首页/文章/ 详情

【新文速递】2024年9月30日固体力学SCI期刊最新文章

2小时前浏览6

 

今日更新:Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 6 篇

Journal of the Mechanics and Physics of Solids

Numerical and Experimental Crack-tip Cohesive Zone Laws with Physics-Informed Neural Networks

H. Tran, Y.F. Gao, H.B. Chew

doi:10.1016/j.jmps.2024.105866

基于物理信息神经网络的裂纹尖端内聚区规律的数值和实验研究

The cohesive zone law represents the constitutive traction versus separation response along the crack-tip process zone of a material, which bridges the microscopic fracture process to the macroscopic failure behavior. Elucidating the exact functional form of the cohesive zone law is a challenging inverse problem since it can only be inferred indirectly from the far-field in experiments. Here, we construct the full functional form of the cohesive traction and separation relationship along the fracture process zone from far-field stresses and displacements using a physics-informed neural network (PINN), which is constrained to satisfy the Maxwell-Betti's reciprocal theorem with a reciprocity gap to account for the plastically deforming background material. Our numerical studies simulating crack growth under small-scale yielding, mode I loading, show that the PINN is robust in inversely extracting the cohesive traction and separation distributions across a wide range of simulated cohesive zone shapes, even for those with sharp transitions in the traction-separation relationships. Using the far-field elastic strain and residual elastic strain measurements associated with a fatigue crack for a ZK60 magnesium alloy specimen from synchrotron X-ray diffraction experiments, we reconstruct the cohesive traction-separation relationship and observe distinct regimes which suggest corresponding transitions in the micromechanical damage mechanisms.

黏聚区规律代表了材料沿裂纹尖端过程区的本构牵引与分离响应,它将微观断裂过程与宏观破坏行为联系起来。由于在实验中只能间接地从远场推断出内聚带定律的确切函数形式,因此阐明内聚带定律的确切函数形式是一个具有挑战性的逆问题。在这里,我们利用物理信息神经网络(PINN)构建了沿断裂过程带的远场应力和位移的内聚牵引和分离关系的完整函数形式,该网络被约束于满足麦克斯韦-贝蒂的互易定理,并具有互易间隙以解释塑性变形的背景材料。我们的数值研究模拟了小尺度屈服I型加载下的裂纹扩展,结果表明,即使对于那些牵引-分离关系发生急剧转变的区域,PINN在反提取大范围模拟黏结区形状的黏结牵引和分离分布方面也是鲁棒的。利用同步x射线衍射实验得到的ZK60镁合金试样的远场弹性应变和残余弹性应变,重构了疲劳裂纹的内聚牵引-分离关系,并观察到微观力学损伤机制的不同转变。


Mechanics of Materials

Failure analysis of unidirectional fiber reinforced plastics based on computational micromechanics and PUCK failure theory

Xiaofei Pang, Yonglyu He, Xun Chen, Shufeng Zhang

doi:10.1016/j.mechmat.2024.105169

基于计算细观力学和PUCK破坏理论的单向纤维增强塑料失效分析

Achievement of accurate and reliable failure criterion is fundamentally important for designing composite structures. This study comprehensively evaluated the failure of unidirectional fiber-reinforced plastics (FRP) from the perspectives of failure theory and computational micromechanics. Further, PUCK failure criterion was analyzed in detail to identify the specific effects of the interfacial reinforcement coefficient on the failure mechanism. The representative volume element model of FRP with randomly distributed fibers was established. The comparative analysis of the results between current failure theory and experiment, indicates that the load bearing capacity of FRP under bi-axial compressive stress and shear stress is understated by the PUCK failure criterion. Microscopic finite element analysis was adopted to investigate the failure envelope of FRP, considering interface reinforcement coefficient. The results reveal that the strength of FRP under the combination of moderate transverse compressive stress and in-plane shear stress is significantly affected by the interface reinforcement coefficient. The accuracy of PUCK failure criterion heavily depends on the value of the interface reinforcement coefficient and if the criterion does not consider the coefficient, it can cause notable error on strength prediction. Consequently, determination of interface reinforcement coefficient would be helpful to achieve more accurate failure criterion for FRP.

