis of thermo-chemically fractured solids, with emphasis on the post-fracture thermal and chemical interfacial behavior. The theoretical model is based on the thermodynamically-consistent formulation of Loeffel and Anand (IJP, 2011). The computational method extends the scalable discontinuous Galerkin/Cohesive Zone Model (DG/CZM) of Radovitzky et al. (CMAME, 2011) to thermo-chemo-mechanics, which facilitates coupled, large-scale simulations of materials and structures containing failed interfaces. In the proposed framework, all balance laws are enforced weakly via the DG formalism, resulting in a unified formulation for multiphysics problems in solids. This naturally enables the incorporation of general interface models, e.g. to account for effects such as the aeolotropic reduction in thermochemical transport due to the presence of fractures, or the acceleration of chemical reactions along crack flanks. The approach is verified against two analytical solutions of boundary value problems drawn from thermo-poro-elasticity and thermally-driven delamination. A scalable, three-dimensional simulation of thermochemically-driven concrete cracking illustrates the complete capabilities of the interfacial multiphysics modeling framework.许多工程材料和天然材料都会出现热-化学-机械耦合现象,从而导致脆化和断裂。这些断裂反过来又会改变后续的热、化学和机械响应。我们提出了热化学断裂固体分析的理论公式和计算框架,重点关注断裂后的热界面和化学界面行为。理论模型基于 Loeffel 和 Anand 的热力学一致性公式(IJP,2011 年)。该计算方法将 Radovitzky 等人(CMAME,2011 年)的可扩展非连续伽勒金/粘合区模型(DG/CZM)扩展到了热-化学-力学领域,有助于对包含断裂界面的材料和结构进行大规模耦合模拟。在提议的框架中,所有平衡定律都是通过 DG 形式主义弱化执行的,从而为固体中的多物理场问题提供了统一的表述方式。这就自然而然地使一般界面模型成为可能,例如,考虑到由于裂缝的存在而导致热化学传输的各向异性降低,或沿裂缝侧面的化学反应加速等效应。该方法根据热孔弹性和热驱动分层的两个边界值问题的分析解决方案进行了验证。对热化学驱动的混凝土开裂进行了可扩展的三维模拟,展示了界面多物理场建模框架的全部能力。Mechanics of MaterialsProbabilistic analysis of homogenized elastic property for resin products fabricated by additive manufacturing based on three-dimensional random field modeling of microstructureSei-ichiro Sakata, George Stefanou, Takayoshi Kikkawa, Yuki Aikawadoi:10.1016/j.mechmat.2024.105071基于微观结构三维随机场建模的增材制造树脂产品均质弹性性能概率分析Additive manufacturing (AM) techniques have been used in several fields of science and industry, and fabrication techniques are being updated. For this fact, especially, for industrial use, mechanical property evaluation methodologies for AM products and standards for product quality assessment should also be well established. In this paper, a probabilistic evaluation of the homogenized elastic properties of a resin product fabricated by a material extrusion-based AM technique is attempted by considering the randomness of both material and microscopic geometrical quantities. This AM method fabricates a resin structure by piling up melted resin, and to decrease consumed material and influence of thermal deformation, the inner structure of the fabricated products will include many pores and its geometry is difficult to be well controlled. From this fact, the products will be regarded as a heterogeneous material with complex random microstructure. This will cause difficulty in the evaluation of its apparent material properties and therefore a probabilistic homogenization analysis is attempted for quantitative estimation of the apparent material property in this study. In particular, to investigate probabilistic properties of microscopic geometry, a random field modeling technique is employed for the evaluation of autocorrelation of the microscopic geometrical parameter, and the results of the autocorrelation identified by experimental observation are introduced to the probabilistic homogenization analysis. The two-dimensional or three-dimensional random field modeling is attempted, and the effectiveness of this approach is investigated by comparing it with the experimental result.快速成型制造(AM)技术已在多个科学和工业领域得到应用,其制造技术也在不断更新。因此,特别是在工业应用中,应建立完善的 AM 产品机械性能评估方法和产品质量评估标准。本文通过考虑材料和微观几何量的随机性,尝试对基于材料挤压的 AM 技术制造的树脂产品的均质弹性特性进行概率评估。这种 AM 方法通过堆积熔化的树脂来制造树脂结构,为了减少材料消耗和热变形的影响,制造产品的内部结构将包括许多孔隙,其几何形状难以很好地控制。