获得准确可靠的失效准则对复合材料结构的设计至关重要。本文从破坏理论和计算细观力学的角度对单向纤维增强塑料(FRP)的破坏进行了综合评价。进一步对PUCK破坏准则进行了详细分析,明确了界面配筋系数对破坏机制的具体影响。建立了具有代表性的纤维随机分布FRP的体积元模型。对现有破坏理论与试验结果的对比分析表明,PUCK破坏准则低估了FRP在双轴压应力和剪切应力作用下的承载能力。考虑界面配筋系数,采用细观有限元方法研究FRP的破坏包络线。结果表明:在中等横向压应力和面内剪应力作用下,界面配筋系数对FRP强度有显著影响;PUCK破坏判据的精度很大程度上取决于界面配筋系数的取值,如果不考虑界面配筋系数,则会对强度预测产生较大的误差。因此,界面配筋系数的确定有助于获得更准确的FRP破坏判据。


International Journal of Plasticity

A 3D finite deformation constitutive model for anisotropic shape memory polymer composites integrating viscoelasticity and phase transition concept

Chengjun Zeng, Yunqiang Hu, Liwu Liu, Xiaozhou Xin, Wei Zhao, Yanju Liu, Jinsong Leng

doi:10.1016/j.ijplas.2024.104139

结合粘弹性和相变概念的各向异性形状记忆聚合物复合材料三维有限变形本构模型

The phase transition theory of shape memory polymers (SMPs) often involves a phenomenological assumption that the reference configuration of the newly transformed phase deviates from that of the initial phase. This distinction serves as a crucial mechanism in the manifestation of the shape memory effect. However, elucidating the precise definition of the reference configuration of the transformed phase poses a significant challenge in the formulation of the constitutive model. To tackle this challenge, a three-dimensional (3D) finite deformation constitutive model incorporating effective phase evolution for SMPs has been developed. This model merges insights from the classical viscoelastic framework with the phase transition theory. The anisotropic thermo-viscoelastic constitutive model is further developed by introducing hyperelastic fibers, which integrate the anisotropy of the fibers into a continuous thermodynamic framework through structure tensors. Implemented within the ABAQUS software via a user material (UMAT) subroutine, the proposed model has been meticulously validated against experimental data, showcasing its prowess in simulating stress-strain responses and shape memory characteristics of SMPs and their composites (SMPCs). This innovative model stands as an invaluable instrument for the design and of sophisticated SMP and SMPC structures.

形状记忆聚合物(SMPs)的相变理论通常涉及一个现象学假设,即新转变相的参考构型偏离初始相。这种区别是形状记忆效应表现的关键机制。然而,在本构模型的制定中,阐明转换相的参考构型的精确定义是一个重大的挑战。为了应对这一挑战,研究人员开发了包含有效相演化的smp三维有限变形本构模型。该模型融合了经典粘弹性框架与相变理论的见解。引入超弹性纤维,将纤维的各向异性通过结构张量整合到一个连续的热力学框架中,进一步发展了各向异性热粘弹性本构模型。该模型通过用户材料(UMAT)子程序在ABAQUS软件中实现,并通过实验数据进行了仔细验证,展示了其在模拟应力应变响应和smpc及其复合材料(smpc)形状记忆特性方面的能力。这种创新的模型是设计和复杂的SMP和SMPC结构的宝贵工具。


Thin-Walled Structures

Dynamic Analysis of Carbon Fiber-Wound Reinforced Composite Truncated Conical Shell Under Thermal Conditions: Theory and Experimental Validation

Shufeng Lu, Richa Hu, Hailong Qiao, Yang Yang, Wei Zhang, Xiaojuan Song

doi:10.1016/j.tws.2024.112496

热条件下碳纤维缠绕增强复合材料截锥形壳的动力学分析:理论与实验验证

This work aims to investigate the dynamic behavior of a carbon fiber-wound reinforced composite (FW-RC) truncated conical shell structure under various operating conditions, including transverse excitation and winding pre-stress in thermal environment. In particular, a dynamic model for the FW-RC truncated conical shell is established, taking into account the first-order shear deformation theory and the von Karman geometric relationship. By utilizing Hamilton's principle and Galerkin method, the dynamic equations for the FW-RC truncated conical shells are derived. The natural frequencies of the system are afterward determined, and a vibration test bench is constructed specifically for the truncated conical shells. The validity of the theoretical model is verified by measuring the natural frequency of the specimen. In addition, the effects of various factors such as temperature field, pre-stress, boundary conditions, geometric parameters, and fiber winding parameters on the inherent characteristics and dynamic behavior of the system are further studied. By delving into these aspects, a comprehensive understanding of the dynamic behavior of FW-RC truncated conical shell structures can be achieved, which is of great significance for their design and application in practical engineering scenarios.

本文旨在研究碳纤维缠绕增强复合材料(FW-RC)截顶锥形壳结构在不同工况下的动力行为,包括横向激励和缠绕预应力。考虑一阶剪切变形理论和von Karman几何关系,建立了FW-RC截锥壳的动力模型。利用Hamilton原理和Galerkin方法,推导了FW-RC截顶圆锥壳的动力学方程。随后确定了系统的固有频率,并搭建了专门针对截锥壳的振动试验台。通过对试件固有频率的测量,验证了理论模型的有效性。此外,还进一步研究了温度场、预应力、边界条件、几何参数、纤维缠绕参数等因素对系统固有特性和动态行为的影响。通过对这些方面的深入研究,可以全面了解FW-RC截锥壳结构的动力特性,对其设计和实际工程应用具有重要意义。


Design of lattice metamaterials under the equal strength concept and research on the mechanical properties of their sandwich structures

Chenglin Tao, Zhao Wang, Rui Zhao, Zeliang Liu

doi:10.1016/j.tws.2024.112498

等强度概念下晶格超材料的设计及其夹层结构的力学性能研究

This study proposes a novel lattice metamaterial with equal strength struts based on the concept of equal strength of beams, which has been designated the strut-enhanced body-centered cubic lattice structure (EBCC). The structure is capable of effectively reducing the stress concentration of the lattice structure at the nodes and increasing the structural energy absorption. The effective elastic properties of EBCC unit cells are investigated in detail under periodic boundary conditions (PBC), and the results show that the deformation response of the unit cell under compressive loading is dominated by bending. A novel sandwich structure, designated S-EBCC, was developed utilizing EBCC as the core material. The effects of geometrical parameters and relative density on the deformation mechanism and mechanical properties of the sandwich structure were analyzed through experiments, numerical simulations and theoretical predictions. The results show that under compressive loading, the stress concentration at the nodes of the EBCC structure is effectively improved and the peak stress is reduced while the energy absorption is increased compared with the traditional S-BCC structure. Under three-point bending load, the larger the strut angle of the S-EBCC structure, the higher the load capacity. Comparison of experimental and theoretical results shows that the failure modes of the S-EBCC structure under both compressive and three-point bending loads are plastic yield.

基于梁的等强度概念,提出了一种具有等强度杆的新型晶格超材料,并将其命名为杆增强体心立方晶格结构(EBCC)。该结构能够有效降低节点点阵结构的应力集中,增加结构的能量吸收。详细研究了周期边界条件下EBCC单元格的有效弹性特性,结果表明,在压缩载荷作用下,单元格的变形响应以弯曲为主。以EBCC为核心材料,开发了一种新型的夹层结构,称为S-EBCC。通过实验、数值模拟和理论预测,分析了几何参数和相对密度对夹层结构变形机理和力学性能的影响。结果表明:与传统的S-BCC结构相比,在压缩荷载作用下,EBCC结构节点应力集中得到有效改善,峰值应力降低,能量吸收增加;在三点弯曲荷载作用下,S-EBCC结构的杆角越大,承载能力越高。实验结果与理论结果的比较表明,S-EBCC结构在压缩和三点弯曲荷载作用下的破坏模式均为塑性屈服。


Energy dissipation and power flow analysis based on acoustic black hole laminated beams