因此,产品将被视为具有复杂随机微观结构的异质材料。这将给表观材料特性的评估带来困难,因此本研究尝试采用概率均质化分析方法对表观材料特性进行定量评估。其中,为了研究微观几何的概率特性,采用了随机场建模技术来评估微观几何参数的自相关性,并将实验观察所确定的自相关性结果引入概率均质化分析。尝试了二维或三维随机场建模,并通过与实验结果的比较研究了这种方法的有效性。The extended scaling laws of the mechanical properties of additively manufactured body-centered cubic lattice structures under large compressive strainsZhi Chen, Souvik Sahoo, María Teresa Pérez-Prado, Dan Mordehaidoi:10.1016/j.mechmat.2024.105075增材制造体心立方晶格结构在大压应变下力学性能的扩展缩放规律Additively manufactured lattice structures are porous light-weight structures with mechanical properties that are dictated both from the topology and the parent material properties. When printed from metals, these structures can withstand large continuous plastic deformation. In this paper, we focus on body-centered cubic (BCC) lattice structures under compression up to large deformation strains, and we propose relations between the slenderness ratio of struts and the following mechanical properties: Young’s modulus, yield strength, hardening rate of the structure and the densification strain. We perform a systematic study using finite element modelling (FEM) to find how both material properties and lattice structures are affecting the effective mechanical properties of BCC lattice structures under compression. Based on this analysis we propose the scaling laws of the mechanical properties. The scaling laws can be explained as an extension of the Gibson-Ashby power law relations for bend-dominated structures with non-slender beams. We also discuss how rounding the connections between the struts using fillets affects the scaling laws. We demonstrate the scaling laws in the analysis of experimental results, showing the accuracy and limitations of the scaling laws in predicting the mechanical properties, with an emphasis on large deformations. In the analysis, we use experimental values published in literature, and we also present here experimental results of lattice structures printed from Inconel 718.叠加制造的晶格结构是一种多孔轻质结构,其机械特性由拓扑结构和母体材料特性共同决定。当用金属打印时,这些结构可以承受较大的连续塑性变形。在本文中,我们重点讨论了体心立方(BCC)晶格结构在压缩至大变形应变时的力学性能,并提出了支杆细长比与以下力学性能之间的关系:我们提出了细长比与下列力学性能之间的关系:杨氏模量、屈服强度、结构硬化率和致密化应变。我们使用有限元建模(FEM)进行了系统研究,以了解材料特性和晶格结构如何影响 BCC 晶格结构在压缩条件下的有效机械特性。在此分析基础上,我们提出了机械性能的缩放规律。这些缩放定律可以解释为吉布森-阿什比幂律关系的扩展,适用于以弯曲为主的非细长梁结构。我们还讨论了使用圆角对支柱之间的连接进行圆角处理如何影响缩放定律。我们在实验结果分析中演示了缩放定律,显示了缩放定律在预测力学性能方面的准确性和局限性,重点是大变形。在分析过程中,我们使用了文献中公布的实验值,并在此介绍了由 Inconel 718 印刷而成的晶格结构的实验结果。International Journal of PlasticityOn the anisotropic coalescence of elliptic cylindrical voids considering the geometric and distributive propertiesJiawei Chen, Tsuyoshi Furushimadoi:10.1016/j.ijplas.2024.104036 考虑几何和分布特性的椭圆柱形空洞各向异性凝聚问题The geometric and distributive properties of voids significantly influence anisotropic coalescence behavior. However, this problem has received little attention owing to the complexity of considering all the properties in the current analytical framework of limit analysis. To address this issue, this study proposes an analytical framework based on an elliptic coordinate system, including the determination of the ligament zone, characterization of plastic flow, and derivation of the void coalescence criterion, for porous materials with various geometric and distributive properties, including size, shape, spacing, and orientation. This framework is motivated by our observations that the evolution of the void geometry and surrounding plastic flow can be well characterized by the grid of the elliptic coordinate system. Subsequently, an analytical function is proposed to determine the ligament zone and coalescence direction with various void properties. A hollow nonaxisymmetric cylindrical unit cell is proposed to describe this ligament zone, and the corresponding trial velocity field is derived by extending the previous Gurson-like velocity field into the elliptic cylindrical coordinate system. The rationality