Weijie Yu, Yuhao Zhao, Mingfei Chen, Guoyong Jin

doi:10.1016/j.tws.2024.112503

基于声黑洞层合梁的能量耗散与潮流分析

To enhance the understanding of the dynamic performance of composite beams, assessing their energy accumulation and dissipation capabilities is crucial. The purpose of this paper is to establish a dynamic analysis model of acoustic black hole (ABH) laminated beams based on the Timoshenko beam theory and isogeometric method and to analyze structural intensity and power flow. The vibration governing equation for the ABH laminated beam is derived by calculating its potential and kinetic energy. The convergence of the results is confirmed through multiple mesh refinements, while the model's accuracy and applicability are substantiated through comparisons with the literature, traditional finite element simulations, and experimental data. This investigation into the power flow and structural intensity under varying parameter conditions elucidates the energy transfer mechanisms within ABH laminated beams, offering valuable insights for the deployment of ABH technologies in practical engineering applications.

为了提高对组合梁动力性能的认识,对其能量积累和耗散能力进行评估是至关重要的。本文的目的是基于Timoshenko光束理论和等几何方法建立声黑洞(ABH)层合梁的动力学分析模型,并对其结构强度和功率流进行分析。通过计算ABH层合梁的势能和动能,推导出ABH层合梁的振动控制方程。通过多次网格细化验证了结果的收敛性,并通过与文献、传统有限元仿真和实验数据的对比验证了模型的准确性和适用性。本研究对不同参数条件下的功率流和结构强度进行了研究,阐明了ABH层合梁内部的能量传递机制,为ABH技术在实际工程应用中的部署提供了有价值的见解。


In-plane crashworthiness study of bio-inspired metallic lattice structure based on deep-sea glass sponge

Hongbo Zhang, Dayong Hu, Haojie Peng, Wentao Yuan, Zhen Zhang, Zhenyu Yang, Zhixian Zhang

doi:10.1016/j.tws.2024.112505

深海玻璃海绵仿生金属晶格结构的机内耐撞性研究

Inspired by the double-diagonal reinforced configuration of deep-sea glass sponges, a metallic bio-inspired lattice structure (BLS) was fabricated using additive manufacturing (AM) techniques. In-plane quasi-static compression tests demonstrated the energy absorption (EA) of BLS was improved by about 60% compared to conventional lattice designs. Subsequent experimental and numerical investigations examined the effects of wall thickness, elucidating the corresponding variations in crashworthiness indicators. The study revealed that when the wall thickness increased from 0.40 mm to 0.60 mm, the EA and mean crushing force (Pm) exhibited a substantial increment of 58.1% and 91.1%, respectively. The finite element (FE) simulations underwent experimental validation, exhibiting satisfactory agreement. Parametric studies using the validated FE model explored the effects of geometric factors, such as diagonal distance, unit size, unit number and graded thickness on the crushing performance of BLS. Results indicated that enhancing the EA performance of BLS was achievable by concurrently reducing the unit size and increasing the unit number. The maximum EA achieved was 3535.5 J, representing a 62.9% improvement compared to the initial configuration, which exhibited an EA of 2170.7 J. Additionally, the introduction of graded thickness facilitated a controllable collapse pattern, thereby improving the crashworthiness performance. Lastly, the in-plane dynamic crushing simulations were conducted, identifying three distinct collapse patterns, where the U-Mode exhibiting a negative Poisson's ratio (NPR) behavior. A deformation mode map and rigid-perfectly plastic-lock (R-PP-L) model were developed to evaluate the dynamic response of BLS under varying relative density (RD) and impact velocity (V). These findings provided valuable insights for designing sponge-inspired structures with enhanced crashworthiness performance.

受深海玻璃海绵双对角线增强结构的启发,采用增材制造(AM)技术制造了金属仿生晶格结构(BLS)。平面内准静态压缩试验表明,与传统的点阵设计相比,BLS的能量吸收提高了约60%。随后的实验和数值研究检查了壁厚的影响,阐明了相应的耐撞性指标的变化。研究表明,当壁厚从0.40 mm增加到0.60 mm时,EA和平均破碎力(Pm)分别大幅增长58.1%和91.1%。有限元模拟结果与实验结果吻合较好。利用验证的有限元模型进行参数化研究,探讨了对角线距离、单元尺寸、单元数量和分级厚度等几何因素对BLS破碎性能的影响。结果表明,通过同时减小单元尺寸和增加单元数量,可以提高BLS的EA性能。最大EA为3535.5 J,与初始配置的2170.7 J相比,提高了62.9%。此外,渐变厚度的引入促进了可控的坍塌模式,从而提高了耐撞性能。最后,进行了面内动态破碎模拟,确定了三种不同的破坏模式,其中u型表现为负泊松比(NPR)行为。研究人员建立了变形模式图和刚性-完美塑性锁(R-PP-L)模型,以评估BLS在不同相对密度(RD)和冲击速度(V)下的动态响应。这些发现为设计具有增强耐撞性能的海绵结构提供了有价值的见解。


Energy absorption structure with negative stepped plateau force characteristics under quasi-static loads

Xin Wang, Liuxiao Zou, Chaocan Cai, Ruojun Wang, Xin Huang, Huiran Zou, Minglong Yang, Zengyan Jiang, Weilong Yin

doi:10.1016/j.tws.2024.112506

准静态载荷下具有负阶梯平台力特性的吸能结构

The force-displacement curve is the key to determine the energy absorption performance. Customizing the force-displacement curve enables the design of more advanced and efficient energy absorption systems. In this paper, we introduce a negative stepped plateau force structure (NSPFS) design by combining crooked plate units with curved and straight combined cross-section (CSCC) units. First, the NSPFS is fabricated by using additive manufacturing technology, and a compression experiment is conducted to validate the design methodology. Then, a finite element model is developed and compared with the experimental results to verify its effectiveness. The peak force (PF) and mean crushing force (MCF) of the crooked plate unit are primarily controlled by wall thickness t1 and initial angle θ1. When θ1=1.146° and t1=1.0mm of crooked plate unit, the lowest point of the plateau phase decreases by 84% compared to the PF, and the ratio of PF to MCF is 4.9. When the PF of the crooked plate unit is greater than the PF of the CSCC unit, the structure has the characteristics of negative stepped plateau force. More phase plateau forces can be obtained when multiple NSPFS are compressed in series. When multiple NSPFS units are compressed in parallel, multi-phase continuous negative stepped plateau force can be achieved. Therefore, NSPFS allows for the customization of complex force-displacement curves through series and parallel design.

力-位移曲线是确定吸能性能的关键。定制力-位移曲线可以设计出更先进、更高效的能量吸收系统。本文介绍了弯曲板单元与弯曲直截面组合单元相结合的负阶梯式平台受力结构设计。首先,采用增材制造技术制备了NSPFS,并进行了压缩实验来验证设计方法。建立了有限元模型,并与实验结果进行了对比,验证了该方法的有效性。弯板机组的峰值力(PF)和平均破碎力(MCF)主要受壁厚t1的控制初始角θ1。当θ1=1.146°和t1=1.0mm弯板单元时,平台相最低点较PF降低84%,PF与MCF之比为4.9。当弯板单元的PF大于CSCC单元的PF时,结构具有负阶梯平台力的特征。对多个NSPFS进行串联压缩可以得到更多的相平台力。当多个NSPFS单元并联压缩时,可以实现多相连续负阶梯平台力。因此,NSPFS允许通过串联和并联设计定制复杂的力-位移曲线。


Characterization of the stress-state dependent ductile fracture behavior for Q960 ultra-high-strength structural steel