of the field is validated by comparing its equivalent strain rate field with numerical simulations. Finally, a coalescence criterion is derived via the limit analysis of the proposed unit cell undergoing internal necking. Two heuristic adjustments are formulated for the overflow phenomenon in the rigid zone and outer ligament zones. Numerical assessments with various void properties confirm the accuracy of the analytical model. The coalescence criterion can predict the independent and coupling effects of geometric and distributive properties on anisotropic void coalescence. This study provides possible solutions to future plasticity problems of ellipsoidal inclusions.空隙的几何特性和分布特性对各向异性凝聚行为有重大影响。然而,由于在当前的极限分析框架中考虑所有属性的复杂性,这一问题很少受到关注。为了解决这个问题,本研究提出了一个基于椭圆坐标系的分析框架,包括韧带区的确定、塑性流动的表征以及空隙凝聚准则的推导,适用于具有各种几何和分布特性(包括尺寸、形状、间距和取向)的多孔材料。我们观察到,椭圆坐标系的网格可以很好地描述空隙几何形状和周围塑性流动的演变过程,因此我们提出了这一框架。随后,我们提出了一个分析函数,用于确定具有各种空隙属性的韧带区和凝聚方向。提出了一个空心非轴对称圆柱单元来描述该韧带区,并通过将之前的古尔森速度场扩展到椭圆圆柱坐标系得出了相应的试验速度场。通过将其等效应变率场与数值模拟进行比较,验证了该场的合理性。最后,通过对发生内部缩颈的拟议单元尺寸进行极限分析,得出了凝聚准则。针对刚性区和外韧带区的溢出现象,提出了两种启发式调整方法。利用各种空隙特性进行的数值评估证实了分析模型的准确性。凝聚准则可以预测几何特性和分布特性对各向异性空隙凝聚的独立和耦合效应。这项研究为未来椭圆形夹杂物的塑性问题提供了可能的解决方案。Double-peak Strain Hardening Behavior of Mg–1.2 wt.%Y AlloyBo Guan, Li Wang, Yunchang Xin, Peidong Wu, Jing Xu, Xiaoxu Huang, Qing Liudoi:10.1016/j.ijplas.2024.104041 Mg-1.2 wt.%Y 合金的双峰应变硬化行为In this study, the mechanical behavior and deformation mechanism of an extruded Mg–1.2 wt.%Y rod under tension and compression along the extrusion direction (ED) were systematically investigated through experiments and crystal plasticity simulations. A double-peak strain hardening behavior comprising five distinct stages was observed under compression along the ED. The five stages are as follows: a fast drop in the strain hardening rate (stage I), steady increase in the strain hardening rate (stage II), gradual decrease in the hardening rate (stage III), second increase in the strain hardening rate (stage IV), and rapid decrease in the strain hardening rate (stage V). This unique strain hardening behavior led to an ultimate compressive strength of up to 539 MPa at a high strain of 0.4. Crystal plastic simulations using an elastic viscoplastic self-consistent model revealed a high activity and a long process of {101¯2} twinning in a strain range of 0–0.35 under compression along the ED. The twinning behavior examined via electron backscattering diffraction indicated that the {101¯2} twinning was activated in both grains with relatively high and very low Schmid factors. Subsequently, the mechanism for the presence of this double-peak strain hardening was established and, finally, the significance of this double-peak strain hardening for strengthening Mg alloys was discussed.本研究通过实验和晶体塑性模拟,系统地研究了挤压 Mg-1.2 wt.%Y 棒在沿挤压方向(ED)拉伸和压缩条件下的力学行为和变形机制。在沿 ED 方向压缩时,观察到了由五个不同阶段组成的双峰应变硬化行为。这五个阶段如下:应变硬化率快速下降(第一阶段)、应变硬化率稳定上升(第二阶段)、硬化率逐渐下降(第三阶段)、应变硬化率第二次上升(第四阶段)和应变硬化率快速下降(第五阶段)。这种独特的应变硬化行为使其在 0.4 高应变下的极限抗压强度高达 539 兆帕。使用弹性粘塑性自洽模型进行的晶体塑性模拟显示,在沿 ED 压缩的 0-0.35 应变范围内,{101¯2}孪晶的活性很高,过程很长。通过电子反向散射衍射检查的孪生行为表明,{101¯2}孪生在施密德因子相对较高和非常低的两种晶粒中都被激活。随后,确定了这种双峰应变硬化的存在机制,最后讨论了这种双峰应变硬化对强化镁合金的意义。Thin-Walled StructuresTransient behavior of a plate partially immersed in the fluid subjected to impact loadings: Theoretical analysis and experimental measurementsChan-Yi Liao, Guan-Wei Chen, Chien-Ching Madoi:10.1016/j.tws.2024.112134部分浸入流体中的板材在受到冲击载荷时的瞬态行为:理论分析和实验测量This study aimed to investigate the transient behavior of a rectangular plate partially in contact with fluid subjected to a dynamic external force. To this purpose, a theoretical model was developed to analyze vibration characteristics and transient wave propagation. Based on superposition method, the dry mode shapes and natural frequencies of the plate under vacuum could be obtained. The dry mode shapes were treated as the fundamental function to construct the wet mode that describes