Mingxu Shang, Hua Yang, Sebastian Münstermann

doi:10.1016/j.tws.2024.112508

Q960超高强度结构钢应力状态相关韧性断裂行为表征

Ultra-high-strength structural steels are gaining popularity in civil engineering due to their exceptional strength-to-weight ratio. However, their inherent lower ductility compared to normal strength structural steel warrants particular attention and further investigation for safety assessment. In this study, a total of 24 specimens made of Q960 ultra-high-strength steel (UHSS), including 21 tensile specimens with various stress states and 3 three-point bending specimens, were tested to assess its mechanical behavior undergoing large deformation. Subsequently, the impact of stress state on plasticity, damage evolution and fracture initiation was analyzed and characterized. The Bai-Wierzbicki yield surface with a deviatoric associated flow rule was identified to characterize the complex plasticity behavior of Q960 UHSS. With respect to damage evolution, the stress-state dependent fracture energy Gf was proposed in this study to describe the damage softening behavior. The uncoupled Hosford-Coulomb locus with a non-linear weight function was utilized to predict the fracture initiation behavior. Finally, the utilized stress-state dependent constitutive models for Q960 UHSS, with the calibrated parameters and user-defined material subroutine VUMAT, were successfully verified through the three-point bending test with good agreement. Moreover, based on a parametric analysis of radius-to-thickness ratio, the bendability design regarding the minimum radius-to-thickness ratio of Q960 UHSS was proposed.

由于其卓越的强重比,超高强度结构钢在土木工程领域日益受到青睐。然而,与普通强度结构钢相比,其固有的塑性较低,这一特性在安全评估中值得特别关注和深入研究。在本研究中,总共对 24 个由 Q960 超高强度钢(UHSS)制成的试样进行了测试,其中包括 21 个处于不同应力状态的拉伸试样和 3 个三点弯曲试样,以评估其在大变形情况下的力学行为。随后,分析并表征了应力状态对塑性、损伤演化和断裂起始的影响。采用具有偏应力相关流动法则的 Bai-Wierzbicki 屈服面来刻画 Q960 UHSS 的复杂塑性行为。对于损伤演化,本研究提出了与应力状态相关的断裂能 Gf ,以描述损伤软化行为。利用具有非线性权重函数的非耦合 Hosford-Coulomb 轨迹来预测断裂起始行为。最后,通过三点弯曲试验成功验证了所采用的 Q960 UHSS 应力状态相关的本构模型,校准后的参数和用户自定义材料子程序 VUMAT 与试验结果吻合良好。此外,基于对半径厚度比的参数分析,提出了 Q960 UHSS 关于最小半径厚度比的弯曲性设计方案。



来源:复合材料力学仿真Composites FEM
ACTMechanicalMaxwellAdditiveSystem振动疲劳断裂复合材料非线性增材裂纹理论材料仿生控制
著作权归作者所有,欢迎分享,未经许可,不得转载
首次发布时间:2024-11-27
最近编辑:2小时前
Tansu
签名征集中
获赞 4粉丝 0文章 776课程 0
点赞
收藏
作者推荐

【新文速递】2024年11月1日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇International Journal of Solids and StructuresMicrovoiding and constitutive damage modeling with artificial neural networksNing Li, Huck Beng Chewdoi:10.1016/j.ijsolstr.2024.113125基于人工神经网络的微空洞和本构损伤建模Continuum models of porous media have revolutionized computational fracture mechanics for traditional ductile materials, but the inherent assumptions have limited generalizability to other target materials or loading conditions. Here, we adopt a series of artificial neural networks (ANNs) to predict both the microscopic voiding characteristics (void shape, porosity) and macroscopic stress–strain constitutive response of porous elasto-plastic materials under various deformation states. We train the ANNs on a dataset generated from finite element models of 3D representative volume elements (RVEs), each containing a discrete spherical void, subjected to combinations of loading states. Results show that the data-driven model is capable of interpolative predictions as well as some levels of extrapolative predictions across a wide range of initial porosities (0–20%) and loading states outside of the training dataset, even at high deformation strains which induce extensive material softening and void growth. Through transfer learning, we further demonstrate that the ANNs, originally trained on a specific porous material dataset, can be readily adapted to other porous materials with substantially different properties through a significantly reduced training dataset. We discuss the implications of this machine learning approach vis-à-vis the extensively-developed Gurson model for porous material damage and failure predictions.多孔介质的连续介质模型已经彻底改变了传统韧性材料的计算断裂力学,但其固有的假设在其他目标材料或加载条件下的推广能力有限。本文采用一系列人工神经网络(ann)来预测多孔弹塑性材料在不同变形状态下的微观孔隙特征(孔隙形状、孔隙率)和宏观应力-应变本构响应。我们在三维代表性体积单元(RVEs)的有限元模型生成的数据集上训练人工神经网络,每个RVEs包含一个离散的球形空隙,受到加载状态的组合。结果表明,数据驱动的模型能够在大范围的初始孔隙率(0-20%)和训练数据集之外的加载状态下进行内插预测和一定程度的外推预测,即使在高变形应变下也能引起广泛的材料软化和空隙增长。通过迁移学习,我们进一步证明,最初在特定多孔材料数据集上训练的人工神经网络,可以通过显着简化的训练数据集,很容易地适应具有不同性质的其他多孔材料。我们讨论了这种机器学习方法对-à-vis的影响,广泛开发的Gurson模型用于多孔材料的损伤和失效预测。International Journal of PlasticityUnderstanding Stacking Fault Tetrahedron Formation in FCC Stainless Steel: A Fusion of Transmission Electron Microscopy, Molecular Dynamics, and Machine LearningPan-Dong Lin, Jun-Feng Nie, Wen-Dong Cui, Lei He, Shu-Gang Cui, Guo-Chao Gu, Gui-Yong Xiao, Yu-Peng Ludoi:10.1016/j.ijplas.2024.104157 理解FCC不锈钢层错四面体的形成:透射电子显微镜、分子动力学和机器学习的融合The stacking fault tetrahedron (SFT) formation displays a pronounced size effect, progressing from vacancy equilateral triangular plate to perfect SFT, and eventually to truncated SFT, as demonstrated in numerous irradiated face-centered cubic metals. However, the presence of distinct SFT structures in F321 stainless steel has not been reported. This study explored the SFT formation mechanism in irradiated F321 stainless steel using transmission electron microscopy (TEM), molecular dynamics (MD) simulations, and machine learning. SFTs, Frank loops, and Lomer-Cottrell locks were found to be widely generated in the irradiated F321 steel. The critical size for truncated and perfect SFTs was determined using MD simulations; the results were consistent with the theoretical predictions. Additionally, the twin boundaries observed through TEM, which were attributed to the elevated tensile stress near the boundaries, facilitated the formation of perfect SFTs. Moreover, interstitial Frank loops also facilitated the formation of perfect SFTs. This study also explored the influence of variations in Ni and Cr concentrations on the critical size n1 for the transition from vacancy plates to perfect SFTs and n2 for the transition from perfect SFTs to truncated SFTs, using a combination of MD and machine learning methods. As the Ni concentration increased and the Cr concentration decreased, n1 and n2 increased; conversely, the critical sizes decreased when the Ni concentration decreased and the Cr concentration increased. These insights reveal the systematic mechanism of SFT formation under varied conditions, offering new perspectives for understanding the nano-defects in F321 stainless steel.