the vibration behavior of the fluid-plate coupled system. The velocity potential and fluid pressure within a finite tank due to the plate deflection were derived using an equation governing the incompressible fluid. Based on the relationship between dry mode shape and wet mode shape, the fluid-plate coupled system's wet mode shape and resonant frequency could be determined from the frequency response function. Applying the normal mode method, the transient displacement of plate and fluid pressure can be obtained by solving a system of non-homogeneous differential equations. The theoretical predictions were verified by finite element method (FEM) and experimental measurements. Experiments were conducted using piezoelectric film sensors (polyvinylidene fluoride, PVDF) to measure the force history induced by a steel ball impact to quantitatively analyze the transient response. The comparison results proved that the theoretical predictions and experiments were in good agreement, including the transient responses of the displacement and in-plane strain of a plate partially submerged in the fluid. The results indicate that changes in water depth can induce resonance frequency shifts and wet mode shape distortions, which also illustrate that the vibrational properties of wet modes affect transient behavior. The proposed transient solution demonstrates an analytical approach that connects the physical significance of the dynamic behavior of the fluid-plate coupled system in time and frequency domains; it provides a connection between the transient behaviors and vibration characteristics.本研究旨在探讨部分与流体接触的矩形板在动态外力作用下的瞬态行为。为此,建立了一个理论模型来分析振动特性和瞬态波传播。基于叠加法,可以得到真空条件下板的干模态振型和固有频率。干模态形状被视为基本函数,用于构建描述流体-板耦合系统振动行为的湿模态。利用不可压缩流体方程推导出了板挠度导致的有限槽内速度势能和流体压力。根据干模态振型和湿模态振型之间的关系,可以从频率响应函数中确定流体-板耦合系统的湿模态振型和共振频率。应用法向模态方法,通过求解非均质微分方程系统,可以得到板的瞬态位移和流体压力。有限元法(FEM)和实验测量验证了理论预测。实验使用压电薄膜传感器(聚偏氟乙烯,PVDF)测量钢球撞击引起的受力历史,以定量分析瞬态响应。对比结果证明,理论预测与实验结果非常吻合,包括部分浸没在流体中的平板的位移和平面应变的瞬态响应。结果表明,水深变化会引起共振频率偏移和湿模态形状扭曲,这也说明了湿模态的振动特性会影响瞬态行为。所提出的瞬态解决方案展示了一种在时域和频域上连接流体-板耦合系统动态行为的物理意义的分析方法;它提供了瞬态行为和振动特性之间的联系。User friendly FE Formulation for anisotropic distortional hardening model based on non-associated flow plasticity and its application to springback predictionQi Hu, Lorenz Maier, Takeshi Nishiwaki, Christoph Hartmann, Wolfram Volk, Jeong Whan Yoondoi:10.1016/j.tws.2024.112142基于非关联流塑性的各向异性变形硬化模型的用户友好型 FE 公式及其在回弹预测中的应用Based on non-associated flow plasticity, a newly developed anisotropic distortional hardening model developed by Hu and Yoon [15] is implemented in finite element analysis in a user-friendly manner. The derivatives of complex hardening models are calculated using the Finite Difference Method (FDM), which is much more convenient than using the analytical derivatives. To further improve the accuracy of the proposed method, the step size analysis in FDM is performed by analyzing the derivative formation. To evaluate the accuracy and computational efficiency of a proposed step size for FDM, single element simulations are performed under different loading paths. It has been found that the maximum absolute error of the flow curves between the simulation and the theoretical result is less than 0.3 %. The U-bending tests for DP600 and TRIP1180 are used to verify the ability of the distortional hardening model for springback prediction. The simulation result of the strain hardening model is in good agreement with the experiment. The computational efficiency is also increased by 24 % due to the improved convergence rate.基于非关联流塑性,Hu 和 Yoon [15] 新开发的各向异性变形硬化模型以用户友好的方式在有限元分析中实现。复杂硬化模型的导数采用有限差分法(FDM)计算,这比使用解析导数要方便得多。为了进一步提高所提方法的精度,通过分析导数的形成,对 FDM 中的步长进行了分析。为了评估所提出的 FDM 步长的精度和计算效率,我们在不同的加载路径下进行了单元素模拟。结果发现,模拟结果与理论结果之间流动曲线的最大绝对误差小于 0.3%。DP600 和 TRIP1180 的 U 形弯曲试验用于验证变形硬化模型预测回弹的能力。应变硬化模型的模拟结果与实验结果非常吻合。由于收敛速度提高,计算效率也提高了 24%。来源:复合材料力学仿真Composites FEM

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