堆垛层错四面体(SFT)的形成具有明显的尺寸效应,从空位等边三角形板到完美的SFT,再到截断的SFT,这一现象在众多辐照的面心立方金属中都有体现。然而,在F321不锈钢中尚未发现明显的SFT结构。本研究利用透射电子显微镜(TEM)、分子动力学(MD)模拟和机器学习探究了辐照F321不锈钢的SFT形成机制。研究发现,SFTs、弗兰克环和洛默-科特尔锁在辐照F321钢中广泛存在。通过MD模拟确定了截断和完美SFT的临界尺寸,结果与理论预测一致。此外,通过TEM观察到的孪生边界被归因于边界附近的高拉伸应力,促进了完美SFT的形成。此外,间隙弗兰克环也促进了完美SFT的形成。本研究还采用结合分子动力学和机器学习的方法,探索了Ni和Cr浓度变化对从位错滑移带过渡到完美滑移面以及从完美滑移面过渡到截断滑移面的临界尺寸n1和n2的影响。随着Ni浓度的增加和Cr浓度的降低,n1和n2增大;相反,当Ni浓度降低和Cr浓度增加时,临界尺寸减小。这些发现揭示了在不同条件下滑移面形成过程中的系统性机制,为理解F321不锈钢中的纳米缺陷提供了新的视角。Thin-Walled StructuresNumerical study on the effects of alloying variations on the crushing behaviour of an aluminium profileMarcos Fernandez, Miguel Costas, Odd Sture Hopperstad, David Morindoi:10.1016/j.tws.2024.112618合金含量变化对铝型材破碎性能影响的数值研究The effects of variations in the chemical composition of an aluminium alloy AA6005 on the axial crushing and bending behaviour of a double chamber extruded profile are investigated by shell-based finite element analyses. A novel sequential modelling method, including nanostructure modelling, virtual tensile testing and localisation analyses, is used to determine the yield strength, work-hardening, and ductility of several variants of the AA6005 alloy. The data obtained from the models are used to calibrate the parameters of an isotropic elastic–plastic constitutive model and an uncoupled damage criterion. Explicit finite element analyses of axial crushing and three-point bending of the double chamber extruded profile are conducted for all variants of the AA6005 alloy in temper T6. By comparing the results of the finite element analyses with existing experimental data, the results reveal how variations in the chemical composition significantly influence the structural integrity of the extruded aluminium profile in axial crushing and bending.采用基于壳体的有限元分析方法,研究了AA6005铝合金化学成分变化对双腔挤压型材轴向破碎和弯曲性能的影响。采用一种新的序列建模方法,包括纳米结构建模、虚拟拉伸测试和局部化分析,来确定几种变体AA6005合金的屈服强度、加工硬化和延展性。利用这些模型得到的数据对各向同性弹塑性本构模型和非耦合损伤准则的参数进行了标定。对T6回火下AA6005合金各变型双腔挤压型材的轴向破碎和三点弯曲进行了显式有限元分析。通过将有限元分析结果与现有的实验数据进行比较,结果揭示了化学成分的变化如何显著影响挤压铝型材在轴向破碎和弯曲过程中的结构完整性。Isogeometric Flutter Analysis of a Heated Laminated Plate with and without CutoutWenliang Yu, Rongshen Guo, Yuhao Zhao, Mingfei Chendoi:10.1016/j.tws.2024.112652带和不带切口的加热层合板的等几何颤振分析Understanding the flutter characteristics of heated laminated plates, both with and without cutout, is crucial. This study presents the first exploration of flutter analysis in a thermal environment for a laminated plate featuring a cutout. To facilitate this study, the motion equations of the heated laminated plate with a cutout are derived using the first-order shear deformation theory (FSDT), incorporating a nonlinear term. Employing the isogeometric method combined with multi-path coupling technology, we establish accurate geometric and solution domains for the laminated plate. The effects of the thermal stresses and the aerodynamics calculated by the linear piston theory are considered. The accuracy and effectiveness of the proposed model are validated through several comparisons with ANSYS results and existing solutions. Additionally, the study examines the impact of key parameters on flutter characteristics, including thermal conditions, number of layers, lay-up angles, inflow angles, and cutout dimensions. The insights gained from this research will serve as a valuable benchmark for future analyses and design concerning flutter characteristics.了解加热层合板的颤振特性是至关重要的,无论是否有切口。这项研究提出了在热环境下的颤振分析的第一个探索夹层板具有一个切口。为了便于研究,利用一阶剪切变形理论(FSDT)推导了带切口的加热层合板的运动方程,其中包含一个非线性项。采用等几何方法结合多径耦合技术,建立了层合板的精确几何域和解域。考虑了用线性活塞理论计算的热应力和空气动力学的影响。通过与ANSYS计算结果和已有解的对比,验证了所提模型的准确性和有效性。此外,研究还考察了关键参数对颤振特性的影响,包括热条件、层数、铺层角、流入角和切口尺寸。从这项研究中获得的见解将为未来有关颤振特性的分析和设计提供有价值的基准。来源:复合材料力学仿真Composites FEM

未登录
还没有评论
课程
培训
服务
行家
VIP会员 学习 福利任务 兑换礼品
下载APP
联系我们
帮助与反馈